ADAPTIVE CHARGER DEVICE AND METHOD

• US 20080238361A1
• Filed: 07/11/2007
• Published: 10/02/2008
• Est. Priority Date: 03/26/2007
• Status: Active Grant

• Current Assignee: Duracell U.S. Operations, Inc. (Berkshire Hathaway Incorporated)
• Original Assignee: Gillette Company (The Procter & Gamble Company)
• Inventors: Batson, David C., Pinnell, Leslie J., Kaplan, Alexander
• Granted Patent: US 9,013,139 B2
• Time in Patent Office: Days
• US Class Current: 320/107
• CPC Class Codes: H02J 7/00041 in response to measured battery parameters, e.g. voltage, current or temperature profile
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage

Abstract

Disclosed is a method for charging a rechargeable battery that includes at least one rechargeable electrochemical cell is disclosed. The method includes measuring at least one electrical characteristic of the battery, and determining a charging current to be applied to the battery based on the at least one measured electrical characteristic.

Claims

1. A method for charging a rechargeable battery comprising at least one rechargeable electrochemical cell, the method comprising:

measuring at least one electrical characteristic of the battery; and

determining a charging current to be applied to the battery based on the at least one measured electrical characteristic.

2. The method of claim 1, further comprising applying the determined charging current to the battery.

3. The method of claim 2, further comprising:

regulating current applied to the battery according to the determined charging current.

4. The method of claim 1, wherein measuring the at least one electrical characteristic comprises:

measuring voltage between terminals of the battery in response to applying current to the battery at a first time instance; and

measuring voltage between the terminals of the battery in response to applying current to the battery at a subsequent time instance.

5. The method of claim 4, wherein measuring the at least one electrical characteristic further comprises:

computing a steady-state charging resistance based on a difference between the voltage measured at the first and subsequent time instances divided by a difference in currents applied at the first and subsequent time instances.

6. The method of claim 1, wherein determining the charging current comprises:

accessing a lookup table storing multiple charging current values, associated with a corresponding one of a plurality of values for a measured parameter; and

selecting one of the multiple charging current values stored in the lookup table based, at least in part, on the computed value.

7. The method of claim 6, wherein the measured parameter is representative of a steady-state charging resistance of the battery.

8. The method of claim 1, further comprising:

periodically measuring the voltage between terminals of the battery; and

adjusting the charging current applied to the battery when the measured voltage between the terminals of the battery reaches a pre-determined voltage value such that the voltage between the terminals of the battery is maintained at the pre-determined voltage value.

9. The method of claim 1, further comprising:

periodically adjusting the charging current to cause a pre-determined voltage level between terminals of the battery to be reached within a specified time period.

10. The method of claim 9, wherein periodically adjusting the charging current comprises:

determining a rate of voltage rise at the terminals of the battery; and

computing the charging current based on the determined rate of voltage rise using a predictor-corrector computation technique.

11. The method of claim 10, wherein the predictor-corrector computation technique is based on a Kalman filter.

12. A charging device configured to charge a rechargeable battery comprising at least one rechargeable electrochemical cell, the device comprising:

a charging compartment configured to receive the battery, the charging compartment having electrical contacts configured to be coupled to respective terminals of the battery; and

a controller configured to;

measure at least one electrical characteristic of the battery; and

determine a charging current to be applied to the battery based on the at least one measured electrical characteristic.

13. The device of claim 12, wherein the controller is further configured to:

cause the determined charging current to be applied to the battery.

14. The device of claim 13, further comprising:

a power conversion module; and

a current/voltage regulating circuit electrically coupled to the power conversion module, the current/voltage regulating circuit configured to cause current substantially equal to the determined charging current to be applied to the battery based, at least in part, on the charging current determined by the controller.

15. The device of claim 14, wherein the current/voltage regulating circuit comprises:

a buck converter circuit configured to operate with an adjustable duty cycle and to supply current to the battery during time periods corresponding to the adjustable duty cycle, wherein the adjustable duty cycle is determined by the controller.

16. The device of claim 12, wherein the controller configured to measure the at least one electrical characteristic is configured to:

measure voltage between the terminals of the battery in response to current applied to the battery at a first time instance; and

measure voltage between the terminals of the battery in response to current applied to the battery at a subsequent time instance.

17. The device of claim 16, wherein the controller is further configured to:

computing a steady-state charging resistance based on a difference between the voltage measured at the first and subsequent timer instances divided by a difference in currents applied at the first and subsequent time instances.

18. The device of claim 12, wherein the controller comprises a lookup table having multiple charging current values, each of the multiple charging current values associated with a corresponding one of a plurality of values representative of an electrical characteristic, and wherein the controller configured to determine the charging current is configured to:

access the lookup table; and

select one of multiple charging current values stored in the lookup table based, at least in part, on a computed value representative of the electrical characteristic.

19. The device of claim 18, wherein the computed value is representative of a steady-state charging resistance of the battery.

20. The device of claim 12, wherein the controller is further configured to:

periodically measure a voltage between the terminals of the battery;

adjust the charging current applied to the battery when the measured voltage between the terminals of the rechargeable battery reaches a pre-determined voltage value such that the voltage between the terminals of the rechargeable battery is maintained at the pre-determined voltage value.

21. The device of claim 12, wherein the controller is further configured to:

periodically adjust the charging current such that a pre-determined voltage level between terminals of the battery is reached within a specified time period.

22. The device of claim 21, wherein the controller configured to periodically adjust the charging current is configured to:

determine a rate of voltage rise at the terminals of the battery;

compute the charging current based on the determined rate of voltage rise using a predictor-corrector computation technique.

23. The device of claim 22, wherein the predictor-corrector computation technique is based on a Kalman filter.

24. The device of claim 12, wherein the controller includes a processor-based micro-controller.

25. The device of claim 12, further comprising the rechargeable battery.

26. The device of claim 25, wherein the rechargeable battery include a lithium-iron-phosphate rechargeable battery.