From what I recall(looked in to this a while ago) hand crank chargers are cheaper and more efficient. They also give you something to do in your tent.

I looked into hand crank chargers extensively and I really wanted them to be the answer. Unfortunately, they just don't put out enough power for much of anything. The commercially available ones put out enough juice so that 10 minutes of cranking gives you 1-2 minutes of talk time on a cellphone. What they don't tell you is that as soon as you put a load on them (cellphone battery), they get HARD to crank. If you can actually do 10 minutes of hand cranking on one of those things without grasping your wrist / elbow in pain or running out of breath, I'd be very surprised.

And of course, the question is about charging a laptop - no way. Way too hard.

Treadle power looks more interesting (your legs are a lot stronger than your arms, and treadles seem to be more efficiently designed) but the so-called portable units are still huge and very heavy.

I have thought about making a flexible solar charger using something like this. Weight is .8oz but even after you add a cable & voltage regulator it should be quite light. A non flexible crystalline cell would be almost 2x the efficiency but I would have to build a frame to keep it from breaking.

Edited by Bender on 01/15/2010 13:40:52 MST.

Bradley, that's good to know thanks for the info. I guess there's a market for everything hand cranks are as cheap as 15 bucks (now I know why) while solar can get quite expensive. It would be nice to have a cool solution in place. But personally I like getting away from technology. The only technological comfort I need out there is the cold sidearm resting next to me :)

Hugo, Just a thought... I reread your initial post and noticed you're bringing your laptop for mostly gps mapping software. For the cost of the solar and charger etc. could it not prove to be more cost/weight effective to just get a different GPS system that includes that in its list of features? Then you can just bring extra batteries.

It's just not sounding like charging up a laptop battery is very practical.

Edited by Vertigo on 01/15/2010 14:35:18 MST.

I was hiking along a trail one time, and I came up behind another hiker who had some apparatus hanging over his pack. I glanced at it and couldn't figure out what it was, so I asked, and the other hiker told me.

It was a Pelton Wheel. This was a very small-scale hydro turbine generator. This guy knew exactly where he was going to camp by a roaring stream, and he knew exactly where he was going to place the Pelton Wheel, and he had a good idea how many watts it was going to generate. I don't think he was going to run a toaster on it, but he had some ideas with lights and stuff.

The Pelton hiker and I parted ways at the next trail junction, so I never got to see it work. You think a crank or a PV panel are impractical, just go put up your own Pelton Wheel.
--B.G.--

I use this model:
http://store.sundancesolar.com/pow15v100maf.html

to charge this:
http://www.sparkfun.com/commerce/product_info.php?products_id=8484

via this:
http://www.sparkfun.com/commerce/product_info.php?products_id=726

I'm going to be using this setup to maintain my iphone for an upcoming thru hike of the Arizona trail. The panel is overkill in terms of voltage and I regulate it with a 5v regulator but the benefit is that it charges the battery with even the slightest ambient light.

Hi Dean

Yeah, I have that problem. Sorry about that.

But I don't mind if someone wants to contradict me bluntly - it's a free world. I might even be wrong (utterly unlikely of course, but let's not be too dogmatic about it :-) )

About all I can say is that when I do sound like that, I have usually,/i> spent some time checking my facts. Nothing worse than having to eat one's words later :-)

In this case - yes, I have spent over 30 years doing and supervising electronics design at a fairly technical level. It can be fun.

Cheers

"But I don't mind if someone wants to contradict me bluntly - it's a free world. I might even be wrong (utterly unlikely of course, but let's not be too dogmatic about it :-) ) "

Remember, on the Internet, nobody knows that you are a dog.

--B.G.--

Brady how flexible is the encapsulated film cell? I may make a phone charger for bike trips. Hanging it lengthwise on my Camelback would work well for sun position since my back is closer to parallel than it would be hiking.

FYI the SUL backpackers have nothing on the weight freaks over at rcgroups.com :) Can you imagine sub 10g for a solar powered RC plane or non solar planes in the 200-500mg range!

Edited by Bender on 01/19/2010 15:26:09 MST.

Bender,
It's very flexible, however I have since bought this panel for my wife's charger:
http://www.sparkfun.com/commerce/product_info.php?products_id=7845
and its performance in our particular application is better than the larger panel. Its cheaper too! And plug and play with our charging circuit (no voltage regulator needed).

I just ordered (3) of these:
http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=12269
which I will wire up in series to max out my charger (300mA). I'll report back when I've done some testing.

Edited by bfulton on 02/10/2010 15:17:00 MST.

So guys the last I seen of any netbooks small enough in design and internal spec to recharge via solar was the Gyy but all I can find are year-old press releases. Google doesn't even seem to index the Spanish company's site anymore.

So instead I find a how-to - here

I don't know much about electronics offhand but for those who are is such a system possible?

I appreciate those enthusiasts who are probably horrified at taking all this electronic junk but for me personally I *need* to bring a machine, not for staying in touch but for saving data etc while out in the wilderness.

Edited by rutherford on 08/06/2010 19:14:57 MDT.

The first question that comes to mind is: is a laptop the right device?

Hugo, you said you wanted to use Google Earth coupled with a GPS device. Can you use Google Earth in an offline mode without access to the Internet and still have the map detail you need?

Secondly, I think an iPhone or iPad could meet your needs but I'm guessing you don't want to spend $500 for the solution.

Mike

Hi Nick:
I am very interested in your comment on a tent trailer with solar that allows you to be self-contained indefinitely. Could you please provide a company name, or any additional information? Thanks! I travel self-contained by bicycle indefinitely, so this would be great for me! Diane

If you have a tent trailer with a lead acid battery, you can get a solar panel intended for home use - maybe 50 watts, $200, 3 feet x 2 feet, battery is maybe 50 amp hours so it takes maybe a couple days to charge, you can connect it directly to the battery - at least that's what I do - you have to disconnect it during the night or if it gets fully charged - helpful to have a volt meter to see when battery is charged fully so you don't over-charge

Find an article in some RV magazine

If you are going to use a solar panel of 50 watts, then you really want to hook it up to the battery with a charge controller. That way, you don't need to fool around with night disconnections, volt meters, and all that.

It works like a voltage regulator.

--B.G.--

I will be trying this out labor Day weekend. I will post up my thoughts. They do claim that their recharge rates are based on real world experience, not simply specs.

@ Brady
Did you ever get the three solar panels to work in series?
http://www.bgmicro.com/PWR1241.aspx

Curious if you have any instructions for the rest of us looking to do something similar :)