Battery Ah to kWh calculator

Preliminary estimate

Inputs

Calculation note

Use manufacturer usable-energy data when available. This calculator converts Ah and voltage into planning kWh.

Method

Nominal kWh = amp-hours x nominal volts / 1000

Usable kWh = nominal kWh x depth of discharge x efficiency

Wh = amp-hours x nominal volts

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Formula variables

  • Amp-hours is the battery capacity entered by the user.
  • Nominal volts is the battery-bank voltage used for the estimate.
  • Depth of discharge is the usable portion of nominal capacity.
  • Efficiency accounts for conversion and delivery losses.

Assumptions

  • Nominal energy is calculated from amp-hours and nominal battery voltage.
  • Usable energy applies entered depth of discharge and efficiency assumptions.
  • Actual usable energy depends on chemistry, BMS limits, temperature, discharge rate, battery age, and inverter behaviour.
  • This calculator does not select battery equipment, fuses, conductors, disconnects, ventilation, or energy-storage installation requirements.

Examples

48 V battery bank. A 200 Ah battery at 48 V has 9.6 kWh nominal energy. At 80 percent depth of discharge and 92 percent efficiency, usable energy is about 7.07 kWh.

Battery data workflow. Use manufacturer usable-energy or BMS data when available, then use this calculator for quick planning conversions.