A battery management system includes a power converter, a first switch, a second switch, a first detecting unit, and a CPU. The power converter is configured to divide current provided by the power supply into a first and a second output current, according to a working current of a system load in a normal state, the first output current is used to power the system load, and the second output current is used to charge a battery unit. The CPU is configured to determine whether the value of current detected by the first detecting unit is greater than a threshold value, and further controls turning on the first switch to power the system load using the first output current, and turn on the second switch to charge the battery unit using the second output current.