Systems, methods, and apparatus for providing a homopolar generator charger with an integral rechargeable battery. A method is provided for converting rotational kinetic energy to electrical energy for charging one or more battery cells. The method can include rotating, by a shaft, a rotor in a magnetic flux field to generate current, wherein the rotor comprises an electrically conductive portion having an inner diameter conductive connection surface and an outer diameter conductive connection surface, and wherein a voltage potential is induced between the inner and outer diameter connection surfaces upon rotation in the magnetic flux field. The method can also include selectively coupling the generated current from the rotating rotor to terminals of the one or more battery cells.