A rechargeable DC power supply includes a housing including an interior, an exterior, and an integral heat sink including a heat absorbing surface formed in said interior and a heat dissipating surface formed in said exterior. The rechargeable DC power supply includes a rechargeable battery having battery terminals positioned in said interior, power supply terminals positioned at said exterior of said housing, and a first printed circuit board (PCB) assembly including a bidirectional DC-DC converter module connected between said battery terminals and said power supply terminals. The first PCB assembly is in coplanar contact with said heat absorbing surface.