:New heavy duty vehicle power requirements have generated the need for more efficient, reliable, electrically quiet vehicle power sources. A single voltage system is no longer practical. Present accessories are primarily 12VDC. The requirement for larger motors, air conditioners, heaters, heated windshields and other power devices is resulting in 24V, 36V, 48V or higher voltage requirements.Existing dual voltage charging system technology is being refined and new systems are being developed to effectively meet the increased power demands. Past and present dual voltage systems along with new technology and concepts will be explored to provide a solution for upcoming power requirements. Several hybrid systems may be cultivated to meet specific needs for specific applications.