Thermal runaway detection methods and warning systems

1. A method for detecting thermal runaway of a cell, comprising:

positioning a battery pack having multiple cells in an automobile vehicle;

measuring, using a controller having at least one computer individually having at least one processor and at least one memory storing instructions, a cell voltage of the multiple cells at a predetermined sample rate;

identifying, using the controller, if the cell voltage decreases and modulates indicating initiation of a cell short coincident with or preceding a cell surface temperature increase indicating initiation of a thermal runaway event;

identifying if a power spectrum exceeds a predetermined threshold following initiation of the cell short;

initiating, using the controller, an alarm after the predetermined threshold is exceeded;

confirming the automobile vehicle to be stopped prior to measuring the cell voltage;

identifying if a cell threshold temperature is reached defining approximately 70 C; and

identifying if a cell temperature rise up to approximately 500 C occurs within approximately 5 seconds after the cell temperature reaches the threshold temperature during the battery cell thermal runaway event; and

initiating, using the controller, action following the initiation of the alarm including at least one of:

releasing, using the controller, a battery pack pressure;

communicating, using the controller, a warning via a smart phone to a vehicle operator; and

contacting, using the controller, an emergency service.

2. The method of claim 1 , further including determining a mean value of all cell voltages of the multiple cells by subtracting a minimum cell voltage from a sum the cell voltages.

3. The method of claim 2 , further including:

calculating a derivative of the cell voltage of individual ones of the multiple cells with respect to time; and

passing the derivative of the cell voltage through a buffer.

4. The method of claim 3 , further including calculating a fast fourier transform power spectrum applying the derivative of the cell voltage of the multiple cells with respect to time.

5. The method of claim 4 , further including calculating a released energy applying the power spectrum.

6. The method of claim 1 , further including initiating an action following the initiation of the alarm including at least one of:

stopping a charging operation of the battery pack;

initiating flow of a coolant into the battery pack; and

communicating a status of the battery pack to a remote cloud-based security service.

7. The method of claim 1 , further including continuing to analyze the cell voltage and the cell surface temperature following the initiation of the cell short and during a time period having a cell voltage decrease and rapid cell voltage modulation and as the cell surface temperature increases.

8. A method for detecting thermal runaway of a cell, comprising:

positioning a battery pack having multiple cells in an automobile vehicle;

measuring, using a controller having at least one computer individually having at least one processor and at least one memory storing instructions, a cell voltage of the multiple cells at a predetermined sample rate;

identifying, using the controller, if a cell short is occurring in at least one of the multiple cells;

decomposing a signal of the cell voltage into multiple signal time domain scales through a scalable wavelet filter applying a discrete wavelet distribution (DWT);

determining, using the controller, if a cell surface temperature increases to or above a threshold temperature indicating initiation of a cell thermal runaway event;

identifying if a power spectrum exceeds a predetermined threshold following initiation of the cell short;

initiating, using the controller, an alarm after the predetermined threshold is exceeded; and initiating, using the controller, an action following the initiation of the alarm including at least one of:

releasing, using the controller, a battery pack pressure;

communicating, using the controller, a warning via a smart phone to a vehicle operator; and

contacting, using the controller, an emergency service.

9. The method of claim 8 , further including:

passing a cell voltage signal through the wavelet filter; and

applying a scaling function to differentiate and remove frequencies of the signal predesignated as noise.

10. The method of claim 9 , further including applying the scaling function to split a first high frequency extraction portion into a first high frequency component and a first low frequency extraction portion into a first low frequency component.

11. The method of claim 10 , further including:

halving the low frequency component from the first low frequency extraction portion; and

generating level 1 coefficients.

12. The method of claim 11 , further including:

calculating a derivative of the cell voltage of individual ones of the multiple cells with respect to time;

calculating a fast fourier transform power spectrum applying the derivative of the cell voltage of the multiple cells with respect to time;

calculating a released energy applying the power spectrum; and

initiating an alarm if the power spectrum exceeds a predetermined spectrum threshold following initiation of the cell short.

13. The method of claim 8 , further including identifying if the cell voltage decreases and modulates coincident with the cell surface temperature increase.

14. The method of claim 8 , further including stopping a charging operation of the battery pack following the initiation of the alarm.

15. The method of claim 8 , further including initiating flow of a coolant into the battery pack following the initiation of the alarm.

16. The method of claim 8 , further including communicating a status of the battery pack to a remote cloud-based security service following the initiation of the alarm.

17. A system for detecting thermal runaway of a cell, comprising:

a controller having at least one computer, with the at least one computer individually having:

at least one processor; and

at least one memory storing instructions, such that the at least one processor is programmed to:

confirm an automobile vehicle stop;

measure a cell voltage of multiple cells of a battery pack of the automobile vehicle at a predetermined sample rate;

identify a cell short by a cell voltage decrease and a start of cell voltage modulation;

identify if a power spectrum exceeds a predetermined threshold following initiation of the cell short;

indicate, a battery cell thermal runaway event in response to a cell threshold temperature being reached;

initiate an alarm after the threshold temperature is reached;

calculating a derivative of the cell voltage of individual ones of the multiple cells calculated with respect to time;

calculating a fast fourier transform power spectrum calculated applying the derivative of the cell voltage of the multiple cells with respect to time;

calculating a released energy calculated by applying the power spectrum; and

initiating the alarm when the power spectrum exceeds a predetermined threshold following initiation of the cell short; and

initiate an action following the initiation of the alarm including at least one of:

release a battery pack pressure;

communicate a warning via a smart phone to a vehicle operator; and

contact an emergency service.

18. The system of claim 17 , further including:

a cell voltage signal passed through a wavelet filter;

a scaling function applied to split a first high frequency extraction portion of the cell voltage signal into a first high frequency component and a first low frequency extraction portion into a first low frequency component; and

frequencies of the cell voltage signal predesignated as noise being differentiated and removed.

19. The system of claim 17 , wherein the controller is further programed to stop a charging operation of the battery pack following the initiation of the alarm.

20. The system of claim 17 , wherein the controller is further programed to initiate a flow of a coolant into the battery pack following the initiation of the alarm.