Battery control system for hybrid vehicle and method for controlling a hybrid vehicle battery

A battery control system for a hybrid vehicle, comprising:

• a hybrid powertrain battery;
• a vehicle accessory battery;
• an electrical power generating means for charging the vehicle accessory battery;
• detecting means for monitoring the vehicle accessory battery's state of charge;
• and
• a controlling means for:
• activating the electrical power generating means to recharge the vehicle accessory battery in response to the vehicle accessory battery's state of charge falling below a first predetermined level, and
• transferring electrical power from the hybrid powertrain battery to the vehicle accessory battery in response to the vehicle accessory battery's state of charge falling below a second predetermined level.

A method for controlling a hybrid vehicle powertrain system, comprising the steps of:

• providing a hybrid powertrain battery, a vehicle accessory battery, and a prime mover driven generator adapted to charge the vehicle accessory battery;
• monitoring the vehicle accessory battery's state of charge;
• and
• activating the prime mover to drive the generator and recharge the vehicle accessory battery in response to the vehicle accessory battery's state of charge falling below a first predetermined level, or transferring electrical power from the hybrid powertrain battery to the vehicle accessory battery in response to the vehicle accessory battery's state of charge falling below a second predetermined level.