A system and method includes a secondary energy storage system (SESS) and a control system. The SESS is configured to be disposed onboard a vehicle and conductively connected via switch devices to a primary battery and a cranking device of the vehicle. The control system is configured to control the switch devices to close a conductive path to discharge electric current from the SESS for powering the cranking device to rotate an engine shaft during a cranking operation. The control system is configured to control the switch devices to open the conductive path and prevent discharge of electric current from the SESS after the cranking operation is complete.