US Patent 7094496 Electrical accumulator batteries

An electric accumulator battery, constituted of a series of independent modules, each of which comprises a recipient with a lid subdivided into cells in which positive and negative helically wound electrodes and an intermediate separator are housed. The recipient of each module comprises an outer wall, of straight rectangular prismatic shape, and an inner wall which defines three cylindrical cells (9) of coplanar axes, tangent to each other and closed on the lower base. Axial ventilation passages are defined between these two walls, which pass through the base through openings (5 and 6).