12V battery runtime calculator

Estimate runtime from battery capacity and your appliance's average power draw. For cycling fridges, use average watts rather than the compressor's running wattage.

Battery capacity (Ah)Battery chemistryAverage continuous load (W)Estimated system efficiency (%)

Estimated runtime: 20.5 hours

Approximately 0.85 days, with 922 Wh of usable energy after the chosen allowances.

Example: a fridge rated at 60 W but running 40% of the time averages about 24 W. Battery usable-depth assumptions are planning defaults, not manufacturer specifications.

Planning estimates only. Real-world consumption varies with temperature, usage, equipment specifications and system losses. Consult a qualified installer for electrical design, wiring and protection.