Method and system for charge rate adjustment to enhance battery cycle life

• US 20070139008A1
• Filed: 12/15/2005
• Published: 06/21/2007
• Est. Priority Date: 12/15/2005
• Status: Active Grant

• Current Assignee: Dell Products LP (Dell Technologies Inc.)
• Original Assignee: Dell Products LP (Dell Technologies Inc.)
• Inventors: Wang, Ligong, Sterz, Stephen
• Granted Patent: US 7,518,340 B2
• Time in Patent Office: Days
• US Class Current: 320/125
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 7/0071 with a programmable schedule

Abstract

Methods and systems are disclosed for charge current adjustment to enhance battery cycle life thereby allowing batteries to be charged quickly without accelerating the aging process of the battery. As the charge capacity of the battery degrades over time, the charge current for the battery charging cycles is also reduced so that the effective charge rate for the battery is adjusted to account for the reduction in charge capacity. In this way, battery capacity life is enhanced by avoiding an accelerated charge rate as the battery capacity drops over the operational life of the battery. The methods and systems disclosed are useful for battery-powered information handling systems, as well as other devices where fast charging and long cycle life is desirable, such as cell phones, personal digital assistants (PDAs), electric vehicles and/or any other battery powered devices.

Claims

1. A method of managing a charge rate for a battery, comprising:

utilizing a first charge current to charge a battery in a charge cycle, the first charge current being based at least in part upon a total battery charge capacity for the battery and being applied at a start of the charge cycle;

reducing the charge current for the battery to a new charge current based at least in part upon a reduction in the total battery charge capacity for the battery; and

charging the battery in a subsequent charge cycle with the new charge current, the new charge current being applied at a start of the subsequent charge cycle.

2. The method of claim 1, associating the first charge current with a design total battery charge capacity of the battery.

3. The method of claim 1, wherein the reducing step relies upon a determination of a current total battery charge capacity for the battery.

4. The method of claim 3, further comprising determining the current total battery charge capacity for the battery at least in part from data associated with operation of the battery within an information handling system, and repeating the reducing and charging steps as the information handling system is operated over time.

5. The method of claim 4, wherein the data comprises a full charge capacity (FCC) data for the battery, temperature data for the battery, or a charge cycle count data for the battery, or a combination thereof.

6. The method of claim 3, wherein the reducing step comprises utilizing an expected total battery charge capacity degradation rate for the total battery charge capacity of the battery in order to make the reductions in the charge current.

7. The method of claim 6, further comprising reducing the charge current at regular intervals based upon the expected degradation rate for the battery.

8. The method of claim 7, wherein the regular intervals are based upon charge cycle count data for the battery.

9. The method of claim 1, further comprising selecting the first charge current in order to facilitate the battery charging to a selected percentage of its total battery charge capacity in a selected amount of time.

10. The method of claim 9, wherein the selected percentage is 80% and the selected amount of time is 1 hour.

11. The method of claim 9, wherein the reducing step comprises selecting the new charge current in order to facilitate the battery charging to a selected percentage of its new total battery charge capacity in a selected amount of time.

12. An information handling system configured to be powered by a battery or an alternating current to direct current (AC/DC) converter, comprising:

an alternating current to direct current (AC/DC) converter;

a load coupled to the AC/DC converter, the load representing powered circuitry for an information handling system;

a charger coupled to the AC/DC converter;

a battery coupled to the charger and to the load; and

a battery management unit (BMU) configured to use a first charge current to charge the battery in a charge cycle, to adjust the charge current for the battery to a new charge current based at least in part upon changes to the total battery charge capacity for the battery, and to use the new charge current in a subsequent charge cycle to charge the battery;

wherein the first charge current is applied at a start of the charge cycle and the new charge current is applied at a start of the subsequent charge cycle.

13. The information handling system of claim 12, wherein an initial charge current for the battery is associated with a design total battery charge capacity of the battery.

14. The information handling system of claim 12, wherein the BMU is configured to adjust the charge current based upon a determination of a current total battery charge capacity for the battery.

15. The information handling system of claim 14, wherein the BMU is configured to determine the current total battery charge capacity at least in part from data associated with operation of the battery within the information handling system, and the BMU is configured to repeat this determination and to reduce the charge current based upon reductions in the total battery charge capacity as the information handling system is operated over time.

16. The information handling system of claim 14, wherein the data comprises a full charge capacity (FCC) data for the battery, temperature data for the battery, or a charge cycle count data for the battery, or a combination thereof.

17. The information handling system of claim 14, wherein the BMU is configured to reduce the charge current based upon an expected total battery charge capacity degradation rate for the battery.

18. The information handling system of claim 17, wherein the BMU is further configured to reduce the charge current at regular intervals as the information handling system is operated over time based upon the expected degradation rate for the battery.

19. The information handling system of claim 18, wherein the regular intervals are based upon charge cycle count data for the battery.

20. The information handling system of claim 12, wherein charge currents are selected in order to facilitate the battery charging to a selected percentage of its total battery charge capacity in a selected amount of time.