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

• US 7,518,340 B2
• Filed: 12/15/2005
• Issued: 04/14/2009
• 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 D.
• Primary Examiner(s): Ullah; Akm E
• Assistant Examiner(s): Berhanu; Samuel
• Application Number:
  US11/300,721
• Publication Number:
  US 20070139008A1
• Time in Patent Office: 1,216 Days
• Field of Search: 320/112, 320/114, 320/160, 320/DIG.12, 320/132, 320/131
• US Class Current: 320/132
• 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 charge rates for a battery to reduce total battery charge capacity degradation over time, comprising:

for a first charge cycle, determining a first charge current (R) for a battery to charge the battery to a percentage (X) of a total battery charge capacity (C) for the battery in an amount of time (T) according to a relationship R=XC/T;

utilizing the first charge current to charge the battery toward the total battery charge capacity (C) for the battery in the first charge cycle;

for a subsequent charge cycle, determining a reduction in the total battery charge capacity for the battery to a reduced total battery charge capacity (C_NEW) and determining a new charge current (R_NEW)for the battery to charge the battery to the percentage (X) of the reduced total battery charge capacity (C_NEW) for the battery in the amount of time (T) according to a relationship R_NEW=X(C_NEW/C)C/T;

charging the battery toward the reduced total battery charge capacity (C_NEW) for the battery in the subsequent charge cycle with the new charge current (R_NEW), the new charge current (R_NEW) being applied in the subsequent charge cycle to reduce a rate of charge for the battery.

2. The method of claim 1, further comprising using a design total battery charge capacity of the battery in determining the total battery charge capacity (C).

3. The method of claim 1, further comprising determining a current total battery charge capacity for the battery in determining the reduced total battery charge capacity (C_NEW).

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 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 1, further comprising utilizing an expected total battery charge capacity degradation rate for the total battery charge capacity of the battery in determining the new charge current (R_NEW).

7. The method of claim 6, further comprising determining new charge currents for a plurality of subsequent charge cycles 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, wherein the percentage (X) is 80% and the selected amount of time (T) is 1 hour.

10. 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 determine for a first charge cycle a first charge current (R) for a battery to charge the battery to a percentage (X) of a total battery charge capacity (C) for the battery in an amount of time (T) according to a relationship R=XC/T, to use the first charge current to charge the battery toward the total battery charge capacity (C) for the battery in a the first charge cycle, to determine for a subsequent charge cycle a reduction in the total battery charge capacity for the battery to a reduced total battery charge capacity (C_NEW);

to determine a new charge current (R_NEW) for the battery to charge the battery to the percentage (X) of the reduced total battery charge capacity (C_NEW) for the battery in the amount of time (T) according to a relationship R_NEW=X(C_NEW/C)C/T, and to use the new charge current (R_NEW) in the subsequent charge cycle to charge the battery toward the reduced battery charge capacity (C_NEW) for the battery;

wherein the first charge current is applied in the first charge cycle and the new charge current is applied in the subsequent charge cycle to reduce a rate of charge for the battery.

11. The information handling system of claim 10, wherein the BMU is configured to use a design total battery charge capacity of the battery in determining the total battery charge capacity (C).

12. The information handling system of claim 10, wherein the BMU is configured to use a determination of a current total battery charge capacity for the battery in determining the reduced total battery charge capacity (C_NEW).

13. The information handling system of claim 12, 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 as the information handling system is operated over time.

14. The information handling system of claim 12, 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.

15. The information handling system of claim 10, wherein the BMU is configured to use an expected total battery charge capacity degradation rate for the battery in determining the reduced total battery charge capacity (C_NEW).

16. The information handling system of claim 15, wherein the BMU is further configured to determine new charge currents for a plurality of subsequent charge cycles at regular intervals as the information handling system is operated over time based upon the expected degradation rate for the battery.

17. The information handling system of claim 16, wherein the regular intervals are based upon charge cycle count data for the battery.

18. The information handling system of, wherein the percentage (X) is 80% and the selected amount of time (T) is 1 hour.