AAA solar battery charger

[Paul Weiss]

Does anyone use a solar battery recharger for extended tours?
I will be using AAA only.
Weight, charging time and weather resistance are factors.

[d k]

We had a AA solar charger once and it was pretty inefficient – never got a good charge from it. Recently picked up a windup 3-LED flashlight from Costco to keep in my car that does not need batteries (1 minute winding gives 45 min light). It is not UL (I think about 5 oz) but I would take that on an extended trip rather than solar recharger and batteries.

Similar to this:

http://www.x-tremegeek.com/templates/searchdetail.asp?productID=7022&sk=MX51419

[John Chan]

Don’t forget that you only have so many daylight hours during the winter… and if those hours are overcast then you’re pretty much pooched.

There’s no really practical alternative to having a small inverter generator (1000 W) if you want wilderness power. Even the “power packs” with AGM sealed cells weigh more than a modern 1000 W generator.

So maybe someone should start another thread in the “chaff” section.

UL Watts

[David Wiesenfeld]

Brunton makes a set of solar chargers, one of which looks like it has a built-in AAA battery charger and is the sturdiest of the group – weights 19oz though. http://www.brunton.com/catalog.php?subcat=7

The hand charger does sound more reliable though, and it would give you something to do on long nights as well as work out arm muscles that don’t normally get much use while hiking. Definitely multi-purpose.

[Ryan Faulkner]

My dad has a foldable Brunton solar port. the first one he got was a dud, it just dident work, this was a liitle bit of a problem for him because he was leaving for philmont the next week. but luckily, he got Brunton to replace it in time for his 100 mile philmont trip. he used it with the battery charger for his GPS and also tested out the phone charger for his blackberry.

no complaints about the prouduct or the Brunton customer service. ( alittle heavy in my opinion so I would look for a lighter option but for everyone else not as weight obsessive as me, it is a great prouduct)

[Douglas Frick]

>Brunton makes a set of solar chargers, one of which looks like it has a built-in AAA battery charger and is the sturdiest of the group – weights 19oz though.

Weight is 21.2 oz including the BattJack charger (required to charge batteries). I didn’t have much luck with mine in overcast conditions, although it might charge AAAs easier than AAs in less than optimal conditions.

I wish Freeplay would make a battery charger from their 7 oz winding cell-phone charger.

[Stephen Stone]

Here are a few solar rechargers to consider. The lightest is a AA (sorry, not AAA) recharger that weighs in at less than 3.5 oz (minus batteries) and can charge 2 AA batteries in 4 hours. Bearing in mind that you wouldn’t expect to totally drain a headlamp – or the Steripen – in a single day’s use, this should present no problem in terms of recharging time.

AAA chargers weigh more, because they require a special AAA holder. Much heavier, but still less than 1 pound.

In case you view this type of charger as a “toy” or not something to be used in the field, all of these chargers were developed and are currently in use by the military in Iraq and Afghanistan.

Web Site: http://www.powerfilmsolar.com/products/military/foldables/index.htm

[Craig Shelley]

http://solarworld.com/specials.htm

This supposedly charges 2-4 AA or AAA batteries. They also state it weighs 1.5 OZ. The price is $25 versus $150 for AA PowerFilm charger mentioned above.

I don’t know how well it works. I’m very interested in solar recharging but haven’t done it yet.

Craig Shelley

[Ian Rae]

seems to me that in order to charge a AAA battery, all you need is something conductive to make the AAA the same length as the AA. This could essentialy be a round “plug” wrapped in foil. The voltage of a AAA and AA is nominally 1.5V. In fact, you should be able to use any of these solar or wind up chargers as long as they are the correct voltage, and you can come up with a way to connect the output wires to the batteries. For example, if your charger puts out 3 volts, you could simply put 2 batteries in line to charge them. Alternatively, you could reduce the voltage by adding the correct resistor in line. This seems like an ideal place for some of you MYOG wizards to do some cool stuff.

Oh, here’s another idea… take a Lithium Ion battery pack out of a cell phone, and have that run your headlamp. As we all know about the benefits of lithium batteries, this seems like a better option than recharging Ni-MH batteries anyway.

[Mike Barney]

One area you want to be careful with in putting a smaller battery into the charger designed for a larger battery(s), is the charging rate.
Example: An AA battery may have a capacity of 2400 maH, a C 4000maH, a D 8000maH and an AAA battery may have a capacity of 800 maH.
The batteries typically like a charge rate of no more than their capacity divided by 20 or 10, typically stated as c/20 or c/10. By putting an AAA battery in the AA/C/D charger, you may exceed the charge rate. This is typically not a big deal once or twice, it just means the battery is going to get warmer than normal, and may not charge to full capacity.
The real issue is to avoid heating up the battery during charging.

Doing this repeatedly however, will cause the battery chemistry to change and the battery will exhibit diminished performance until it dies.
I have seen in an emergency, a rechargable AA 1.5v battery recharged with a 12V car battery in *seconds*, but you run the risk of an explosion worst case, or seriously damaging the AAA battery long term best case. (***Don’t try this at home without the fire department and EMT’s present / do so at your own risk***)

That’s probably why the SPC-2A charger from solarworld referenced above doesn’t spec AAA batteries, but does support AA, C and D.

[Paul Weiss]

One I have been looking at is at
http://store.sundancesolar.com/flsobachfor4.html.
“We’ve simply soldered a 4 AA or AAA holder to the solar panel and included a blocking diode to prevent power leakage”
The combo AA or AAA are 3.6volt 100mA for 2 or 4 batteries or 7.2 volt 200mA for 4 AAs.

I may buy one of these to field test .
It seems the most elegant out of the options.
Any comments?

Paul

[Mike Barney]

I like the flexible part. Mount that on the top of your pack and you could charge while you hike. Let us know how the test comes out.

[Mark Hurd]

Just wondering if anyone has experience with Aurora Solar.
http://www.aurorasolar.com/aurora2/index.html
Their stuff look pretty good. 2.5- 3.5 oz for their weatherproof chargers. Appears very packable. Giving some thought to getting their iPod charger.
So if anyone has any experience with any of these chargers I’d love to hear about it.
Thanks,
-Mark

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