Monitoring state of charge of a battery

1. A method for determining a reported state of charge (“SOC”) of a battery system, the method comprising:

determining the reported SOC according to a first determining method when a previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

determining the reported SOC according to a second determining method when the previous SOC is greater than a second threshold percentage and less than or equal to the first SOC threshold percentage; and

determining the reported SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage.

2. The method of claim 1 wherein:

determining the reported SOC according to the first determining method comprises monitoring a monitored current of the battery system; and

determining the reported SOC according to the third determining method comprises monitoring a monitored voltage of a cell of the battery system.

3. The method of claim 2 wherein determining the reported SOC according to the second determining method comprises combining information of the first and third determining methods.

4. The method of claim 3 wherein determining the reported SOC according to the first determining method further comprises counting coulombs of the monitored current of the battery system.

5. The method of claim 3 wherein determining the reported SOC according to the first determining method further comprises determining an estimated SOC based on an estimated capacity of the battery system and the counted coulombs of the monitored current of the battery system.

6. The method of claim 3 wherein determining the reported SOC according to the second determining method further comprises:

calculating a new estimated SOC; and

weighting the previous SOC against the new estimated SOC.

7. The method of claim 3 wherein determining the reported SOC according to the third determining method further comprises determining an estimated SOC using at least one predetermined discharge voltage model.

8. The method of claim 7 , wherein:

the at least one predetermined discharge voltage model is selected from a plurality of stored discharge voltage models according to a current of the cell and a temperature of the cell; and

the estimated SOC is determined by using a measured voltage of the cell to look up a corresponding model SOC indicated by the at least one predetermined discharge voltage model.

9. The method of claim 1 , further comprising calculating a learned capacity of the battery system using the reported SOC of the battery system and a coulomb discharge value.

10. The method of claim 9 wherein calculating a learned capacity of the battery system further comprises:

calculating a new estimated capacity of the battery system; and

weighting a previous estimated capacity of the battery system against the new estimated capacity of the battery system.

11. A method for determining a reported state of charge (“SOC”) of a battery system, the method comprising:

determining a calculated SOC according to a first determining method when a previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

determining a calculated SOC according to a second determining method when the previous SOC is greater than a second threshold percentage and less than or equal to the first SOC threshold percentage;

determining a calculated SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage; and

determining the reported SOC by correcting the calculated SOC based on a current temperature in the battery system.

12. A method for determining a reported state of charge (“SOC”) of a battery system, the method comprising:

determining a calculated SOC according to a first determining method when a previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

determining a calculated SOC according to a second determining method when the previous SOC is greater than a second threshold percentage and less than or equal to the first SOC threshold percentage;

determining a calculated SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage;

determining the reported SOC to be equal to the calculated SOC if 1) the calculated SOC is less than the previous SOC or 2) the battery system is electrically coupled to a charge current; and

determining the reported SOC to be equal to the previous SOC when the calculated SOC is greater than the previous SOC and the battery system is not electrically coupled to a charge current.

13. A method for determining a reported SOC of a battery system, the method comprising:

determining the reported SOC according to a first determining method when 1) a charge current is present in the battery system, or 2) a previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

determining the reported SOC according to a second determining method when the learned capacity is greater than a learned capacity threshold percentage, or when the previous SOC is greater than a second SOC threshold percentage and less than or equal to the first SOC threshold percentage; and

determining the reported SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage.

14. A method for determining a reported SOC of a battery system, the method comprising:

calculating a learned capacity of the battery system using a previous SOC of the battery system and a coulomb discharge value;

determining the reported SOC according to a first determining method when the previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

determining the reported SOC according to a second determining method when 1) the learned capacity is greater than a learned capacity threshold percentage, or 2) the previous SOC is greater than a second SOC threshold percentage and less than or equal to the first SOC threshold percentage; and

determining the reported SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage.

15. An apparatus for determining a reported SOC of a battery system, the apparatus comprising a computer processor and a computer memory operatively coupled to the computer processor, the computer memory having disposed within it computer instructions capable of:

determining the reported SOC according to a first determining method when a previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

determining the reported SOC according to a second determining method when the previous SOC is greater than a second threshold percentage and less than or equal to the first SOC threshold percentage;

determining the reported SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage.

16. The apparatus of claim 15 wherein:

determining the reported SOC according to the first determining method comprises monitoring a monitored current of the battery system; and

determining the reported SOC according to the third determining method comprises monitoring a monitored voltage of a cell of the battery system.

17. The apparatus of claim 16 wherein determining the reported SOC according to the second determining method comprises combining information of the first and third determining methods.

18. The apparatus of claim 17 wherein determining the reported SOC according to the first determining method further comprises counting coulombs of the monitored current of the battery system.

19. The apparatus of claim 17 wherein determining the reported SOC according to the first determining method further comprises determining an estimated SOC based on an estimated capacity of the battery system and the counted coulombs of the monitored current of the battery system.

20. The apparatus of claim 17 wherein determining the reported SOC according to the second determining method further comprises:

calculating a new estimated SOC; and

weighting the previous SOC against the new estimated SOC.

21. The apparatus of claim 17 wherein determining the reported SOC according to the third determining method further comprises determining an estimated SOC using at least one predetermined discharge voltage model.

22. The apparatus of claim 21 , wherein:

the at least one predetermined discharge voltage model is selected from a plurality of stored discharge voltage models according to a current of the cell and a temperature of the cell; and

the estimated SOC is determined by using a measured voltage of the cell to look up a corresponding model SOC indicated by the at least one predetermined discharge voltage model.

23. The apparatus of claim 15 , the computer memory further comprising instructions capable of calculating a learned capacity of the battery system using the reported SOC of the battery system and a coulomb discharge value.

24. The apparatus of claim 23 wherein calculating a learned capacity of the battery system further comprises:

calculating a new estimated capacity of the battery system; and

weighting a previous estimated capacity of the battery system against the new estimated capacity of the battery system.

25. An apparatus for determining a reported SOC of a battery system, the apparatus comprising a computer processor and a computer memory operatively coupled to the computer processor, the computer memory having disposed within it computer instructions capable of:

determining a calculated SOC according to a first determining method when a previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

determining a calculated SOC according to a second determining method when the previous SOC is greater than a second threshold percentage and less than or equal to the first SOC threshold percentage;

determining a calculated SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage; and

determining the reported SOC by correcting the calculated SOC based on a current temperature in the battery system.

26. An apparatus for determining a reported SOC of a battery system, the apparatus comprising a computer processor and a computer memory operatively coupled to the computer processor, the computer memory having disposed within it computer instructions capable of:

determining a calculated SOC according to a first determining method when a previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

determining a calculated SOC according to a second determining method when the previous SOC is greater than a second threshold percentage and less than or equal to the first SOC threshold percentage;

determining a calculated SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage;

determining the reported SOC to be equal to the calculated SOC if 1) the calculated SOC is less than the previous SOC or 2) the battery system is electrically coupled to a charge current; and

determining the reported SOC to be equal to the previous SOC when the calculated SOC is greater than the previous SOC and the battery system is not electrically coupled to a charge current.

27. An apparatus for determining a reported SOC of a battery system, the apparatus comprising a computer processor and a computer memory operatively coupled to the computer processor, the computer memory having disposed within it computer instructions capable of:

determining the reported SOC according to a first determining method when 1) a charge current is present in the battery system, or 2) a previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

determining the reported SOC according to a second determining method when the learned capacity is greater than a learned capacity threshold percentage, or when the previous SOC is greater than a second SOC threshold percentage and less than or equal to the first SOC threshold percentage; and

determining the reported SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage.

28. An apparatus for determining a reported SOC of a battery system, the apparatus comprising a computer processor and a computer memory operatively coupled to the computer processor, the computer memory having disposed within it computer instructions capable of:

calculating a learned capacity of the battery system using a previous SOC of the battery system and a coulomb discharge value;

determining the reported SOC according to a first determining method when the previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

determining the reported SOC according to a second determining method when 1) the learned capacity is greater than a learned capacity threshold percentage, or 2) the previous SOC is greater than a second SOC threshold percentage and less than or equal to the first SOC threshold percentage; and

determining the reported SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage.

29. A computer program product embodied on a tangible computer-readable medium for determining a reported state of charge (“SOC”) of a battery system, the computer program product comprising:

computer program instructions for determining the reported SOC according to a first determining method when a previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

computer program instructions for determining the reported SOC according to a second determining method when the previous SOC is greater than a second threshold percentage and less than or equal to the first SOC threshold percentage; and

computer program instructions for determining the reported SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage.

30. The computer program product of claim 29 wherein:

determining the reported SOC according to the first determining method comprises monitoring a monitored current of the battery system; and

determining the reported SOC according to the third determining method comprises monitoring a monitored voltage of a cell of the battery system.

31. The computer program product of claim 30 wherein determining the reported SOC according to the second determining method comprises combining information of the first and third determining methods.

32. The computer program product of claim 31 wherein determining the reported SOC according to the first determining method further comprises counting coulombs of the monitored current of the battery system.

33. The computer program product of claim 31 wherein determining the reported SOC according to the first determining method further comprises determining an estimated SOC based on an estimated capacity of the battery system and the counted coulombs of the monitored current of the battery system.

34. The computer program product of claim 31 wherein determining the reported SOC according to the second determining method further comprises:

calculating a new estimated SOC; and

weighting the previous SOC against the new estimated SOC.

35. The computer program product of claim 31 wherein determining the reported SOC according to the third determining method further comprises determining an estimated SOC using at least one predetermined discharge voltage model.

36. The computer program product of claim 35 , wherein:

the at least one predetermined discharge voltage model is selected from a plurality of stored discharge voltage models according to a current of the cell and a temperature of the cell; and

the estimated SOC is determined by using a measured voltage of the cell to look up a corresponding model SOC indicated by the at least one predetermined discharge voltage model.

37. The computer program product of claim 29 , further comprising computer program instructions for calculating a learned capacity of the battery system using the reported SOC of the battery system and a coulomb discharge value.

38. The computer program product of claim 37 wherein calculating a learned capacity of the battery system further comprises:

calculating a new estimated capacity of the battery system; and

weighting a previous estimated capacity of the battery system against the new estimated capacity of the battery system.

39. A computer program product embodied on a tangible computer-readable medium for determining a reported state of charge (“SOC”) of a battery system, the computer program product comprising:

computer program instructions for determining a calculated SOC according to a first determining method when a previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

computer program instructions for determining a calculated SOC according to a second determining method when the previous SOC is greater than a second threshold percentage and less than or equal to the first SOC threshold percentage;

computer program instructions for determining a calculated SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage; and

computer program instructions for determining the reported SOC by correcting the calculated SOC based on a current temperature in the battery system.

40. A computer program product embodied on a tangible computer-readable medium for determining a reported state of charge (“SOC”) of a battery system, the computer program product comprising:

computer program instructions for determining a calculated SOC according to a first determining method when a previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

computer program instructions for determining a calculated SOC according to a second determining method when the previous SOC is greater than a second threshold percentage and less than or equal to the first SOC threshold percentage;

computer program instructions for determining a calculated SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage;

computer program instructions for determining the reported SOC to be equal to the calculated SOC if 1) the calculated SOC is less than the previous SOC or 2) the battery system is electrically coupled to a charge current; and

computer program instructions for determining the reported SOC to be equal to the previous SOC when the calculated SOC is greater than the previous SOC and the battery system is not electrically coupled to a charge current.

41. A computer program product embodied on a tangible computer-readable medium for determining a reported state of charge (“SOC”) of a battery system, the computer program product comprising:

computer program instructions for calculating a learned capacity of the battery system using a previous SOC of the battery system and a coulomb discharge value;

computer program instructions for determining the reported SOC according to a first determining method when the previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

computer program instructions for determining the reported SOC according to a second determining method when 1) the learned capacity is greater than a learned capacity threshold percentage, or 2) the previous SOC is greater than a second SOC threshold percentage and less than or equal to the first SOC threshold percentage; and

computer program instructions for determining the reported SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage.

42. A computer program product embodied on a tangible computer-readable medium for determining a reported state of charge (“SOC”) of a battery system, the computer program product comprising:

computer program instructions for calculating a learned capacity of the battery system using a previous SOC of the battery system and a coulomb discharge value;

computer program instructions for determining the reported SOC according to a first determining method when the previous SOC is greater than a first SOC threshold percentage and less than or equal to 100%;

computer program instructions for determining the reported SOC according to a second determining method when the learned capacity is greater than a learned capacity threshold percentage, or when the previous SOC is greater than a second SOC threshold percentage and less than or equal to the first SOC threshold percentage; and

computer program instructions for determining the reported SOC according to a third determining method when the previous SOC is greater than or equal to 0% and less than or equal to the second SOC threshold percentage.