A capacity test measures how much energy a fully charged battery can deliver to a defined cutoff under a defined load. The result is meaningful only when the test conditions are recorded.

Basic controlled process

  1. Inspect the pack and confirm the correct charger and cutoff limits.
  2. Charge fully, allow a consistent rest period and record temperature.
  3. Discharge with a calibrated electronic load or controlled vehicle test.
  4. Record current, voltage, time, Wh and cutoff voltage.
  5. Repeat at a safe current and compare with the rated capacity.

Do not open a lithium pack or bypass its BMS casually. A service centre with insulated tools and appropriate fire controls should perform pack-level testing.