Battery charger, and method of judging charging condition

• US 20050099161A1
• Filed: 11/05/2004
• Published: 05/12/2005
• Est. Priority Date: 11/07/2003
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Sato, Masanao
• Granted Patent: US 7,696,723 B2
• Time in Patent Office: Days
• US Class Current: 320/134
• CPC Class Codes: H02J 7/0047 with monitoring or indicating devices or circuits
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]

Abstract

A battery charger and a method of judging a charging condition of a secondary battery capable of judging precisely a charging condition of the secondary battery are provided. Charging conditions of the secondary battery are classified to four charging conditions depending on change of the voltage value of the secondary battery during charging operation, and one of these four charging conditions is displayed on the secondary battery by detecting the voltage value of the secondary battery at predetermined intervals.

Claims

1. A battery charger comprising:

a charging device for charging a secondary battery;

a voltage detector for detecting a voltage value of the secondary battery; and

a controller for receiving voltage values of the secondary battery as detected by said voltage detector at a predetermined time interval while the secondary battery is being charged by said charging device, and for judging a charging condition of the secondary battery based on a rate of change of the received voltage values.

2. The battery charger as claimed in claim 1, further comprising:

a display for displaying information, wherein

said controller controls to display the judged charging condition of the secondary battery on said display.

3. The battery charger as claimed in claim 1, wherein

said charging condition of the secondary battery is classified stepwise to four successive charging conditions which are allocated in accordance with boundaries at a point where a first rise ceases, at a point where a second rise occurs, and a point where the second rise ceases when voltage of the secondary battery shows relatively large two rises, during charging of the second battery, and wherein

said controller means judges that the detected charging condition is a next charging condition when one of said points is detected based on a rate of change of the received voltage value from said voltage detector.

4. The battery charger as claimed in claim 1, wherein

said controller controls said charging device to temporarily stop charging of the secondary battery when said voltage detector detects voltage value of the secondary battery.

5. The battery charger as claimed in claim 1, wherein

said controller controls to detect the voltage values of the secondary battery by said voltage detector as for the secondary battery before charging, and judges the charging condition based on whether a detected voltage value falls within a predetermined threshold value.

6. The battery charger as claimed in claim 5, wherein

said threshold value is changed depending on an ambient temperature.

7. The battery charger as claimed in claim 5, wherein

said controller performs discharging in a short time before detecting the voltage value of the secondary battery.

8. The battery charger as claimed in claim 7, further comprising:

a display for displaying information, wherein

said controller controls to display the judged charging condition of the secondary battery on said display.

9. A battery charger comprising:

charging means for charging a secondary battery;

voltage detection means for detecting voltage values of the secondary battery; and

control means for receiving voltage values of the secondary battery as detected by said voltage detection means at a predetermined time interval while the secondary battery is being charged by said charging means, for judging a first charging condition of the secondary battery based on a rate of change of the received voltage values, for judging a second charging condition of the secondary battery depending on whether or not the received voltage value falls within a range of predetermined threshold voltage values, and for judging the first charging condition as the charging condition of the secondary battery when the first charging condition and the second charging condition agree with each other, wherein

the predetermined threshold values are switched in response to an ambient temperature.

10. The battery charger as claimed in claim 9, wherein

said control means judges the charging condition of the secondary battery as one of said first charging condition and the second charging condition by priority when said first charging condition and said second charging condition do not agree with each other, or the judged charging condition immediately before.

11. The battery charger as claimed in claim 9, further comprising:

display means for displaying information, wherein

said control means controls to display the judged charging condition of the secondary battery on said display means.

12. The battery charger as claimed in claim 9, wherein

said charging condition of the secondary battery is classified stepwise to four successive charging conditions which are allocated in accordance with boundaries at a point where a first rise ceases, at a point where a second rise occurs, and a point where the second rise ceases when voltage of the secondary battery shows relatively large two rises, during charging of the second battery;

and

said control means judges that the detected charging condition is the next charging condition when one of said points is detected based on a rate of change of the received voltage value from said voltage detection means.

13. The battery charger as claimed in claim 9, wherein

said control means controls said charging means to temporarily stop charging of the secondary battery when said voltage detection means detects voltage value of the secondary battery.

14. The battery charger as claimed in claim 9, wherein

said control means controls to detect the voltage values of the secondary battery by said voltage detection means as for the secondary battery before charging, and judges the charging condition based on whether the detected voltage value falls within a predetermined threshold value.

15. The battery charger as claimed in claim 14, wherein

said threshold value is changed depending on an ambient temperature.

16. The battery charger as claimed in claim 14, wherein

said control means performs discharging in a short time before detecting the voltage value of the secondary battery.

17. The battery charger as claimed in claim 16, further comprising:

display means for displaying information, wherein

said control means controls to display the judged charging condition of the secondary battery on said display means.

18. A method of judging charging condition comprising:

charging a secondary battery;

detecting voltage values of the secondary battery; and

controlling receiving of the voltage values of the secondary battery as detected at a predetermined time interval while the secondary battery is being charged, and judging the charging condition of the secondary battery based on a rate of change of the received voltage values.

19. The method of judging charging condition as claimed in claim 18, further comprising:

controlling display of the judged charging condition of the secondary battery on a display.

20. The method of judging charging condition as claimed in claim 18, wherein

said charging condition of the secondary battery is classified stepwise to four successive charging conditions which are allocated in accordance with boundaries at a point where a first rise ceases, at a point where a second rise occurs, and a point where the second rise ceases when voltage of the secondary battery shows relatively large two rises, during charging of the second battery;

and wherein

judging is controlled such that the detected charging condition is a next charging condition when one of said points is detected based on a rate of change of the received voltage value from said voltage detection step.

21. The method of judging charging condition as claimed in claim 18, wherein

charging is controlled to temporarily stop charging of the secondary battery when said voltage detection step detects voltage value of the secondary battery.

22. The method of judging charging condition as claimed in claim 18, further comprising:

detecting the voltage values of the secondary battery by said voltage detection step as for the secondary battery before charging, and judging the charging condition based on whether the detected voltage value falls within a predetermined threshold value.

23. The method of judging charging condition as claimed in claim 22, wherein

said threshold value is changed depending on an ambient temperature.

24. The method of judging charging condition as claimed in claim 22, wherein

said control step performs discharging in a short time before detecting the voltage value of the secondary battery.

25. The method of judging charging condition as claimed in claim 24, further comprising

controlling display of the judged charging condition of the secondary battery on a display.

26. A method of judging charging condition comprising:

charging a secondary battery;

detecting voltage values of the secondary battery; and

controlling receiving of the voltage values as detected while the secondary battery is being charged by said charging step at a predetermined time interval, judging a first charging condition of the secondary battery based on a rate of change of the received voltage values, judging a second charging condition based on whether or not the received voltage values fall within predetermined threshold values, and judging the first charging condition is a charging condition of the secondary battery if the first charging condition and the second charging condition agree with each other, wherein

the predetermined threshold values are switched in response to an ambient temperature.

27. The method of judging charging condition as claimed in claim 26, further comprising:

controlling judging of the charging condition of the secondary battery as one of said first charging condition and the second charging condition by priority when said first charging condition and said second charging condition do not agree with any one of each other and the judged charging condition immediately before.

28. The method of judging charging condition as claimed in claim 26, wherein

controlling display of the judged charging condition of the secondary battery on a display.

29. The method of judging charging condition as claimed in claim 26, wherein

said charging condition of the secondary battery is classified stepwise to four successive charging conditions which are allocated in accordance with boundaries at a point where a first rise ceases, at a point where a second rise occurs, and a point where the second rise ceases when voltage of the secondary battery shows relatively large two rises, during charging of the second battery;

and

said control step judges that the detected charging condition is a next charging condition when one of said points is detected based on a rate of change of the received voltage value during voltage detection.

30. The method of judging charging condition as claimed in claim 26, wherein

controlling said charging step to temporary stop charging of the secondary battery when voltage detection detects a voltage value of the secondary battery.

31. The method of judging charging condition as claimed in claim 26, wherein

controlling detection of the voltage values of the secondary battery as for the secondary battery before charging, and judges the charging condition based on whether the detected voltage value falls within a predetermined threshold value.

32. The method of judging charging condition as claimed in claim 31, wherein

said threshold value is changed depending on an ambient temperature.

33. The method of judging charging condition as claimed in claim 31, wherein

discharging is controlled in a short time before detecting the voltage value of the secondary battery.

34. The method of judging charging condition as claimed in claim 33, wherein;

controlling display of the judged charging condition of the secondary battery on a display.