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Wizard of Oz
(wizardofoz)

Locale: New England
Project: 4oz 1A USB Charger on 09/18/2012 13:11:20 MDT Print View

So I'm planning a Grand Canyon Corridor R2R2R for early November, and in an effort to save weight, my Iphone 4S is my GPS, music player, camera, camcorder, etc. It's a 6 day trip, so even in airplane mode the whole time, I'm pretty sure it won't make it all the way through. I plan on enjoying music in the evenings and morning, and doing lots of videos and photos. A few years ago I made a 3.2oz USB charger that worked with my old HTC droid and iPod, but it doesn't generate enough juice for my iPhone.

My new design will use a waterproof flexible panel by Powerfilm. Power Film 12V 5W Solar Panel

I'm modify the F15-300($60)to eliminate the heaviest parts which is the connector that is hanging on it and the velcro closure. I believe that the panels themselves on the nylon fold-up backing will be 3 oz. and that gives me 1 oz to work with to interface to my USB.

Since I used 6V panels before, I used a linear regulator design on my previous solar panel. But this one will be a 12V panel design, a linear regulator would be very inefficient and I want to harness as much of the 5W power generator as possible. I'm going to use a buck regulator switching design based around a National LM2675-5.0 Eval Board to the heavy lifting.LM2675-5.0EVAL

This should be about 90% efficient which is about as good as I can get and it has great regulation so I don't hurt my iPhone. There's an updated design called the LM22675 with wider input specs, but I couldn't get an eval design and I'm short on time. So I'll be adding the circuitry required to charge the iPhone in both the 500mA (car charger mode) and the 1A (wall charger mode) to hopefully be able to adapt to overcast sun conditions. It should charge it from dead to 90% in 60-120 minutes. I'll also design in an auto shutoff if the sun goes behind a cloud of I leave it out and LED that indicates whether it's outputing the 5V. I found on my old design that if I left a device plugged in when the sun wasn't strong enough, the panel would actually discharge my phone/iPod.

IPhone USB Connections

So I know there are other options such as a spare battery or emergency power plug in, but I thought this would be fun and useful. And I'm a geek so I enjoy this stuff. Plus it's fun to try to make the 4oz goal!

I've got alot out of this site, so I thought it would be fun to post progress here, and get input along the way. Your thoughts and ideas would be much appreciated! I'll keep you posted...literally.

Eric Lundquist
(cobberman) - F - M

Locale: Northern Colorado
Re: Project: 4oz 1A USB Charger on 09/18/2012 13:19:13 MDT Print View

Is this a Rim to Rim to Rim or Rim to River to Rim trip?

If you're staying at Phantom Ranch you could buy batteries there and use them in a AA iPhone charger.

GPS is unlikely to be needed as the corridor trails are very well marked.

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Re: Project: 4oz 1A USB Charger on 09/18/2012 13:33:47 MDT Print View

It's a Rim to Rim to Rim in November...BRRRR....

GC Snow

We'll be eating at Phantom Ranch on both ways through but alas I couldn't get a night in the dorms there. Plus I'm planning on spending my money on beer and snickers instead of batteries there :)

LOL, GPS isn't for finding my way on the corridor. I like to mark my picture spots with GPS sometimes, so I know exactly where they were taken.

I looked at some AA Iphone charger, and that's def a great option. I love the flexibility of using this for 12V devices as well though. Do you know of a particular good brand/model of AA Phone Charger? Thanks!

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
Do Keep Me Posted on 09/18/2012 13:34:25 MDT Print View

Dear Wiz,

Keep the technical details coming, and I'm waiting to see how the final design works out.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Project: 4oz 1A USB Charger on 09/18/2012 13:46:03 MDT Print View

It might be helpful to you to get a schematic on a full blown solar charge controller. That is what is used on a big solar panel, and it takes care of all sorts of things like blocking the reverse current during a cloud. If you could scale that down to small charging like you need, it might be helpful.

All I have are the big solar charge controllers, so I can't help much. They really make life easier in a big rig.

In a lot of rigs, there is a rechargeable battery between the solar panel and the load. That adds weight, but it also regulates the charge properties. It might be worth looking into.

--B.G.--

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Project: 4oz 1A USB Charger on 09/18/2012 13:56:13 MDT Print View

What if you connected panel directly to iphone? Would it blow it up?

If you did linear regulator you'de be 83% efficient, which is pretty close to your 90%. Maybe a 1 ohm resistor would be good enough. What if you put in less than 5 volts?

Spare batteries would probably weigh less, but less fun : )

Franco Darioli
(Franco) - M

Locale: Melbourne
Project: 4oz 1A USB Charger on 09/18/2012 16:52:51 MDT Print View

When I was fiddling with the power Pot and the Bio Lite stove I came across this battery :
12000mAh batt
2000mAh , output 1000mA/2100mA for $26 .
Oddly the manufacturer of that battery ,totally unrelated to my search, sent me a price list of that and several others.
I can tell you that the 1000 price is not all that much better than the one from this eBay seller


http://www.ebay.com.au/itm/12000mAh-Dual-USB-output-Charger-External-Battery-Power-Bank-Pack-/180951601619?pt=AU_MobilePhoneAccessories&hash=item2a218e51d3
No experience with the seller nor the battery or the manufacturer but it may be worth having a look.
I think that it is about 350g, 12oz.
If the link does not work is listed under
12000mAh Dual USB output charger external battery power bank pack
To add.
I did order that.
I have only tested that by charging my AA and running LED lights, it works for that.
225g for the battery , about 150g with USB cable and adaptors.

Edited by Franco on 11/05/2012 22:08:11 MST.

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
Beer and Snickers on 09/18/2012 17:29:18 MDT Print View

Wizard writes, "Plus I'm planning on spending my money on beer and snickers instead of batteries there."

I see you think like me. Very good!

Franco -- that 12 A/h 12 oz battery pack looks like a beast, and at a very reasonable price. Someone, other than me, will need to try it to make sure it's properly-regulated and won't $moke an iPhone.

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Re: Re: Project: 4oz 1A USB Charger on 09/18/2012 18:00:29 MDT Print View

WOZ*: I've long wondered about the approach Jerry mentioned: Directly connect the solar cells to the iPhone. If they max below one amp, won't they be fine (until the iPhone battery is full)? If so, then you just need to disconnect them before the iPhone is fully recharged. Since the iPhone pretty accurately reports its state of charge, you can disconnect at 85-90% and skip all the weight and complications of the circuitry.

An early generation iPhone could serve as a test bed for anything you cobble together.

If you want music, bring a Nano. An iPhone is going to use a lot more power to play music than a Nano (that does nothing but music). Yes, base weight is up, slightly, but there's much less time spent babysitting the batteries in the iPhone.

*I once sold him an Apple II, of all things.

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
12+ volts on an iPhone on 09/18/2012 19:22:19 MDT Print View

David, can the iPhone survive 12 or more volts -- which is what a solar panel can put out -- on its 5V input line?

Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: 12+ volts on an iPhone on 09/18/2012 19:55:44 MDT Print View

Most small 12 volt solar panels actually put out 13v-15v. They have to to overcome the resistance of battery being charged. A regulated 5v charger is probably able to put out close to 7v. Too many volts (and amps) will cook a battery. I have a 250w 12 volt system on my tent trailer and open circuit voltage is over 17 volts.

I played around with a Goal Zero Nomad 7 this summer while camping in our trailer. In perfect sun during optimum sunlight and orientation it took 2.5 hours to bring an iPhone 4 from 0% to 100% at 6,000 feet in the Southern Sirras. If I were inclined to bring electronics backpacking I would opt for spare batteries, which doesn't work for an iPhone and the batterie packs to recharge the phone are too heavy for what they do.

We camp for weeks on end self contained in our trailer without any energy conservation tactics. I am a solar fan. But for backpacking I wouldn't consider it. Of course I never really have a need for battery operated devices, except for an occasional trip where I carry a camera.

Wizard of Oz
(wizardofoz)

Locale: New England
Re: 12+ volts on an iPhone on 09/18/2012 20:14:53 MDT Print View

Franco, That looks really awesome! I'll look into that for sure. Thanks! But definitely not as much fun.

David, no you can't connect a solar panel or 12V directly to the iphone. It will not charge it and will likely ruin it.

So I wanted to try to test my weight goal tonight, so here's what happened...

First I tested to make sure each panel to makes sure they worked, because I'm PRETTY SURE what I did later voids the warranty...

I weighed the 'manufacturers suggested setup' using a mini Cigarette to USB converter which has a 500mA output. (The final version will be a 1A output)
original setuporiginal setup weightoriginal panel weight

I took the plug apart and found a circuit board inside. The small board included a diode on the +V line to eliminate discharge of the device when there's not enough sun and a automatically resetting fuse rated at about 1.33A at room temperature (no clue what the is actually for).
plug disassembled
PCB

After I removed the heavy plug, , circuit board, excess fabric, metal eyes, and velcro, I reweighed the panel.
panel modded
modded weight


So with a modded panel, stripped down voltage regulator, and mini iPhone cord, I'm at 3.8oz. So it'll take me a while to get the parts and make the final circuit board and waterproof everything, but it seems possible!!! And it's a serious upgrade from my previous .6W version! Over 8 times the power and only .6 oz heavier, that's a good day in the sun! If it works :)
theoretical weightold vs new

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Re: 12+ volts on an iPhone on 09/18/2012 20:30:29 MDT Print View

I'll look into more commercial solar charger circuitry designs to see if I can glean any more ideas, that a great thought!

Yea, this panel will also output about 17V when unloaded, which is very common for 12V solar panels. Solar Panels need regulation to do just about anything.

A linear regulator basically dissipates the 'excess' voltage into heat, which is why you usually see those little three prong black ICs with metal tabs on the back.linear regulator That is what I used for my old panel with 6V panels. It's basically a Zener Diode. So the 1V overage at 100MA was dissipating 100mW into heat. I could deal with that. Although that means that it was only .5/.6 efficient or 83%. However using an appropriate linear regulator on a 12V 5W system would dissipate the 7 V overage or 2.9W, which gives me a 2.1/5 efficiency or 42%. pretty crappy, plus Linear regulators don't up the current on the lower voltage, so I'd only get the 400mA to my 5V device, or 2.1W. Using a Boost Regulator is MUCH more efficient, and hopefully will give me 4.5W to my USB port,or .9A. The Boost Regulator basically stores the charge in an inductor and is able to send it back out in little packets as it switches, so there's much less loss and less heat buildup.

Please keep the ideas and thoughts coming! I'm hoping to get the parts in this weekend and be able to do some tests and weights!

Wizard of Oz
(wizardofoz)

Locale: New England
Solar Panel Theory on 09/18/2012 20:51:00 MDT Print View

One more note while I'm thinking of it. The voltage out of a solar panel (before the regulator) will decrease as more current is pulled (lower resistance load).Solar Panel IV Plot
So this example is a 7.2V 100mA spec'd panel. So as you over draw current (i.e. larger load or lower resistance), the voltage will go down a bit.

So there are two nice thing about the design I'm hoping to use and the iPhone charging feature. First, the Switching (Boost) Regulator only needs 8V to run, so I might be able to squeak a bit more current out of the Solar Panels than they are spec'd to since I can pull them right down to 8V and still have a solid output for the USB port. BUT that assumes solid full sunlight! That's why I'm going to try to include a switch so I can change the iPhone charging mode from 'wall' to 'car'. Basically, if I don't have enough sun to keep the 5V going in 'wall' mode (the phone pulls 1A or has a 5ohm charging resistance) which may cause too far of a drop of the panel output voltage in lower light conditions, I'll disconnect it, switch my solar charger to 'car' mode, and reconnect it which will change the PHONE to 10ohm charge resistance or .5A draw allowing my solar panel voltage output to rise hopefully high enough to continue to charge even in poor conditions.

As I mentioned before, I also plan to include a small 3mA LED to let me know when the 5V is being output properly (iPhone is charging), and I will include a circuit that will turn off the regulator output if the panel voltage drops below 8V. I think this combination of features will make it really usable in the field and allay some of the normal concerns and hassles with solar chargers. But, as has been mentioned, I will still have to babysit a bit,hopefully for only an hour or so a day if I'm blessed with clear skies, and hopefully while taking in SPECTACULAR inner canyon views, and a crazy expensive Phantom Ranch Beer! So I won't complain too much for the privilege of tunes, pics and videos to my hearts content! If it works...

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Solar Panel Theory on 09/18/2012 21:06:43 MDT Print View

A couple of comments. One is the 3mA LED. That is small, but it will be burning all of the time even when you know that charging is happening. Instead, drop some teeny tiny switch in series with it. That way, you can push the switch button and see what you have, but then you release it and there is no 3mA drain.

If you are getting about 17V open circuit in a big solar panel, that is pretty good. As a general rule, only the fairly good solar panels will get you 17V, and many of the cheaper and lighter panels get you only 15 or 16V open circuit. I guess this thing you are doing now is aimed more for 7.2V.

Everything that I have done is with a big panel, so I think only in terms of nominal 12V, so I don't want to steer you wrong about this smaller scale rig.

I was trekking in Nepal, and I was eating dinner in a Sherpa lodge that was candlelit. The proprietor went into the back room and then carried out a 12V car battery. He sat it down on the table and set up a battery operated slide projector. After showing slides of himself on Mount Everest in 1972, he explained the problem to me. He had a good solar panel on the roof, but his charge controller had failed, so he was trying to do things the hard way. I studied it and agreed that it was a charge controller problem. So, when I got home, I ordered up a perfect-size charge controller, received that, and then sent it to San Francisco to his employer. They sent it over to Nepal in a satchel, he hooked it up by my diagram, and it worked. So, now they show more slide shows, solar powered.

--B.G.--

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
Thanks for update on 09/18/2012 21:09:26 MDT Print View

Thanks for the update, Wizard. Sounds like you're on the right path here.

Next step: make a version to sell.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Re: Solar Panel Theory on 09/18/2012 21:13:57 MDT Print View

I just connect 12 V solar panel directly to car battery - a controller just adds inefficiency.

Like in Wizard's chart, the voltage drops by itself to reasonable voltage for battery.

You have to disconnect it at night.

This may or may not be applicable to Wizard's problem - but I wouldn't try it on my ipod - if I had one

It would be better if it was a 6 Volt panel

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
3mA is Tinkertoys on 09/18/2012 21:14:53 MDT Print View

Bob, I think the added complexity and possible decreased reliability by adding a switch isn't worth it. 3mA compared even with "car" (0.5A) mode is only stealing, like, 0.6% of the regulator's output.

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
USB spec on 09/18/2012 21:32:31 MDT Print View

BTW, the iPhone is a USB-powered device, and the spec for USB power is 5.00 ±0.25 V

So it's likely not designed to be connected to a 6 or greater voltage source. Unlike a big ol' lead acid battery, which can soak up a lot of current, overvoltaging the iPhone's DC input circuitry is likely to end up badly.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: 3mA is Tinkertoys on 09/18/2012 21:32:35 MDT Print View

"Every little bit helps" said the woman who p!ssed into the sea.

--B.G.--

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Re: Solar Panel Theory on 09/18/2012 21:39:09 MDT Print View

"a controller just adds inefficiency."
"You have to disconnect it at night."

How do you monitor for overvoltage disconnect and undervoltage disconnect? How do you do equalization? You don't need some of these features if you have no battery in the middle.

Charge controllers are very handy.

My point was to study which of the features might be handy for little or no penalty, and roll them in.

--B.G.--

Edited by --B.G.-- on 09/19/2012 02:11:31 MDT.

Stuart R
(Scunnered) - F

Locale: Scotland
Re: Solar Panel Theory on 09/19/2012 01:59:51 MDT Print View

WOZ: That graph is the key to understanding pv solar panels. Note that as the load attempts to draw more current, the voltage goes down. 7.2V is the point of maximum efficiency for conversion of light to electricity. So, if you hook a 7.2V panel directly to a 6V battery, the panel will simply supply as much current as it can at 6V, (the voltage on a charging battery does not change much). You need a reverse blocking diode, but otherwise this is a very electrically efficient system. A linear regulator can also be used to prevent overcharging/overvoltage but adds nothing to the overall efficiency.

Now, an active regulator is a different beast - it will draw as much power as it needs to supply its load. So, if you want to supply a load of say 5V @ 1A, the regulator will draw 5/0.9 = ~5.5W from the panel. IF you have sufficient area of panel with sufficient sunlight intensity to supply this power, then ok. But in less optimal conditions, as you attempt to draw more current from the panel, the voltage goes down = LESS power. The regulator will drop out, but then the panel voltage will come back and you get in a cycle of oscillations. A (normal) active regulator will not work unless you have oversized panels that can always supply sufficient power.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Solar Panel Theory on 09/19/2012 02:21:14 MDT Print View

"That graph is the key to understanding pv solar panels."

As Stuart points out, the graph is the key.

Most single crystal silicon panels have similar curves, although some are slightly shifted. So, you really need to work with the curve for your specific panel product, and you don't want to just blindly assume a curve that somebody else has for a different one.

Personally, I am a big believer in reverse blocking diodes, typically with very low voltage across it.

Linear regulators were good about twenty years ago, but active regulators are in now.

Once you get the charger thing cooking just right, you can play around with setting it to the sun angle above the horizon, tracking the sun from east to west, and all sorts of things to improve total charging performance. A dinky shadow can really foul it up.

--B.G.--

Wizard of Oz
(wizardofoz)

Locale: New England
Answers on 09/19/2012 06:34:58 MDT Print View

Bob, that's a really good idea that never crossed my mind. I was thinking a single 3mA LED for low drain, but with a 'test' switch, I could put a descent brightness LED on there, or maybe a few SMD indicators to see how much the panel is producing and I no longer have to worry about the loss. That would definitely increase my options without sacrificing any performance (other than a few grams of weight). Plus brighter LEDs could be easier to see in bright light, which by definition is the condition that I'd prefer to use the panel! Thanks! BTW, I am using a 12V spec'd panel, the 7.2V was just an example. It was actually cheaper to buy this Powerfilm 5W unit rather than 5W of 6 or 7 Volt Panels. I'm not sure why that is. All the wiring in the panel unit is inside the stitching so I can't really see how they are wired to guess what spec panels they are and series vs parallel design. BTW, the quality of the build on the Powerfilm is fantastic! High quality wire, Brass rivets (non-corrosive), electrical parts are sealed with silicon and routing and wiring is taped in place to minimize stress. I was very impressed when I took it apart! The little circuit board has two diodes on it and only one is being used, so it must be a generic PCB that they used for their 10W version as well, which is basically 2 of mine in parallel.

Jerry, battery charging is freakishly complex! Luckily the iPhone has alot of built in protection so as long as I stay in the USB 4.75-5.25V spec, I should be ok. You can actually charge batteries at a fairly wide range but it will affect their lifespan and cause excess heat. One of the huge advantages of Lithium Ion batteries, besides their low weight, is the ridiculous # of charge cycles that they can go through. Technically each charge takes a little bit of their capacity away, but poorly designed/spec'd chargers make it much worse. Lead Acid batteries are much more forgiving except that they can heat up and be damaged if overcharged, especially at high (quick) charging voltages. But obviously, the assumption is that if you're charging your car with a solar panel, your battery is dead, and you just want to up the juice, not replace your alternator with a solar panel :)

Jack, think I'm into this one for $100 bucks already :) I'm not sure how well they would sell at that price! But maybe this project will give me some insight into building another one much cheaper. NOW TAKING ORDERS!!! (MUST PAY UP FRONT!!!)

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Answers on 09/19/2012 08:17:56 MDT Print View

Two problems with solar panel into lead acid batteries:

You want to keep the battery fully charged. If you don't have enough panel then the battery will be undercharged and over time it can kill the battery, like if the battery goes below 50% charged or so.

If you over-charge the battery, the water in the electrolyte get's conveted to hydrogen and oxygen. If it goes low enough and exposes the plates inside the battery, that will kill the battery.

If you have solar panels on your house charging batteries, you need good controller to prevent these problems. You won't remember to do it manually reliably enough.

If you're vacationing and hooking up the panel each day, you can remember to check and prevent. And disconnect at night to prevent reverse current. The controller and blocking diodes consume some of the power.

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Re: Solar Panel Theory on 09/19/2012 09:08:20 MDT Print View

Stuart, that's a really good point about the oscillation. I didn't think of that. So I'm not sure how best to reduce that on my boost regulator. e.g. So let's say that it's lower than ideal light and I'm charging my device with my panel, and it's pulling .5A so it's folding back the voltage on the panel. I can put a voltage divider on the enable pin of the regulator, to disable it at any given level, but when the reg shuts off, it'll obviously stop drawing current, and the panel voltage will bounce back up. repeat ad infinitum. I don't think I need the diode since the regulator will shut down. I guess I may simply not care if my phone doesn't complain. The output cap on the regulator may be enough to keep the oscillating output voltage of the reg ever getting high enough to even trigger charge mode, or the iPhone may be smart enough to wait a small amount of time seeing a 'good' charge voltage being charging. Either way, it's def a concern...test needed...come on UPS, I need my parts!

Wizard of Oz
(wizardofoz)

Locale: New England
Minty Boost AA Battery Pack on 09/19/2012 09:14:59 MDT Print View

I saw this alternative that I thought was promising for lightweight 'general use'. ($20, you assemble)

http://www.ladyada.net/make/mintyboost/index.html
minty boost

It uses a buck regulator (step-up) to charge USB devices with 2 AA batteries. A rechargable AA battery can have up to about 2500mAH of charge! But they say this won't quite bring an iPhone up to full power, and will only last two partial charges on two new AA batts.

But then again each AA battery is about 1oz, so I'm guessing this is a 3oz charger, and you only get two partial charges out of it. For another oz. I'll take my infinite number of charges under clear skies :)

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
Think big! on 09/19/2012 09:18:40 MDT Print View

"Jack, think I'm into this one for $100 bucks already :) I'm not sure how well they would sell at that price!"

People will pay Big Bucks to save grams. There might be one or two folk eyeing a summer-long hike and planning to take an iPhone.

"But maybe this project will give me some insight into building another one much cheaper."

You'd need to buy the bits wholesale and in quantity to drop prices. Hie thee to Shenzhen city!

"NOW TAKING ORDERS!!! (MUST PAY UP FRONT!!!)"

That's the spirit.

Keep us posted on development.

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Re: 12+ volts on an iPhone on 09/19/2012 16:55:07 MDT Print View

>David, "can the iPhone survive 12 or more volts -- which is what a solar panel can put out -- on its 5V input line?"

I'm not proposing using an 80-watt, 12-volt panel. But rather, an array of cells that puts out somewhat more than 5 volts (open circuit) at something less than 1 amp at 5 volts. The array will have a performance curve in full sun. The batteries will have a very differently shaped charging curve (almost nothing until near 5 volts, then steep as 5 volts is approached. Where those curves (amps versus volts) intersect is where the combined array and battery will charge. Until the battery nears capacity. THEN, yes, bad things could happen if the phone has no protective circuits and is left connected.

It would be akin to filling a gasoline tank with no auto-shut-off on the hose. How much empty tank? Filling rate? Don't leave it unattended for longer than that. Filling the hot tub, refilling propane cylinders, or drinking beer all take a certainly mindfullness so as not to overdo it. The OP seemed to understand circuits well enough to plot those graphs and select an appropriately small array of cells.

Going with cells only, no circuitry; reduces weight AND increases efficiency. It does place the burden of oversight on the user. You definitely couldn't "set it and forget it".

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Re: 12+ volts on an iPhone on 09/19/2012 18:09:43 MDT Print View

Touché on the beers David. It's easy to know when you've had enough...you run out of beer! Seriously good points!!

Matthew Naylor
(mrnlegato)

Locale: Mid-Atlantic
waterproofing / canvas-backed panels on 09/21/2012 10:59:13 MDT Print View

How were you planning on waterproofing your electronics? Not having any other practical solution in my head, I've built mine into a heavy Otterbox:
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=64564
If you've thought of a lighter solution, I'd love to see it...

Also, I don't know if you considered building it with just the WeatherPro panels without the canvas backing; you might save some money and total weight.... I haven't posted my update to the thread above, but the bare panels held up fine on an overnighter a few weeks ago.

Matthew Naylor
(mrnlegato)

Locale: Mid-Atlantic
charging batteries on 09/21/2012 11:18:08 MDT Print View

As a continuation to the comments about battery chargers, I strongly recommend these:

New Trent iTorch 5200 mAh $33
http://www.amazon.com/New-Trent-IMP52D-Thunderbolt-Blackberry/dp/B0013G8PTS/ref=sr_1_4?ie=UTF8&qid=1348246805&sr=8-4&keywords=smartphone+battery+charger

Anker Astro2 8400 mAh $50
http://www.amazon.com/Upgraded-Version-External-Flashlight-Smartphones/dp/B0067UPRQ4/ref=sr_1_6?ie=UTF8&qid=1348246805&sr=8-6&keywords=smartphone+battery+charger

These are both brands that have been in the business for at least a few years, and seem very high quality to me. Plus they have LED flashlights (the iTorch even has a laser) built-in!

My wife keeps the iTorch, but the Astro2 that I keep on me is 187 g, 6.6 oz... a bit heavy but enough to charge a smartphone several times over... I use it for travel

Wizard of Oz
(wizardofoz)

Locale: New England
Re: waterproofing / canvas-backed panels on 09/24/2012 09:24:08 MDT Print View

Matt,

The Panels actually are the weather proof already, so I'm good there! Which is why I went with the canvas backed type instead of the individual bare panels. This was MUCH cheaper that buying them individually.

So I have a couple of issues with weatherproofing my controller electronics. First, obviously the open USB port can't be waterproofed. It has to be open to the world to accept the USB cable/Ipod cord. Second, there is a small amount generated by the inefficiencies inherent in the design and I don't want to insulate it too much so that is overheats. I'm requiring one amp from this guy, so I will be generating a bit of junction heat! The circuit does have a thermal shutoff, but that kind off defeats the purpose! Especially because I'll be setting this in the hot sun. So I'm looking at two options. The easiest, is plasti-dip spray. It's easy to apply, won't damage anything and can be scraped of easily enough to make changes. Of course that offers no mechanical protection. My other option is a small cover which I'd sew directly to the fabric on back of the 'last' panel. I'd use something akin to half of a square dental floss case. This would provide the mechanical protection and could be combined with the plastidip spray or even some liquidtape brush on if the heat buildup turns out not to be an issue! That being said, it's only a one sided board, so I'd only need to seal one side, which helps considerably for heat.

Wizard of Oz
(wizardofoz)

Locale: New England
Control Electonics Size and CKT Details on 09/24/2012 09:31:19 MDT Print View

So here's a pic of the actual board and a sketch of the modifications I plan to make to it. The LED is switched, and therefore can be a brighter 8mA light. The USB D- contact can also be switched from .5mA to 1A charging mode. Note that this charger will be mainly for Apple Devices since Apple requires the strange data voltages, so I may wire straight into the iPhone cable to further minimize weight and separable parts. I may also put a mini connector on the solar panel wires to the board, so I can swap this out for a 12V or other charge controller on the fly. I intend to use surface mount parts glued to the very small 'spare areas' of the board accessing the traces as needed. And I have no idea where to put the switches, which may have to go on the inside of the cover!

USB Solar Controller Circuit

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Solar Panel Theory on 09/24/2012 17:06:04 MDT Print View

> The voltage out of a solar panel (before the regulator) will decrease as more current is pulled.

Correct. But I don't think many people really understand what happens with a solar panel. All the discussion has been about volts and amps, but that is the wrong way to look at the whole system. Let me explain.

What really matters with a solar panel is the incoming POWER from the sun. The solar panel can only deliver as much power as it gets (allowing for inefficiencies of conversion). What the output voltage is does not really matter, nor is it fixed. The panel voltage will adapt to the situation.

This means that you can stick a solar panel rated at 12 V onto a 7 V battery and it will happily deliver power to the battery at around 7 V and charge it up. Of course, if you try to use a 3 V solar cell you won't get very far. If you try to use a 100 V solar cell, bad things might happen as well.

The next thing to consider is how the rechargable Lithium battery behaves. Most rechargable Lithium batteries have internal circuitry to limit the input voltage. Very often that circuit also limits output current in the event of a short circuit. That is a safety feature they are required to have, to prevent fires. When the battery is fully charged the internal cell voltage rises of course; at some point the little safety circuit inside says 'enough' and shuts off. It won't accept any more charge. At that point the apparent external terminal voltage can rise several volts.

So my solar charging system sticks the output of the 12 V solar cell straight onto the 7.2 V recharable lithium battery, and charges it. When the battery is fully charged the safety circuit switches off and the battery stops taking charge. Ah, but that means the solar cell is no longer delivering power, so its terminal voltage rises up towards 13 V. Yes, the safety circuit in Lithium battery can handle that. The high voltage is then enough to push current through a series combination of white LED (3.6 V) plus 10 V zener diode. So when I see the white LED shining I know the battery is fully charged, and I can take it out.

Yes, this does mean that I recharge the 7.2 V lithium battery OUT of whatever it goes in. It may well be that the phone/whatever cannot take 13 V on the input. That's OK, I don't stress it. I carry two small lithium batteries and recharge one externally while the other one drives the phone/whatever.

Of course, this also works on a PAIR of 3 V rechargables for a UV Steripen. Been recharging them that way for years.

Cheers

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
iPhone? You go first . . . on 09/24/2012 18:09:56 MDT Print View

Of course, here we are talking about charging an iPhone which does not have removable batteries and we don't know how much voltage it can take at its USB input charge line without breaking. The designers don't have much reason to design for voltages higher than the USB standard of 5.25V. Alas, Apple doesn't give out any useful specs for things like maximum input voltage.

Mike H
(mikehaf)
Re: Control Electonics Size and CKT Details on 09/24/2012 19:24:05 MDT Print View

Wow, that's a pretty clean looking board, you have some serious skills. I don't envy one who needs to glue surface mount components to the spare areas and "access traces as needed"!

If it was me, I'd just access the pin outs on the side (assuming that is what's going on). Do you have a bench to validate functionality, or will you just field test it cold turkey? Fun project indeed!

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: iPhone? You go first . . . on 09/24/2012 19:29:45 MDT Print View

> an iPhone which does not have removable batteries
Oh well, defective design.
And now you have Apple maps...

Cheers

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
And it gets better on 09/24/2012 19:38:45 MDT Print View

"[...] an iPhone which does not have removable batteries [...]"

"Oh well, defective design.
And now you have Apple maps..."

Oh, it gets better: the CDMA (non-GSM) version used by Verizon, a major carrier in the US, does not permit shutting off the phone's radio without also shutting off the GPS receiver. So if you're in the backcountry, away from any cell towers, the phone goes into high power "search" mode, rapidly draining the battery. Unless you put it into Airplane Mode, which then kills the GPS receiver.

Why? It is a mystery.

(Not trying to create thread drift here, just sayin')

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Re: Re: Solar Panel Theory on 09/24/2012 20:11:21 MDT Print View

Why is it that, despite being highly opinionated and blunt, Roger and I don't get into arguments? I suspect we're "reading from the same book(s)" and they are mostly engineering references.

Roger: I agree with your logic and practice of using a 12-volt array to charge a 7.2 volt lithium battery. BUT, I think you could save weight with little loss of charging rate if you had a 9-10 volt array. Alas, that's not an off-the-shelf item, but if you wire individual solar cells in series, than you can choose a lower max voltage, save weight, and gain a bit of efficiency.

Question: Do even AA lithium batteries have the internal circuits you describe? Disposables and/or rechargeables?

Anecdote: I had a ChemEng friend from high school Math Club days who went to work at a lithium battery company back in the early days. The fastest way to empty a room was to yell "hot cell" and then everyone would belly-crawl out to the fire escapes. These were auto-battery-sized lithiums and held A LOT of energy. Their joke, since they were going into cruise missles, was, if it doesn't work, it blows up. If it works, it blows up.

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
Different Li tech on 09/25/2012 11:57:51 MDT Print View

"Question: Do even AA lithium batteries have the internal circuits you describe? Disposables and/or rechargeables?"

Two different chemistries.

AA and similar disposable nonrechargable lithium batteries use lithium iron disulphide chemistry, and are not the same as the rechargeable lithium-ion technology used in cell phones.

There are no rechargeable AA Li-ion batteries on the market for a few reasons, one being that Li-ion tech gives 4.20V/cell which would kind of smoke your usual flashlight or digital camera, and because without careful charging, Li-ion batteries can overpressure and create messy and embarrassing explosions.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Solar Panel Theory on 09/25/2012 15:19:07 MDT Print View

Hi David

Ah, but which of us is the ' highly opinionated and blunt' person?
Probably me.
OK, definitely me :-) :-)

> if you wire individual solar cells in series [to get a 9-10 V array]
Oh, true. It would work well.
But my gut feel is that the result might be more rather expensive, since you would have to buy a number of them. The 12 V units are really mass-produced, packaged and distributed.

Would you get better results/performance? I am not sure about that. The limiting factor with solar cells is always the area of the cells (and the angle of incidence).OK, and the intrinsic efficiency of the cell. Hum ... interesting question. Dunno.
Would it make all that much difference? Doubtful imho, but I might be wrong.

> Do even AA lithium batteries have the internal circuits you describe? Disposables and/or rechargeables?
My understanding (I could be wrong) is that the 1.5 V AA primaries (Energiser brand) do have that internal circuit.
Don't think I have seen rechargable AA batteries yet. Not sure the chemistry which gives 1.5 V can be recharged.

Are there other brands offering rechargable 1.5 V yet? If I am missing something here I am sure someone will help out.

Cheers
PS: rechargable 3 V and 3.6 V, yes, they are available. But we are talking about 1.5 V here.

Edited by rcaffin on 09/25/2012 15:21:13 MDT.

Wizard of Oz
(wizardofoz)

Locale: New England
Breadboard and initial efficiency calculations! on 09/26/2012 13:09:46 MDT Print View

So the breadboard was a success in that it gladly accepted 12V and output 5V! I haven't hooked it up to my iPhone quite yet to do any time tests or mode tests. The LED circuit is a no brainer and really nice to see what's going on (no switch in the breadboard, it's just constantly connected and shows when the 5V is coming out). I changed the shutoff circuitry values slightly (I'll post an updated schematic later) to accommodate variation chip to chip better, so that circuit pulls .4mA so it's only a SLIGHT drain.

Solar Breadboard Detail

I also took apart a 30 dollar iPhone specific USB Car Charger from Griffin. I've had it for a while, and I thought it would be fun to do a comparison as it's pretty good quality. It's a 500mA unit so I did my measurements apples to apples with just the 10ohm load, although both circuits do function under the 5ohm load.

So here's how the fight went...
In the red corner, hailing from China, Griffin with an input of 11.93V pulled .287A to generate 5.1V out at .467A. That is a 3.424W use of power to generate 2.382W or a paltry 69.56% efficiency.

And in the blue corner representing the USA, the brainchild of National, Texas Instruments, and the Wiz, the FUCD (Four ounce Usb Charging Device, I crack myself up) at the same 11.93V pulling only .217A, put up 5V at .455A. USA is the clear winner with a 2.589W use of power for a 2.275W output, yielding 87.9% efficiency!!! Just shy of the hoped for 90%, but I'll take it. Technically the LED and shutoff circuit are taking 50mW of power (most of that is the LED), so with the switch that was so wisely suggested, I'd be at about 89.8%.

More to come. Next, the iPhone test, then I'll finally let the sun do the powering and see if it can push a full 1A!!! Let me know if you have any additional optimization ideas!

Edited by wizardofoz on 09/26/2012 13:28:34 MDT.

Wizard of Oz
(wizardofoz)

Locale: New England
Some thoughts on 09/26/2012 13:45:44 MDT Print View

At a few points during this fun, I thought about limiting the system to just the 500mA setting for simplicity sake. But I found this graph, that basically says it really will charge almost twice as fast at 1A and if I can get that much juice from the panel, that's worth while.

Charging graph

And since I destroyed my Griffin Charger, well the case anyway. I might go ahead and pick up one of these as maybe even use it as a test subject! http://www.thinkgeek.com/product/eea9/?srp=3

2.1A

Edited by wizardofoz on 09/26/2012 13:46:19 MDT.

David Lowry
(huskyrunnr) - F
Re: Some thoughts on 09/26/2012 22:30:09 MDT Print View

Oz, fantastic! I'll probably copy your work sometime, although I don't have the intestinal fortitude to surface mount the mods on the eval board. Two questions, the specs are a bit picky on coupling to the inductor, which should not be a problem if I take the mods off board. Do you not see that as a problem? That's probably much ado ... What is the 2V rail for? I know nothing about charging smart-phones.

Thanks for documenting your progress.

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Re: Some thoughts on 09/27/2012 07:14:57 MDT Print View

David, so the inductor pretty much takes up one end of the board, and the spec sheet details some of the proper component placement and routing on a PCB to help with noise. I'll put the mods on the other end of the board (or maybe on the backside beneath a ground plane) to reduce the probability of issues, but I really don't think it'll matter in full sun. My only real concern is the shutoff pin, and I may add a diode and capcitor to give just a bit of hysterisis to minimize (though it won't eliminate) oscillation in low light conditions.

I talked a bit about the 2V/2.5V rail on the USB Data lines in my original post, but basically they are an iPhone specific requirement to ensure that the charger is 'proper' and also it tells the iPhone which charging mode to use. The iPhone won't necessarily charge without it, you'll get a "not a compatible charging device" message if you don't add the Data Line voltages. In addition, the level of those voltages changes the internal charge controller in the phone and allows it to charge in 2 different modes depending on the capacity of your charger.

I still need to check if I need or want an additional diode if the phone discharges when the solar panel output too low of a voltage and shuts the IC off. So more to come!

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Cheaper sources of 5-volt sources on 09/27/2012 09:10:12 MDT Print View

Rather than a $15+shipping, one-port charger from Thinkgeek, how about a $1.50+free shipping, two-port car charger off ebay? Or a 1.0A + 2.1A dual-port charger for $3.60+free shipping:

http://www.ebay.com/itm/Dual-2-Port-USB-Car-Charger-12v-DC-for-iPad-iPhone-4G-4S-iPod-2A-/140848961563?pt=PDA_Accessories&hash=item20cb40981b

They're all made in China, right? Might as cut out the middleman (middlemonkey?) and have it shipped direct. That's been my approach for years now on camera batteries, chargers, etc.

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Re: Re: Re: Re: Solar Panel Theory on 09/27/2012 09:26:13 MDT Print View

Roger: I was observing that neither of us holds back in technical realms.

Agreed on the mass-produced aspect of 12-volt PV panels.

http://www.lettingchiboboshine.org.au/pages/activities/investigating-the-characteristics-of-photovoltaic-solar-panels.php has this chart:PV volts versus amps

Here's a link to another chart:

http://www.flickr.com/photos/mitopencourseware/3323453932/

with a less flat curve as you approach short-circuit current, but again, max power is at 18 volts and near-max power is in the 15-19 volt range. Instead of 36 cells in series, 12 cells in series would give max power at 5.5 volts and a max voltage of 7 volts. Such a panel producing 1 amp or less could be hooked directly to a phone for charging (give or take that 2-volt, iPhone-specific signal WofOZ speaks of).

Ideally one would rewire a 3-row, "12-volt" array of 0.3 amps into a 5-volt, 0.9 amp array by changing the rows of cells from being in series to being in parallel while utilizing as much of the mass-produced packaging as possible.

J P
(jordo_99) - MLife

Locale: Midwest
...just awesome on 09/27/2012 10:09:55 MDT Print View

This just might be my favorite MYOG thread I've seen yet.

Some of this still goes over my head (realizing I remember less of my electronics course from years ago than I thought) but it's definitely encouraging me to give something like this a try. I don't think it would take long to refresh my memory of this stuff.

Edited by jordo_99 on 09/27/2012 10:47:25 MDT.

Wizard of Oz
(wizardofoz)

Locale: New England
'Chinese' knockoffs on 09/27/2012 11:52:44 MDT Print View

Yea, not so much on the ebay one...I see your point, but if you take a few apart, the knockoffs (from china, or wherever) are generally assembled poorly with very bad quality control. If they don't have oversight of a good company, they buy the cheapest parts possible (which may be seconds or fakes), and monkey's often put them together. You can get great leftovers and surplus on ebay and for some electronics you can even do the knockoffs, but $15 bucks for a quality part designed by thinkgeek is well worth it to me.

An aptly timed comment though :) How un-american of you David.. :)

Wizard of Oz
(wizardofoz)

Locale: New England
Sun Power!!! YEA! on 09/27/2012 13:27:17 MDT Print View

So I had intermittent clear skies here so I got outside with the actual solar panel to see how it all came together. I forgot to bring the iPhone cable that I could hack up so I didn't implement the .5A/1A mode switch yet, or test it out with a real phone but i used dummy loads purposefully made just under 5 and 10 ohms to make sure I reached full current draw.

So what do you want first, the good news or the bad news...

THE BAD:
1A mode is not possible with this panel! At least least not with the sun this time of year. The sun was very string about 1:30PM today, but try as I might with angle and waiting patiently for zero cloud cover. I could not reach full 1A output! So I think that, as is way too common, the manufacturer is just a little optimistic. Looking closer at the powerfilmsolar website, it's supposed to output 15.4V at .3A, which is actually 4.62W and at a clean 90% efficiency of my converter in perfect sun, that's only 831mA. Now I didn't see just how much I could have pulled, but suffice to say, my circuit CAN handle 1 full Amp, the panel couldn't provide that much power in the sun today. (BTW, the open circuit voltage on these little panels is 19.4V!)

So I've decided to nix the 1A/.5A mode switch option. Oh well, there something to be said for simplicity

THE GOOD:
500mA output was fantastic. even with the sun behind a very descent cloud such that I could stare at it without getting fully blinded, it was still able to pump out the .5A! So yea, you need sun to charge, but I won't have to worry about perfect positioning and babysitting too much, which is good news for me, even if it's not quite as fast as a wall charger.

I also found a pretty cool little device to help with the low sunlight turn-off oscillation issue. I played with capacitors and such, but they didn't really fix the problem. So another Texas Instrument special (seriously, I'm not affiliated in any way, they just make great stuff), a TPS3808, come to the rescue. It's a supervisory circuit that draws VERY little power and can be set up to have a 10s delay on the Step-Down Converter On/Off pin. So I ordered that and I think it'll really help solve that issue! Basically if the sun goes behind a big enough cloud that I love panel power below some level that I can choose (8V), it'll shutdown the converter circuit for 10s, then try to power it back on again, and see if the sun is back. I'll keep you posted on that, but it looks very promising.

THE UGLY: well currently the state of the my breadboard...since it's all in test setup mode right now, but it's been a great tool in figuring out little details. I really want to have a custom PCB made for final version of this as a nice icing on the cake.

THE FUTURE: I'm running a 'drain' test right now to see if the circuit will kill my battery if accidentally let plugged into the solar panel over night or something. I really don't want to add diode to block back current and it looks like I won't have to. Preliminary measurements say that it is drawing no current backwards at all! but I'm going to leave it for a hour and half or so in airplane mode and see what happens.

So other than figuring out the detail on the low power shutdown circuit, all the testing that remains is to do a charge time test. I should be able to drain my phone enough by tomorrow to do a full charge through the circuit and I'll let you know.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Sun Power!!! YEA! on 09/27/2012 13:42:59 MDT Print View

You ever buy components from digikey.com?

I've bought stuff from them and they have more selection and cheaper than local "brick and mortar" places

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
The Bad, The Good, The Ugly, The Future on 09/27/2012 16:13:28 MDT Print View

Pity about the panels not being powerful enough for 1A operation. Are we married to 0.5 or 1A options? Could you try for .75A?

But anyway, nice job -- and good idea about using that supervisory IC.

Once you get the thing debugged, maybe you could post schematic and BOM?

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Re: Re: Solar Panel Theory on 09/28/2012 01:44:35 MDT Print View

Hi David

Ahhh, techie stuff :-)

> Ideally one would rewire a 3-row, "12-volt" array of 0.3 amps into a 5-volt, 0.9 amp array
> by changing the rows of cells from being in series to being in parallel
Um - that's not quite as easy as it sounds. One can have problems if the cells are significantly mismatched. However, putting a Schottky diode in series with each one can solve that problem. The voltage drop is small.
Yeah, that's a thought, but the 12 V panels I have seen here seem to be rather integrated, so that rejigging them might damage them. But I know I have not seen anywhere near the full range of what is commercially available.

Cheers

Wizard of Oz
(wizardofoz)

Locale: New England
Parts and determination on 09/28/2012 05:55:34 MDT Print View

Yea, I definitely love digikey! newark online is my other favorite if I actually have to break down and 'buy' parts. My favorite is the free sample places :) TI and other big names are great at sending samples of 1 or two chips out, then I just have to find or buy the small caps and such that go around them.

Jack, you've motivated me to try a bit more. Unfortunately there's no sun today...But I did hook up both the 1A and .5A modes on the bench with the actual iPhone 4S and they worked great. The current draw on each is right on spec by less that 10mA difference from expected. Of course this is using a lab power supply for my 12V rather than the panel.

I let my phone die this morning, so I'm running a full charge up time test in .5A mode right now. It's been 25 minutes and I'm already up to %21 percent. so I'm guessing it'll be an hour and a half.

When I get some more sunny days, I'm going to try the solar panel in 1A mode with the actual phone, just to see what happens, but my guess is that since my circuit is a voltage source and not a current source, it won't work. The StepDown regulator is trying to output 5V and when the phone tries to draw the 1A, it will shut off, not just fold back the voltage. Not knowing exactly what the internal circuitry is on the iPhone, you never know though.

It's a rainy weekend here in MA, so I probably won't get to test out the new shutoff circuit till next week. I'll definitely be posting a schematic and material list in the end with whatever I find works best. I'll likely have some left over ICs and maybe a few extra custom PCBs as a minimum buy if anyone wants to claim them for a few bucks.

Wizard of Oz
(wizardofoz)

Locale: New England
Realworld Results! on 09/28/2012 08:03:11 MDT Print View

Two updates:

1. Started from a completely dead iPhone 4S with the charging circuit on .5A mode. 100% charge reached in 94 minutes!

2. I forgot to post this before, but this circuit does NOT drain the iphone when it's not powered (i.e. no sun), so no diode is needed!

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
Only two choices? on 10/01/2012 11:24:35 MDT Print View

So Oz, does the iPhone only give two options, 1A and 1/2A, and won't recognize or use 3/4A?

Great results so far.

Wizard of Oz
(wizardofoz)

Locale: New England
And the winner is... on 10/08/2012 06:18:35 MDT Print View

Received that last IC I was waiting for to help with the low light issues. The TPS3808 works like a charm! It completely takes care of the oscillation and gives a variable 7-12 sec pause when the panel voltage drops below 7.6V before trying again, but ONLY once the panel voltage comes back over 8V! Really nice! So the circuit is highly efficient (90% measured!), has a very bright 'output check' LED and a 1A-.5A switch onboard. Even though my panel isn't powerful enough to actually power the 1A mode, I figured I could use this in the future with another panel or if someone develops a better lightweight, flexible, and weather resistant photo panel :)

I did go ahead and keep the USB output port, so I can charge other devices or a AA batter charger with that port. i was going to hard wire in an iPhone connector to save a few grams, but figured the versatility was worth it, plus I suppose this will now work with the iPhone 5's new connector since you can just plug a different cable into it. Or a Droid, Samsung, BB, etc.

Anyway, the final board size is 1.275" x1.725"!

Here's the parts I used:
USB A Female Connector
C1 6.8uF Sprague 594D685X9050D
C2 68uF Sprague 594D686X9010C
C3 10nF 50V Ceramic
C4 1.75uF 1.75uF ceramic
C5 1nF 1nF ceramic
D1 Diodes Inc B120B
D2 LED LED 9mA
L1 47uH Coilcraft D03316P-473
R1 58k 58.5kohm
R2 12.5k 12.5kohm
R3 49k 50kOhm
R4 98.1k 98.1kOhm
R5 47.9k 47.9kOhm
R6 8.1k 8.1kOhm
R7 1M 1MOhm
R8 330 340ohm
SW1 NC Momentary ON
SW2 SPDT
U1 LM2675 National LM2675-5.0
U2 TPS3808 TI TPS3808G

And the Schematic:
Final Schematic

I have 6 board being made and have enough SMD parts for at least 2 of them. here's the board layout! Soldering will be TOUGH!
PCB layout

I should have everything by Thursday and I'll let you know my progress. I've got a 16 mile training hike this weekend, but I should be able to find time to get started. Let me know what you think. I'll throw some pics up of the work in progress. And if anyones wants to buy a board off me (bare or assembled), just let me know! Where else can you get a sub 4oz 5W Solar Charger :)

Edited by wizardofoz on 10/09/2012 07:22:38 MDT.

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
Of or or? on 10/09/2012 05:18:28 MDT Print View

Wiz, you wrote, "And if anyones wants to buy a board off me (bare of assembled), [...]

Is that "bare of assembled" or "bare or assembled"?

'Cause I'd buy an assembled board.

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Of or or? on 10/09/2012 07:28:30 MDT Print View

Good catch Jack! Fixed that typo...

What, you don't want to do all that miniscule soldering, haha! Yea, I had to buy the board in a batch...well it cost the same whether I got 1 or 6, so I got 6. I can definitely assemble an extra one for you. I'll just ask for the cost of PCB and parts, which is about $30. I hope to have mine done early next week if everying arrives as expected and I'll get it tested to make sure everything works. Then I'll get another one together for you. The only thing you'd have to do is to solder in your solar panel wires right to the board, or if you want I could put some small 6" wires on there hanging with bare ends so you can connect by whatever means to your panel if you don't solder.

Who else! 1 is spoken for, 4 more available :)

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Re: Of or or? on 10/09/2012 08:09:54 MDT Print View

You should charge more - enough to pay for yours for example - like $60

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Re: Re: Of or or? on 10/09/2012 08:32:54 MDT Print View

I like your thinking Jerry! But I'm just looking to make sure the design gets some use at this point. This is fun for me. If 40 people want these, I can do them up with the the full solar panel and all and actually charge for a final product. But I'm guessing a full up solar panel/board/ and the mini-case that I'm going to do to protect the board will be like $110 when all said and done!

George Geist
(geist) - M

Locale: Smoky Mountains
Re: Who else! on 10/10/2012 12:25:33 MDT Print View

> I can definitely assemble an extra one for you.
> I'll just ask for the cost of PCB and parts, which is about $30.
> I hope to have mine done early next week
> Who else! 1 is spoken for, 4 more available :)

Hi Oz,
I'll take one of the 4 remaining. And I'm happy to pay for
not only the PCB and parts, but your labor for assembling it.
You can contact me at gst (at) ornl (dot) gov

I was wondering if you ever had a chance to test the ThinkGeek
plug to see how it's efficiency compared?

Al

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Re: Who else! on 10/10/2012 14:24:47 MDT Print View

Board 2, SOLD to George :) NP at all. 3 left to claim at this LOW, LOW price...is this how hookers feel??? :)

I didn't end up testing the ThinkGeek cigarette lighter to USB adapter. Basically since I couldn't get even a full 1A out of my solar panel, I didn't see the need to test an even higher capacity circuit. And I'm pretty happy with 90% efficiency I was able to acheive! No need for greener grass other than pure curiosity. Plus when the low light oscillation because an issues, I pretty much knew that a custom solution would be best for the device I'm charging so I'm not strobing it like a little kid standing at a light switch for the halloween party.

I'd still be curious to try it out someday for comparison!

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
Wait, wait -- I want one, too! on 10/11/2012 04:57:41 MDT Print View

P-mail sent.

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Wait, wait -- I want one, too! on 10/11/2012 06:24:24 MDT Print View

You got it Jack! Thanks for all your great comments and suggestions during the design too! I got confirmation that the boards are on their way to me and should arrive tonight. I'll let you guys know when they are together and working and get some pics up too!

Wizard of Oz
(wizardofoz)

Locale: New England
Putting it all together...and so pretty... on 10/15/2012 06:10:00 MDT Print View

Bare boards made it in and look shiny and green...until I started to goop them up with flux :) They came out REALLY nice and I'm pretty impressed with the quality of the PCB House! The detail is really clean.

Here's a pre-cut pic:
Bare Board

Didn't get time to do a full assembly yet. I've got two parts that are delayed, but hope to have them early this week, and have the first one fully together on Tuesday. I did get the 'toughest' parts on the first one though, you can see just how SMALL the ICs are. The pains we go through to save weight... Everything soldered on really nicely since the board was so new and tinned.

I didn't clean it yet cause I want to do that all at once, but here's the first partial board!Partially Assembled

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
Ain't it nice on 10/15/2012 07:20:03 MDT Print View

Ain't it nice to get your board back from the house, and start putting parts on it? After staring at the board design on the monitor, holding the real thing in your hand is quite rewarding. Even better is powering it up and seeing no smoke!

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Putting it all together...and so pretty... on 10/15/2012 12:12:48 MDT Print View

Many years ago, it was not so easy to buy complete printed circuit boards like this one. For one thing, everything was through-hole soldered then. Now I see this one is part through-hole and part surface mount. That makes it harder to stuff the board.

I used to make my own single-sided boards from scratch. Those were the good old days. Ahh, yes, the smell of hot ferric chloride solution...

And then, you want to think about weatherproofing this thing. We used to use a full potting compound to make the entire thing into a plastic brick. That is probably unnecessary now, but a clear spray that hardens might be useful as long as it doesn't add much weight.

--B.G.--

Matthew Naylor
(mrnlegato)

Locale: Mid-Atlantic
Re: Re: Putting it all together...and so pretty... on 10/15/2012 12:16:30 MDT Print View

Bob, Are there any specific spray products that you recommend for this kind of thing? And does that lead to any problems with overheating?
Matt

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Re: Putting it all together...and so pretty... on 10/15/2012 12:29:27 MDT Print View

There probably are some spray products, but I don't know the current ones.

When we were less sophisticated, we would simply paint on clear fingernail polish to any exposed conductors.

If you had components that were radiating a lot of heat, then the coatings can become a problem. However, I'm guessing the high efficiency means that there isn't that much heat radiated, so coatings wouldn't be a big deal. If you do full encapsulation, it can become a big deal. I did that badly once about forty years ago, and I had a smoking hole in the middle of the encapsulation plastic.

If you get too much protectant gooped onto the circuit, then you might have a maintenance problem. You can't easily hook test clips onto it anymore.

I guess it all boils down to the environment that you intend to use it in. Maybe this thing needs to reside in its own cuben fiber bag.

--B.G.--

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Waterproofing on 10/15/2012 16:13:17 MDT Print View

How about the spray version of Plasti Dip?

http://www.plastidip.com/

The can I have says, "flexible, won't crack" "insulates electrical shock, vibration" "provides non-slip grip" and "resists weather, chemicals, impact and abrasion".

That's been my experience with it. I've used multiple coatins to provide more cushioning on tool handles, but you can make it even thinner by adding xylene or toluene.

I concur with Bob's thoughts on overheating. Definitely a consideration, but with a high-efficiency circuit, there's not much power to disapate.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Waterproofing on 10/15/2012 17:17:32 MDT Print View

What David said about flexibility could be important.

If you had the wrong stuff, when it dries it might "force up" a surface mount component. With flexible stuff, it wouldn't have such force.

Think about it the other way around. If you got the circuit cold enough (high in the mountains), it might have unpredictable problems with the cold. But, with an extra layer of waterproof insulation on it, the cold problem can't last long.

--B.G.--

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
RC guys face the same issues on 10/15/2012 23:06:14 MDT Print View

This might give some ideas for weatherproofing.

http://www.rccrawler.com/forum/electronics/26785-water-proofing-electronics-14.html

Steve G
(sgrobben) - M

Locale: Ohio
Re: Waterproofing on 10/16/2012 06:51:18 MDT Print View

I have successfully used "hot glue" but am not sure how it compares in weight to other solutions.

Wizard of Oz
(wizardofoz)

Locale: New England
Success!!! for 'green' solar! on 10/16/2012 12:31:08 MDT Print View

I'll definitely check that site out Jack. I think I agree that Plasti-dip is probably a good spray on candidate. It wouldn't affect the components and can be easily removed if necessary. Heating up of the whole assembly isn't a concern, but localized component overheating can cause degradation and short life (inductor), so I don't think I'll go that route personally. I think a bit of silicone based dielectric grease (like you use on spark plugs and bulbs) is all I'll use to keep corrosion down. That way I'll always have access to the components and allow heat to 'get out'.

I remember etching boards from scratch :) and then adding jumpers when your mask didn't quite hold and you got a questionable trace! This board came out better than I expected, and most of the credit is due to the quality pads and soldermask. This was really fun and useful project for me. I learned tons and have something I can take with me on all my long excursions, so thanks for all the inputs and help.

Here's the first board! Lovingly called my E-Lite Gear (pronouced EE light). Works like a charm on both .5A and 1A mode.
Done Board

I had a little issue with the momentary 'test switch' being a intermittent just after I cleaned the board, but it's must have just had a little cleaner or oxidation on the contacts, cause it's working great now. Actually I had a short-lived gulp when I plugged it in because I forgot that the same circuit that protects it from oscillation in low light, also delays the turn on for about 12 seconds as the cap charges up. Green is good, and this is no exception to the rule! Lighted

I'm going to do some more testing this week to make sure everything as expected and then I'll start putting the rest of the board together. I'll get in touch with those who've asked for one in the order they made the request as I get them done!

Next step, (forget all this talk of sprays and sealants) I'll design a snap together case for it, and have it 3D printed! A friend of mine just has something done in stereolithography and it's SWEET! so I figure all this effort should culminate in an awesome little case with the extra .2 oz I have :) Not sure I can get it done before my Nov trip, but I can try...

Jack Elliott
(JackElliott) - F

Locale: Bend, Oregon, USA
Looking good on 10/16/2012 16:48:28 MDT Print View

The project seems to be coming along swimmingly, and looks like you'll have something to take on your GC trip. Once I get my copy of the board I'll set it with the rest of the backpacking gear for next season (gonna start snowing here and Jack don't backpack in the snow, preferring someplace warm and comfortable, like a pub, under such conditions), and in the meantime start looking for a solar panel array for something less than the $120 (or so) that the one you're using lists for.

Wizard of Oz
(wizardofoz)

Locale: New England
Powerfilm Solar Panel on 10/18/2012 07:15:26 MDT Print View

Jack,

I'm using the 5W Powerfilm, P/N F15-300N. It's $76 bucks on Amazon shipped with a couple buy options. If memory serves (it was in an early post), it's 3.2oz stripped down. Please let me know if you find something cheaper, or more watts per oz! I used these guys in the past, so they were easy for this project. But I looked for other options and didn't come up with much that could beat it! I'm hoping someone will breakthrough with an even higher efficiently/weight panel soon and I can keep my project improving by just swapping out panels!

Jay

Wizard of Oz
(wizardofoz)

Locale: New England
the case for a Case on 10/19/2012 09:19:01 MDT Print View

So I've got two weeks before the trip that started this project! and now that i have my board done and working. I need to finish the thought and protect it, right. You guys have thrown out lots of great ideas, but I'm old fashioned and don't like slop all over my creation, so I'm going clamshell style.

Case

This way I can, if needed, still get inside it. And although it won't be waterproof, I wasn't planning on taking it swimming.

I'm hoping to get this 3D printed quickly (times a ticking), so let me know your thoughts or suggestions! I'm looking at i.materialise.com to do the job, but I'm waiting on a quote now. And in between all this, I'm trying to get some extra boards made for all those folks who've asked for them!

Richard Cullip
(RichardCullip) - M

Locale: San Diego County
Re: the case for a Case on 10/19/2012 09:42:08 MDT Print View

That's a cool looking case. Should do the job for you. What material do you plan to make it out of?

Wizard of Oz
(wizardofoz)

Locale: New England
Case Material on 10/19/2012 09:44:24 MDT Print View

I'm looking at their PG12. It seems durable, cheap, and good detail. They have alot of options though!

http://i.materialise.com/materials

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Case Material on 10/22/2012 10:25:59 MDT Print View

It looks like PG-12 is NOT UV resistant. Not the best material for a Solar Panel Controller :)

I have a few options in polymide and ABS plastic that are much more durable for real-world use. Apparently, it's pretty tough to get anything on short notice, but I'm hoping to find someone who can make me a case in less than 2 weeks!

George Geist
(geist) - M

Locale: Smoky Mountains
Strong Volt Solar Panel on 10/23/2012 15:18:58 MDT Print View

> Please let me know if you find something cheaper, or more watts per oz!

Hi Jay,

I too have a 5W Powerfilm panel, and look forward to upgrading it with your board.
While looking on Amazon yesterday I stumbled on a smaller higher efficiency panel called "Strong Volt Solar: six". I have ordered one - only $29.99 on Amazon). It is 6W and about the size of the 0.6W panel you showed earlier in this thread. Manufacturer's claim is they are using 16% efficient cells. Worth checking out.

Out of the box this folding, cloth panel is 12.2 oz on my scale. I plan to put it on a diet and see how light I can get it. Will post my results and pictures when I start lightening this Strong Volt panel.

I done just a couple preliminary tests and it appears to be reaching the 1A threshold on the USB port. More tests needed to confirm.

For now your board and a striped down 5W powerfilm is the lightest watts/oz.

Edited by geist on 10/23/2012 15:24:38 MDT.

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Strong Volt Solar Panel on 10/24/2012 08:11:28 MDT Print View

George, Keep us posted! Sounds interesting. I'm assuming this in NOT flexible, and the panels are susceptible to damage in a backpack? can't beat it for the price. interested to know how light you can get it stripped down too. Thanks!

George Geist
(geist) - M

Locale: Smoky Mountains
Re:: Strong Volt Solar Panel on 10/24/2012 21:44:46 MDT Print View

> Sounds interesting. I'm assuming this in NOT flexible, and the panels are susceptible to damage in a backpack?

Hi Jay,

The two 7"x7" panels on the 6W charger seem well protected. They fold facing each other and are backed by metal plates to prevent bending. I suspect that the metal plates are the majority of the 12oz and I'm considering options for replacing the metal with something nearly as stiff but a lot lighter. Unfortunately I have only been able to find carbon fiber flat plates in 4" and 6" squares, not 7" or 8".

Paul McLaughlin
(paul) - MLife
carbon sheets on 10/24/2012 21:49:28 MDT Print View

pricey, but:

http://www.mcmaster.com/#standard-carbon-fiber-sheets/=jv9ie5

Wizard of Oz
(wizardofoz)

Locale: New England
Lightweight backing on 10/25/2012 05:53:35 MDT Print View

With the high cost of carbon fiber (I love McMaster Carr though), I wonder if fiberglass would be sufficient for that purpose but save serious weight? You'd still have to probably store on the outside of your pack because I believe even a slight bend will crack the monocrystalline type solar panel. The size sounds great though. 7X7 isn't bad.

Here a pic of what I'm taking in the canyon for reference. Just waiting on a couple parts, and I can ship some board out to those who have requested them!

Found a small plastic case that tooth picks come in to give it some protection untill my 3D printed case comes in. Got it all sown up nice and use some heavy duty fabric tape to secure the case/board onto the panel.
folded

There are 6 panels of course, but the end two are folded in. I wanted to show the cleaned up edges. I definitely had an easier time cleaning up the edge that I left more fabric on. Since I used the Thread Injector, it's better to leave extra and cut the excess off later that try to sew on a tiny fold. IMHO
unfolded

Edited by wizardofoz on 10/25/2012 05:54:49 MDT.

George Geist
(geist) - M

Locale: Smoky Mountains
Re: Lightweight backing on 10/25/2012 12:54:24 MDT Print View

> With the high cost of carbon fiber (I love McMaster Carr though), I wonder if fiberglass would be sufficient for that purpose but save serious weight?

Fiberglass could certainly be made to work, it is just a matter of how thick it would need to be to match the rigidity of the existing 1/16" metal plates. And then determine what weight savings that thickness of fiberglass would give. Taking that thought experiment further... What do folks think about mounting the cells on two 1/2" thick 7"x7" Styrofoam sheets? With the thought of getting rigidity from thickness of the material rather than its strength. Dense, closed cell polystyrene is 1.6 lb/cu. ft. Each sheet would only be 0.3oz.

Each solar cell is small (about 2"x3") so some flex can be tolerated between cells on the 7"x7" panel and if the cells are held to the sheet by a drop of flexible silicon at their center, then they would be able to withstand much more flex without breaking, compared to mounting them flat to the sheet with glue or tape.

That said, it is hard to compete against the durability and waterproofness of the PowerFilm panels Jay is using.

I'm just thinking out loud how one might build a smaller, lightweight solar panel to hook Jay's cool board to.

George Geist
(geist) - M

Locale: Smoky Mountains
Strong Volt Solar Panel Power Test on 10/27/2012 18:18:41 MDT Print View

Before I began ripping the Strong Volt panel apart to lighten it, I did a head to head test against the 5W PowerFilm panel to make sure it was going to be worth my trouble. The results were surprising. I sat the panels side by side on the ground charging my Smartphone for one hour each. Side by side it is really apparent how small the Strong Volt panels are. The PowerFilm has 162 sq.in. of collector area. The Strong Volt has 52 sq.in of collector area. In the same amount of sunlight in the same amount of time the Strong Volt put in just a little over double the amount of energy as the PowerFilm panel.

OK. 1/3 the area, 2x the power, and 1/2 the cost of the PowerFilm
But several ounces heaver - seems like a worthwhile project to try to lighten the Strong Volt Solar Panel.

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Strong Volt Solar Panel Power Test on 10/27/2012 18:23:28 MDT Print View

Side by side picture please :)

That sounds great! So curious how far you can strip it down!

Got the last parts for my boards today. Hope to get two done tomorrow! Yours is one of them!

George Geist
(geist) - M

Locale: Smoky Mountains
Lightening Strong Volt Panel on 10/27/2012 19:15:10 MDT Print View

The was some initial concern that the polycrystal solar cells in the Strong Volt panel would make it more fragile and you couldn't just stuff it down in a backpack. Now that I have tried to take it apart, let me say that the Strong Volt panel is really tough. I would go so far as to say you could drive a car over this Strong Volt Solar six panel and not break the cells.

In taking the panel apart I discovered that it is made by placing a piece of clear tape over a 0.039" thick metal plate so the cells do not short themselves by touching the plate. The 1.5"x1.5" solar cells are laid out on top of this tape in a 3 by 4 pattern. Then clear silicon is poured over the cells and metal plate, encasing the cells in a solid block of clear plastic with a metal back. There are no air gaps and the silicon flows under as well as above the cells, gluing them to the metal plate and forming protective clear window above the cells. Being soft I find the window easily gets little scratches and scuffs on it.

Starting point: I put the 6W panel on my scale and it weighed 12.3 oz.

I then proceeded to cut away all the extraneous fabric, velcro, and grommets just as Jay had done to lighten the 5W Powerfilm panel. I put the stripped down version of the Strong Volt back on the scale and it was 9.3 oz.

I felt 9.3 oz was still too heavy for my taste so I then began the process of trying to remove the metal plates and that's when I discovered that the plastic was tightly adhered to the metal under the cells. I am slowly trying to pull the two apart without damaging the solar cells. Any suggestions from anyone?

Wizard of Oz
(wizardofoz)

Locale: New England
Extra Boards Done and Tested! on 11/01/2012 13:00:21 MDT Print View

Just wanted to update on my progress. I got the last parts for the boards this week, and despite the power outage from the storm I was able to finish all of the boards!

6 boards

Unfortunately, I was short two of the SPDT switches, so until they come in, I have 2 of the 6 boards jumpered to 0.5A mode for test purposes. I'll use one for my trip since I my panel won't support the 1A mode anyway.

Board w jumper

My case came in from the 3D printer too. Red ABS plastic from PartSnap.com. The resolution wasn't as good as I wanted, so the lettering didn't come up great. I'm going to have to try again with a different material because I know it can look much better, but his will be more than functional for the Grand Canyon next week!

Red Case

Everything lines up and it's super sturdy, and I have a great little 3.8oz solar panel ready to go! And I'm able to check the 10 day forecast for the Canyon and clear sunny skies are predicted for all of next week on both rims!
Full package

Everyone I've shown this too has been really excited about this, so I'll likely try to set up a website to offer it to like minded backpackers.
E-Lite Gear

Thanks to all who helped with great ideas and support! Backpackinglight is AWESOME! For those who have asked for a board, I'll get them sent out tomorrow! They've all been tested. Please let me know your feedback too, I'll be eager to hear how they treat you and what panels and cases you pair them with!

George Geist
(geist) - M

Locale: Smoky Mountains
Powerfilm panel and Strong Volt panel side by side on 11/02/2012 20:43:30 MDT Print View

> Side by side picture please :)

I got sidetracked for a few days by this pesky thing called a job.

Here are the side by side pictures of the 5W Powerfilm panel verses the 6W Strong Volt panel. My earlier post gave more details of measured output and actual cell area.


Here they are folded up


Powerfilm vs Solar 6 solar panels folded


Here they are unfolded


powerfilm vs solar 6 panels unfolded

I may get some time this weekend to continue to see how light I can get the Solar 6 panels

James Marco
(jamesdmarco) - MLife

Locale: Finger Lakes
Re: Lightening Strong Volt Panel on 11/03/2012 03:52:29 MDT Print View

"I am slowly trying to pull the two apart without damaging the solar cells. Any suggestions from anyone??"

You can try warming the cells/metal. I think this would have an overall effect on the glue. Be carefull though.

George Geist
(geist) - M

Locale: Smoky Mountains
Re: Lightening Strong Volt Panel on 11/04/2012 20:24:36 MST Print View

Here is an update on lightening a 6W Strong Volt Panel.
Marco's suggestion turns out to be a good one.

The Solar 6 is made of two panels. Each panel has a metal plate that has a 1/16 think clear plastic poured around the solar cells and adhering to the metal plate.

The metal plate weighs 2.4 oz.
The plastic with cells embedded weighs 1.9 oz.

The first panel I tried a process of clamping the plastic face down on a flat surface and using thin shims to slowly pry the metal plate off the back of the plastic block.
The theory was to avoid flexing the plastic and cracking the solar cells. The process ALMOST worked. Two of the twelve solar cells broke. Studying what went wrong. In a couple spots the plastic that flowed under the cell stayed stuck to the metal rather than staying with the plastic block. when it pulled away from the back of the cell the cell was cracked.

I then tried Marco's suggestion on the second panel. I heated the back of the metal plate with a propane torch (slowly, carefully) testing if the plastic would release from the hot plate. Trying a little hotter each time. It released on my third try.

Hopefully this information will be helpful to other MYOG'ers

Richard Cullip
(RichardCullip) - M

Locale: San Diego County
Got mine in today's mail on 11/05/2012 14:27:51 MST Print View

I went out to get the mail today and had a pleasant surprise waiting for me. It was a box from the Wizard of Oz and inside was his neat little (and I emphasize little)circuit board. Very clean and detailed work. Now I just need to wire it up to the solar panels and get it in action. Thanks for the quick delivery.

George Geist
(geist) - M

Locale: Smoky Mountains
My PowerFilm lightening steps on 11/06/2012 10:07:44 MST Print View

Like Rich my board from Jay came yesterday. I got so excited I started trying to build my own 4 oz USB charger from a 5W PowerFilm panel. I bought my PowerFilm several years ago and found my panel was 1.5 oz heavier than Jay's starting weight. So it looks like I'm going to end up with a 4.9 oz charger in the end.

Here the steps I took.
1. Test the panel and be sure it works before you start cutting it apart
I also weighed my untouched PowerFilm panel and it was 6.9 oz

PowerFilm panel 6.9 oz

2. I used a dremel tool to remove the rivets holding the heavy plug and I removed the velcro (I found the velcro was both glued and sewn on) I put the panel back on the scale and it was 5.6 oz

PowerFilm panel 5.6 oz

3. I carefully slit the top flap to see where the wires ran, pulled them out from under their tape, and out of harms way before I prepared to cut off the top flap and grommets. I drew a line with a ruler and chalk at the bottom hole.

PowerFilm at 5.6 oz showing flap

4. I cut off the top flap and put the panel back on the scale -- 4.8 oz. Given I hadn't removed the bottom grommets, This is almost exactly 1.0 oz more than Jay's panel was at this same point.

PowerFilm 4.8 oz

5. I then set my new charging board about where I plan to install it and my scale reads 5.0 oz with the bottom grommets still on the panel.

PowerFilm panel 5.0 oz

My next step is to loosely wire the board in and repeat my power test head-to-head with a Solar 6 panel only this time using Jay's 90% efficient charger board. It is going to rain here the next two days. So I have to wait for the sun to come back out.

Right now I'm thinking of installing the board inside the panel (between the two layers of canvas) and build a little clear window to see the test button and light. Do folks think this will work OK?

George Geist
(geist) - M

Locale: Smoky Mountains
Re: My PowerFilm lightening steps on 11/08/2012 14:57:17 MST Print View

One more important tip for those following in Jay's wake and lightening the PowerFilm.
Those tiny copper wires coming out of the panel look bare, but are actually well insulated.

The sun came out today and I hooked Jay's board to my lightened PowerFilm to run some power tests and.... no green light. I hooked a volt meter across the two copper wires and got zero volts. Jay's board was fine -- no power was being fed into it. What I discovered (and maybe should have guessed sooner) was that you have to scrape the copper colored insulation off the wires where you hook them to the board.

Just a heads up so the next person doesn't do the same stupid thing I did.

By the time I had the green light and was ready to test head-to-head against a Solar 6,
the sun was going down and so weak I was getting the 15 second oscillation built into Jay's board. Will try again tomorrow to do a comparison test between the PowerFilm and Strong Volt panels.

George Geist
(geist) - M

Locale: Smoky Mountains
Board Oscillation -- Anyone else seen this? on 11/09/2012 12:06:27 MST Print View

> Will try again tomorrow to do a comparison test between the PowerFilm and Strong Volt panels.

Jay, do you have any ideas what might be causing the board to oscillate on and off?
My 5W PowerFilm panel is feeding the board 17.3V instead of the designed for 12V. Could that cause any problem?

Here are the details from my test. Done in bright noontime sun.
The load is my Motorola Razr Maxx phone with battery about half full. Lithium batteries have a pretty flat charging curve in the middle of their range so I wanted to run my tests in this range and not have to account for non-linear effects that are sometimes seen below 20% or above 90%.

Here are the two panels folded up showing the respective charging board sitting on each.


Strong Volt and PowerFilm 5oz with charger boards shown

Here they are unfolded side-by-side in full sun to start the test.


Strong Volt and PowerFilm 5 oz unfolded

First test. My 5 oz PowerFilm: Board switch set to 0.5A. Test button shows green.
Phone plugged in at 12:00 noon with battery power level at 51%
Here is what was observed: Phone screen came on showing "charging"
Charging symbol went out after 1 second. Then 9 seconds later the charging
symbol came back on for 1 second. This cycle repeated for 5 minutes.

After 5 minutes I decided to try the 1.0A switch setting to see if this stopped or at least changed the oscillation being observed. I unplugged the phone, flipped the switch to 1.0A, pressed the test button and got a green light, then re-plugged in the phone.
The charge symbol continued to come on for 1 second, then go out for between 9-10 seconds, then come back on for 1 second. The frequency did not change for 5 minutes.

Phone unplugged at 12:10 with battery power at 48% (drain most likely caused by the screen being held on the whole time and battery charge circuits being flipped on and off in the phone.

Second test. Strong Volt Solar 6 panel
Phone plugged in at 12:12pm with batter level 48%
Screen came on showing charging, after 30 seconds screen time out blanked screen. I turned on the screen every few minutes to check that charge symbol was still on steadily. After 10 minutes I unplugged the phone.

Phone unplugged at 12:22pm with battery level 52%

Third test. My 5oz PowerFilm panel Leaving setting at 0.5A for 10 minutes.
Phone plugged in at 12:26pm with battery level at 52%
Same 1 sec charge, 9 second pause, 1 sec charge cycle observed for 10 minutes
Phone unplugged at 12:36 with battery level at 50%

So my question to Jay and the forum. Any idea what might be causing the cycling?
Any suggestions on what I might be able to do about it?

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Board Oscillation -- Anyone else seen this? on 11/11/2012 17:55:59 MST Print View

What is the voltage to the phone during the 1 second and 9 second periods?

What is the allowed voltage to the phone?

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Board Oscillation -- Anyone else seen this? on 11/12/2012 05:31:03 MST Print View

George!

Sorry for the delayed response, just got back from the Grand Canyon on Saturday night! So the easy answer is...your problem is a feature! I'm sure that's real helpful right...

So the PCB is set up to shut down the 5V output if the input voltage from the panel drops below about 7 or 8 volts. It waits between 7 and 12 seconds before turning the 5V back on and trying again. So the oscillation you are seeing is your device drawing too much current from the solar panel and folding back the voltage below 8 volts. Or conversly, the solar panel cannot produce enough current to support the device at a voltage above 8 V.

Normally, a 5V converter like this would oscillate MUCH faster, and basically it's output would just look like 2 or 3 volts to your device instead of the required 5V. however that can be bad for your device, so the PCB does a completely shutdown and waits a few seconds. I found, especially in the canyon, that even someone walking across the path of the solar panel was enough to lose the voltage, but the PCB safely shuts off the 5V, waits a bits, and then turns it back on properly, so my phone didn't freak out!

Remember that the .5 and 1A switch setting is a control output that tells an Iphone which charging mode to go into. You're RAZR may pull a different current and the 5W panel may not be powerful enough to drive the PCB and your phone, at least in fall light conditions!

Hope that helps, let me know how it all goes, or if I can help out!

George Geist
(geist) - M

Locale: Smoky Mountains
Re: Re: Board Oscillation -- Anyone else seen this? on 11/12/2012 22:27:08 MST Print View

> You're RAZR may pull a different current and the 5W panel may not be powerful enough to drive the PCB and your phone, at least in fall light conditions!

Hi Jay,

I think your assessment is dead on. My experience is that the Motorola RAZR MAXX with its big battery (3300 mAh) just pulls as hard as it can on any charger that is plugged into it; be it a house outlet or solar panel. The 5W PowerFilm panel just doesn't seem powerful enough to keep up with what this phone wants, especially in the low Fall sun.

How was your iPhone charging experience in the Grand Canyon? Where you able to keep the phone fully charged? How long did you have it in the sun each day?

Thanks for the helpful reply.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Board Oscillation -- Anyone else seen this? on 11/13/2012 07:56:51 MST Print View

If it pulls as hard as it can, will it pull less hard if the voltage goes too low?

Then you could use chargers with different capacities.

Another thing is, you could just connect a solar panel directly to phone.

Wizard of Oz
(wizardofoz)

Locale: New England
Solar Panel Provides 6 days of Iphone Fun in Grand Canyon! on 11/15/2012 08:02:48 MST Print View

Sunshine

So here's the skinny on how the whole setup worked in the Canyon! Good to Great! The sun is fairly low this time of year, and I found that I had between about 9AM and 3PM where I had enough power to charge my iPhone 4S in .5A mode. I already knew the panel wouldn't support 1A mode, so I didn't try.

Cedar Point, SK

I was down for 6 days, and because of poor planning, I only had about 60% charge as I headed down from the South Rim. Basically I found about two 20 minute opportunities to charge each day. Breakfast time wasn't sunny enough yet, so I got about 20 minutes when I sat down for lunch, and another 20-40 minutes when I got to camp. Because the sun was so low, I couldn't lay the panel flat on the ground most times, so I often had to prop in up on a pretty steep angle on some rocks especially in the evenings. I was able to charge it up by about 40% each day, but I used about 50% a day (amazingly, since I use airplane mode). So each day, i ended up with a bit less charge than I started with. Turns out that taking videos and pictures all day (and looking at them) takes a drain on the battery! My 4th day, I was able to get into camp early enough to get a full 1.5hr charge on my phone and go from 8% to 100%! That was prodigious since the last two days were quite cloudy and that was the last opportunity I got to charge my phone!

Colorado River, BA

The 'supervisory' circuit did a great job of minimizing oscillations in low light, but there was still a period of time where it would (as George has described) come on and off about every 10 seconds when the light was bright enough to reach 12V when unloaded, but dropped below 8 V when the phone started charging. That on-off cycling, although significantly slowed by the supervisory circuit, does drain the battery a bit as the screen keeps coming on and off with each cycle. I'm sure the amount of drain that the causes will be different for other types of phones.

We did see one other guy who had a solar panel and hung it off of his backpack, he had a goal zero one Nomad 7, but at 12 oz, that's 3X the weight with only 40% more power, so I could add almost 3 more slimmed down 5W powerfilms for that weight and be at 20W for 4+3.2+3.2+3.2 or 13.6 oz! (or course folded out side would be much larger too) I don't know how well his worked, or what he thought of it. However, based on the way the fall sun is and the switchbacks, I think it hanging it off the backpack is very inefficient in the canyon, so I had no inclination to try it.

I have to say, I seriously enjoyed the music each day and the lightweight photo/video capability that my iPhone provided! I got some GREAT pics, and was able to send some text messages from Indian Gardens Campground and the North Rim. This was a fantastic solution for me!

George, glad that last post could shed some light on your issue! Any more progess on the 6W panels? I got a chance to get my hand on a Brunton Solar Panel (very heavy!) at Grand Canyon Village and they use the brittle panels as well. But for the weight, I'd rather use two modified 5W Solarfilm Flexible Panels. Can't wait to hear what your final solution is!

Wizard of Oz
(wizardofoz)

Locale: New England
New flexible solar panel options... on 11/15/2012 08:56:04 MST Print View

Just found another company that makes the flexible panel. can't find too much data on them, but I see a 5W panel for 3.7 oz! I sent them a note asking for more detail on just their new panels.

http://www.solarmade.com/AscentSolarFlexibleModules.htm

powerfilm also seems to have a new DW-80 and DW-160 panel available, at 30mW/square in! which is fantastic, but they don't have the weight posted, so I asked them for that info too.

George Geist
(geist) - M

Locale: Smoky Mountains
Re: More Solar Panel Tests on 11/18/2012 16:11:37 MST Print View

> George, glad that last post could shed some light on your issue!
> Any more progress on the 6W panels?

Hi Jay,

This sunny weekend I got a chance to do a few more tests.

Test 1. Try a smaller load:
I took my lightened PowerFilm panel and your board (total 5oz) and plugged it into a friend's HTC Incredible 2, which has a battery more comparable to an iPhone (as opposed to the large battery in my RAZR MAXX). The board behaved comparable to your experience in the Grand Canyon. Slowly charging the HTC and only oscillating when the light got too low.
During this same test I plugged my RAZR MAXX in during peak sun and it immediately started oscillating. This test gives our readers important information that they are unlikely to be able to charge a tablet with this set up regardless of how long it is left in the sun, since a tablet will also have a big pull and go into oscillation rather than charge.

Test 2. Try half a Strong Volt 6 panel.
I took the 1.9oz panel I removed with heat from the metal plate backing.
Theoretically, it should be about 3W and from my earlier tests should be about equal to the 5W PowerFilm in real power output. I wired it to the Strong Volt charging board. It gave zero output on the USB. OK I should have checked the panel output first. The half panel puts out 3.6 V and the USB board correctly shuts down the output
due to low voltage.

As a followup I measured the voltage of a full Strong Volt 6W panel and it was 7.2 V, which is no surprise. I am surprised it can be that close to the USB 5V output and not pull below 5V under load. But it seems to work very well. Even with the pull of my RAZR MAXX in low sun that was starting to oscillate the HTC with the PowerFilm.

Test 3. Try a different charging board with the lightened PowerFilm panel
I started with this and tore it apart.
elago-Aelago-B


Inside was the following circuit board shown top and bottom.

elago-top
elago-bottom


The board weighed 0.2 oz and when wired to the PowerFilm would actually charge my RAZR MAXX. Not as fast as the Strong Volt panel. But need to more head to head tests before I can definitively say how much faster or slower this set up is.

Stay tuned.

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Re: More Solar Panel Tests on 11/19/2012 08:59:51 MST Print View

George, Sound like you're having fun! Wish I could see the current draw and output 5VDC waveforms you were getting! Yea, An iPad or 1A phone would likely need a 8-10W panel in my estimation to work properly. I don't think the 5W or even 6W panels are cut out for the job, because my experience says that the sun is never 'perfect' enough.

That little .2oz board is interesting! I see the two big caps on there, but no inductor. I'm really curious how that circuit works and what the output looks like. I'll throw one caution at you, that board is expecting a strong 12V from the car, and since it doesn't have the supervisory circuit, it MAY be be oscillating fast enough to fool your phone into thinking it's charging without really adding any power. That is what my circuit did in the early stages as well. A DMM (voltmeter) isn't fast enough to see this as it can be in the 100s of times a second range, but might register it a something less than 5V if you probe the output since it's kind of averaging a pulsed waveform. An Oscilloscope would tell you more. But your further testing of charge time should answer that question.

So I'm confused by something that you wrote. The full Stongvolt 6W panel only outputs 7.2V? That shouldn't really be enough to run my board at all. So how is it charging the Razor with my board? There are other circuits that can use linear regulators to allow something like 5.1V to power a 5V USB, and even boost circuits that allow 2 AA batteries (3V) to power 5V USB, but most circuits expecting 12V are a different methodology and can't go down that low (though they can often go quite a bit higher (like 30-40 V).

George Geist
(geist) - M

Locale: Smoky Mountains
Re: The 0.2 oz board more details on 11/19/2012 16:09:44 MST Print View

> That little .2oz board is interesting! I see the two big caps on there, but no inductor. I'm really curious how that circuit works

Hi Jay,

While I am no electrical wizard like yourself, the heart of the little board is the eight lead IC your see on the back side. That is an XLSEMI XL4001E1, which is pretty flexible DC/DC converter. You can read the data sheet online. On the topside are the two capacitors (35V 47 microF) and (10V 220 microF), a small induction coil similar in size to the one on your board, and an LED that stays on all the time the circuit is charging - a waste of power that your board avoids.

> The full Stongvolt 6W panel only outputs 7.2V? That shouldn't really be enough to run my board at all.

The Strong Volt panel comes with its own USB charging board. That is what I have been using with the Strong Volt panel. You are correct that your board wants at least 8 V from a panel to run.

Hope the explanation of what's on the 0.2 oz board is helpful in figuring out how it works.

Wizard of Oz
(wizardofoz)

Locale: New England
Buck Converter on 11/20/2012 06:06:46 MST Print View

I just didn't see the inductor from the pics. Thanks for the info, I was able to pull the spec sheet. it's a 'standard' boost converter, the little 8 pin IC is the controller that pulses the input voltage to the induction coil. The XLSEMI data sheet has much less info than TI gives for theirs, so I can't tell how efficient it is from the specs.

I would still be cautious that isn't not oscillating or outputing a lower voltage. it doesn't have the protection that mine has to shut off for a few seconds if it can't support the power needs of the charged device, so that one has a 150kHz switching frequency and could conceivable being turning on and off VERY quickly! It's just going to keep trying even if it cant regulate properly.

Keep us up to date!

Aaron Johnson
(merdock69)
Re: Success!!! for 'green' solar! on 11/20/2012 08:26:15 MST Print View

Do you still have any of these boards available for sale?

Thanks!
Aaron

Wizard of Oz
(wizardofoz)

Locale: New England
Watertight USB option now available.... on 11/21/2012 11:03:13 MST Print View

Behold the waterproof USB Connector: https://www.sparkfun.com/products/11582

You can now charge you stuff in the rain!!! MUAHHAHAHA (cynical laugh).

I won't be using it anytime soon for this project, but thought I'd share :)

Aaron, to answer your question...YES! I have one of the original boards , minus one switch I'd have to buy and install. That's the end of the first batch I made, so once it's gone, I'll have to do an order for some more bareboards! Set up your email address and PM (personal message) me for details!

Benjamin Evison
(benevision) - M
Re: My PowerFilm lightening steps on 11/22/2012 23:23:19 MST Print View

Hi,
I have a PowerFilm 5W unit and I'd like to reduce the weight, however I do like the versatility of the lighter socket arrangement because I can run a AA/AAA battery charger off it as well as other devices, including a mini USB charger (rated 5V/1A) which seems to have no trouble charging my backup battery for iPhone: - a 5000mAh unit with dual .5A and 1A usb outputs. While this battery weighs as much as an iPhone in itself, it can provide close to two full charges of my iPhone 4s, which gives me a nice secure feeling...

So, I'm considering:
1/ trimming the PowerFilm's fabric down as shown on this thread,
2/ retaining the original charging board (moved to the rear of the last panel) and
3/ cutting out the waterproof socket/clip arrangement and shortening the cable to the lighter socket considerably, perhaps replacing it with a thinner gauge cable.

I'd be very interested in opinions on whether this is a sensible thing to do, in particular what methods are employed to re-attach the charger boards (original or Jay's new ones) behind the solar panel - are they riveted in place or glued?

Thanks in advance for any advice!

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Re: My PowerFilm lightening steps on 11/26/2012 11:02:39 MST Print View

Ben, out of curiosity, how long does your battery pack take to charge? and how do you like using it? I didn't try one cause of the weight, but I've heard mixed reviews.

There is no 'charging board' persay in the Power Film, I think I posted pictures way back in this thread of what's inside. it's basically just a diode to prevent the panel from DISCHARGING your device in low or no sun. When you drill out the rivets for the big clunkly cord interface and take it off, you'll see the TINY wires from the panels. You definitely don't need the 14 or 12 gauge wires they use to the female cigarette lighter adapter.

Depending on what you want to do, you might want to attach a piece of velcro to the back of the last panel and just put a straight connector on the solar panels leads, then you could add or remove a stripped down female ciggarette lighter socket, or a true charging board for USB, or a AA battery charger unit.

I used some heavy duty fabric tape to attached my board case to the panel, and it holds VERY securely. I wish I knew what type it was, but I threw the box away long ago. it basically is straight glue with thread in that is attached to silicon release paper on a roll. you cut off a piece, stick if on your fabric, and then peel of the silicone release paper so only glue and thread are left, there no actual TAPE part to speak off, just glue! But again if want lots of options, velcro might give you flexibility!

Hope that helps!

Jay

Richard Cullip
(RichardCullip) - M

Locale: San Diego County
Re: My PowerFilm lightening steps on 11/26/2012 15:40:19 MST Print View

Finally starting to play with connecting the Powerfilm solar panel unit to Jay's circuit board and I've got a question about the connection. As said earlier, the insulation on the solar panels wires needs to be cleaned off prior to being connected to the wires on the circuit board. I took a close look at the wires on the Powerfilm Solar Panels and they are actually a twisted bundle of much smaller wires. How did you guys clean the insulation off of this twisted bundle of small wires? Any hints would be appreciated.

edited for spelling

Edited by RichardCullip on 11/26/2012 15:41:55 MST.

Benjamin Evison
(benevision) - M
Re: Re: Re: My PowerFilm lightening steps on 11/27/2012 07:42:16 MST Print View

Jay, its been a while since I charged it from empty with the solar panel but as I recall it took three or so hours in full sun. I really should time it properly for you...

I tend to use the battery pack at night when I'm using my iPhone (camping & writing emails/notes etc.) because I can't stand seeing the phone battery charge plummeting below 50%. I then recharge/top-up the battery pack when I can the next day from the panel.
This battery pack is branded Fission, weighs 155g (5oz?) and has .5A & 1A usb outlets. The label says "for iPad" which I guess is why it will do close to two full charges of my iPhone4s.

I take your point on the lack of a "board" in the Powerfilm, but I expect the diode is worth keeping in the loop. I'm not so handy with things electrical but the various devices I can connect via the lighter socket all seem to require different plugs etc which is a pain - it would be great to have one board which can drive everything...

Thanks for your thoughts on the connector & glue/velcro!

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Re: My PowerFilm lightening steps on 11/27/2012 07:43:55 MST Print View

Richard, it was HUGE PAIN! I don't have an easy answer, but here's what I did. Burnt it off! The key for me was to crank up the iron to about 370. I used external rosin flux and lots of solder on the tip to melt/burn the red coating off. It doesn't shrink back like some speaker wire, so it kinda melts and burns at the same time and leaves black sludge, you have to scrape off with your fingernail because if you use a knife, you'll likely damage the wire! it took about 5 minutes per wire once i got the hang of it to get it cleaned and tinned. I found the flux really helped the solder to 'flow' on the metal of the individual strands and separate it from the coating. But the gob of hot solder gave the heat to actually burn the coating away, and leave nasty black/red plastic and flux residue all over the end of the strand.

like I said, not easy, but I tried a number of other ways, and nothing else kept the strands intact nearly as well. it just takes patience. Let us know how it works or if you find a better solution!

Jay

Richard Cullip
(RichardCullip) - M

Locale: San Diego County
Re: My PowerFilm lightening steps on 11/27/2012 08:14:46 MST Print View

Thanks Jay. I was afraid that you would say it wasn't easy. I've never used a soldering gun/iron so this could be a learning experience for me. I'm waiting to hear from George and hoping he found an easier way. If not, I'll try your approach to burn and scrap the insulation off without burning down my garage and house ;)

George Geist
(geist) - M

Locale: Smoky Mountains
Re: My PowerFilm lightening steps on 11/27/2012 10:40:13 MST Print View

> I'm waiting to hear from George and hoping he found an easier way.

Hi Richard,

I lightly scrapped the insulation off with my pocket knife. The bare metal is silver so it is easy to see your progress. The process of scrapping flattens out all the little wires. I flipped it over and scrapped the other side as well. I didn't worry about getting every bit of insulation off. I just tried to be sure that every little wire had bare metal exposed.

Let us know how your lightening process goes. How light you get your solar charger and how well it works to keep your phone charged in the field.

Richard Cullip
(RichardCullip) - M

Locale: San Diego County
Re: My PowerFilm lightening steps on 11/27/2012 16:51:07 MST Print View

I combined the burning method with the scraping method and it worked well. I just singed the end of the wires carefully with a mini Bic lighter and then scraped off the burnt insulation. Quick and easy and no fuss. However the sun went down before I could connect everything up and test the charging. I did confirm that the solar panel was putting out voltage and my wire cleaning attempt did no harm. Perhaps tomorrow afternoon I can test out the USB circuit board and plug in my iPhone 5 for charging. Is there a way to test for the 5V output on the USB circuit board before plugging in my iPhone?

P.S. My trimming must not be a severe as Jay's or my board is heavier. I have not taken off the velcro strip yet (the last thing I have to remove) and the solar panel plus USB circuit board is current weighing in at 5oz.


edit - added current weight info

Edited by RichardCullip on 11/27/2012 16:53:37 MST.

George Geist
(geist) - M

Locale: Smoky Mountains
Re: My PowerFilm lightening steps on 11/27/2012 17:40:28 MST Print View

Hi Richard,

My lightened panel (including velcro removed) with USB board is also 5.0 oz. In my case I weighed my panel before starting and it started out a little over an ounce more than Jay's. Your PowerFilm panel may have been a little heavier to start with as well.

Al

Richard Cullip
(RichardCullip) - M

Locale: San Diego County
Re: Re: My PowerFilm lightening steps on 11/27/2012 17:49:27 MST Print View

Thanks Al. My apologies for calling you George in previous posts and PM's


P.S. I'm going to show my ignorance here and ask, is there a proper way to connect Jay's USB charging circuit board to the PowerFilm solar panel? In other words, is there a possibility of connecting the solar panel to the circuit board backwards - wrong solar panel wires to the 12V input (red wire) and the GND (black wire) on the circuit board? I didn't pay attention when I originally clipped the solar panel wires.

George Geist
(geist) - M

Locale: Smoky Mountains
Re: My PowerFilm lightening steps on 11/28/2012 19:29:18 MST Print View

Richard,
Yes the board can be hooked up wrong. You need to get your volt meter take the panel out into the sun and hook the wires to the meter to determine positive and negative

let us know how well the panel charges your phone

Richard Cullip
(RichardCullip) - M

Locale: San Diego County
Re: My PowerFilm lightening steps on 11/29/2012 15:07:32 MST Print View

Making slow progress. I found my wiring error (had it wired up backwards) and now can get the green light to come on and signify success. Verified that the output is 5V. However, due to a cloudy day down here in San Diego this afternoon, I haven't been able to run it long enough to get any battery charge into my iPhone5. For the brief moment that the sun peeks thru the clouds, I get the green light and the phone signifies that it's charging but this only lasts a short moment before the sun hides again and the unit fails to generate enough power. I'll have to wait for a sunny afternoon to complete the charging test. This has been fun and I'm relearning lots about electricity and circuits. It's been an enlightening experience.

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Re: My PowerFilm lightening steps on 12/03/2012 08:27:07 MST Print View

Rich,

Glad to hear you're making progress! Yea, as was said, it can, but shouldn't, be hooked up backward. I honestly don't know if it can cause any damage to the board, as I've never tried it. It's fairly low power from the Powerfilms, so hopefully it's ok.

I will throw out there, that a standard incandescent lightbulb (not a flourescent) can generate a small voltage on the panel to allow you to check the polarity in the house. I think I got between 1.6 and 3.5V on my panel indoors, which wont run the board obviously, but is enough to measure the leads with a DMM and label them. I just marked the negative wire with a black sharpie since they are orginally red (or at least mine were). That way if/when I change panels, I'll know how it was and not have to measure each time.

The winter sun is DEFINITELY way less powerful here in New England (I'm in MA). I think that for winter use a heavier 10W panel may be helpful, if not necessary.

Jay

Richard Cullip
(RichardCullip) - M

Locale: San Diego County
Re: My PowerFilm lightening steps on 12/04/2012 11:58:45 MST Print View

The good news - The sun finally came out in San Diego and I got to run the first test charge into my iPhone5. Without the phone plugged in, I get a nice steady green light and the USB connector is putting out a nice steady 5V. No flucuations, just a nice steady green light. Both the solar panel and the circuit board are working as designed. Things are looking good.

The bad news - as soon as I plug in my iPhone5 the circuit board and iPhone5 go thru the same 1 sec on, 9-10 sec off cycle that George's (or is it Al's) Motorola Razr Maxx Phone experienced. The circuit board is set to the 0.5A option. In spite of a good strong sun and clear no cloud day, the system won't charge my iPhone5. Bummer. I might need the larger 10W panel to handle the charging needs of an iPhone5.

Any thoughts?

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Re: My PowerFilm lightening steps on 12/04/2012 13:50:38 MST Print View

Aren't you supposed to be in 'sunny' california :)

Fake Suggestion: Downgrade to an iPhone 3G...I think they take less power

Real Suggestions:
1. So I wonder if you have a bad panel in your 6 panel powerfilm, cause I would think at your latitude, that if I can charge in AZ with the same panel, you should be fine. You've probably already done this, but to check it. Clip a voltmeter onto the panel leads that go to the board (you can leave it connected to the board, just don't plug you're phone in. So you should get the green light. Measure the voltage to the board, it should be just under 20V! Then take a strategically cut piece of plane white paper, and cover just one of the 6 power film panels. You should see the voltage drop to the board, record that change for that panel. Remove the paper, see that the voltage goes back up, put the paper on the next panel, see that it goes back down about the same amount, and repeat. You might find that your total voltage out of the unloaded panels is low, and/or that covering one of your panels does not change the output voltage to the board by as much as other ones indicating a poorly performing panel or panels.
*****Most solar panels will drain energy from the system if they are damaged, so it's very important to know! With the same 5W powerfilm, my setup would NOT charge my iPhone 4S at .5A when any single one of the panels were covered! A bad or covered panel not only doesn't produce power, but sucks power, so it's a double hit.


2. The angle of the panel to the sun is VERY important. I'm sure you tried many placements, but I found in the canyon that 10AM to noon sun was the best even though I had to have the panel at a steep angle to catch the low sun.
*****The easiest way to gauge if your angle is right is to make sure that SHADOW it makes on the ground is a perfect rectangle or is is a trapezoid! I always held it up to see the shadow and get the angel in my head, I made sure the phone would charge at that ideal positioning, then I looked for a place to leave it in the same orientation for a while.


3. I haven't tried it, but I've heard of some guys using mylar or tinfoil wrapped cardboard to make a lightweight reflector to direct additional sun to the panel! If you try this, let us know how it works! It's probably not a permanent solution for you, but might give you some insight if the above stuff doesn't help.

Keep us posted!
Jay

Richard Cullip
(RichardCullip) - M

Locale: San Diego County
Re: Re: Re: My PowerFilm lightening steps on 12/04/2012 15:50:38 MST Print View

Thanks for the troubleshooting tips, Jay.

I did manage to measure the total voltage on my PowerFilm unit, before the clouds rolled in this afternoon, and it came in ranging btwn 18.0V and 18.8V, depending on the angle with the sun. Didn't have the opportunity to test individual panels but I should be able to, weather permitting, take that step tomorrow. Currently it looks like my panel is not only a bit heavier (by an ounce) than yours but it may also be under powered. (Frownie Face icon goes here)

George Geist
(geist) - M

Locale: Smoky Mountains
Re: My PowerFilm lightening steps on 12/04/2012 22:46:30 MST Print View

Hi Richard,

Given that your and my 5W PowerFilms have the same behavior, I'm inclined to say that ours are not underpowered. Our's are probably normal and Jay's PowerFilm is a bit more powerful. In strong noontime sun my panel produces a little over 19V, but it won't charge my RAZR MAXX smart phone. I plug it in and I just get oscillation and battery discharge.

I'm going out with the scouts this weekend and I'm going to take my StrongVolt Solar 6 panel with me and see if I can keep my RAZR MAXX charged.

Richard Cullip
(RichardCullip) - M

Locale: San Diego County
Re: My PowerFilm lightening steps on 12/06/2012 23:01:33 MST Print View

I have not yet been successful charging my iPhone 5 with my 5W PowerFilm Solar Panel and Jay's nifty little circuit board. This has led me to wandering around cyberspace reading lots of info on charging an iPhone 5. I have not yet reached the end of the Internet but I think I'm close. As best I can tell, Apple changed something in the iPhone 5 (or maybe in the new 9-pin lightning connector the iPhone 5 uses). The change renders useless some chargers that would charge an iPhone 4. I wish I could find the details on the change but reliable info has been hard to find. There's some speculation that the iPhone 5 requires 1A to charge. Other speculation is centered on the idea that an iPhone 5 talks to a charger differently than an iPhone 4 and is more stringent about accepting chargers than the iPhone 4 was. Wish I had an iPhone 4 to plug into my PowerFilm/Jay's charging circuit board to see if my setup will charge an iPhone 4.

Edited by RichardCullip on 12/07/2012 10:09:39 MST.

Wizard of Oz
(wizardofoz)

Locale: New England
Iphone 5 charging and New Board Case on 12/11/2012 06:55:00 MST Print View

I'm trying to catch a friend of mine with an Iphone 5 to run that test to see if the switch works with the new Iphone and cable or not, to adjust from .5 to 1A modes. I'll let you know!

Some folks wanted the case that I made for the Canyon, and taking some lessons that I learned, I've updated the orignal case design to slim it down a little and give better access for the buttons and switches. I think it looks sweet! I'll post real pics when it comes in!

Updated case

Jay

Richard Cullip
(RichardCullip) - M

Locale: San Diego County
Re: Iphone 5 charging and New Board Case on 12/11/2012 08:40:52 MST Print View

Jay, I'm trying to run down an iPhone 4 to borrow for a sunny hour or so to test my panels/circuit board setup. I'm still wondering if the new iPhone 5 Lightning connection is doing something your circuit board doesn't like (e.g. draw enough current at handshake that your board drops below the 7-8 volts and shuts off) or if there's something funny about my solar panel. I'm getting ready to sacrifice a short USB extension cable to allow me to measure the current being drwan by my iPhone 5 as it get plugged in. However, I'm not sure my simple (cheap) multimeter and electrical skills are up to that task.

BTW - nice looking design on that case.

Ryan Lusso
(Loosenuts)

Locale: Pacific Northwest
Wiz - are still making these? on 12/26/2012 23:57:04 MST Print View

Wiz,

Awesome project you took on. I'm not too good at the electronics. Would this work for a Samsung Galaxy note 1? Wondering if you are interested in selling one that works on a Galaxy note and iPhone? I have some ultra light stuff for trade and/or cash - titanium MYOG caldera cone keg and stuff like that. If you are still tinkering with this and interested please drop me a note.

Thanks

Wizard of Oz
(wizardofoz)

Locale: New England
Re: Wiz - are still making these? on 12/30/2012 16:11:12 MST Print View

Yea Definitely! It looks like the Galaxy Note 1 charges off of a micro-USB, so as long as you have the cable that plugs into your computer's USB to charge it, than it'll work! The key is to take a look at your phone, car, and wall charger and get an idea of how much current it draws. This board can control a max of 1.3A which is good for most phones, and some tablets like the iPad, BUT YOUR SOLAR PANEL HAS TO MEET THE PHONE'S CURRENT REQUIREMENT. For an iPhone, it can be set by the board for a .5A mode, but folks still find that a 10W panel is good idea if you're not in max bright sun (which can be hard to find!)

I'm working on getting a website together, but it's slow working out all the details! hopefully it'll be up the next week or so. But we can talk over PM and figure it out. I've got a couple board ready to go!

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Iphone 5 charging and New Board Case on 12/30/2012 16:19:07 MST Print View

"I'm not sure my simple (cheap) multimeter"

As a general rule, the really cheap multimeters are operated by those with poor multimeter skills, and those can get toasted in a hurry. As you move up to a slightly better multimeter, it will likely have some better scales for amperage (current). That is pretty handy once you start experimenting with solar panels.

You can troubleshoot a lot with just a voltmeter, but the current scales are much more useful for measuring just how perfectly the panel is working.

--B.G.--

Wizard of Oz
(wizardofoz)

Locale: New England
New Case Design is in! on 12/30/2012 16:31:07 MST Print View

Got two colors of the new case in. It's just a bit slimmer, much nicer finish than the original case, and allows for easier access to the switches without having them stick out and get caught on gear. The lettering is no longer extruded so it's easier to get in and out of the pack too. It doesn't snap shut, so I expect to use a small bit of silicon to seal it up and am contemplating looking for some really flexible clear silicon to really make it water resistant!

I've got 6 colors available to me but got two colors to start. Here's the red, this is a laser sintered material and is strong but still a bit flexible. It's got a nice matte finish.

Red Case

same in white but this is a very smooth, shiny material. The detail is really nice, but it's more expensive and heavier.

white

This gives you a feel for the 2 parts of the case, and the size relative to the board.

2 parts and board

Edited by wizardofoz on 12/30/2012 16:34:31 MST.

Stuart R
(Scunnered) - F

Locale: Scotland
Re: Project: 4oz 1A USB Charger on 12/31/2012 05:23:16 MST Print View

As I mentioned on page 2 of this thread, the big problem with a standard voltage converter is that there is no limit to the amount of current it will try to draw from the solar panel. If the combination of panel area and incident sunlight is insufficient to provide the power demanded by the load, the voltage converter will short circuit the solar panel and almost no power will be delivered.
Large commercial instalations avoid this problem by incorporating an electronic circuit (usually a microcontroller) which performs Maximum Power Point Tracking - so the panel output is always maintained at the voltage/current that provides maxumum power from the available light.

MPPT diagram

I have designed a simple modification to a standard LM2596 regulator circuit that will perform a simple form of Maximum Power Point Tracking. Parts are on order and I'll start a new thread when I have something to show.

Edited by Scunnered on 12/31/2012 05:31:27 MST.

Wizard of Oz
(wizardofoz)

Locale: New England
MPPT Idea on 12/31/2012 06:23:19 MST Print View

Definitely post the thread link here, I've very curious to see what you come up with. MPPTs are usually used in very large arrays and require a secondary conditioning step because they inherently vary the output voltage, and we obviously need a fixed 5V output for USB devices.

"If the combination of panel area and incident sunlight is insufficient to provide the power demanded by the load, the voltage converter will short circuit the solar panel and almost no power will be delivered" So if the panel and sunlight is insufficient for the load, how will the MPPT find the missing power? The problem in this case is lack of panel surface, right?

I've looked at this option (such as the SPV1040), but found greater efficiency with a step-down converter.

Keep us posted on your progress!!

Stuart R
(Scunnered) - F

Locale: Scotland
Re: MPPT Idea on 12/31/2012 07:23:11 MST Print View

"So if the panel and sunlight is insufficient for the load, how will the MPPT find the missing power? The problem in this case is lack of panel surface, right?"

Yes, MPPT can't find power that isn't there, it can only deliver the maximum power that is available. It does this by controlling the output voltage/current, so in the case of a USB output, the voltage will drop below 5V. From wikpedia: "A USB charging port supplies up to 500 mA at 5 V, up to the rated current at 3.6 V or more, and drop its output voltage if the portable device attempts to draw more than the rated current." so dropping the output voltage is permissable. Whether an i-phone will accept that is another matter. However, I was thinking more in terms of charging AA NiMh directly and MPPT would simply have the effect of varying the charge current.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: MPPT Idea on 12/31/2012 13:56:27 MST Print View

"charging AA NiMh directly"

That also gets a little complicated since different NiMH cells require or tolerate different charging voltages, currents, and time. You want to consult the manufacturer's specifications for cells of this type, but in general you want to get a charging current that is approximately 5% to 10% of the cell's maximum output current. In other words, you charge the cell at 10 times or 20 times slower than you can use up the charge. Some people try to charge the cell much faster than that, and they toast the cell chemistry. Not recommended.

--B.G.--

Richard Cullip
(RichardCullip) - M

Locale: San Diego County
Re: iPhone5 success at last on 01/08/2013 13:46:03 MST Print View

As best I can tell, my first PowerFilm panel was underpowered and wouldn't charge my iPhone5. I was curious enough to find out why, so I bought another PowerFilm panel and this one works. Wired up to Jay's neat little circuit board, this new panel has enough power to charge my iPhone5. Today, in the noontime bright winter sun in San Diego, my iPhone5 went from 89% charge to 99% charge in 30 minutes with no problems. It never went thru the low voltage shut-down cycle that plagued my first setup.

The big difference in the two panels is that the first (bad) panel has 17.65 volts with no load. The second (good) panel has 20.5 volts with no load.

During testing, the good PowerFilm panel and Jay's circuit board had 4.95 volts and .471 amps thru a 10ohm resistor and 4.95 volts and .097 amps thru a 50ohm resistor.