Battery Runtime Calculator
Hours = (Wh × efficiency%) ÷ load W. Click any i for detail.
Battery & load
Battery capacity (Wh)
i
Wh
Watt-hours of usable capacity (or Ah×V). |
|
|---|---|
Load (W)
i
Load
Continuous power draw. |
|
Efficiency (%)
i
Eff
Inverter/system efficiency. |
How to use this calculator
- Enter battery Wh.
- Enter load watts.
- Set efficiency %.
- Read hours and minutes of runtime.
Results explained
Runtime hours equal usable watt-hours times efficiency, divided by load watts. Temperature, Peukert effects, and inverter idle draw can shorten real runtime.
Quick reference: runtime
hours = (Wh × eff/100) / W.
| Item | Detail |
|---|---|
| 500 Wh @ 100 W | 5 hr at 100% eff |
| 85% eff | ≈ 4.25 hr |
| Ah × V | Converts to Wh |
| Surge loads | Not modeled |
Estimate only — check manufacturer usable capacity.
How the estimate is built
hours = batteryWh × (efficiency/100) / loadW.
Example scenario
500 Wh, 100 W, 85% → 4.25 hr.
FAQ
I have Ah not Wh?
Wh ≈ Ah × battery voltage.
50% DoD limit?
Reduce Wh to the usable fraction first.
Solar input?
Not netted here.
See electricity cost?
For grid kWh pricing.