Battery coolant circuit control

A vehicle comprising:

• a traction battery;
• a refrigerant system including a compressor, a condenser, a battery chiller, and a cabin evaporator;
• a coolant system including
• a proportioning valve including an inlet connected in fluid communication with an outlet side of the battery, and a pair of first and second outlets, wherein the valve is configured such that each of the outlets selectively receives a proportion of coolant flowing into the inlet depending upon a position of the valve,
• a chiller loop connected in fluid communication with the first outlet of the proportioning valve, and arranged to convey coolant between the battery and the chiller to transfer heat from the coolant system to the refrigerant system, and
• a radiator loop connected in fluid communication with the second outlet of the proportioning valve, and arranged to convey coolant between the battery and a radiator to transfer heat from the coolant system to the outside air;
• and
• a controller configured to, in response to the refrigerant system being ON, actuate the proportioning valve to proportion the coolant between the first and second outlets such that heat transfer through the chiller is limited to a chiller capacity.