System and method of battery capacity reporting

• US 20060049805A1
• Filed: 11/01/2005
• Published: 03/09/2006
• Est. Priority Date: 07/05/2001
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Phat H. Tran
• Inventors: Tran, Phat H.
• Granted Patent: US 7,301,305 B2
• Time in Patent Office: Days
• US Class Current: 320/149
• 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 an available capacity of a rechargeable battery, comprising:

storing a battery capacity model, the battery capacity model including a first set of data and a second set of data,

the first set of data relating battery voltage to available capacity when the battery is charging,

the second set of data relating battery voltage to available capacity when the battery is discharging;

measuring a battery voltage;

determining if the battery is charging or discharging;

if the battery is charging, then using the first set of data from the battery capacity model to determine the available capacity from the measured battery voltage; and

if the battery is discharging, then using the second set of data from the battery capacity model to determine the available capacity from the measured battery voltage.

2. The method of claim 1, wherein the first set of data represents a charge curve and the second set of data represents a discharge curve.

3. The method of claim 1, further comprising:

reporting the available capacity to a user.

4. The method of claim 1, further comprising:

detecting a change in state of the rechargeable battery between a discharge state and a charge state;

if the detected state change is from the charge state to the discharge state, then reporting only decreases in the available capacity until another state change is detected; and

if the detected state change is from the discharge state to the charge state, then reporting only increases in the available capacity until another state change is detected.

5. The method of claim 1, further comprising:

measuring a battery current; and

correcting the measured battery voltage based at least in part on the measured battery current and an effective serial resistance;

wherein the available capacity is determined based on the corrected battery voltage.

6. The method of claim 1, further comprising:

measuring an ambient temperature of the battery;

correcting the measured battery voltage based at least in part on the measured ambient temperature;

wherein the available capacity is determined based on the corrected battery voltage.

7. A mobile communication device, comprising:

a rechargeable battery;

a memory device storing a battery capacity model, the battery capacity model including a first set of data and a second set of data,

the first set of data relating battery voltage to available capacity when the rechargeable battery is charging,

the second set of data relating battery voltage to available capacity when the rechargeable battery is discharging;

a charging subsystem configured to measure a battery voltage of the rechargeable battery, and determine if the rechargeable battery is charging or discharging;

the charging subsystem being further configured to use the first set of data from the battery capacity model to determine the available capacity from the measured battery voltage if the rechargeable battery is charging, and use the second set of data from the battery capacity model to determine the available capacity from the measured battery voltage if the rechargeable battery is discharging.

8. The mobile communication device of claim 7, wherein the first set of data represents a charge curve and the second set of data represents a discharge curve.

9. The mobile communication device of claim 7, further comprising:

a user interface configured to report the available capacity to a user.

10. The mobile communication device of claim 9, wherein:

the charging subsystem is further configured to detect a change in state of the rechargeable battery between a discharge state and a charge state;

if the detected state change is from the charge state to the discharge state, then the user interface reporting only decreases in the available capacity until another state change is detected; and

if the detected state change is from the discharge state to the charge state, then the user interface reporting only increases in the available capacity until another state change is detected.

11. The mobile communication device of claim 7, further comprising:

circuitry for measuring a battery current;

wherein the charging subsystem is further configured to correct the measured battery voltage based at least in part on the measured battery current and an effective serial resistance;

wherein the available capacity is determined based on the corrected battery voltage.

12. The mobile communication device of claim 7, further comprising:

circuitry for measuring an ambient temperature of the battery;

wherein the charging subsystem is further configured to correct the measured battery voltage based at least in part on the measured ambient temperature;

wherein the available capacity is determined based on the corrected battery voltage.

13. A mobile communication device, comprising:

means for storing a battery capacity model, the battery capacity model including a first set of data and a second set of data,

the first set of data relating battery voltage to available capacity when the battery is charging,

the second set of data relating battery voltage to available capacity when the battery is discharging;

means for measuring a battery voltage;

means for determining if the battery is charging or discharging;

means for using the first set of data from the battery capacity model to determine the available capacity from the measured battery voltage if the battery is charging; and

means for using the second set of data from the battery capacity model to determine the available capacity from the measured battery voltage if the battery is discharging.