Method for battery state-of-health monitoring using battery voltage during vehicle starting
View Patent ↗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.
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.
2. The method of claim 1 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.
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.
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.