Secondary battery charging method and apparatus which controls protecting voltage level of battery protecting circuit

• US 5,654,622 A
• Filed: 02/06/1996
• Issued: 08/05/1997
• Est. Priority Date: 02/16/1995
• Status: Expired due to Fees

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Toya, Shoichi, Mino, Takayuki
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US08/595,961
• Time in Patent Office: 546 Days
• Field of Search: 320/5, 320/20, 320/21, 320/22, 320/30, 320/39, 320/40, 320/48, 361/86, 361/91
• US Class Current: 320/129
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A secondary battery is connected to a protecting circuit. The protecting circuit interrupts charging of the secondary battery when the battery voltage of the secondary battery reaches a first protecting voltage which is higher than a first voltage, the first voltage being the full charge voltage of the secondary battery. After constant current charging of the secondary battery, the secondary battery is charged until the battery voltage of the secondary battery becomes higher than the first protecting voltage for achieving rapid charging of the secondary battery. When the secondary battery is charged in this condition, the protecting voltage of the protecting circuit is changed over to a second protecting voltage which is higher than the first protecting voltage for this preventing the protecting circuit from operating.

Claims

1. A method for charging a secondary battery provided with a protecting circuit which interrupts charging of the secondary battery when the battery voltage of the secondary battery reaches a first protecting voltage which is higher than a first voltage, the first voltage being a full charge voltage of the secondary battery, comprising:

a step of constant current charging the secondary battery; and

a step of further charging the secondary battery until the battery voltage of the secondary battery becomes higher than the first protecting voltage, and then charging the secondary battery after changing the protecting voltage of the protecting circuit to a secondary protecting voltage which is higher than the first protecting voltage when the battery voltage of the secondary battery becomes higher than the first protecting voltage.

2. A method for charging a secondary battery as claimed in claim 1, in which after the step of constant current charging of the secondary battery, said method includes repeating constant voltage charging of the secondary battery with the first voltage and constant voltage charging of the secondary battery with a second voltage which is higher than the first protecting voltage.

3. A method for charging a secondary battery as claimed in claim 2, in which the step of the constant voltage charging of the secondary battery with the first voltage includes a step of suspending the charging of the secondary battery.

4. A method for charging a secondary battery as claimed in claim 2, in which the secondary battery is a lithium ion secondary battery.

5. A method for charging a secondary battery as claimed in claim 4, in which the first voltage is 4.1 V.

6. A method for charging a secondary battery as claimed in claim 5, in which the first protecting voltage is 4.2 V.

7. A method for charging a secondary battery as claimed in claim 4, in which the second voltage is 4.5 V.

8. A method for charging a secondary battery as claimed in claim 7, in which the second protecting voltage is 4.6 V.

9. A method for charging a secondary battery provided with a protecting circuit which interrupts charging of the secondary battery when the battery voltage of the secondary battery reaches a first protecting voltage which is higher than a first voltage, the first voltage being a full charge voltage of the secondary battery, by means of a charging circuit, comprising:

a step of constant current charging the secondary battery; and

a step of further charging the secondary battery until the battery voltage of the secondary battery becomes higher than the first protecting voltage, and then sending a first change over signal from the charging circuit to the protecting circuit to cause the protecting voltage of the protecting circuit to change over to a second protecting voltage which is higher than the first protecting voltage.

10. A method for charging a secondary battery as claimed in claim 9, in which after the step of constant current charging of the secondary battery, said method includes repeating constant voltage charging of the secondary battery with the first voltage and constant voltage charging of the secondary battery with a second voltage which is higher than the first protecting voltage.

11. A method for charging a secondary battery as claimed in claim 10, in which by sending a second change over signal from the charging circuit to the protecting circuit before changing over from the constant voltage charging with the second voltage to the constant voltage charging with the first voltage, the protecting voltage of the protecting circuit is changed over from the secondary protecting voltage to the first protecting voltage.

12. A method for charging a secondary battery as claimed in claim 11, in which the charging circuit sends pulse current signals formed of the charging current as the first and the second change over signals to the protecting circuit.

13. A method for charging a secondary battery as claimed in claim 10, in which the step of the constant voltage charging of the secondary battery with the first voltage includes a step of suspending the charging of the secondary battery.

14. A method for charging a secondary battery as claimed in claim 10, in which the second battery is a lithium ion secondary battery.

15. A method for charging a secondary battery as claimed in claim 14, in which the first voltage is 4.1 V.

16. A method for charging a secondary battery as claimed in claim 15, in which the first protecting voltage is 4.2 V.

17. A method for charging a secondary battery as claimed in claim 14, in which the second voltage is 4.5 V.

18. A method for charging a secondary battery as claimed in claim 17, in which the second protecting voltage is 4.6 V.

19. An apparatus for charging a secondary battery provided with a protecting circuit which interrupts charging of the secondary battery when the battery voltage of the secondary battery reaches a first protecting voltage which is higher than a first voltage, the first voltage being a full charge voltage of the secondary battery, comprising:

(a) a charging circuit for charging the secondary battery and including

(1) a constant current charging means for constant current charging of the secondary battery,

(2) a charging means for charging the secondary battery to a voltage which is higher than the first protecting voltage, and

(3) a first signal sending means for sending a first change over signal to the protecting circuit at the time of charging the secondary battery to a voltage which is higher than the first protecting voltage, and

(b) the protecting circuit including

(1) a first change over means for changing over from the protecting voltage to a second protecting voltage which is higher than the first protecting voltage in correspondence with the first change over signal.

20. An apparatus for charging a secondary battery provided with a protecting circuit which interrupts charging of the secondary battery when the battery voltage of the secondary battery reaches a first protecting voltage which is higher than a first voltage, the first voltage being a full charge voltage of the secondary battery, comprising:

(a) a charging circuit for charging the secondary battery and including

(1) a constant current charging means for constant current charging the secondary battery,

(2) a first constant voltage charging means for constant voltage charging the secondary battery with the first voltage,

(3) a second constant voltage charging means for constant voltage charging the second battery with the second voltage which is higher than the first protecting voltage,

(4) a control means for controlling a charging operation after the constant current charging of the secondary battery by the constant current charging means, so as to repeat constant voltage charging by the first constant voltage charging means and constant voltage charging by the second constant voltage charging means, and

(5) a first signal sending means for sending a first change over signal to the protecting circuit before the constant voltage charging of the secondary battery by the second voltage charging means; and

(b) a protecting circuit which interrupts charging of the secondary battery when the battery voltage of the secondary battery reaches the first protecting voltage which is the full charge voltage of the secondary battery, including

a first change over means for changing over from the first protecting voltage to a second protecting voltage which is higher than the second voltage in correspondence with the first change over signal.

21. An apparatus for charging a secondary battery as claimed in claim 20, in which the charging circuit further includes a second signal sending means for sending a second signal to the protecting circuit before the changing over from the constant voltage charging by the second constant voltage charging means to the constant voltage charging by the first constant voltage charging means, and the protecting circuit further includes a second change over means for changing over from the second protecting voltage of the first protecting voltage in correspondence with the second change over signal.

22. A method for charging a secondary battery provided with a protecting circuit which interrupts charging of the secondary battery when the battery voltage of the secondary battery is above a protecting voltage which is higher than a first voltage, the first voltage being a full charge voltage of the secondary battery, for more than a predetermined time, comprising:

a step of pulse charging the secondary battery for a time which is shorter than the predetermined time set in the protecting circuit;

a step of pulse discharging the secondary battery in such a manner that the battery voltage of the secondary battery does not becomes higher than the protecting voltage for more than the predetermined time;

a step of temporarily suspending the pulse charging and the pulse discharging and detecting the battery voltage of the secondary battery; and

a step of controlling the charging of the secondary battery in correspondence with the detected battery voltage.

23. A method for charging a secondary battery as claimed in claim 22, in which the pulse charging is executed by a constant current charging in such a manner that the battery voltage of the secondary battery does not become higher than a second voltage which is higher than the protecting voltage.

24. A method for charging a secondary battery as claimed in claim 22, in which the secondary battery is a lithium ion secondary battery.

25. A method for charging a secondary battery as claimed in claim 24, in which the first voltage is 4.1 V.

26. A method for charging a secondary battery as claimed in claim 25, in which the protecting voltage is 4.2 V.