A battery pack for a cordless power has a plurality of battery cells disposed in a housing. In an embodiment of the invention, battery cells are interconnected with a laminated plate structure having non-conductive layers interspersed with conductive layers, at least one of the conductive layers connected to the battery cells to interconnect them. In an embodiment of the invention, battery cells in a battery pack are interconnected with a flexible printed circuit board having conductive traces thereon that are attached to the battery cells to interconnect them. In an embodiment of the invention, a cordless power tool has one or the other of the foregoing battery packs. In an embodiment of the invention, the battery cells are Lithium Ion battery cells.