A method of rapidly testing the discharge capacity of a battery comprises discharging the battery at a first discharge rate until a first cutoff potential is reached, relaxing the battery during a first period, discharging the battery at a lower discharge rate until a second cutoff potential is reached and relaxing the battery during a second, longer period. The process is repeated with successively lower discharge rates and successively longer relaxation periods until the battery is substantially exhausted. The cumulative value of all of the discharges is taken as a tested capacity of the battery. Optionally, cleanup charges can be sent to the battery during the relaxation periods and a low-frequency, low-amplitude current can be supplied throughout testing in order to shorten testing time.