Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

Initial (Ah) (Ah)

Required number input.

Final (Ah) (Ah)

Required number input.

Calculate one-month battery self-discharge percentage from stored charge before and after an approximately one-month rest; exclude external loads. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Self Discharge (%) (%)

The resulting self discharge (%) returned as a number.

• Battery capacity, state of charge, runtime, and aging depend on chemistry, temperature, discharge profile, cutoff voltage, cell balance, charge method, rate capability, self-discharge, and prior history. Nominal amp-hour or watt-hour ratings do not guarantee usable energy under every load.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

• Battery Capacity Fade

  Calculate capacity loss as a percentage of initial battery capacity, using measurements at comparable discharge rate and temperature.

• Battery Remaining Capacity

  Calculate remaining battery charge in ampere-hours from measured full-charge capacity and state of charge percentage.

• Battery State Of Health

  Calculate battery state of health as measured full-charge capacity divided by rated new capacity, expressed as a percentage; values over 100% can be valid measurements.