A system, apparatus, method, and manufacture for generating backup power in a wireless communications system such as a wireless communications service base station. The system includes a communications interface, a primary power interface, a generator, rectifiers, and a battery circuit. During normal operation, the communications interface is powered from the primary power interface. During a power outage, the communications interface is powered from either the generator or the battery circuit. The generator is cycled on and off during power outages to charge the battery circuit while conserving fuel. To decrease rectification loss, rectifiers are run near full load while rectifying the generator output.