Apparatus and method to maximize vehicle functionality and fuel economy with improved drivability during engine auto stop-start operations

An auto stop-start equipped vehicle power management system includes a primary power source 12 supplying energy to an electrical starter 16 to crank a vehicle engine and a secondary power source 14 coupled in parallel to the primary power source 12. Secondary power source 14 supplies energy to electric loads 18 during an engine auto stop-start operation. Electrical loads 18 maintain vehicle subsystem functionality during the engine auto stop-start operation. Energy supplied to the electrical loads 18 may be current limited during the engine auto stop-start operation. A controllable switch 32 decouples the secondary power source 14 from the primary power source 12 and starter motor 16 during the engine auto stop-start operation. Operating parameters of the electrical loads are monitored during the engine auto stop-start operation. If a respective operating parameter threshold associated with the electrical loads is exceeded during this operation, the vehicle engine is automatically restarted and the controllable switch 32 is subsequently closed.