Cell balancing considerations for lithium-ion battery systems

Charge algorithms for Li-Ion batteries require that charging current stop once a maximum voltage threshold is reached. Each battery in a Li-Ion pack must be individually monitored for this condition, so charging of the entire pack ceases as soon as one cell reaches this voltage limitation. ''Cell balancing'' algorithms seek to remove charge from the offending cell to equalize voltage and enable additional charging of the pack. This paper considers the technical merits of this approach and the issues associated with its implementation.