Concorde’s RG-380E/44, RG-380E/60 and RG-390E series of heated batteries incorporate internal AC (115 V nominal) and DC (28 V nominal) heater blankets that surround cells in the most optimal manor for equalizing cell heating. These blankets are controlled by a Heater Control Unit (HCU) offered in four different TSO authorized varieties. HCU-1 is a DC only unit and uses DC power supply to operate the heaters. HCU-2 is an AC only unit that heats the battery using AC power. HCU-3 and HCU-4 are dual power units that allow for either AC or DC power supply. For more operation visit www.concordebattery.com.