System and method of dynamically balancing a rechargeable energy storage assembly having two or more respective units, a respective switch for each of the respective units and at least one sensor. The system includes a controller configured to control operation of the respective switch. The respective switch is configured to enable a respective circuit connection to the respective units when in an ON state and disable the respective circuit connection when in an OFF state. The respective units are characterized by a respective state of charge obtained based in part on the at least one sensor. A controller is configured to selectively employ at least one of a plurality of charging modes to charge one or more of the respective units, through operation of the respective switch. The plurality of charging modes includes a rest charging mode, a rapid initial charging mode and a rapid final charging mode.