US Patent 8739909 Battery frame structure for automobile

A battery frame includes an outer frame (1) which has a generally rectangular shape in planar view and a lower plate (2) which is joined to the lower surface of the outer frame and made from an aluminum alloy. The outer frame (1) has a pair of frame members (3, 4) which have an identical shape and are respectively made of aluminum alloy hollow extruded material bent at 90° at two portions in the longitudinal direction and joined to each other so that the ends (3a) of one frame member (3) face the ends (4a) of the other frame member (4).