Abstract: Systems and methods for operating a hybrid vehicle are presented. In one example, electric current may be supplied to or withheld from a positive temperature coefficient (PTC) heater and an electrically heated catalyst. In particular, electric current may be delivered to the PTC heater and withheld from the electrically heated catalyst, or vice-versa, in response to a catalyst temperature and battery state of charge.

Abstract: Systems and methods provide voltage stability for a low voltage bus coupling a DC/DC converter with a low voltage load comprising one or more vehicle accessories. The DC/DC converter can be coupled to a high voltage battery, the low voltage load, and a starter circuit configured for starting an engine. Prior to engaging a starter motor to start the engine, the DC/DC converter can be isolated from the starter circuit so as to be shielded from any large current demand during an engine start event. While starting the engine, the starter motor can draw current from a secondary battery, while the DC/DC converter provides a sufficient and stable voltage to the vehicle low voltage accessories. After completion of the engine start event, the DC/DC converter can be recoupled to the starter circuit, allowing the high voltage battery to charge the secondary battery.

Abstract: Systems and methods provide voltage stability for a low voltage bus coupling a DC/DC converter with a low voltage load comprising one or more vehicle accessories. The DC/DC converter can be coupled to a high voltage battery, the low voltage load, and a starter circuit configured for starting an engine. Prior to engaging a starter motor to start the engine, the DC/DC converter can be isolated from the starter circuit so as to be shielded from any large current demand during an engine start event. While starting the engine, the starter motor can draw current from a secondary battery, while the DC/DC converter provides a sufficient and stable voltage to the vehicle low voltage accessories. After completion of the engine start event, the DC/DC converter can be recoupled to the starter circuit, allowing the high voltage battery to charge the secondary battery.