BATTERY SYSTEM

A battery system includes a plurality of battery packs - each of the plurality of battery packs including a plurality of battery cells -; a plurality of slave battery management systems (BMSs) managing the plurality of battery packs with respect to each of the plurality of battery packs - each of the plurality of slave BMSs including a BMIC connected to a plurality of corresponding battery cells and measuring a plurality of cell voltages, and a relay turned on when the BMIC operates -; a plurality of first resistors located on a wiring extending between both ends of a power source in correspondence to the plurality of slave BMSs; a plurality of second resistors connected between one end of the plurality of relays and the wiring - the other ends of the plurality of relays connected to the wiring -; a third resistor connected between the power source and the plurality of first resistors on the wiring; and a master BMS determining positions and number of BMICs operating among the plurality of BMICs based on a sensing voltage obtained by dividing a voltage of the power source by at least one of the third resistor, the plurality of first resistors, and the plurality of second resistors.