# For using an inverter, what determines the power usage?

Say I have a 12V battery hooked up to an inverter (assume no inefficiency). I guessed that if a 1A, 120V draw was placed on it, because 120W was pulled from the inverter, it would pull 120W, and therefore 12V/10A from the 12V battery. Is this assumption flawed?

• Yes, because your 100% efficiency assumption is not true. Apr 4 '17 at 15:23

$$P_{in}*Efficency = P_{out}$$