AUTOMOTIVE BATTERY SYSTEM

An automotive battery system includes: a first battery pack including a plurality of first battery cells connected in series; and a second battery pack connected in parallel to the first battery pack. The second battery pack includes: n second battery cells connected in series; n voltage sensitive switching devices respectively connected to the n second battery cells; and n balancing resistors respectively connected in parallel to the n second battery cells through the n voltage sensitive switching devices. Each of the voltage sensitive switching devices is turned on if a corresponding second battery cell of the n second battery cells has a cell voltage higher than a reference voltage. The reference voltage is set to be higher than a value obtained by dividing a maximum operation voltage of the first battery pack by n where n is a natural number equal to or greater than 2.