Battery charging apparatus and full-charging detecting method

• US 6,232,746 B1
• Filed: 07/05/2000
• Issued: 05/15/2001
• Est. Priority Date: 07/05/1999
• Status: Expired due to Fees

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Yamanashi, Hidenori
• Primary Examiner(s): Tso, Edward H.
• Assistant Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US09/610,366
• Time in Patent Office: 314 Days
• Field of Search: 320/161, 320/162, 320/132, 324/430
• US Class Current: 320/132
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: H02J 7/0049 Detection of fully charged condition

Abstract

A battery charging apparatus 1 includes a full-charging detecting system 11. While a battery is charged, the full-charging detecting system operates as follows. A charging current supplied from an DC power source is detected. The internal impedance is computed on the basis of the charging current thus detected and charging voltage of the DC power source. The full-charging of the battery is detected on the basis of the comparison between the internal impedance thus computed and a prescribed value. In this configuration, even when the full-charging capacity varies owing to the degradation of the battery, the full-charged state of the battery can be detected precisely.

Claims

1. A battery charging apparatus including full-charging detecting means for detecting a full-charged state of a battery, wherein said full-charging detecting means comprises:

charging current detecting means for detecting a charging current supplied from a DC power source while the battery is charged with a constant voltage; and

internal-impedance computing means for computing an internal impedance on the basis of a charging voltage of the DC power source and said charging current detected by said charging current detecting means,

wherein the internal impedance computed by said internal impedance computing means is compared with a prescribed value to detect the full-charged state.

2. A battery charging apparatus according to claim 1, wherein said prescribed value is smaller than the internal impedance when the battery has been fully charged, and said full-charging detecting means detects the full-charging when the computed internal impedance exceeds the prescribed value.

3. A battery charging apparatus according to claim 1, wherein where the battery is subjected to boost charging with a constant voltage that is higher than a voltage across the battery, said prescribed value is set at a value equal to the internal impedance of said battery, and said full-charging detecting means detects the full-charging when the computed internal impedance is equal to said prescribed value.

5. A battery charging apparatus according to claim 1, further comprising:

charging stopping means for stopping supply of the charging current from said battery to the battery when the full-charging is detected by said full-charging detecting means.

7. A battery charging apparatus according to claim 1, wherein said battery is an in-vehicle battery, said DC power source is an AC/DC converter for converting an AC current from an alternator into a DC current, and when the full-charging is detected by said full-charging detecting means, supply of the charging current from said AC/DC converting means to said in-vehicle battery is stopped.

8. A battery charging apparatus according to claim 1, wherein said battery is an in-vehicle battery, said DC power source is an AC/DC converter for converting an AC current from an alternator into a DC current, and when the full-charging is detected by said full-charging detecting means, supply of the charging current from said AC/DC converting means to said in-vehicle battery is stopped.

9. A battery charging apparatus according to claim 1, further comprising:

warning generating means for generating warning when the full-charging is detected.

4. A battery charging apparatus including full-charging detecting means for detecting a full-charged state of a battery, wherein said full-charging detecting means comprises:

charging current detecting means for detecting a charging current supplied from a DC power source while the battery is charged with a constant voltage; and

internal-impedance computing means for sequentially computing an internal impedance on the basis of a charging voltage of the DC power source and said charging current detected by said charging current detecting means,

wherein the full-charging is detected when there is no variation on the basis of the internal impedance computed by said internal impedance computing means.

6. A battery charging apparatus according to claim 4, further comprising:

charging stopping means for stopping supply of the charging current from said battery to the battery when the full-charging is detected by said full-charging detecting means.

10. A battery charging apparatus according to claim 4, further comprising:

warning generating means for generating warning when the full-charging is detected.

11. A method of detecting full-charging of a battery comprising the steps of:

detecting a charging current supplied from a DC power source to a battery while the battery is charged with a constant voltage;

computing an internal impedance of the battery on the basis of a charging voltage of said DC power source and said charging current; and

comparing said internal impedance with a prescribed value to detect the full-charging of the battery.

12. A method of detecting full-charging of a battery comprising the steps of:

detecting a charging current supplied from a DC power source to a battery while the battery is charged with a constant voltage;

sequentially computing an internal impedance of the battery on the basis of a charging voltage of said DC power source and said charging current; and

detecting the full-charging when there is no variation in said internal impedance.