Rechargeable cells in cylindrical form are arranged within frames in a honeycomb structure and coupled by connecting straps outside the frames to form cell pack. Several cell packs, an electronic switch and control circuit are integrated into the battery housing. A bus bar extends around the perimeter of the housing. A high density MOSFET switch is coupled between the bur bar and the battery contact. A high power electronic clamp disposed across the battery terminals absorbs or redirects transients. An active, high-efficiency, low-noise cell balance converter or a LC based resonant converter may also be provided. For advanced battery applications a +5V CAN bus interface is provided via two circular connectors. Thermistors are provided for use in a thermal protection scheme.