An apparatus, method and system are disclosed, relating to a dual-chemistry battery subsystem having different battery chemistries and performance properties, and relating to an algorithm of charging and discharging the battery subsystem. For an EV application, the battery subsystem is a tailored solution that combines two different battery configurations, a first battery configuration and a second battery configuration, to satisfy the unique needs of different driving modes and performance profiles of an EV, such as a typical workday commute versus an occasional extended range trip on the weekend. The present disclosure provides intelligent control and heuristics to maximize useful energy on a wide variety of battery applications.