Method of charging a rechargeable battery with pulses of a predetermined amount of charge

• US 5,747,969 A
• Filed: 11/13/1996
• Issued: 05/05/1998
• Est. Priority Date: 11/21/1995
• Status: Expired due to Term

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Tamai, Mikitaka
• Primary Examiner(s): Tso, Edward
• Application Number:
  US08/748,631
• Time in Patent Office: 538 Days
• Field of Search: 320/21, 320/22, 320/23, 320/30, 320/31, 320/32, 320/39, 320/40, 320/35, 320/37
• US Class Current: 320/141
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The charging method repeatedly charges and suspends charging to pulse charge a rechargeable battery. Charging is suspended only after a given amount of charge is transferred to the battery. Battery voltage is measured during the period of suspended charging, and charging is resumed only after the voltage of the battery drops below a first prescribed voltage. This situation is continuously repeated to pulse charge a rechargeable battery.

Claims

1. A method of charging a rechargeable battery comprising:

pulse charging the rechargeable battery by

detecting battery voltage of the rechargeable battery,

determining whether the battery voltage is equal to or less than a first prescribed voltage,

charging the battery by applying a predetermined amount of charge to the battery when the battery voltage is determined to be equal to or less than the first prescribed voltage, wherein the predetermined amount of charge is based on an amount of charging current and a pulse time period, and

suspending charging of the battery after the predetermined amount of charge has been applied to the battery,

wherein the detecting, determining, charging, and suspending are sequentially performed a plurality of times, the first prescribed voltage is the same each of the plurality of times, and the predetermined amount of charge is the same each of the plurality of times.

2. A method of charging a rechargeable battery as claimed in claim 1, wherein the predetermined amount of charge is less than or equal to 10% of a full charge capacity of the rechargeable battery.

3. A method of charging a rechargeable battery as claimed in claim 1, wherein the predetermined amount of charge is less than or equal to 5% of a full charge capacity of the rechargeable battery.

4. A method of charging a rechargeable battery as claimed in claim 1, wherein the predetermined amount of charge is less than or equal to 1% of a full charge capacity of the rechargeable battery.

5. A method of charging a rechargeable battery as claimed in claim 1, wherein the charging of the battery with a predetermined amount of charge is performed only if the battery voltage is determined to be equal to or less than the first prescribed voltage and a prescribed time period has elapsed within which the battery has not been charged.

6. A method of charging a rechargeable battery as claimed in claim 1, wherein the first prescribed voltage is decreased when ambient temperature increases.

7. A method of charging a rechargeable battery as claimed in claim 1, wherein the predetermined amount of charge is decreased when ambient temperature increases.

8. A method of charging a rechargeable battery as claimed in claim 1, further comprising:

preventing charging when the battery voltage is determined to be greater than or equal to a maximum prescribed voltage which is greater than the first prescribed voltage.

9. A method of charging a rechargeable battery as claimed in claim 8, wherein the rechargeable battery is a lithium ion rechargeable battery and the maximum prescribed voltage is 4.35V/cell.

10. A method of charging a rechargeable battery as claimed in claim 8, wherein the maximum prescribed voltage is decreased when ambient temperature increases.

11. A method of charging a rechargeable battery as claimed in claim 1, further comprising:

constant-voltage charging the battery when the battery voltage is determined to be greater than or equal to a maximum prescribed voltage which is greater than the first prescribed voltage.

12. A method of charging a rechargeable battery as claimed in claim 11, wherein the rechargeable battery is a lithium ion rechargeable battery and the maximum prescribed voltage is 4.35V/cell.

13. A method of charging a rechargeable battery as claimed in claim 11, wherein the maximum prescribed voltage is decreased when ambient temperature increases.

14. A method of charging a rechargeable battery as claimed in claim 1, further comprising:

prior to the pulse charging of the rechargeable battery, constantly charging the battery until the battery voltage reaches a second prescribed voltage, wherein the pulse charging of the battery is performed only after the battery reaches the second prescribed voltage.

15. A method of charging a rechargeable battery as claimed in claim 14, wherein the first prescribed voltage and the second prescribed voltage are equal.

16. A method of charging a rechargeable battery as claimed in claim 14, wherein the second prescribed voltage is greater than the first prescribed voltage.

17. A method of charging a rechargeable battery as claimed in claim 16, wherein the rechargeable battery is a lithium ion rechargeable battery and the first prescribed voltage is 4.10V/cell.

18. A method of charging a rechargeable battery as claimed in claim 14, wherein the rechargeable battery is a lithium ion rechargeable battery and the second prescribed voltage is 4.15V/cell.

19. A method of charging a rechargeable battery as claimed in claim 14, wherein second prescribed voltage is decreased when ambient temperature increases.

20. A method of charging a rechargeable battery comprising:

pulse charging the rechargeable battery by

detecting battery voltage of the rechargeable battery,

determining whether the battery voltage is equal to or less than a first prescribed voltage,

charging the battery by applying an amount of charge to the battery when the battery voltage is determined to be equal to or less than the first prescribed voltage, wherein the amount of charge is based on an amount of charging current and a pulse time period and wherein the pulse time period is based on the detected battery voltage, and

suspending charging of the battery after the amount of charge has been applied to the battery,

wherein the detecting, determining, charging, and suspending are sequentially performed a plurality of times such that the battery voltage gradually increases, the first prescribed voltage is the same each of the plurality of times, and the amount of charge is gradually reduced by reducing the pulse time period each of the plurality of times so that the pulse time period is inversely proportional to the battery voltage as the battery voltage gradually increases.

21. A method of charging a rechargeable battery as claimed in claim 20, wherein the charging of the battery with an amount of charge is performed only if the battery voltage is determined to be equal to or less than the first prescribed voltage and a prescribed time period has elapsed within which the battery is not charged.

22. A method of charging a rechargeable battery as claimed in claim 20, wherein the first prescribed voltage is decreased when ambient temperature increases.

23. A method of charging a rechargeable battery as claimed in claim 20, wherein the amount of charge is decreased when ambient temperature increases.

24. A method of charging a rechargeable battery as claimed in claim 20, further comprising:

preventing charging when the battery voltage is determined to be greater than or equal to a maximum prescribed voltage which is greater than the first prescribed voltage.

25. A method of charging a rechargeable battery as claimed in claim 24, wherein the rechargeable battery is a lithium ion rechargeable battery and the maximum prescribed voltage is 4.35V/cell.

26. A method of charging a rechargeable battery as claimed in claim 24, wherein the maximum prescribed voltage is decreased when ambient temperature increases.

27. A method of charging a rechargeable battery as claimed in claim 20, further comprising:

constant-voltage charging the battery when the battery voltage is determined to be greater than or equal to a maximum prescribed voltage which is greater than the first prescribed voltage.

28. A method of charging a rechargeable battery as claimed in claim 27, wherein the rechargeable battery is a lithium ion rechargeable battery and the maximum prescribed voltage is 4.35V/cell.

29. A method of charging a rechargeable battery as claimed in claim 27, wherein the maximum prescribed voltage is decreased when ambient temperature increases.

30. A method of charging a rechargeable battery as claimed in claim 20, further comprising:

prior to the pulse charging of the rechargeable battery, constantly charging the battery until the battery voltage reaches a second prescribed voltage, wherein the pulse charging of the battery is performed only after the battery reaches the second prescribed voltage.

31. A method of charging a rechargeable battery as claimed in claim 30, wherein the first prescribed voltage and the second prescribed voltage are equal.

32. A method of charging a rechargeable battery as claimed in claim 30, wherein the second prescribed voltage is greater than the first prescribed voltage.

33. A method of charging a rechargeable battery as claimed in claim 32, wherein the rechargeable battery is a lithium ion rechargeable battery and the first prescribed voltage is 4.10V/cell.

34. A method of charging a rechargeable battery as claimed in claim 30, wherein the rechargeable battery is a lithium ion rechargeable battery and the second prescribed voltage is 4.15V/cell.

35. A method of charging a rechargeable battery as claimed in claim 30, wherein second prescribed voltage is decreased when ambient temperature increases.