An electronic device includes a fuel cell, a first switch, a rechargeable battery, a second switch, and a relay. The fuel cell provides a fuel voltage. The first switch provides the fuel voltage to a first node according to a first control signal. The rechargeable battery provides a battery voltage. The second switch is coupled to the first node and charges the rechargeable battery with the fuel voltage according to a second control signal. The relay provides a voltage of the first node to the load according to the third control signal.