Patent attributes
A power supply device comprises a lead-acid battery disposing a plurality of cells in a battery case of a rectangular parallelepiped shape having a pair of facing walls and a pair of end surface walls at the circumference of a rectangular bottom surface plate, and a power storage device connected in parallel to the lead-acid battery. The power storage device has a larger storage capacity by regenerative braking than that of the lead-acid battery, and the power storage device has an external case having a heat radiation plate disposed in a thermally connected state to the facing wall of the lead-acid battery, and the heat radiation plate is thermally connected to the facing wall of the lead-acid battery.