Hybrid powertrain with dual energy storage devices

A powertrain for a vehicle, the powertrain comprising:

• an engine;
• an electrical circuit including:
• a motor-generator coupled to the engine, and operable as either a motor to provide power to the engine, or as a generator to generate an electrical current from power supplied from the engine;
• a starter mechanism coupled to the engine and operable to start the engine from a cranking current;
• a first energy storage device disposed in a parallel electrical relationship with the starter mechanism, wherein the first energy storage device is operable to supply the cranking current to the starter mechanism;
• a second energy storage device disposed in a parallel electrical relationship with the motor-generator, wherein the second energy storage device is operable to receive a current from the motor-generator, or provide a current to the motor generator;
• a first auxiliary electric system disposed in a parallel electrical relationship with both the first energy storage device and the second energy storage device;
• wherein the electrical circuit exhibits a first electrical resistance between the first energy storage device and the motor-generator, and exhibits a second electrical resistance between the second energy storage device and the motor-generator, with the first electrical resistance being greater than the second electrical resistance so that electrical energy from the motor-generator more easily flows to the second energy storage device than the first energy storage device, and so that the motor-generator more easily draws electrical energy from the second energy storage device than from the first energy storage device;
• and
• characterized by the electrical circuit lacking a switch disposed between the first energy storage device and the motor-generator.