Patent ID: 7771865

Claim:
A battery unit comprising: a battery case having an inlet to let in a cooling gas and an outlet to let out the gas; a plurality of battery modules stored and held in the battery case; and a bypass structure whereby part of the cooling gas bypasses the battery modules arranged on the side of a first end of the battery case at which the inlet is formed, the bypass structure including: a bypass exit opening formed at one end of a second direction traversing a first direction at the first end of the battery case, the first direction being oriented from the first end to a second end at which the outlet is formed; a bypass entrance opening formed in a central part of the battery case along the first direction and in a central part along the second direction; a bypass duct by which the bypass exit opening communicates with the bypass entrance opening; and a flow path which guides the cooling gas downstream of the bypass entrance opening to both sides of the second direction.