Systems, methods, and apparatus for battery charging

A method comprising:

• determining that a charge operation on a rechargeable battery pack is to be performed;
• comparing a supply voltage to a battery voltage of the rechargeable battery pack to determine a line voltage offset value;
• generating a charging voltage from the supply voltage;
• and
• initiating charging of the rechargeable battery pack by coupling the charging voltage to the rechargeable battery pack, wherein coupling the charging voltage to the rechargeable battery pack includes coupling a heating element between the supply voltage and a set of power inputs to a power supply providing the charge voltage to the rechargeable battery pack when the battery voltage is less than a line voltage offset value, and bypassing the heating element when the battery voltage is not less than the line voltage offset value.

A system comprising:

• a vehicle including a rechargeable battery pack, the rechargeable battery pack to provide at least a portion of the power used to propel the vehicle;
• a heating element to heat a fluid to be circulated through the rechargeable battery pack, the fluid thermally coupled to battery cells within the rechargeable battery pack;
• a charger operable to couple to a line source of electrical power and to detachably coupled to the vehicle, the charger to provide electrical power from the line source for performing charging operations of the rechargeable battery pack;
• a comparator circuit to compare a battery voltage of the rechargeable battery pack to a line source voltage coupled to inputs of the power supply, 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, the line voltage offset value calculated based on a value added to a determined voltage level for the line source voltage;
• and
• a control circuit coupled to receive the output signal of the comparator, and when a charge operation of the rechargeable battery pack is to be initiated, the control circuit is operable to couple the line source voltage to the power supply, wherein the control circuit is to couple the heating element in series between the line source voltage and the power supply when the comparator circuit is providing the output singal indicating that the battery voltage is less than the line voltage offset value, and to bypass the heating element if the comparator is not providing the output signal indicating that the battery voltage is less than the line voltage offset value.