6. On-Board Power Electronic Battery Management

A battery cell voltage equalizer is essentially a power electronic controller, which takes active measures to equalize the voltage in each cell. Furthermore, by few additional methods, such as measuring the actual capacity and internal resistance of each cell (followed by instantaneous SOC computation), it is capable of equalizing the SOC of each cell. As a result, each of the cells will have the same SOC during charging and discharging, even in conditions of high dispersion in capacity and internal resistance. If all the cells have the same SOC utilization, they will degrade equally, at the average degradation of the pack. If this condition is accomplished, then all the cells will have the same capacity during the whole lifetime of the battery pack, avoiding premature end of life (EOL), due to the EOL of only one cell.