Abstract: A battery charger includes a microcontroller for simultaneously and independently charging the batteries of a number of battery powered devices. The battery charger includes a constant current source associated with each channel that is connectable to a device's battery. Each constant current source is switchable between a trickle charge state and a high charge state under the control of the microcontroller to charge the battery connected thereto quickly and safely. The microcontroller further performs diagnostics continuously throughout the charging of a battery to determine whether malfunctions have occurred in the microprocessor of the microcontroller, in the software of the microcontroller or in any of the current sources.