Method and system for accurately reporting battery capacity

• US 20060100800A1
• Filed: 11/05/2004
• Published: 05/11/2006
• Est. Priority Date: 11/05/2004
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Fu, Runbo, Ahmed, Farhad
• Granted Patent: US 7,107,161 B2
• Time in Patent Office: Days
• US Class Current: 702/63
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• 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: Y02E 60/10 Energy storage using batteries

Abstract

A method and a system for accurately reporting battery capacity that do not rely on a coulomb counter are disclosed herein. The method comprises the steps of determining if the battery is in a transition phase and determining the battery capacity based on a transition phase battery capacity model when the battery is in the transition phase. The transition phase occurs upon one of attachment of the battery to a power source and disconnection of the battery from the power source. The behaviour described by the transition phase battery capacity model approaches the behaviour of real transition phase battery capacity so as to minimize the error of the determined battery capacity. The method and system accurately report battery capacity during a transition phase from discharging to charging and a transition phase from charging to discharging.

Claims

1. A method of determining the capacity of a battery, comprising the steps of

determining if the battery is in a transition phase;

determining the battery capacity based on a transition phase battery capacity model when the battery is in the transition phase,

wherein the transition phase occurs upon one of connection of the battery to a power source and disconnection of the battery from a power source, and the behaviour described by the transition phase battery capacity model approaches the behaviour of real transition phase battery capacity so as to minimize the error of the determined battery capacity.

2. The method of claim 1, wherein the step of determining the battery capacity based on a transition phase battery capacity model comprises the steps of determining a battery voltage, and calculating the battery capacity from the transition phase battery capacity model using the battery voltage.

3. The method of claim 1, wherein the step of determining the battery capacity based on a transition phase battery capacity model comprises the steps of determining a battery voltage, and determining the battery capacity by looking up a table corresponding to the transition phase battery capacity model based on the battery voltage.

4. The method of claim 1, wherein the step of determining the battery capacity based on a transition phase battery capacity model comprises the steps of

determining a battery ID of the battery;

selecting the transition phase battery capacity model from a plurality of transition phase battery capacity models based on the battery ID, wherein each of the plurality of transition phase battery capacity models corresponds to a battery ID;

determining a battery voltage, and

calculating the battery capacity from the selected transition phase battery capacity model using the battery voltage.

5. The method of claim 1, wherein the step of determining the battery capacity based on a transition phase battery capacity model comprises the steps of

determining a battery ID of the battery;

selecting the transition phase battery capacity model from a plurality of transition phase battery capacity models based on the battery ID, wherein each of the plurality of transition phase battery capacity models corresponds to a battery ID;

determining the battery voltage, and

determining the battery capacity by looking up a table corresponding to the selected transition phase battery capacity model based on the battery voltage.

6. The method of claim 1, wherein the step of determining if the battery is in a transition phase comprises the steps of

monitoring a power source connector of the battery;

determining that the battery is in a transition phase if there is an abrupt voltage change in the power source connector of the battery from 0 V to a predetermined value or from a predetermined value to 0V.

7. The method of claim 1, wherein the step of determining if the battery is in a transition phase comprises the steps of

monitoring current direction of the battery;

determining that the battery is in a transition phase if there is a change in the current direction of the battery.

8. The method of claim 1, further comprising the steps of

determining a start battery voltage of the battery when the battery is in a transition phase;

determining a battery voltage change from the start battery voltage;

determining that the transition phase is over when a battery voltage change is equal to a predefined amount.

9. The method of claim 1, further comprising the steps of

determining a start time of the transition phase;

determining a time change from the start time;

determining that the transition phase is over when a time change is equal to a predefined amount.

10. The method of claim 1, wherein the transition phase is one of a first transition phase from discharging to charging and a second transition phase from charging to discharging, and the transition phase battery capacity model is one of a first transition phase battery capacity model corresponding to the first transition phase from discharging to charging and a second transition phase battery capacity model corresponding to the second transition phase from charging to discharging.

11. The method of claim 10, further comprising the steps of

comparing the battery capacity determined from the transition phase battery capacity model with a battery capacity determined from a charging curve model when the battery is in the first transition phase from discharging to charging,

determining that the transition phase is over when the battery capacity determined from the transition phase battery capacity model is equal to the battery capacity determined from the charging curve model.

12. The method of claim 10, further comprising the steps of

comparing the battery capacity determined from the transition phase battery capacity model with a battery capacity determined from a discharging curve model when the battery is in the second transition phase from charging to discharging, and

determining that the transition phase is over when the battery capacity determined from the transition phase battery capacity model is equal to the battery capacity determined from the discharging curve model.

13. The method of claim 10, wherein the first transition phase battery capacity model is described by a first transition phase battery capacity function, and the second transition phase battery capacity model is described by a second transition phase battery capacity function.

14. The method of claim 13, wherein the first transition phase battery capacity function is associated with battery voltage, charge curve model and discharge curve model, the second transition phase battery capacity function is associated with battery voltage, charge curve model and discharge curve model.

15. The method of claim 14, wherein the error of the determined battery capacity falls within 2% of full battery capacity when the battery is in the second transition phase from charging to discharging.

16. The method of claim 14, wherein the error of the determined battery capacity falls within 6% of full battery capacity when the battery is in the first transition phase from discharging to charging.

17. The method of claim 13, wherein the first transition phase battery capacity function is

F1(V)=(1−

a)×

F_discharge(V)+a×

F_charge(V),

Where a=(V−

V_start)/Δ

V;

V is battery voltage;

F_discharge(V) is a discharging curve model;

F_charge(V) is a charging curve model;

Δ

V defines the first transition phase from discharging to charging, and Δ

V=V_end−

V_start;

V_start is a start battery voltage in the first transition phase, and V_end is an end battery voltage in the first transition phase.

18. The method of claim 17, wherein Δ

V is 0.2V.

19. The method of claim 13, wherein the second transition phase battery capacity function is

F2(V)=(F_discharge(V)×

SQRT((V_start−

V)/Δ

V)+F_charge(V)×

(1−

SQRT((V_start−

V)/Δ

V));

where V is battery voltage;

F_discharge(V) is a discharging curve model;

F_charge(V) is a charging curve model;

Δ

V defines the second transition phase from charging to discharging, and Δ

V=V_start−

V_end;

V_start is a start battery voltage in the second transition phase, and

V_end is an end battery voltage in the second transition phase.

20. The method of claim 19, wherein Δ

V is 0.15V.

21. The method of claim 14, wherein each of the first transition phase and the second transition phase is further associated with a voltage change amount.

22. The method of claim 14, wherein each of the first transition phase and the second transition phase is further associated with a time change amount.

23. The method of claim 21, wherein the voltage change amount is substantially between 0.05 and 0.3V.

24. The method of claim 22, wherein the time change amount is substantially between 0.5 hours to 3 hours.

25. The method of claim 1, further comprising the steps of

determining a battery ID of the battery;

determining a current battery operating temperature, and

compensating the determined battery capacity by using a battery capacity offset based on the battery ID and the current battery operating temperature.

26. The method of claim 1, wherein the step of determining the battery capacity based on a transition phase battery capacity model comprises the steps of

determining a battery ID of the battery;

determining a current battery operating temperature;

selecting a transition phase battery capacity model from a plurality of transition phase battery capacity models according to the battery ID and the current battery operating temperature, wherein each of the plurality of transition phase battery capacity models corresponds to a battery ID and a predetermined battery operating temperature range;

determining a battery voltage, and

calculating the battery capacity from the selected transition phase battery capacity model using the battery voltage.

27. The method of claim 1, wherein the step of determining the battery capacity based on a transition phase battery capacity model comprises the steps of

determining a battery ID of the battery;

determining a current battery operating temperature;

selecting a transition phase battery capacity model from a plurality of transition phase battery capacity models according to the battery ID and the current battery operating temperature, wherein each of the plurality of transition phase battery capacity models corresponds to a battery ID and a predetermined battery operating temperature range;

determining a battery voltage, and

determining the battery capacity by looking up a table corresponding to the selected transition phase battery capacity model based on the battery voltage.

28. The method of claim 26, wherein the predetermined battery operating temperature range is one of the battery operating temperature ranges provided by dividing a temperature range from −

20°

C. to 50°

C. according to a predetermined format.

29. The method of claim 27, wherein the predetermined battery operating temperature range is one of the battery operating temperature ranges provided by dividing a temperature range from −

20°

C. to 50°

C. according to a predetermined format.

30. The method of claim 1, wherein the step of determining the battery capacity based on a transition phase battery capacity model comprises the steps of

determining a battery ID of the battery;

determining a current battery operating temperature, and

selecting a transition phase battery capacity model from a plurality of transition phase battery capacity models according to the battery ID and the current battery operating temperature, wherein each of the plurality of transition phase battery capacity models corresponds to a battery ID and a predetermined battery operating temperature;

determining a battery voltage, and

calculating the battery capacity from the selected transition phase battery capacity model using the battery voltage.

31. The method of claim 1, wherein the step of determining the battery capacity based on a transition phase battery capacity model comprises the steps of

determining a battery ID of the battery;

determining a current battery operating temperature, and

selecting a transition phase battery capacity model from a plurality of transition phase battery capacity models according to the battery ID and the current battery operating temperature, wherein each of the plurality of transition phase battery capacity models corresponds to a battery ID and a predetermined battery operating temperature;

determining a battery voltage, and

determining the battery capacity by looking up a table corresponding to the selected transition phase battery capacity model based on the battery voltage.

32. The method of claim 30, wherein the predetermined battery operating temperature is between −

20°

C. and 50°

C.

33. The method of claim 31, wherein the predetermined battery operating temperature is between −

20°

C. and 50°

C.

34. The method of claim 1, further comprising the steps of

determining a state of the battery if the battery is not in the transition phase, and

determining the battery capacity by examining a state curve model of the correlation between battery voltage, battery state and battery capacity based on the determined state.

35. The method of claim 34, wherein the state of the battery is one of a discharging state and a charging state, and the state curve model is one of a discharging curve model corresponding to a discharging state and a charging curve model corresponding to a charging state.

36. The method of claim 34, further comprising the steps of

determining a battery ID of the battery;

determining a current battery operating temperature, and

compensating the determined battery capacity by using a battery capacity offset based on the battery ID and the current battery operating temperature.

37. The method of claim 34, wherein the step of determining the battery capacity by examining a state curve model of the correlation between battery voltage, battery state and battery capacity based on the determined state comprises the steps of

determining a battery ID of the battery;

selecting a corresponding state curve model from a plurality of state curve models based on the battery ID, wherein each of the plurality of the state curve models corresponds to a battery ID;

determining a battery voltage, and

determining the battery capacity by looking up a table corresponding to the selected state curve model.

38. The method of claim 34, wherein the step of determining the battery capacity by examining a state curve model of the correlation between battery voltage, battery state and battery capacity based on the determined state comprises the steps of

determining a battery ID of the battery;

determining a current battery operating temperature;

selecting a corresponding state curve model from a plurality of state curve models based on the battery ID and the current battery operating temperature, wherein each of the plurality of the state curve models corresponds to a battery ID and a predetermined battery operating temperature range;

determining a battery voltage, and

determining the battery capacity by looking up a table corresponding to the selected state curve model.

39. The method of claim 38, wherein the predetermined battery operating temperature range is one of the battery operating temperatures provided by dividing a temperature range −

20°

C. to 50°

C. according to a predetermined format.

40. A system for determining the capacity of a battery, the system comprising

transition phase determining means operatively connected to the battery for determining if the battery is in a transition phase;

battery capacity determining means operatively connected to the transition phase determining means for determining the battery capacity based on a transition phase battery capacity model if the battery is in the transition phase,

wherein the transition phase occurs upon one of connection of the battery to a power source and disconnection of the battery to a power source, and the behaviour described by the transition phase battery capacity model approaches a behaviour of a real transition phase battery capacity so as to minimize the error of the determined battery capacity.

41. The system of claim 40, further comprising

battery ID determining means operatively connected to the battery for determining a battery ID of the battery;

means for selecting a transition phase battery capacity model from a plurality of transition phase battery capacity models based on the battery ID, operatively connected to the battery ID determining means, each of the plurality of transition phase battery capacity models corresponding to a battery ID, and

voltage reading means operatively connected to the battery for determining a battery voltage, and wherein the battery capacity determining means calculates the battery capacity from the selected transition phase battery capacity model based on the battery voltage.

42. The system of claim 40, further comprising

battery ID determining means operatively connected to the battery for determining a battery ID of the battery;

means for selecting a transition phase battery capacity model from a plurality of transition phase battery capacity models based on the battery ID, operatively connected to the battery ID determining means, each of the plurality of transition phase battery capacity models corresponding to a battery ID, and

voltage reading means operatively connected to the battery for determining a battery voltage, and wherein the battery capacity determining means determines the battery capacity by looking up a table corresponding to the selected transition phase battery capacity model based on the battery voltage.

43. The system of claim 40, further comprising

temperature sensor means operatively connected to the battery for sensing a battery operating temperature;

battery ID determining means operatively connected to the battery for determining the battery ID;

voltage reading means operatively connected to the battery for determining a battery voltage;

means for selecting a corresponding transition phase battery capacity model from a plurality of transition phase battery capacity models according to the battery ID and the battery operating temperature, operatively connected to the temperature sensor means and the battery ID determining means, wherein each of the plurality of transition phase battery capacity models corresponds to a battery ID and a predetermined battery operating temperature range,

wherein the battery capacity determining means calculates the battery capacity from the selected transition phase battery capacity model using the battery voltage.

44. The system of claim 40, further comprising

temperature sensor means operatively connected to the battery for sensing a battery operating temperature;

battery ID determining means operatively connected to the battery for determining the battery ID;

voltage reading means operatively connected to the battery for determining a battery voltage;

means for selecting a corresponding transition phase battery capacity model from a plurality of transition phase battery capacity models according to the battery ID and the battery operating temperature, operatively connected to the temperature sensor means and the battery ID determining means, wherein each of the plurality of transition phase battery capacity models corresponds to a battery ID and a predetermined battery operating temperature range, and

wherein the battery capacity determining means determines the battery capacity by looking up a table corresponding to the selected transition phase battery capacity model based on the battery voltage.

45. The system of claim 43, further comprising battery capacity compensating means operatively connected to the temperature sensor means for compensating the determined battery capacity by using a battery capacity offset based on the battery ID and the battery operating temperature.

46. The system of claim 44, further comprising battery capacity compensating means operatively connected to the temperature sensor means for compensating the determined battery capacity by using a battery capacity offset based on the battery ID and the battery operating temperature.

47. The system of claim 40, further comprising

battery state determining means operatively connected to the battery for determining a battery state if the battery is not in the transition phase,

wherein the battery state is one of a discharging state and a charging state, and the battery capacity determining means determines the battery capacity by examining a state curve model correlating battery voltage, battery state and battery capacity based on the determined state.

48. A handheld device having a system for determining the capacity of a battery, the system comprising

transition phase determining means operatively connected to the battery for determining if the battery is in a transition phase;

battery capacity determining means operatively connected to the transition phase determining means for determining the battery capacity based on a transition phase battery capacity model if the battery is in the transition phase, and

wherein the transition phase occurs upon one of connection of the battery to a power source and disconnection of the battery to the power source, and the behaviour described by the transition phase battery capacity model approaches a behaviour of a real transition phase battery capacity so as to minimize the error of the determined battery capacity.

49. The handheld device of claim 48, further comprising voltage reading means operatively connected to the battery for determining a battery voltage, wherein battery capacity determining means calculates the battery capacity from the transition phase battery capacity model using the battery voltage.

50. The handheld device of claim 48, further comprising voltage reading means operatively connected to the battery for determining a battery voltage, wherein battery capacity determining means determines the battery capacity by looking up a table corresponding to the selected transition phase battery capacity model based on the battery voltage.

51. The handheld device of claim 48, further comprising

battery ID determining means operatively connected to the battery for determining an battery ID of the battery;

means for selecting a transition phase battery capacity model from a plurality of transition phase battery capacity models based on the battery ID, operatively connected to the battery ID determining means, wherein each of the plurality of transition phase battery capacity models corresponds to a battery ID, and

voltage reading means operatively connected to the battery for determining a battery voltage, wherein battery capacity determining means calculates the battery capacity from the selected transition phase battery capacity model using the battery voltage.

52. The handheld device of claim 48, further comprising

battery ID determining means operatively connected to the battery for determining an battery ID of the battery;

means for selecting a transition phase battery capacity model from a plurality of transition phase battery capacity models based on the battery ID, operatively connected to the battery ID determining means, wherein each of the plurality of transition phase battery capacity models corresponds to a battery ID, and

voltage reading means operatively connected to the battery for determining a battery voltage, wherein battery capacity determining means determines the battery capacity by looking up a table corresponding to the selected transition phase battery capacity model based on the battery voltage.

53. The handheld device of claim 48, further comprising

battery state determining means operatively connected to the battery for determining a battery state if the battery is not in the transition phase,

wherein the battery state is one of a discharging state and a charging state, and the battery capacity determining means determines the battery capacity by examining a battery state curve model correlating battery voltage, battery state and battery capacity based on the determined state.