My turn to ask a battery question.

TahoeDawgZ71

As some of you may know, Georgia is supposedly about to experience the worst ice storm in the history of the state... Supposedly.... But who knows. I'm not real concerned with it but my wife wants to know the answer and I'm no mathematician. My question is for the battery gurus who can calculate a few things for me. I've got three Trojan T-1275 12 volt batteries wired in parallel. I've got a 400 watt power inverter, and I've got an extension cord run into my living room from the garage where the batteries and inverter are located. How long will this setup effectively allow me to run two table lamps? They each have one 13w flourescent bulb. The batteries are fully charged and in good condition.

BGW

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Great white north

Can any one say ohms law , series parallel circuits ?
Basic electronics 101 , I'll leave it at that and see who responds

gornoman

I'll leave the math to JohnnyB, but my gut tells me 72 hours.

kgsc

Well sir, depending on the inverter, the times vary. Last numbers I saw said conversion from 12 to 120 stunk like to the tune of 11 amps dc to 1 amp AC. Now that said, voltage X current = watts so 13 + 13= 26 watts at 120 AC. Now 1amp at 120 AC is 120 watts and you are at roughly 26 so 1/5 of 120 watts. Back to the original math and 1/5 of 11 to say 2 ish amps dc. Three 1275s with a 2 amp draw should be ok. If I did my math right.

sunoco

lol! Get some candles tahoedawg! They say its going to be the worst east of Atlanta - from Athens to Eatonton

TahoeDawgZ71

Candles won't charge a cell phone... lol

But yeah I heard it was gonna be bad. Jim Cantore from the weather channel is here in town because he said it's gonna be the hardest hit place in the state. Oh boy.

Sergio

Assuming at most 80% efficiency on the converter plus losses in the extension cord etc, I would double the usage for estimation.
So (13w+13w) * 2 = 52w or about 5 amps @ 12v.
From the graph below a single T1275 would supply approximate 24 hours at a 5 amp discharge, or pretty much what gornoman estimated.
Keep it in a warm stop in the garage since the capacity of the battery drops to 80% at 40F.

Attached Images

trojan_t1275.png (86.2 KB, 0 views)

TahoeDawgZ71

Thanks. Sounds good.

Fishing Dude

My guess about a week. Stay safe Tahoe,

caokgafamily

TahoeDawg,

All you need is alot of dry wood and a fireplace. Be safe..

Steve