Patent ID: 7261974

Claim:
A battery power supply system comprising: a box having a cooling air inlet on one end face and a suction fan for guiding cooling air flow from the cooling air inlet toward the other end of the box; and a battery assembly installed in an intermediate section within the box, the battery assembly comprising a plurality of battery module groups arranged at intervals in parallel to each other along a cooling air flow direction, each of the battery module groups comprising a plurality of rod-shaped battery modules arranged, within a first imaginary plane intersecting the cooling air flow direction, at equal intervals with the axes thereof intersecting the cooling air flow direction, and one rod-shaped battery module and another rod-shaped battery module that is adjacent thereto in the cooling air flow direction having their axes positioned within a second Imaginary plane that is parallel to the cooling air flow direction; wherein when a gap between outer peripheral faces of two adjacent rod-shaped battery modules of the first battery module group, which is closest to the cooling air inlet, is a, and a gap between the outer peripheral face of the rod-shaped battery modules of the first battery module group and the outer peripheral face of the adjacent rod-shaped battery modules of the second battery module group is b, the ratio a/b of the gaps a and b is set so that 1.0<a/b≦2.0.