Abstract: 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 with the first battery pack. The second battery pack includes: n second battery cells connected in series; n voltage sensitive switching devices each connected to a corresponding second battery cell of the n second battery cells; and n balancing resistors each connected in parallel to the corresponding second battery cell through the n voltage sensitive switching devices. Each of the voltage sensitive switching devices is turned on when the corresponding second battery cell of the n second battery cells has a cell voltage higher than a reference voltage.