Systems and methods for supplying electrical power between two electric energy storage devices are disclosed. In one example, an electric isolation switch is held open after engine starting until a voltage of a first electric energy storage device and a voltage of a second electric energy storage device are within a threshold voltage of at least one predetermined voltage level.

A starting device is used in a starting system that includes a starting electric motor unit and a rotating electrical machine; the starting electric motor unit including a motor that rotates a pinion gear, and a pushing member that pushes out the pinion gear toward a ring gear, the ring gear rotating together with a crankshaft of an engine; the rotating electrical machine being connected to the crankshaft and rotating the crankshaft; the starting system being configured to push, using the pushing member, the pinion gear toward the ring gear, and drive the motor to rotate, based on driving force of the motor, the ring gear via the pinion gear, thus starting the engine. The starting device includes a drive instruction unit that instructs the rotating electrical machine to rotate the ring gear via the crankshaft during a pre-drive period before drive of the motor.

A method and system for operating a vehicle that includes feedback of operating status of an engine starting system is described. In one example, the method inhibits automatic engine pull-down in response to feedback from an engine starting system that does not meet expectations. The system and method may provide diagnostics for the engine starting system.

There is provided an engine starting device, including: a motor generator coupled to a crankshaft of an engine; and a starter including a pinion provided in a detachable manner from a ring gear provided on the crankshaft, and configured to mesh with the ring gear when the engine is started, wherein the engine is cranked through simultaneous cranking by both of the motor generator and the starter when a condition set in advance is satisfied, and wherein, in the simultaneous cranking, the starter starts rotating after the motor generator starts rotating.

A method for operating a vehicle that may be automatically stopped and started is described. In one example, the method includes inhibiting automatic engine stopping in response to a temperature of an emissions device exceeding a threshold temperature. In addition, additional actions may be taken to reduce the temperature of the emissions device when automatic engine stopping is inhibited.

Systems and methods for supplying electrical power between two electric energy storage devices are disclosed. In one example, an electric isolation switch is held open after engine starting until a voltage of a first electric energy storage device and a voltage of a second electric energy storage device are within a threshold voltage of at least one predetermined voltage level.

A method for operating a vehicle that may be automatically stopped and started is described. In one example, the method includes starting an engine via expansion stroke combustion in response to a request to urgently start the engine. In addition, the method includes adjusting a position of a compression relief valve in response to a predicted urgency of an engine start.

A method for controlling a start of a mild hybrid vehicle that includes an engine, a starter-generator starting the engine or generating electricity by an output of the engine, a starter starting the engine, and a battery supplying electric power to the starter-generator may include: determining, by a controller configured for controlling an operation of the vehicle, whether a start of the vehicle is requested; checking, by the controller, current limit data of the battery when the start of the vehicle is requested; checking, by the controller, start torque current data of the starter-generator according to state data of the vehicle; comparing, by the controller, the current limit data with the start torque current data; and starting, by the controller, the engine using the starter-generator or the starter according to a result of the comparing, by the controller, the current limit data with the start torque current data.

A method for operating a vehicle that includes a DC/DC converter is described. In one example, the method includes adjusting an output voltage of the DC/DC converter to increase torque of a belt integrated starter/generator. The output voltage of the DC/DC converter may be adjusted before and during engine cranking.

A method for operating a vehicle that includes a DC/DC converter is described. In one example, the method includes adjusting an output voltage of the DC/DC converter after the DC/DC converter is used to crank an engine. The output voltage of the DC/DC converter may be adjusted responsive to a state of charge of an ultra-capacitor.