Patent ID: 8679659

Claim:
A method for controlling a battery temperature of a vehicle battery pack, comprising the steps of: (a) flowing a coolant through coolant passages within the battery pack and into a first 3-way valve; (b) while an ambient air temperature is lower than said battery temperature, actuating the first 3-way valve to direct the coolant from the first 3-way valve through a heat source and back into the coolant passages within the battery pack, and activating the heat source to maintain the coolant at a reference temperature; (c) while the ambient air temperature is greater than said battery temperature, actuating the first 3-way valve to direct the coolant to a second 3-way valve in a self-contained refrigeration system and actuating the second 3-way valve to direct the coolant through an evaporator as the self-contained refrigerant system is activated to remove heat from the coolant and directing the coolant from the evaporator back into the coolant passages within the battery pack; and (d) while the ambient air temperature is between the temperature of steps (a) and (b), actuating the first 3-way valve to direct the coolant to the second 3-way valve and actuating the second 3-way valve to direct the coolant to bypass the evaporator and direct the refrigerant to a battery radiator to transfer heat from the coolant into air flowing through the battery radiator, and direct the coolant from the battery radiator to a third 3-way valve in the self-contained refrigeration system, and actuating the third 3-way valve to direct the coolant back into the coolant passages within the battery pack.