Results
Estimated runtime—
≈ in hours—
Real power (load)—
Battery energy—
Required total capacity—
Batteries needed (parallel)—
Real power (load)—
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Frequently Asked Questions
How is UPS runtime calculated?
Runtime (minutes) = (battery voltage × Ah × efficiency) ÷ load watts × 60. More battery watt-hours and a lower load give longer runtime.
What is power factor?
Power factor (PF) converts apparent power (VA) to real power (W): watts = VA × PF. Many modern UPS units use a PF of about 0.9 to 1.0.
How many batteries do I need?
Use sizing mode: required Ah = (load watts × target hours) ÷ (battery voltage × efficiency). Divide by the per-battery Ah to get the number of strings.
Why is real runtime shorter?
At high discharge currents usable capacity drops (the Peukert effect), and capacity fades with battery age and temperature, so real runtime is lower than the ideal estimate.
This is a simplified estimate. Real runtime is lower at high loads due to the Peukert effect and battery ageing. For critical loads, size conservatively and add redundancy.