How many watt-hours is a 3kWh battery?

A 3kWh battery is about 3.0 kWh (3000 Wh nominal). On LiFePO4 roughly 2280 Wh is usable; on lead-acid about half is.

What can a 3kWh battery run?

A 3kWh LiFePO4 battery (~2280 Wh usable) can run, for example, a 150W refrigerator for about 15.2 hours, or LED lights (40W) for about 57.0 hours.

Battery capacity

What can a 3kWh battery power?

A 3kWh LiFePO4 battery holds about 3.0 kWh, of which roughly 2280 Wh is usable. Here is roughly how long it runs common devices — adjust any load in the calculator below.

Device	Typical power	Run-time
Refrigerator	150 W	15.2 hours
CPAP	45 W	50.7 hours
TV	90 W	25.3 hours
Laptop	50 W	45.6 hours
LED lights	40 W	57.0 hours
Space heater	1500 W	1.5 hours
Ceiling fan	60 W	38.0 hours
Router	12 W	190.0 hours

Calculate for your device

Battery capacity (Ah)

Battery voltage (V)

Device load (W)

Chemistry

Run-times assume LiFePO4 (~80% usable) and typical inverter loss. Lead-acid of the same rating gives roughly 60% as long, since only ~50% is usable. To build a full system, use the system calculator.

Estimates for planning only. See the methodology.