Control system for battery charge maintenance in a power system with main ac generator control

An electrical power system may comprise an AC generator and a generator control unit (GCU) for varying AC output voltage of the AC generator. A DC bus may be connected to the AC generator via a Transformer Rectifier Unit (TRU) so that DC voltage on the DC bus is directly proportional to the AC output voltage. A battery may be connected directly to the DC bus. A control loop may be connected to receive battery current information and provide control signals to vary the AC output voltage so that battery charge may be maintained without battery damage.