Patent ID: 7504799

Claim:
A battery pack comprising: plural battery modules comprising at least first and second battery modules, each of which comprises a row of plural unit cells, the battery modules being arranged such that unit cell cases of the unit cells integrated in the first battery module face unit cell cases of unit cells integrated in the adjoining second battery module across a space; and a spacer intervening between the adjoining first and second battery modules, the spacer defining a cooling passage between an inlet side and an outlet side of the adjoining first and second battery modules which allows cooling medium flowing between the adjoining first and second battery modules to touch a plurality of the unit cell cases of the adjoining first and second battery modules, wherein the spacer is structured such that: the cooling medium flows in the cooling passage between the unit cell cases belonging to the first and second battery modules from the inlet side to the outlet side, and a first cooling medium contact area is defined between the cooling medium and the inlet side unit cell cases, the first cooling medium contact area having a first width, and a second cooling medium contact area is defined between the cooling medium and the outlet side unit cell cases, the second cooling medium contact area having a second width, wherein the second width is greater than the first width.