BATTERY SYSTEM

A battery system includes a first battery module including a plurality of first battery cells, a second battery module including a plurality of second battery cells, and a battery disconnection unit (BDU) connected between the first battery module and the second battery module. The battery disconnection unit (BDU) includes a first main switch connected in series between the plurality of first battery cells and the plurality of second battery cells, and a precharge switch and a precharge resistor connected in parallel with the first main switch and connected in series with each other.