There are two common methods to achieve car battery balance: active balance and passive balance. Car battery balance uses a DC/DC converter to charge low-power battery cells, thereby redistributing the power of the battery cells. Nowadays, battery cell manufacturing and classification technology has made significant progress, which has greatly reduced the degree of mismatch of battery cells in the battery pack. Therefore, it is possible to avoid using a larger battery balancing current to balance the battery cells with severely mismatched power levels at the beginning of the operation. Car battery balance is performed on a regular basis with a smaller balance current, which can manage any mismatch problems that gradually arise during operation.

Car battery balance will consume more battery cells (usually through heat dissipation) until the power of all battery cells reaches the same level. The key difference between passive balancing and active balancing is that passive balancing does not allocate energy, but consumes energy so that all battery cells with a higher initial power are finally matched with battery cells with a lower power. Because passive balancing is simpler and cheaper, it is more commonly used.

The car battery balance battery power is usually expressed by the state of charge, indicating the percentage of the battery charge level and the battery capacity.