Battery runtime
Formulas, limitations and content checked according to our Editorial method.
Get a cautious runtime estimate that accounts for usable capacity and conversion losses.
Calculate
Usable energy
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Runtime
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Average current
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Worked example
A 12 V 100 Ah battery used to 80%, through a 90% efficient inverter and a 100 W load, provides about 864 Wh or 8.64 hours.
Calculation limits
This estimate does not model temperature, aging, discharge rate, voltage curve or the Peukert effect. Use manufacturer data for final design.
Frequently asked questions
Why can real runtime be shorter?
Capacity, temperature, discharge current, efficiency and the low-voltage cutoff all reduce the energy available to the load.