Question for Solar People

[nosambos]

I have two Wagan Powerdome units for my cars. 400W, 600A peak cranking power, 18A hour DC. I have no particular plans for electricity other than a car vac to clean my tent and if I'm really decadent, charging my toothbrush. Assuming I come up with more uses can these be charge via a solar panel as the transformer is 14W and 500 mA? Should I just bite the bullet and buy deep cycle batteries?

http://www.google.com/products/catalog? ... BYQ8wIwAA#

[some seeing eye]

The unit you have is about 1/3 to 1/8 the storage capacity of a typical marine deep cycle battery. It also has a undersized charge controller, if you look at the specs it takes a long time to charge on both DC and AC - 12-38 hours!

But your needs are small. You can charge for free, either your unit or a deep cycle battery at the solar camp across from the AEZ. They are Snow Koan Solar in Nectar Village. If you bring a deep cycle battery, bring a kid's wagon to haul it.

Unless you are trying to run a sound system, what you have now should be fine, given you can recharge it anytime.

Suggest you pay a visit to the AEZ and get take advantage of all their solar knowledge, which they love to explain, before buying solar panels and more gear, they will save a lot of mistakes (because they made them too).

(And with the air compressor in the unit, bring a blow off nozzle if it can attach)

[Trishntek]

For what your needs are, one of those little 45W solar units at Harbor Freight would be sufficient.

[Zhust]

I have two Wagan Powerdome units for my cars. 400W, 600A peak cranking power, 18A hour DC.

First, from what I've been reading, it seems that nearly all manufacturers of sealed lead acid batteries have gone to absorbed gas mat (AGM) which (from what I understand) offers similar functionality to deep-cycle batteries. The capacity-per-volume or per-weight is less, but they're sealed.

Second, crunching some numbers on the size, 18 amp-hours at 12 volts is 216 watt-hours. Figuring half that for safe measure, you've got about 100 watt-hours in each unit. The Wagan site has their vacuum listed at 90 watts, so one hour with the vacuum and you're done. You might be able to get away with not charging your toothbrush for a while, but it looks like counting on about 50 watt-hours a day would be a practical bet. Unfortunately this means you'll need to recharge at Burning Man — if your consumption was much lower, it's likely that you wouldn't need to charge at all.

Given that there's about 5 hours of usable solar energy each day, that works out to 10 watts for those 5 hours, so with losses and such, you should bank for a 15-watt panel.

[FIGJAM]

Here's the info I used to determine which battery I needed.

http://www.windsun.com/Batteries/Battery_FAQ.htm

http://www.vonwentzel.net/Battery/01.Type/index.html

[gyre]

AGM isn't always sealed or deep cycle.

[Trishntek]

I replaced my pallet jack batteries which requires AGM 6Volt (4 ea.) which put out 225Ah each. They were $250 each because I bought four of them. They are regularly $400 each.

For my solar array, from the same store, I bought lead acid 6 volt (4 ea.) which put out 225 Ah each for $125 each because I bought four of them They would have been $210 each for one battery.

So at Interstate Battery, depending upon how many you buy, you can buy deep cell batteries from around 3.5-5 Watt-hours per dollar for the AGM and around 6-10 Watt-hours per dollar for lead acid.

[FIGJAM]

Mine were factory 2nd's because they did'nt have labels.

$140 instead of $240.