Battery-charging circuit

• US 5,451,880 A
• Filed: 06/08/1993
• Issued: 09/19/1995
• Est. Priority Date: 11/27/1990
• Status: Expired due to Fees

• Current Assignee: Furukawa Denchi Kabushiki Kaisha
• Original Assignee: Furukawa Denchi Kabushiki Kaisha
• Inventors: Yamagishi, Hirokazu, Kojima, Makio
• Primary Examiner(s): Regan, Maura K.
• Application Number:
  US08/073,659
• Time in Patent Office: 833 Days
• Field of Search: 324/429, 324/427, 320/48, 340/636
• US Class Current: 324/429
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: Y10S 320/21 State of charge of battery

Abstract

A battery-charging circuit capable of promptly detecting, during quick charging, an abnormality of a secondary battery of a battery, if any, and making it impossible to continue the quick charge thereafter. As a battery-charging circuit for quickly charging a secondary battery with a predetermined charging current from a battery-charging power source having a constant-characteristic, the battery charging circuit includes a voltage-measuring device for measuring the secondary battery voltage at predetermined regular time intervals; a voltage-setting device for presetting a reference voltage value at a level higher, by a predetermined magnitude, than an expected charge complete voltage value; a comparator device for comparing with the preset reference voltage value a battery voltage actually measured during the quick charge operation; and a current limiter circuit for stopping the quick charge when the battery voltage has risen to the reference voltage value.

Claims

1. A battery-charging circuit, through which at least one secondary battery having at least one cell, is quickly charged with a predetermined charging current, comprising:

a battery-charge control means operably coupled to said secondary battery, for stopping the quick charge when the secondary battery has become fully charged;

a voltage monitoring and charge control means, directly connected to said at least one secondary battery, for detecting abnormality of said battery during charging thereof and before being fully charged to thereby detect abnormality of said battery and detect that the battery is incapable of being reused, wherein the voltage monitoring and charge control means detects abnormality of said battery when voltage of said battery has risen to a preset reference voltage value which is at a predetermined level higher than an expected charge complete voltage, said voltage monitoring and charge control means including;

a voltage-measuring means for measuring a secondary battery voltage at predetermined regular time intervals,

a voltage-setting means for presetting said reference voltage value at a level higher, by a predetermined magnitude, than said expected charge complete voltage, and

a comparator means for comparing between said reference voltage value preset by said voltage-setting means and said secondary battery voltage actually measured by said voltage-measuring means;

a battery-charging power source means, operably connected to said at least one secondary battery and to said voltage monitoring and charge control means, for charging said secondary battery; and

a current limiter circuit means, operably connected to said at least one secondary battery and to said voltage monitoring and charge control means, for stopping the charge when said secondary battery voltage has risen to reach said present reference voltage value.

2. The battery-charging circuit as set forth in claim 1, further comprising a temperature monitoring means, operably connected to said at least one secondary battery and to said voltage monitoring and charge control means, for monitoring temperature readings of said at least one secondary battery and for inputting the monitored temperature readings to said voltage monitoring and charge control means.

3. The battery-charging circuit as set forth in claim 1, further comprising a trickle battery circuit included in the battery-charging circuit so that when the quick charge of the secondary battery has been completed in a normal manner, a charging channel may be switched over to the trickle charge.