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!

> 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.

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.

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.



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!



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!

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, 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.

Inside was the following circuit board shown top and 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.

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).

> 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.

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!

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

Thanks!
Aaron

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!

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!

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

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.

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!

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

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 ;)

> 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.

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.

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