A battery system including: a battery, which includes at least one battery cell; a division circuit configured to receive a first voltage of the battery, generate a second voltage from the first voltage, and output the second voltage; an isolation circuit coupled between the battery and the division circuit, the isolation circuit being configured to electrically isolate the battery from the division circuit according to a control signal; and a battery management system coupled to the division circuit. The battery management system includes an isolation circuit control unit configured to generate the control signal; and a measuring unit configured to measure the second voltage.