A high-voltage energy regulated conversion circuit (HVERCC) (12) for coupling to a vehicle bus (24) includes a battery bus (28) and a heater bus (29). A high-voltage battery pack (30) is electrically coupled to the battery bus and a resistive load element (42) is electrically coupled to the heater bus (29). A high-voltage energy converter (HVEC) module (22) is electrically coupled to the vehicle bus (24), the high-voltage battery pack (30), and the resistive load element (42). The HVEC module regulates power on the vehicle bus (24), the battery bus (28), and the heater bus (29) and operates in multiple functional modes including a constant voltage mode, a constant current mode, and a constant battery current mode.