Electrical storage device heater for vehicle

1. A vehicle, comprising:

a first power source located on-board said vehicle;

a battery system powered by said first power source, wherein said battery system includes a high voltage electrical storage device, a heater that selectively heats said high voltage electrical storage device, and a switch that selectively couples said heater to said first power source; and

a controller that controls the operation of said heater by actuating said switch to couple said heater to said first power source, wherein said controller is powered by an alternative power source that is separate from said first power source.

2. The vehicle as recited in claim 1 , wherein said controller is configured to actuate said switch based on at least one of a temperature of said high voltage electrical storage device, an output from a converter, and a key on/off condition of said vehicle.

3. The vehicle as recited in claim 1 , comprising an engine block heater that is coupled to said battery system by said first power source.

4. The vehicle as recited in claim 3 , wherein said heater and said engine block heater are connected to said first power source by a single connector.

5. The vehicle as recited in claim 1 , wherein said first power source is a battery separate from said battery system.

6. The system as recited in claim 1 , wherein said controller is configured to actuate said heater based on a temperature of said high voltage electrical storage device and a vehicle key ON/OFF condition.

7. The system as recited in claim 1 , wherein said controller is powered by a low voltage battery that is separate from either of said high voltage electrical storage device and said alternative power source from said location separate from said high voltage electrical storage device.

8. The vehicle as recited in claim 1 , wherein said alternative power source is a low voltage battery.

9. A method, comprising:

checking whether a vehicle is in a key ON or key OFF condition with a controller;

connecting a heater to a high voltage electrical storage device of a battery system of the vehicle if a temperature is below a temperature threshold and the vehicle is in the key OFF condition; and

disconnecting the heater from the high voltage electrical storage device if the temperature is above the temperature threshold or the battery system is disconnected from an external power source.

10. The method as recited in claim 9 , comprising periodically awakening from a sleep mode to check the temperature of the high voltage electrical storage device.

11. The method as recited in claim 10 , comprising:

remaining in the sleep mode for a selected time period;

awakening from the sleep mode after the selected time period; and

rechecking whether the battery system is connected to the external power source after the step of awakening from the sleep mode.

12. The method as recited in claim 9 , comprising:

checking whether the battery system is connected to the external power source; and

checking the temperature of the high voltage electrical storage device of said battery system, wherein the checking steps are performed by a controller.

13. The method as recited in claim 9 , wherein connecting the heater to the high voltage electrical storage device is performed if a converter active signal indicates that the heater is connected to the external power source.

14. The method as recited in claim 9 , wherein the heater includes a thermoelectric heater element.

15. A battery heater system for an electrified vehicle, comprising:

a high voltage battery system that includes a plurality of battery cells, a heater that selectively heats said plurality of battery cells, and a switch that selectively controls power flow to said heater;

a power supply separate from said high voltage battery system that selectively powers said heater when said switch is closed; and

a controller configured to control operation of said switch to supply power to said heater based on at least battery cell temperatures, a key ON/OFF condition, and a converter AC/DC active signal.

16. The battery heater system as recited in claim 15 , wherein said heater includes a thermoelectric heater element.