Patent ID: 7112387

Claim:
A battery power supply device comprising: a case; a battery pack including an outlet hood, the battery pack fixed in the case; a holder in the battery pack; a plurality of battery modules housed in the holder; a plurality of cells within each battery module; each cell in the plurality of cells within a respective battery module are serially connected together both electrically and mechanically; wherein the plurality of battery modules are disposed within the holder at suitable intervals from and arranged parallel to one another, so that a cooling medium flows uniformly along each entire longitudinal surface of each battery module; and wherein the battery pack is provided with a plurality of vent holes having different aperture areas which are distributed over at least one of inlet and outlet sides of the battery pack, wherein a vent hole at the center of the inlet or the outlet side of the battery pack has the smallest aperture area, such that the cooling medium, having a substantially uniform flow rate, flows uniformly along each entire longitudinal surface of each battery module; and wherein the cooling medium is exhausted from the outlet hood into the case and flows through a space provided between the battery pack in the case to an outlet provided in the case so that the cooling medium is exhausted to the outside of the case.