Hybrid power systems combine the superb energy density of a fuel cell power source with the outstanding power density of modem batteries. A hybrid power source with an integral power distribution and charge management system was designed and built using standard miniature power regulator integrated circuits with appropriate modifications to implement the necessary controls. The resulting converter not only allows the interconnection of fuel cell systems and batteries having dissimilar operating voltages, but it also imposes a power sharing strategy that elicits peak performance from each part of the device. The resulting hybrid power source can supply 70% greater peak power, with only a 6% increase in weight, and no increase in volume, compared to the as-packaged fuel cell power source on which the hybrid source was based.