# How to properly calculate the run time of a battery using a power converter?

I want to buy a 12v 100ah lithium battery to power a 750 watts power converter that provides 120V.

I would like to know how many hours of energy will I have with this information. I tried some online calculators, but it's not clear if I'm doing it right.

Why?

Well, the 750 watts is related to the 120V part of the power converter, so I don't know how to calculate on the 12V part of the battery.

• Do you have the discharge curves for the battery? And the undervoltage lockout point for the inverter? With those two things you can get a realistic estimate for the run time of the inverter with a given inverter input power. (Input power=output power/efficiency.) Commented Jan 24 at 21:58
• What is the load on the inverter? A 750W inverter can supply a MAXIMUM of 750W. The actual amount depends on the load. The power input to the inverter at 12V will be a few percent more than the output because of inefficiencies. Commented Jan 24 at 22:13
• amazon.com/LiFePO4-Battery-Perfect-Applications-Warranty/dp/… Commented Jan 24 at 23:39
• That's the battery I have in mind. Commented Jan 24 at 23:40