Abstract: A rechargeable battery system is disclosed. The battery system includes a collection of at least four flat cells, each with a positive terminal extending from one side of each cell and a negative terminal extending from an opposite side of each cell, and wherein the cells are arranged in an alternating stack with a first stack side and a second stack side, such that each cell, has its positive or negative terminal mechanically and electrically connected at a junction to the positive or negative terminal of an adjacent cell. A first board located on the first stack side, including a plurality of first connectors extending from the first board for mechanically and electrically connecting to the junctions on the first stack side. A battery management processor is included that is electrically connected to each first connector by a plurality of electrical conductors.