A DC backup system is for providing emergency electric power to an electronic device powered by an input power source, and includes a battery backup unit and a battery control unit. The battery backup unit is operable to output state information indicating a state thereof, and test information associated with a self test performed thereon. The battery control unit is electrically connected to the battery backup unit for receiving the state information and the test information therefrom, and is configured to control, according to the state information and the test information, the battery backup unit to output electric power to the electronic device when the input power source fails.