Bank nominal voltage
Stored capacity · V
Allowed range: 0.1 to 2000
Battery Backup Runtime Calculator
Estimate steady AC backup hours from battery energy and an entered load.
Open this toolBattery energy and the AC load together set a rough steady backup duration. Nominal capacity alone does not tell you the usable hours.
Enter discharge, health and efficiency assumptions alongside the load. Compare the result with observed runtime as the battery and operating conditions change.
Inputs and controls
Bank capacity
Stored capacity · Ah
Allowed range: 0.01 to 10000000
Usable depth of discharge
Stored capacity · %
Allowed range: 0.01 to 100
Inverter efficiency
Conversion and load · %
Allowed range: 0.01 to 100
Steady AC load
Conversion and load · W
Allowed range: 0.01 to 10000000
Inverter DC idle draw
Conversion and load · W
Allowed range: 0 to 1000000
How to use
- Enter bank nominal voltage, bank capacity and usable depth of discharge.
- Enter inverter efficiency, steady AC load and inverter DC idle draw.
- Select Calculate result. Read the returned values alongside the assumptions below before copying, exporting or acting on the result.
Why use this tool
The energy reductions stay visible, helping explain why nominal watt hours are greater than usable AC output.
Before relying on the result
Constant power estimate. Battery age, temperature, discharge rate, BMS cutoffs and inverter idle behaviour can change actual runtime. DoD is an input, not a chemistry recommendation.
Tool limitations
Constant power estimate. Battery age, temperature, discharge rate, BMS cutoffs and inverter idle behaviour can change actual runtime. DoD is an input, not a chemistry recommendation.
Questions
Is the duration a guarantee?
No. Temperature, discharge rate, battery age, cutoffs and inverter behaviour can change actual runtime.
What should I check before using Battery Backup Runtime Calculator?
Check Bank nominal voltage, Bank capacity, Usable depth of discharge and Inverter efficiency. Use the exact units shown beside the controls and replace any example values with your own inputs.
Source page last modified: 2026-10-01T18:56:35+00:00. This profile describes the tool; use its page to run it.
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