Battery Runtime Estimation Guide
Estimate runtime from watt-hours, load, efficiency, discharge limits, and battery chemistry.
For a basic estimate:
Runtime (hours) = usable battery energy (Wh) × conversion efficiency ÷ load (W).
| Term | Example | Notes |
|---|---|---|
| Nominal energy | 12 V × 100 Ah = 1200 Wh | Voltage × amp-hours is an approximation |
| Usable depth of discharge | 80% | Depends on chemistry, required life, and manufacturer guidance |
| Conversion efficiency | 85–95% | Inverter and wiring losses vary with load |
| Load | 120 W | Include standby power and surges where relevant |
Example: 1200 Wh × 0.8 × 0.9 ÷ 120 W ≈ 7.2 hours. Real runtime changes with temperature, aging, discharge rate, voltage cutoffs, and load profile.