BATTERY SYSTEM

Discussed is a battery system including: a battery pack including a plurality of battery cells; a battery monitoring integrated circuit (BMIC) configured to monitor each of a plurality of cell voltages of the plurality of battery cells; a plurality of balancing batteries each charged by a target battery cell requiring a cell balancing among the plurality of battery cells; a power conversion unit including a direct-current to direct-current (DC-DC) converter receiving voltages from the plurality of balancing batteries and configured to convert the voltages into output voltages; and a power supply unit configured to supply the output voltages to the BMIC when the output voltages have a voltage equal to or greater than a predetermined level for driving the BMIC.