best way to recharge AA batteries w/o generator?

_fool · Post by **_fool** » Mon Aug 01, 2005 12:54 pm

so i've got a ton of AA-battery-powered stuff from camera to radios to lights of all descriptions and many of these (lights, radios) will eat a set of batteries every day. being that i hate throwing things away, i have quite a lot of rechargeable NiMH AA batteries (and a decent fast-charger). i also have an inverter that successfully powers my fast-charger from a car battery. what are your recommendations on charging out on the playa, considering the following constraints:

we'll be camping in the walk-in parking, and won't be bringing a generator. this means we also won't be camping with the car and hope to not see it between monday and monday. further we'll be away from the camp the majority of the time so whatever solution we come up with needs to be basically weatherproof so that if it suddenly rains things won't be ruined before we can get back to cover them up. we'll have some covered space not in our tent (ie venting to the outside) that will be basically waterproof, though. finally i don't want to spend more than a hundred bucks on whatever solution...

the routes i've considered so far are:

solar chargers (hard to find ones that are actually waterproof && not a zillion bucks && intended for batteries)

borrowing a plug on a generator and sticking my fast charger in a plastic bag to make it "weatherproof" (has the problem that the charger heats up a lot and wants to vent)

something i was thinking about more in the vein of self-sufficiency was a standalone car battery that i could run the inverter off of, which could then run the fast charger. my only concern there would be that i won't really have a way to recharge that battery on the playa and so i'm wondering if it could hold up to say 3 recharge cycles per day for 7 days (1800 mA x 4 batteries per cycle)? if not a car battery, then some other kind like deep cycle? but remember that we have to be able to carry this thing a half mile (say) since we are hiking into camp.

any advice on any of these routes? particularly devices you've used successfully would be delightful to discover =)

i'm sure i missed a zillion other possibilities, which is why i open this up to the fabulousness of the group consciousness. thanks in advance for your help!

robotland · Post by **robotland** » Mon Aug 01, 2005 1:01 pm

DO NOT use a car battery. Deep cycle battery'd be the way to go...Maybe bring a little red wagon to tote it in- Comes in handy when you're hauling ice, too. You've got time for a dry run on the recharging, to see exactly how many rechargings you can get from a full battery.

Kinetic IV · Post by **Kinetic IV** » Mon Aug 01, 2005 1:06 pm

I picked up a small 400 watt inverter at Sam's Club ($35 or so) that has a cigarette lighter plug and / or clamps to connect directly to a battery. I plug that in to my car's cig lighter, hook up a small surge strip to the inverter and plug my fast charger into it. I've used variations of that setup for over a decade now without trouble. YMMV...but it might be worth considering. I also use the same thing to power my laptop and other equipment as needed.

If you go with the standalone battery go deep cycle / marine type. A car battery isn't designed to be drawn down / cycled like you would be doing. I picked up deep cycle batteries here in the Midwest for $20...I found a industrial battery shop and they had several reconditioned ones available. $20 vs $60 for a new one that won't be used much was a good deal.

Nightterror · Post by **Nightterror** » Mon Aug 01, 2005 1:21 pm

I use a solar charger made just for AA. Takes a while to charge them but it works great in the desert. Bought it on the internet.

_fool · Post by **_fool** » Mon Aug 01, 2005 1:25 pm

Nightterror wrote:I use a solar charger made just for AA. Takes a while to charge them but it works great in the desert. Bought it on the internet.

brand/model name? number of batteries it charges? amount of time it takes to charge batteries, and what amperage-hours (mAh) are they?

thanks!

phil · Post by **phil** » Mon Aug 01, 2005 1:35 pm

Since you're walking in, I hate to say it but your best choice is probably to buy a hundred disposable AAs. Deep cycle batteries are seriously heavy, and buying one plus an inverter puts you deeper into karma debt for the lead and sulfuric acid, electricity to recharge the deep cycle battery, and the juice to run the inverter than just buying alkalis or comparable AAs.

It takes about 125% of the battery's output to charge a lead acid battery (you have to put in more than you bet back out). (Oh, yeah -- and you need to buy the battery charger.) The inverter uses another 115% to 140% depending on its quality to recharge your rechargeables. The rechargeable AAs also take more energy to recharge than you get back.

If I'm figuring this right, here's your requirement:
1.8Ah x 4 batteries = 7.2Ah x 3 times a day x 7 days = 151 Ah
Since deep cycle battery makers suggest never letting the battery be discharged greater then 50%, you need a 300 Ah battery. My 115Ah marine battery is too heavy to carry for more than a few steps. Maybe your estimate of how much juice you're going to use is a little high? Maybe I added it up wrong?

I suggest finding a place that recycles disposable AAs and use them, then recycle.

Nightterror · Post by **Nightterror** » Mon Aug 01, 2005 1:40 pm

ICP Global Tech -I bought from Fry's "Outpost.com"

http://shop1.outpost.com/product/357264 ... IN_RSLT_PG

Works great and if it's raining just find an unlocked car near your camp and plug it into the cig lighter.

_fool · Post by **_fool** » Mon Aug 01, 2005 2:08 pm

phil wrote:Since you're walking in, I hate to say it but your best choice is probably to buy a hundred disposable AAs. Deep cycle batteries are seriously heavy, and buying one plus an inverter puts you deeper into karma debt for the lead and sulfuric acid, electricity to recharge the deep cycle battery, and the juice to run the inverter than just buying alkalis or comparable AAs.

drat. i hate to be such a disposable person, but relatively speaking the waste does seem less with a cubic foot of batteries that i can recycle than by buying a deep cycle battery i basically won't use for anything else and thus will probably go bad pretty quickly. certainly the financial and weight difference is substantially in favor of the "just get disposables" theory by an order of magnitude (dollars and kilograms). however functionality is king! off to find a battery recycler....

thanks to everyone for your responses!

_fool · Post by **_fool** » Mon Aug 01, 2005 2:11 pm

[quote="Nightterror"]if it's raining just find an unlocked car near your camp and plug it into the cig lighter.[/quote]

so you're the reason i had to have my car jumped three times last year!
heh.

Nightterror · Post by **Nightterror** » Mon Aug 01, 2005 2:22 pm

Dusty car, parked next to the shade structure? Could have been my fault.

_fool · Post by **_fool** » Mon Aug 01, 2005 2:31 pm

Nightterror wrote:Dusty car, parked next to the shade structure? Could have been my fault.

heh, i actually kept mine locked since i had a laptop and misc other expensive stuff that wasn't mine inside, so i'm sure you're not to blame. i still can't really figure out what happened unless my campmate left the light on inside or something...shrug. anyway to get around that this year we're pulling everything out and putting the car far away so we won't be tempted to try to live out of it. also i expect about a thousand percent less dust inside afterwards...