Thermal regulation of batteries

1. A battery thermal management system for an air vehicle comprising:

a liquid heat exchange circuit;

an air heat exchange circuit in selective fluid communication with an air heat sink;

a liquid-air heat exchanger positioned on the liquid heat exchange circuit and the air heat exchange circuit to exchange heat therebetween; and

at least one battery in thermal communication with the liquid heat exchange circuit, wherein the at least one battery is configured to at least one of charge or discharge to heat the at least one battery above a pre-determined minimum battery temperature;

a bypass line branching from the liquid heat exchange circuit upstream from the liquid-air heat exchanger and reconnecting to the liquid heat exchange circuit downstream from the liquid-air heat exchanger.

2. The system as recited in claim 1 , further comprising a battery temperature sensor operatively connected to the at least one battery.

3. The system as recited in claim 1 , further comprising a state-of-charge sensor operatively connected to the at least one battery.

4. The system as recited in claim 1 , further comprising at least one of a motor or a generator operatively connected to the at least one battery to receive electric power therefrom or provide power thereto.

5. The system as recited in claim 1 , further comprising a battery resistance heater electrically coupled to the at least one battery.

6. The system as recited in claim 1 , further comprising an auxiliary load circuit electrically coupled to the at least one battery.

7. The system as recited in claim 1 , further comprising a battery heat exchanger positioned on the liquid heat exchange circuit in thermal communication with the at least one battery and the liquid heat exchange circuit.

8. The system as recited in claim 1 , further comprising a bypass valve positioned in the liquid heat exchange circuit upstream from the liquid-air heat exchanger.

9. The system as recited in claim 1 , further comprising bypass line valve positioned on the bypass line.

10. A method for controlling a thermal management system for an air vehicle comprising:

determining if at least one battery is within a thermal range of operation for heating, wherein the battery is in thermal communication with a liquid heat exchange circuit, wherein a liquid-air heat exchanger is positioned on the liquid heat exchange circuit and an air heat exchange circuit to exchange heat therebetween, wherein the air heat exchange circuit is in selective fluid communication with an air heat sink, wherein a bypass line branches from the liquid heat exchange circuit upstream from the liquid-air heat exchanger and reconnecting to the liquid heat exchange circuit downstream from the liquid-air heat exchanger; and at least one of charging or discharging the at least one battery to heat the at least one battery above a pre-determined minimum battery temperature if the at least one battery is within the thermal range of operation for heating.

11. The method as recited in claim 10 , wherein determining if the at least one battery is within the thermal range of operation for heating includes sensing a temperature of at least one battery with a temperature sensor, and wherein at least one of charging or discharging the at least one battery includes at least one of charging or discharging the at least one battery if the temperature is below a pre-determined threshold.

12. The method as recited in claim 10 , wherein determining if the at least one battery is within the thermal range of operation for heating includes referencing a pre-determined operating schedule that corresponds with a phase of flight.

13. The method as recited in claim 10 , further comprising closing a bypass valve positioned in the liquid heat exchange circuit upstream from the liquid-air heat exchanger if the at least one battery is within the thermal range of operation for heating.

14. The method as recited in claim 10 , further comprising opening a bypass line valve in a bypass line branching from the liquid heat exchange circuit upstream from the liquid-air heat exchanger and reconnecting to the liquid heat exchange circuit downstream from the liquid-air heat exchanger if the at least one battery is within the thermal range of operation for heating.

15. The method as recited in claim 10 , wherein at least one of charging or discharging includes charging the at least one battery when a state-of-charge of the at least one battery is below a pre-determined state-of-charge threshold.

16. The method as recited in claim 15 , wherein charging the at least one battery includes charging the at least one battery with energy generated with an engine.

17. The method as recited in claim 10 , wherein at least one of charging or discharging includes discharging the at least one battery when a state-of-charge of the at least one battery is above a pre-determined state-of-charge threshold.

18. The method as recited in claim 17 , wherein discharging includes discharging energy generated from the at least one battery to a motor.

19. The method as recited in claim 17 , wherein discharging includes discharging energy generated from the at least one battery to a battery resistance heater.