Patent ID: 8877364

Claim:
A battery pack comprising: a box main body housing a battery therein, the box main body having an upper side opening, the box main body having a first seal flange formed along an outer peripheral portion of the box main body, the first seal flange extending in an extending direction along the outer peripheral portion of the box main body; and a lid covering the upper side opening of the box main body, the lid having a second seal flange formed along an outer peripheral portion of the lid, the second seal flange extending in the extending direction, the first and second seal flanges being in contact with each other and sealing the battery pack, wherein the first and second seal flanges are formed to have mating curved surfaces curved with a predetermined curvature in a cross section along the extending direction and mating with each other, wherein one of the mating curved surfaces is convex and the other of the mating curved surfaces is concave, wherein the first and second seal flanges are curved in such a manner that the first and second seal flanges are convex upward when the battery pack is mounted on a vehicle with the lid being on an upper side and the box main body being on a lower side, the first seal having a highest point at a central portion of the first seal flange and a lowest point at edge portions of the first seal flange.