Abstract: A battery charger comprises a power supply for supplying current pulses to a battery to be charged. A microprocessor receives from an analog-to-digital converter codes representing the voltage between the battery terminals with the battery off-load between charging pulses and monitors the ratio of the voltage difference (V.sub.3 -V.sub.5) during a first period following a charging pulse to the voltage difference (V.sub.10 -V.sub.12) over a second period following the charging pulse, with the second period ending after the beginning of the first period. The value of this ratio reaches a peak value and then declines, and the microprocessor determines when the value of the ratio falls below a peak value thereof by a predetermined amount to terminate fast charging of the battery, after which the battery may be removed or may remain on a trickle charge. An accurate, reliable, and consistent determination of completion of charging of sealed nickel-cadmium batteries is thus provided.