Disclosed herein is a circuit for passively managing power between a fuel cell stack and a battery in a hybrid system. The circuit includes a buck-boost converter circuit, a direct charge circuit; and a network which interconnects them. The network is configured so that in response to a voltage level in the network being lower than or equal to a maximum battery charge voltage, the battery is charged via the direct charge circuit; and in response to another voltage level in the network which is higher than the maximum battery charge voltage, the battery is charged via the buck-boost converter circuit. Also disclosed is a device incorporating the circuit and a method of passively managing power.