Battery pack thermistor test method

• US 9,488,535 B2
• Filed: 06/18/2013
• Issued: 11/08/2016
• Est. Priority Date: 06/18/2013
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Keeton, Robert C
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): AHMED, NASIR UDDIN
• Application Number:
  US13/921,000
• Publication Number:
  US 20140369376A1
• Time in Patent Office: 1,239 Days
• Field of Search: 324/426
• US Class Current: 1/1
• CPC Class Codes: G01K 15/007 Testing
• CPC Class Codes: G01K 2205/00 Application of thermometers in motors, e.g. of a vehicle

Abstract

A battery pack thermistor test method includes charging a battery pack, monitoring a rise in average temperature reported by at least one thermistor on the battery pack over a predetermined time period, preparing at least one thermistor slope by calculating a least square fit of time vs. temperature for the at least one thermistor and comparing the at least one thermistor slope to process-defined thermistor slope limits.

Claims

1. A battery pack thermistor test method, comprising:

charging a battery pack;

monitoring a rise in average temperature reported by at least one thermistor on the battery pack over a predetermined time period following a start of said charging;

preparing at least one thermistor slope by calculating a least square fit of time vs. temperature for the at least one thermistor over a selected time period following said charging; and

comparing the at least one thermistor slope to pre-defined thermistor slope limits.

2. The method of claim 1 wherein charging a battery pack comprises applying a controlled charge profile to a battery pack cell in the battery pack.

3. The method of claim 2 wherein applying a controlled charge profile comprises applying a stepped current over a predetermined time period.

4. The method of claim 3 wherein applying a stepped current comprises applying a stepped current of constant durations over a predetermined time period.

5. The method of claim 4 wherein applying a stepped current of constant durations over a predetermined time period comprises applying a stepped current of constant durations of about 5.0 seconds each.

6. The method of claim 3 wherein applying a stepped current over a predetermined time period comprises applying a stepped current having a final step corresponding to a predetermined peak current.

7. The method of claim 6 wherein applying a stepped current having a final step corresponding to a predetermined peak current comprises applying a stepped current of about 10.0 seconds.

8. The method of claim 1 further comprising rejecting the battery pack if the thermistor slope falls outside the thermistor slope limits.