Calculate UPS runtime for a load from its installed battery capacity.
UPS runtime is strongly non-linear in load: halving the load more than doubles the runtime, because lower discharge current recovers capacity lost to the Peukert effect. This non-linearity is why a UPS rated for 10 minutes at full load often gives half an hour at a typical 40 per cent load.
UPS Backup Time
Runtime = usable Wh ÷ load watts, with usable capacity reduced at high discharge rates
Runtime = usable Wh ÷ load watts, with usable capacity reduced at high discharge rates UPS runtime is strongly non-linear in load: halving the load more than doubles the runtime, because lower discharge current recovers capacity lost to the Peukert effect.
This non-linearity is why a UPS rated for 10 minutes at full load often gives half an hour at a typical 40 per cent load.
This calculator takes 5 inputs: Installed battery capacity, Battery string voltage, Load, Inverter efficiency, Usable capacity at high discharge rate. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.