an active balancing and battery charging system for a battery including a plurality of packs made up of cells . an h - bridge circuit having a nominal system voltage as an input generates a square wave output to a plurality of step - down transformers each associated with a pack , where the plurality of step - down transformers provide an active balancing voltage of about the nominal pack voltage . each pack may include a balancing transformer including a common primary coil receiving the active balancing voltage from the associated step - down transformer or the pack itself . the balancing transformer also includes a plurality of secondary coils each associated with the respective plurality of cells of the pack . a voltage induced in the secondary coils causes a discrete charge current to flow to any cells in the pack that are undercharged relative to other cells .