Battery charge apparatus controlled by detecting charge current with constant charge voltage

• US 5,028,860 A
• Filed: 01/10/1990
• Issued: 07/02/1991
• Est. Priority Date: 01/20/1989
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Amano, Katsutoshi
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): Peckman, Kristine
• Application Number:
  US07/463,127
• Time in Patent Office: 538 Days
• Field of Search: 320/21, 320/22, 320/23, 320/39, 320/40
• US Class Current: 320/164
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current

Abstract

A nonaqueous secondary battery is charged by a constant voltage. The charging current decreases with time, and, when it becomes smaller than a predetermined reference value, the charging is controlled either by terminating the charging current or by setting it at a very low value.

Claims

1. Apparatus for charging a battery, said apparatus comprising:

means for generating a constant voltage and applying it to a nonaqueous, organic electrolyte, lithium secondary battery for generating a charging current therein, said charging current decreasing rapidly as a function of time from an initial maximum current to a stable, low level of charging current substantially equal to 10% of said initial maximum current;

a detecting circuit responsive to said charging current for generating a control signal when said charging current becomes smaller than a reference value substantially equal to said stable, low level of charging current; and

means responsive to the control signal for controlling said charging current.

2. Apparatus according to claim 1 wherein the controlling of said charging current is effected by terminating said charging current.

3. Apparatus according to claim 1 wherein the controlling of said charging current is effected by setting said charging current at a very low value.

5. Apparatus according to any of claims 1-4 wherein said predetermined value is selected to correspond to a value of said charging current at the end of the charging.

6. Apparatus according to any of claim 1-4 wherein said means for generating a constant voltage comprises an alternating current source, a rectifying circuit and a voltage regulator.

4. Apparatus for charging a battery, said apparatus comprising:

means for generating a constant voltage and applying it to a nonaqueous, organic electrolyte, lithium secondary battery for generating a charging current therein, said lithium secondary battery having a charging current characteristic that rapidly decreases from an initial maximum level before reaching a stable low level that is substantially equal to 10% of said initial maximum level;

a detecting circuit connected to said means for generating a constant voltage for detecting said charging current; and

an electronic switch connected between said detecting circuit and said secondary battery which is turned OFF by an output signal of said detecting circuit when a value of said charging current becomes smaller than a predetermined value substantially equal to said stable low level of charging current.