Methods and systems for power system management

Methods and systems for energy management system for a vehicle are provided. The system includes a first power source configured for cranking an engine wherein the first power source includes a switch configured to electrically couple the first power source to a starter for the engine and wherein the first power source is electrically isolated from auxiliary onboard loads. The system further includes a second power source configured for supplying auxiliary on board loads, a charging subsystem electrically coupled to the first and the second power sources. The charging subsystem is configured to supply charging current to the first and the second power sources. The system further includes a controller configured to maintain the first power source in a substantially fully charged condition and supply the auxiliary loads from the second power source.