IN-SITU BATTERY HEALTH DETECTOR AND END-OF-LIFE INDICATOR

• US 20110089907A1
• Filed: 10/19/2009
• Published: 04/21/2011
• Est. Priority Date: 10/19/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Mank, Richard M., Hwang, Taisup, Bhardwaj, Ramesh C.
• Granted Patent: US 8,415,926 B2
• Time in Patent Office: Days
• US Class Current: 320/136
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• 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 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Some embodiments provide a system that monitors a battery in a portable electronic device. During operation, the system applies a pulse load to the battery and determines an impedance of the battery by measuring a voltage of the battery during the pulse load. Next, the system assesses a health of the battery based on the impedance. Finally, the system uses the assessed health to manage use of the battery in the portable electronic device.

Claims

1. A computer-implemented method for monitoring a battery in a portable electronic device, comprising:

applying a pulse load to the battery;

determining an impedance of the battery by measuring a voltage of the battery during the pulse load;

assessing a health of the battery based on the impedance; and

using the assessed health to manage use of the battery in the portable electronic device.

2. The computer-implemented method of claim 1, wherein determining the impedance of the battery involves:

measuring the voltage of the battery in a fully charged state;

calculating a drop in the voltage after the pulse load is applied; and

dividing the drop in the voltage by a current of the pulse load.

3. The computer-implemented method of claim 1, wherein assessing the health of the battery based on the impedance involves:

monitoring a change in the impedance over time to detect degradation in the battery.

4. The computer-implemented method of claim 3, wherein monitoring the change in impedance over time involves:

analyzing a linearity of the impedance as a function of a number of charge-discharge cycles performed on the battery.

5. The computer-implemented method of claim 4, wherein a lack of linearity corresponds to degradation in the battery.

6. The computer-implemented method of claim 1, wherein using the assessed health to manage use of the battery in the portable electronic device involves at least one of:

adjusting a charge voltage for the battery;

notifying a user of the portable electronic device of an end-of-life for the battery; and

isolating a cell in the battery.

7. The computer-implemented method of claim 6, wherein adjusting the charge voltage for the battery involves:

decreasing the charge voltage to extend a cycle life of the battery and to control cell swelling within the battery.

8. The computer-implemented method of claim 6, wherein adjusting the charge voltage for the battery involves:

stopping charging of the battery at the end-of-life for the battery.

9. A system for monitoring a battery in a portable electronic device, comprising:

a load-generating apparatus configured to apply a pulse load to the battery;

a monitoring apparatus configured to determine an impedance of the battery by measuring a voltage of the battery during the pulse load; and

a management apparatus configured to;

assess a health of the battery based on the impedance; and

use the assessed health to manage use of the battery in the portable electronic device.

10. The system of claim 9, wherein determining the impedance of the battery involves:

measuring the voltage of the battery in a fully charged state;

calculating a drop in the voltage after the pulse load is applied; and

dividing the drop in the voltage by a current of the pulse load.

11. The system of claim 9, wherein assessing the health of the battery based on the impedance involves:

monitoring a change in the impedance over time to detect degradation in the battery.

12. The system of claim 11, wherein monitoring a change in the impedance over time involves:

analyzing a linearity of the impedance as a function of a number of charge-discharge cycles performed on the battery.

13. The system of claim 12, wherein a lack of linearity corresponds to degradation in the battery.

14. The system of claim 9, wherein using the assessed health to manage use of the battery in the portable electronic device involves at least one of:

adjusting a charge voltage for the battery;

notifying a user of the portable electronic device of an end-of-life for the battery; and

isolating a cell in the battery.

15. The system of claim 14, wherein adjusting the charge voltage for the battery involves:

decreasing the charge voltage to extend a cycle life of the battery and to control cell swelling within the battery.

16. The system of claim 14, wherein adjusting the charge voltage for the battery involves:

stopping charging of the battery at the end-of-life for the battery.

17. A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for monitoring a battery in a portable electronic device, the method comprising:

determining an impedance of the battery by measuring a voltage of the battery during application of a pulse load to the battery;

assessing a health of the battery based on the impedance; and

using the assessed health to manage use of the battery in the portable electronic device.

18. The computer-readable storage medium of claim 17, wherein determining the impedance of the battery involves:

measuring the voltage of the battery in a fully charged state;

calculating a drop in the voltage after the pulse load is applied; and

dividing the drop in the voltage by a current of the pulse load.

19. The computer-readable storage medium of claim 17, wherein assessing the health of the battery based on the impedance involves:

monitoring a change in the impedance over time to detect degradation in the battery.

20. The computer-readable storage medium of claim 19, wherein monitoring a change in the impedance over time involves:

analyzing a linearity of the impedance as a function of a number of charge-discharge cycles performed on the battery.

21. The computer-readable storage medium of claim 20, wherein a lack of linearity corresponds to degradation in the battery.

22. The computer-readable storage medium of claim 17, wherein using the assessed health to manage use of the battery in the portable electronic device involves at least one of:

adjusting a charge voltage for the battery;

notifying a user of the portable electronic device of an end-of-life for the battery; and

isolating a cell in the battery.

23. The computer-readable storage medium of claim 22, wherein adjusting the charge voltage for the battery involves:

decreasing the charge voltage to extend a cycle life of the battery and to control cell swelling within the battery.

24. The computer-readable storage medium of claim 22, wherein adjusting the charge voltage for the battery involves:

stopping charging of the battery at the end-of-life for the battery.

25. A portable electronic device, comprising:

a battery;

a set of components powered by the battery;

a charger configured to apply a pulse load to the battery;

a monitoring apparatus configured to determine an impedance of the battery by measuring a voltage of the battery during the pulse load; and

a management apparatus configured to;

assess a health of the battery based on the impedance; and

use the assessed health to manage use of the battery in the portable electronic device.