Control circuit for safe charging a rechargeable battery

• US 5,371,455 A
• Filed: 10/08/1993
• Issued: 12/06/1994
• Est. Priority Date: 10/08/1993
• Status: Expired due to Fees

• Current Assignee: Champion Freeze Drying Co., Ltd.
• Original Assignee: Champion Freeze Drying Co., Ltd.
• Inventors: Chen, Shih-Chao
• Primary Examiner(s): KINCAID, KRISTINE LYNN
• Application Number:
  US08/134,320
• Time in Patent Office: 424 Days
• Field of Search: 320/25, 320/26, 320/48
• US Class Current: 320/165
• CPC Class Codes: H02J 7/0029 with safety or protection devices or circuits
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H02J 7/0034 using reverse polarity correcting or protecting circuits mechanical means of polarity protection H02J7/0045
• CPC Class Codes: H02J 7/0047 with monitoring or indicating devices or circuits
• CPC Class Codes: H02J 7/0049 Detection of fully charged condition

Abstract

A control circuit for safe charging a rechargeable battery comprising a forced short-circuit switch, a safety switch, an automatic change switch, a first rectification circuit, a second rectification circuit, a reverse-polarity detection circuit, a charging-signal output circuit, an oscillation circuit, and a condition-indicating signal assembly. Power supply can be provided from a conventional charging device or a spare battery. During the charging operations, the reverse-polarity detection circuit is used for detecting the correct polarity connection; when reverse polarity was connected, the automatic change switch will correct the polarity by indication the occupance of such condition with the indicating lamps in the condition-indicating signal assembly so as to provide a smooth and safe battery recharging.

Claims

1. A control circuit for safe charging a rechargeable battery from a charging device, said battery and said charging device each having a positive terminal and a negative terminal, and said control circuit comprising:

a reverse-polarity detection circuit detecting whether the positive and negative terminals of said charging device are connected to the positive and negative terminals, respectively, of said battery to be charged, and, as soon as reverse terminal connection is detected, sending out a reverse-polarity control signal;

an automatic change switch having two groups of switching contacts, said automatic change switch being controlled by said reverse-polarity control signal from said reverse-polarity detection circuit, and said automatic change switch automatically switching said contacts upon receiving said control signal;

a first rectification circuit which is a full wave rectifier having a pair of first positive and negative output terminals with an input voltage provided by said charging device, and an output of one of 10 V and 2 V being provided from said first positive output terminal thereof;

a second rectification circuit which is a full wave rectifier having a pair of second positive and negative output terminals, and said second positive output terminal being connected with said first positive output terminal of said first rectification circuit;

a charging-signal output circuit including a transistor, said transistor having a transistor base connected with said first and second positive output terminals of said first and said second rectification circuits, via a diode, said transistor also being connected with a 10 V power supply, via a resistor;

a condition-indicating signal assembly including a charge-indicating lamp and a reverse-connection indicating lamp;

said charge-indicating lamp being controlled by means of an output of said charging-signal output circuit, and said charge-indicating lamp being turned on when said battery is being charged by said charging device;

said reverse-connection indicating lamp being turned on in case said charging device and said battery are in said reverse terminal connection; and

a safety switch including a switch contact to be connected with one of said two groups of contacts in said automatic change switch in said charging circuit;

said safety switch being energized upon charge being started.

2. A control circuit for safe charging a rechargeable battery as claimed in claim 1, which further comprising a forced short-circuit switch, said forced short-circuit switch having a double-pole and single-throw-switch and two groups of contacts;

said two groups of contacts of said forced short-circuit switch being connected with said positive and negative terminals of said charging device and said battery to be charged, respectively.

3. A control circuit for safe charging a rechargeable battery as claimed in claim 1, wherein said reverse-polarity detection circuit includes an exclusive OR gate having two input terminals connected with two over-voltage protection resistors, which further being connected with a negative terminal of a second battery and said positive terminal of said battery being charged, respectively;

in case of said negative terminal of said second battery and said positive terminal of said positive terminal of said battery being charged being incorrectly connected, said reverse-polarity detection circuit generating said reverse-polarity control signal; and

a second transistor having a base terminal connected with a second resistor, and said second transistor being controlled by said reverse-polarity control signal from said reverse-polarity detection circuit;

said second transistor having a collector terminal for controlling said automatic change switch.