Watts Help Needed.

[Community Alumni]

I am trying to figure out how long a battery will last. I have Googled it and read a few sites but I still have a few questions.

I have a small TV that I plugged into my Kill a Watt meter. That shows 22 watts. I plan on using a 1000w inverter hooked to one 12v battery. I havn't purchased a battery yet so i'm not sure how many AH I will have to work with.

At 12v that would be 1.8 amps.
at 124v that would be .18 amps.

Which amp usage would I use, the 1.8 amps or .18 amps?

Thank You
Jim

[prichardson]

Forget the coffee maker when on battery power only.

[Airdaile]

You want to look at a battery's reserve capacity rather than amp hours.

[wa8yxm]

YOu need to add an amp for the inverter overhead

But when you say 1 12 volt battery.... Well that can be anything from a couple amp hours to over a thousand. Just so you know

Minimum recommended for a 1,000 watt inverter is 200 amp hours.

[MEXICOWANDERER]

Inverters at low percentage of potential percentage of power are sooey-sooey pig-pig hogs of power. You are forgetting the 20% Charge Efficiency Factorial. 20% vigorish the battery charges for loans. Do all your VA calculations then add the 30% minimum replenishment energy premium.

I wish it was more efficient.

[MrWizard]

don't confuse DC amps and AC amps

a 5 amp charge at 13v+ is only 65 watts

8 amps at 120v input too a battery charger or converter is 960 watts

you want a charger/converter between 30 and 45 amps DC charge

500 to 700 watts of charging

5 to 10 amps of charging will take days to recharge/replace what you use

[pianotuna]

Divide watts by 10 to get amps @ 12 volts.

Divide amp-hours of capacity by 2 to get usable amp-hours.

[Community Alumni]

That will be plenty I think. Pretty much all I will be doing is the TV and maybe charging two cell phones. I'm also getting the Westinghouse iGen1200 generator. It's a 1000 watt and 1200 watt peak. I'm guessing the max amp battery charger would be 8 amps this generator could handle. I would probably get a 5 amp battery charger and then run the generator 2 to 3 hours or less a day to top of the battery. Almost forgot the 650 watt coffee maker to make a cup or two a day. That shouldn't be to much at 600 watts for about 3 minutes a cup.

Jim

[time2roll]

I would round up to 3 amps and call it 15 hours.

[elivi8]

A standard 12V battery will have around 90 amps and you can only use about half of that so 45 amps else you will shorten the life of the battery.

You would be using the 1.8A number at 12V.

Ryan