A fuel cell power system has a fuel cell capable of generating electrical power, a battery holder releasably mounting at least one rechargeable battery, and a power controller which receives the electrical power from the fuel cell and distributes the electrical power to an output bus for use by an external load and to the battery for charging the battery. The rechargeable batteries may be easily inserted and removed from the system, with the batteries providing start-up power for the fuel cell power source, as well as surge power when the external electrical load is connected to the power system, or when the load exceeds the capacity of the fuel cell.