An apparatus including a rechargeable battery pack installed in an electric vehicle, the rechargeable battery pack coupled to a power supply, the power supply operable to provide a charge voltage to perform charging operations on the battery pack, a heating element to heat a fluid to be circulated through the rechargeable battery pack, a comparator circuit to compare a battery voltage of the rechargeable battery pack to a line source voltage, the comparator circuit operable to compare the battery voltage to the line source voltage and to provide an output signal when the battery voltage is less than a line voltage offset value, and a control circuit coupled to receive the output signal of the comparator, and to couple the line source voltage to the power supply, an to bypass the heating element if the comparator is not providing the output signal.