A power management system for a hybrid vehicle including an engine includes a vehicle power bus distributing power from a battery to vehicle loads. A capacitor includes one of a plurality of supercapacitors and a plurality of ultracapacitors. A starter/generator controller communicates with the capacitor and the battery. A power management module is configured to supply current from the capacitor to the starter/generator controller during cranking of the engine; and supply current from the battery to the starter/generator controller during the cranking of the engine. The power supplied by the battery is greater than or equal to 2% and less than or equal to 20% of a total power supplied to the starter/generator controller during the cranking of the engine.