Looking for a a basic formula

Hairfarm

Greetings,

What is the basic formula that will allow me to convert AC watts into DC amps?

In other words, if a load can potentially draw 2000 watts max from my inverter, then how many DC amps is the inverter pulling from my battery bank?

What is the formula for that?

I couldn't find this anywhere in my notes that I've taken from this forum over the last few days.

thanks,

BB.

Re: Looking for a a basic formula

Here is what I do... I will use "real numbers"--Just substitute your values:

• 2,000 Watt * 1/0.85 Inverter eff * 1/10.5 volt batt cutoff * 1.25 NEC Derating = 280 Amp circuit/fuse/breaker minimum

If you just want the amps at any typical value:

• Power = Watts = Volts * Amps
• Amps = Watts / DC Volts

But, of course, inverters have losses (around 85% is a good number), the inverter will draw more than its loads:

• Amps = Watts * 1/eff * 1/DC Volts
• 2,000 watts * 1/0.85 inverter eff * 1/12.2 volts = 193 amps at nominal battery voltage and inverter efficiency

-Bill