A battery powered device providing battery power to a processing device via a positive terminal and a negative terminal and including a first switch, a second switch, a battery unit and a control unit is provided. The first switch is coupled to the positive terminal. The second switch is coupled to the first switch. The battery unit is coupled between the second switch and the negative terminal. The control unit operates in an off mode when the control unit receives the turn-off command. The control unit operates in a power-saving mode when the control unit receives the save command. When the control unit operates in the off mode, the control unit turns off the first and second switches. When the control unit operates in the power-saving mode, the control unit turns off the first switch and turns on the second switch.