Engineering tools / Power backup

UPS runtime estimator

Estimate the energy budget for a battery-backed network system. Distinguish battery energy, inverter efficiency, output limits and real-world discharge curves.

Battery and load assumptions

Start with editable example assumptions; replace with your real nameplate values.

Estimated result

Energy divided by measured AC load, with clearly illustrative bounds.

Output ratings met

Battery nominal energy: 2400 Wh
Estimated usable AC energy: 864 Wh
Illustrative runtime: 3.60 hours
Illustrative low–high: 2.88 – 4.32 hours
Load apparent power: 300 VA

Battery energy / load is only a theoretical sizing estimate. High-current discharge, temperature, transfer losses and manufacturer runtime curves can change real runtime.

Illustrative low/high values apply ±20% to this estimate; they are NOT statistical confidence intervals or guaranteed runtimes.

Methodology and limitations

This first-order energy balance does not model lead-acid high-current discharge, lithium BMS cutoffs, inverter standby load, temperature or manufacturer-specific UPS runtime curves. Obtain an actual runtime graph and load test before relying on backup duration.