Im looking for a light weight solar charger for kindle and camera and probably GPS at some stage in the future. Ive looked through old threads, but theres not many new threads as of late and the way technology changes I thought its time for a new thread :)
So, whats the latest and lightest solar charger?

I haven't tried this, but these "how to" instructions describe a self-built solar power charger for usb-powered gadgets.

I prefer to purchase a complete unit if possible...I remember playing around with electronic circuitry as a kid and building a few things, however not as of late.
I would probably blow something up today!

Richard, before you go shopping too far for a solar charger, you want to get a good grasp on how much charger output you need.

If you say, "I need +5 volts, 1 amp, for one hour per day" that means something.

If you say, "I want to charge my Kindle and my camera" then that means nothing at all.

--B.G.--

Sorry for not being tech savie...but how do I work out that?

Look up the specs for your devices. How much capacity in miliamps. How much do you use per day (not perfect way to do it) percentage-wise. Do they last 1, 2, 3 days, etc.? Now you can figure out how much you need to but back in. Ohm's Law is the basic formula for calculating electrical stuff... a little research and study on the Web or other places will be beneficial.

Additionally, you need to take the solar charger specifications with a grain of salt. Often they quote some good numbers, but you won't get that kind of maximum performance unless you are sitting in Nick's backyard in perfect sunny weather. I've engineered some larger systems, and I always throw in a +50% factor to account for less-than-maximum solar output.

--B.G.--

Excellent point by Bob. You need to look at your latitude, time of year and weather. All big factors.

For example my tent trailer's solar system can recharge my batteries in a couple hours after a lot of night use... under ideal conditions. But I have a large battery bank (250 amp hours) and a 250 watt solar array. That way if it rains for a week I do not have to be concerned about power (no sun), I have plenty of battery reserve and when the sun comes out can recharge it fairly quickly.

Now if you have a nominal system, when backpacking, that can only replenish what you use under optimum conditions and no method for reserve capacity, you are going to end up with some dead batteries.

I have a GoalZero panel and battery pack but have not really played with it much (it was a gift). If I were to bring electric devices backpacking I would probably be better off with spare batteries and on a long trip like the PCT would recharge at stops in town. Unfortunately the most popular phone, the iPhone, has an internal non-field replaceable battery... a big negative for that device.

Yes, Nick. You can get into all sorts of things like sun angle.

If a backpacker intends to do solar charging on the trail, then he needs to factor in whether he is north-bound or south-bound, because the sun tends to be in our southern sky.

I agree that most often, the best solar charging solution for a backpacker is none at all. Replacement batteries are often lighter in weight. Or, if you can't replace them, a "battery brick" can be used to charge up smaller devices.

I was on a 25-day trek one time, and I kept my cameras going with a whole pocketful of lithium primary batteries.

--B.G.--

You said that you want an off-the-shelf charger, I realize, but it might be prudent to see if you can have someone make one for you. Small photovoltaic cells are now available with better than 20% efficiency, but you will never find any stock USB solar charger incorporating PVs with efficiency greater than about 8-12%. Some remote-control airplane enthusiasts with electrical engineering expertise have posted on online RC forums about extremely lightweight and efficient solar chargers for RC airplanes. These would be far lighter per unit power output than any stock solar charger that I know of.

Wired reviews four portable solar chargers in an article dated January 31, 2012 here.

http://www.wired.com/reviews/2012/01/reviews_roundup_solarchargers/

On the face of it, the Freeloader Pico looks good. And only 49 grams.

http://www.solartechnology.co.uk/shop/freeloader-pico.htm

Has anyone had experience with these?

Edited by GreyBeard on 12/17/2012 20:44:03 MST.

That Pico thing looks cool but 50g? No way that's the weight *including* the battery.

I suspect they're playing games. Seems too good to be true.

Though they DO say 14 hours to charge an ipod... which wouldn't really work in winter.

Hey Richard,
I spend alot of time out in the bush, and take my Galaxy Tab 7 and phone and as I normally go solo I get bored at night and want to watch movies to pass the time. A few years ago I looked into solar and what I ended up getting was a rollable solar panel ( 28watts) and then a universal battery pack ( rated at 75 watt hours ). I can recharge the tablet about 4 times and if I just use the iphone for movies I can recharge around 6 times. Usually I can just take the battery and it will last a week. But..... What you should realize is that to fully recharge even AA batteries and a smartphone or a tablet, you need full sunshine and many hours.My recommendation would be to go on Alibaba and look at the foldable panels that are available from China. They will sell samples real cheap, I would look at something at least around 30 watts. Then the battery pack you can get from Alibaba as well. Look for a universal pack of at least 40 watt hours.
The big trade off is power vs weight. Unfortunately here in Australia there are very few options available and of the ones that are, they are all overpriced. Another good site to look at would be powerenz from the US and also Modern Outpost from Canada.
Hope this helps,
Matt

Edited by mattgugel on 12/18/2012 00:05:58 MST.

Leave it to BPL members to come up with something.



http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=68387

I've given up on solar chargers. They just seem finicky at best and I found myself fussing with them way too much to try to get them working right.

Instead, I carry 1-2 Anker 5600mAh external batteries which weigh 4 ounces each and are rather small. They cost around $30. Each one gives me about 3 complete iPhone 5 charges. On a 3 day trip, I'll take one. On a 7 day trip, I'll take 2. They've given me the reliable power that I need.

http://www.amazon.com/5600mAh-External-Battery-Charger-Flashlight/dp/B005K7192G

Edited by fiestabuckeye on 12/18/2012 11:13:36 MST.

We brought a solar charger with us while bike touring. Every time we went under a tree, the solar charge would kick out and kick back in. My phone turned off and on each time it sensed it was being charged, and used more power than we gained.

Never again.

Max,
That's the problem with solar chargers that feed directly to the device. I had the same problem. It was like I was plugging in and unplugging my device constantly and having the screen turn on.

Ideally, the best setup would be a solar charger like the Joos Orange which has a 5400 mAh internal battery. The solar panels charge the battery and you feed from the battery which creates a more consistent charge. That's a great solar charger, but at 24 ounces, it is not really an option for most of us that are weight conscious.


http://www.youtube.com/watch?v=wnk-3R5IbFM

Edited by fiestabuckeye on 12/18/2012 12:15:31 MST.

For those who have not been paying attention, the solution to this is called a charge controller. Some solar systems have the charge controller features built in. Many don't, because that means extra cost and extra weight, but not by much.

In 1997, I was visiting a solar installation owned by a Sherpa at 14,000' elevation in Nepal. Even he recognized the need for a charge controller, so he leaned on me to get him one. Upon my return to the States, I got him one and had it hand-carried to him.

--B.G.--

I recently purchased the Powerfilm folding charger from gofastandlight.com. I haven't used it, so I cant give you any feedback. But it does charge two AA batteries or you can charge direct. At 6.6oz thats much lighter than most out there.