Battery runtime calculator

Runtime (h) = Capacity (Ah) × efficiency ÷ Load (A). Or by energy: Wh ÷ load watts × efficiency. Adjust efficiency for chemistry — typical 90% Li-ion, 75% lead-acid, 50% old NiCd.

Estimated runtime
0 h
In hours + min
0
Capacity (Wh)
0
Capacity (Ah)
0
Power draw
0 W

Common chemistries

  • Li-ion (laptop, phone, EV): 90–95% efficient, DoD up to 90%.
  • LiFePO₄: 95%+ efficient, DoD 90%, very long cycle life.
  • Lead-acid SLA (UPS, car): 70–85% efficient, DoD only 50% for cycle life.
  • Solar / off-grid storage: use 80% DoD for sizing.