Switched capacitor system for automatic series battery equalization

Abstract

A clocked switched-capacitor circuit can exchange charge between adjacent batteries in a series string. This exchange drives all batteries to identical voltages, without regard to component values, battery technology, or state of charge. This equalization process can proceed while the batteries are in use or under charge, or separately. Transformer-based and transformerless implementations are given, and results of experimental tests are provided. The process is much faster and less stressful than the conventional approach, and is simpler than some active approaches.