Squeeze the Lemon: Balancing as a Way to Use Every Drop of Energy in a Lithium-Ion Battery

This work discusses recent research results obtained in tackling one of the most limiting factor for an effective use of a Lithium-ion battery: the charge unbalance between the cells constituting the battery. First, it is recalled how unbalancing affects the performance of a battery consisting of series-connected cells, then some possible techniques to balance the battery are described and compared to each other. The comparison is made by modeling the balancing circuit topologies and by performing statistical simulations. Finally, we describe two balancing circuits that efficiently address the problem and we report on the experimental results that validate the circuits.