Abstract: A system and method for improving the performance of a hybrid power supply apparatus comprising a power generating device, such as a fuel cell, and a primary energy storage device, such as a battery. The purpose of the invention is to provide an equalization charge to the battery from a source other than the fuel cell when the battery achieves a predetermined state of charge condition, thereby avoiding the need to operate the fuel cell in a low power output mode. When the predetermined state of charge condition is detected by a controller, the fuel cell is shut-down. In one aspect of the invention the equalization charge is provided to the battery by a secondary energy storage device, such as a plurality of capacitors or secondary batteries. The predetermined state of charge condition may be satisfied, for example, when the state of charge of the battery exceeds a predetermined threshold, such as 80% of the battery's storage capacity, for a predetermined period of time.