Full-charge detecting method and charging device for a secondary battery

• US 6,100,669 A
• Filed: 01/12/1999
• Issued: 08/08/2000
• Est. Priority Date: 01/12/1998
• Status: Expired due to Term

• Current Assignee: HTC Corporation
• Original Assignee: NEC Corporation
• Inventors: Tokita, Yoshitaka
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US09/228,927
• Time in Patent Office: 574 Days
• Field of Search: 320/149, 320/162, 324/427, 324/428, 307/112, 307/116, 307/125, 307/131
• US Class Current: 320/149
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current

Abstract

A method of detecting the full-condition of a secondary battery of the present invention integrates the amount of charge current with a microcomputer in an environment of the kind causing a charge current to vary. When the charge current falls, the method interrupts a charging operation until an adequate charge current flows. A charging device for practicing the above method is also disclosed.

Claims

1. In a method of charging a secondary battery comprising:

detecting when a charge current decreases below a current level that is able to be integrated, interrupting a charging operation in response to the detection of the charge current decreasing below said current level that is able to be integrated until, a charge current which is able to be integrated flows.

2. In a method of detecting a full-charge condition of a secondary battery by integrating an amount of charge current, comprising:

interrupting a charging operation when the charge current falls below a current level which is able to be integrated until a charge current that is able to be integrated flows.

3. In a method of detecting a full-charge condition of a secondary battery by integrating an amount of charge current with a microcomputer, said method comprising the steps of:

using said microcomputer to set a minimum charge current which is able to be integrated;

interrupting a charging operation when said microcomputer detects that the charge current is smaller than said minimum charge current;

resuming the charging operation after a preselected period of time; and

repeating said detection, said interruption, and said resumption of the charging operation until the secondary battery has been fully charged.

4. In a charging device for detecting a full-charge condition of a secondary battery by integrating an amount of charge current comprising:

a current interrupter interrupting a charging operation when the charge current falls below a current level which is able to be integrated, until a charge current that is able to be integrated flows.

5. A charging device as claimed in claim 4, wherein said charging device is applied to a handy electronic apparatus.

6. In a charging device for detecting a full-charge condition of a secondary battery by integrating an amount of charge current with comprising:

a microcomputer having leads connected to a resistor, said microcomputer programmed to detect said amount of charge current through said resistor;

a switch for selectively turning on or turning off the charge current being fed from a charge power feeding device;

said microcomputer having stored therein a value of a minimum charge current that is able to be integrated for turning off said switch, when a value of the charge current being sensed by said resistor is below said value of said minimum charge current, and again turning on said switch after an elapse of a preselected period of time.

7. A charging device as claimed in claim 6, wherein said charging device is applied to a handy electronic apparatus.