System and method of battery capacity reporting

• US 20030008202A1
• Filed: 07/03/2002
• Published: 01/09/2003
• Est. Priority Date: 07/05/2001
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Tran, Phat H.
• Granted Patent: US 6,794,852 B2
• Time in Patent Office: Days
• US Class Current: 429/61
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3828 using current integration
• 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: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]

Abstract

A method and system for accurately reporting battery capacity is disclosed herein. The disclosed method and system prevent the reporting of discontinuous capacity values resulting from starting or stopping recharge cycles. The disclosed method and system prevent over or under reporting of battery capacity due to the transition between charge and discharge curves in a battery model.

Claims

1. A method of determining the available battery capacity of a battery comprising:

determining a battery voltage and a current charge state of the battery;

determining a target battery capacity based on the determined battery voltage and the determined current charge state;

comparing the determined target battery capacity to a previous battery capacity; and

adjusting the target battery capacity if the comparison is not indicative of the determined charge state.

2. The method of claim 1 further including the step of reporting the target battery capacity.

3. The method of claim 1 further including the step of storing the reported capacity as the previous battery capacity.

4. The method of claim 1, wherein the two defined charge states are a charging state, and a discharging state.

5. The method of claim 4, wherein a target battery capacity less than the previous battery capacity is not indicative of the charging state.

6. The method of claim 4, wherein a target battery capacity greater than the previous battery capacity is not indicative of the discharging state.

7. The method of claim 1, wherein determining a target battery capacity based on the determined battery voltage and the determined current charge state includes determining the capacity by examining a predetermined model of the correlation between voltage, charge state and capacity.

8. The method of claim 1, wherein the step of adjusting includes changing the target capacity to the value of the previous battery capacity value.

9. The method of claim 1, wherein the step of adjusting includes changing the target capacity to a capacity determined from a predefined fast transition curve that models the relationship between the determined battery voltage, the determined current charge state and battery capacity.

10. The method of claim 1, further including, prior to the step of reporting, the step of adjusting the target capacity to a capacity determined from a predefined slow transition curve that models the relationship between the determined battery voltage, the determined current charge state and battery capacity, if the target capacity is in a play region around the capacity of the battery when the last change in charge state occurred.

11. The method of claim 1, further including the step of adjusting the target battery capacity, prior to the step of reporting, using an effective serial resistance correction factor.

12. The method of claim 1, further including the step of adjusting the target battery capacity, prior to the step of reporting, to compensate for temperature fluctuations.

14. The system of claim 13, further including reporting means, operatively connected to the target capacity adjusting means for reporting the adjusted target battery capacity.

15. The system of claim 13, wherein the target capacity adjusting means further includes means for adjusting the determined target capacity to a capacity determined from a predefined fast transition curve that models the relationship between the determined battery voltage, the determined current charge state and battery capacity after a change in charge state.

16. The system of claim 13, wherein the target capacity adjusting means further includes means for adjusting the target capacity to a capacity determined from a predefined slow transition curve that models the relationship between the determined battery voltage, the determined current charge state and battery capacity when the target capacity is in a play region around the capacity of the battery when the last change in charge state occurred.

17. The system of claim 13, wherein the target capacity adjusting means is further operatively connected to an effective serial resistance tester which is operatively connected to the battery for determining an effective serial resistance correction factor, and wherein the target capacity adjusting means further includes means for adjusting the target capacity based on the effective serial resistance correction factor.

13. A system for determining the capacity of a battery having a memory for storing a previous battery capacity value, the system comprising:

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

charge state determining means operatively connected to the battery for determining the charge state of the battery;

target capacity determining means, operatively connected to the voltage reading means for receiving the determined voltage and to the charge state determining means for receiving the determined charge state, for computing a target battery capacity based on the determined voltage and the determined charge state;

a comparator, operatively connected to the memory for receiving the previous battery capacity value and to the target capacity determining means for receiving the target battery capacity, for generating a comparison signal representative of the comparison of the previous battery capacity value and the target battery capacity; and

target capacity adjusting means operatively connected to the comparator for receiving the comparison signal, to the target capacity determining means for receiving the determined target battery capacity and to the charge state determining means for receiving the determined charge state, for adjusting the determined target battery capacity if the comparison signal is not indicative of the determined charge state, and for storing the adjusted target battery capacity in the memory.

18. A handheld device having a system for determining the capacity of a battery having a memory for storing a previous battery capacity value, the system comprising:

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

charge state determining means operatively connected to the battery for determining the charge state of the battery;

target capacity determining means, operatively connected to the voltage reading means for receiving the determined voltage and to the charge state determining means for receiving the determined charge state, for computing a target battery capacity based on the determined voltage and the determined charge state;

a comparator, operatively connected to the memory for receiving the previous battery capacity value and to the target capacity determining means for receiving the target battery capacity, for generating a comparison signal representative of the comparison of the previous battery capacity value and the target battery capacity; and

target capacity adjusting means operatively connected to the comparator for receiving the comparison signal, to the target capacity determining means for receiving the determined target battery capacity and to the charge state determining means for receiving the determined charge state, for adjusting the determined target battery capacity if the comparison signal is not indicative of the determined charge state, and for storing the adjusted target battery capacity in the memory.