BATTERY DEVICE AND VOLTAGE SUPPLY METHOD

A battery apparatus including a first battery pack for providing a first voltage, a battery management system for managing the first battery pack, and a second battery pack for providing a second voltage lower than the first voltage is provided. The second battery pack includes a plurality of battery cells, and the battery management system selects a battery cell group including a predetermined number of battery cells from among the plurality of battery cells of the second battery pack. The selected battery cell group supplies an operating voltage to an operating device of the battery management system.