Method for battery state-of-health monitoring using battery voltage during vehicle starting

• US 20090322340A1
• Filed: 06/27/2008
• Published: 12/31/2009
• Est. Priority Date: 06/27/2008
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Zhang, Yilu, Salman, Mutasim A., Zhang, Xiaodong, Tang, Xidong, Walters, David W., Kapsokavathis, Nick S.
• Granted Patent: US 8,111,037 B2
• Time in Patent Office: Days
• US Class Current: 324/433
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/386 using test-loads
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A method is provided for determining a battery'"'"'s state-of-health. An initial battery voltage is measured after a first voltage drop during an initiation of an engine cranking phase. A battery voltage is monitored during the remainder of the engine cranking phase. A lowest battery voltage is determined during the remainder of the engine cranking phase. A determination is made if a voltage difference between the lowest battery voltage and the initial battery voltage at the initiation of the engine cranking phase is less than a voltage threshold. A low battery state-of-health is identified in response to the voltage difference being less than the voltage threshold.

Claims

1. A method of determining a state-of-health of a battery, the method comprising the steps of:

measuring an initial battery voltage after a first voltage drop during an initiation of an engine cranking phase;

monitoring a battery voltage during the remainder of the engine cranking phase;

determining a first peak voltage after the first voltage drop;

determining a lowest battery voltage during an interval between the first peak voltage and completion of the engine cranking phase;

determining if a voltage difference between the lowest battery voltage and the initial battery voltage is less than a voltage threshold; and

identifying a low battery state-of-health in response to the voltage difference being less than the voltage threshold.

3. The method of claim 1 wherein measuring a battery voltage at an initiation of an engine cranking phase occurs substantially simultaneously at starter engagement.

4. The method of claim 1 wherein the voltage threshold includes a fixed voltage value.

5. The method of claim 1 wherein the threshold voltage is obtained from a lookup table based on a temperature of the battery.

6. The method of claim 1 wherein the threshold voltage is obtained from a lookup table based on a state-of-charge of the battery.

7. The method of claim 1 wherein the threshold voltage is obtained from the lookup table based on a temperature of the battery and a state-of-charge of the battery.

2. The method of claim 2 wherein the lowest battery voltage is a lowest voltage value measured after the voltage of the battery reaches a first peak voltage and prior to the completion of the engine cranking phase.

8. A method of determining a state-of-health of a battery, the method comprising the steps of:

measuring an initial battery voltage during an initiation of the engine cranking phase;

determining a first voltage peak during the engine cranking phase;

determining a lowest voltage between a time when the first voltage peak is detected and completion of the engine cranking phase;

determining a voltage difference between the lowest voltage and the initial battery voltage;

comparing the voltage difference to a voltage threshold;

determining a low battery state-of-health if the voltage difference is less than the voltage threshold; and

generating an indication of the low battery state-of-health in response to the voltage difference being less than the voltage threshold.

9. The method of claim 8 wherein comparing the voltage difference to a voltage threshold includes comparing the voltage difference to a fixed voltage value.

10. The method of claim 8 wherein the voltage threshold is retrieved from the lookup table based on a temperature of the battery.

11. The method of claim 8 wherein the voltage threshold is retrieved from the lookup table based on a state-of-charge of the battery.

12. The method of claim 8 wherein the voltage threshold is retrieved from the lookup table based on a temperature of the battery and a state-of-charge of the battery.

13. The method of claim 8 wherein lowest voltage is a lowest voltage value measured after the voltage of the battery reaches a first peak voltage and prior to the completion of the engine cranking phase.

14. The method of claim 8 wherein measuring the initial battery voltage occurs after a first voltage drop during an initiation of the engine cranking phase.

15. The method of claim 8 wherein measuring a battery voltage at an initiation of an engine cranking phase occurs substantially simultaneously with a starter engagement.