Bolt-on feature reduces wiring and integration complexity. System validates that all batteries are within acceptable voltage and temperature limits and provides warnings or de-rated vehicle performance if necessary to protect all the cells. Active balancing is more effective and energy-efficient than passive charge dissipation, which is used by most competing BMS products, and generates less waste heat. The unique combination of attributes of the Cell-Saver™ BMS results in a system that is easy to install, maximizes the usable energy of a battery pack of a given size, and minimizes the time required to recharge and rebalance cells. These benefits collectively help reduce vehicle assembly, maintenance, and energy costs while maximizing operating range and performance capability.