A system and method of starting or restarting an engine on a locomotive having at least one of another engine, a fuel cell system and an energy storage system. The method is applicable to large systems such as trucks, ships, cranes and locomotives utilizing diesel engines, gas turbine engines, other types of internal combustion engines, fuel cells or combinations of these that require substantial power and low emissions utilizing multiple power plant combinations. The method is directed, in part, at a flexible control strategy for a multi-engine systems based on a common DC bus electrical architecture so that prime power sources need not be synchronized.