Choosing a 12V battery charger for use with generator?

[percussivepaul]

We're doing a battery setup for camp lighting at night to be recharged in the afternoons via generator. Last year we had all kinds of trouble getting enough charge into the batteries even with hours and hours of generator use and I think the problem was the charger. It looked pretty cheap and I think it probably had very low output current, though not sure.

This year we are doing it proper, planning our power loads and such. I am going to get a 110Ah deep cycle battery and rent a Honda-EU 1000W generator, and ideally I would like to be able to put 50Ah into this battery in an afternoon, maybe 4 hours of generator use, which means I need about, what, 15A of output current?

Prices for these chargers seem to start around $50 and go well into the hundreds. Money is a bit tight. I found this guy for $66: http://www.batterystuff.com/battery-cha ... 1500A.html. Does anyone know if this would work? It seems like it would but I am suspicious that it is so much cheaper than the others. Can anyone recommend a good charger?

[ygmir]

One thing to keep in mind, is the faster you charge, the more heat is built up and, can cause plates to warp in a battery.
And, most chargers regulate themselves down, as charge builds in the battery, so, won't be pushing 15 amps, or whatever, all the time.
As thrifty as those small Honda gennies are with fuel, you might run it with a charger, while the lights are on, too. Unless you are after "no noise" which, is very relative in BRC.

[percussivepaul]

One of the goals is to minimize generator use. At nights in particular it's a problem because people start drifting out of camp and we don't want to run it unless someone is around to babysit. Last year ran the generator in evenings a few times but we all found it annoying.

Is it realistic to charge a big battery in an afternoon? Maybe I need to adjust my expectations here. Could also just spend the money on extra batteries and plan for no recharges at all, I suppose.

[ygmir]

it's hard to say what's realistic, without knowing the amount of drain from the lights, and, the charge rate of said charger.
There may be some sort of table somewhere on google, if you search something like " charge needed, charging rate, battery size".

[percussivepaul]

Draw from the lights should be in the 20 to 40W range, and expected to be on for about 4 hours a night. (Some solar-powered strands will be on all night after everyone leaves). Suppose the battery has to push maybe 60W to account for inverter inefficiency, so for four hours that's 240Wh, which at 12V means 20Ah. Thus a 110Ah battery should be able to run the lights for two or three days between chargings (aim to charge at half capacity). Ideally I would not have to recharge it every day, but maybe do it two or three times throughout the week, hence the goal of 60Ah in an afternoon. Maybe I could instead aim for 20Ah in an afternoon, so 5A output current instead of 15A, and charge every day, though this is less ideal because generator noise is unpleasant. Still not sure what kind of charger I would need. Is this sounding reasonable?

[FIGJAM]

I found this info very helpful when I desided to quick charge from my truck instead of hauling the gear to do it.

http://www.powerstream.com/SLA-fast-charge.htm

[EspressoDude]

? don't the honda EU series have 12volt battery charger output ?

[Trishntek]

Even my cheap-ass Chicago Tools 3kW has 12V, 10A output.

If you are only using 240W per day, and you start with 110Ah, or conservatively say 1200Wh total, you can run the entire week easily with a small (40W) solar charger. If you get conservatively 30W for 3 hours per day from solar, that is 90Wh per day.

Are you running the genset just to charge your battery? Are there things you are running during the day that require extra juice from the genny? I'm jus' sayin' you might be better off to invest in a small solar setup that will last for years and have no fuel costs.

[BBadger]

Buy a smart charger so that it correctly matches the profile of your battery type for optimal charging. Also remember to get the right batteries: you want deep cycle batteries so that they don't suffer permanent damage from not being continuously topped off. Automotive batteries are a BAD choice as they're designed to remain charged all the time, and can endure maybe 10 discharge cycles.

For batteries, I would but a pair of 6V 220AH deep cycle batteries at Costco or Sam's Club. They're about $65 each I've heard, and 100lbs. Should keep your lights running on end for the whole night. Remember to only discharge to 50% or it may damage the battery. The smart chargers will cost you around $300 or more. I just found this link, which is pretty useful:

http://www.templetons.com/brad/burn/burn-power.html

[percussivepaul]

We have to have the generator to power a sound system for two afternoon performances during the week. Otherwise I would happily ditch it in favor of solar. However no room in the budget for both this year.

Seems that a $300 smart charger is unnecessary and that a $50 to $100 charger should work.
Found this charger: http://www.amazon.com/Black-Decker-VEC1 ... to_title_0
Similar to the one on that "desert power" page -- and by the way thank you BBadger for that link, it is an incredibly helpful summary of a lot of info I've been digging up here and there, and I wish I had seen it sooner.

I can see the Honda EU's have 12V DC output at 8A. I didn't know about this so it is helpful, but 8A would be too slow to fill up a big battery, and I think a charge controller is required to properly charge the deep cycle batteries? (maybe not)

Thanks for your help.