Battery charging control using temperature differential circuit

• US 3,917,990 A
• Filed: 04/11/1974
• Issued: 11/04/1975
• Est. Priority Date: 04/11/1974
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Ralph r. Sherman, Jr.
• Inventors: Sherman, Ralph R. Jr.
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): Hickey, Robert J.
• Application Number:
  US05/459,875
• Time in Patent Office: 572 Days
• Field of Search: 320/35,36,22
• US Class Current: 320/150
• CPC Class Codes: N/A

Abstract

A bridge circuit using a battery temperature sensing resistor and an ambient temperature sensing resistor provides signals which can be applied to an output circuit to cause a charging circuit to provide a relatively high charging current when the battery temperature is within a predetermined temperature region relative to the ambient temperature, and to provide a relatively low charging current when the battery temperature is above or below the predetermined temperature region. A memory circuit can be provided to prevent subsequent high charging currents.

Claims

1. An improved battery charging circuit comprising:

a. a charging circuit having control terminals and output terminals for supplying a relatively high direct current in response to a high control signal applied to said control terminals and for supplying a relatively low direct current in response to a low control signal applied to said control terminals;

b. a control circuit comprising;

1. first and second input terminals and first and second output terminals;

2. means connecting said first and second input terminals to said charging circuit output terminals;

3. a first resistor of predetermined magnitude connected between said first input terminal and said first output terminal;

4. a second resistor of predetermined magnitude connected between said first output terminal and said second input terminal;

5. a first temperature sensitive resistor arranged to sense the temperature of a battery being charged, said first temperature sensitive resistor being connected between said first input terminal and said second output terminal;

6. and a second temperature sensitive resistor of the same type as said first temperature sensitive resistor for sensing the ambient temperature of said control circuit, said second temperature sensitive resistor being connected between said second output terminal and said second input terminal;

c. means connected to said first input terminal and said second input terminal of said control circuit for connection to a battery to be charged;

d. and an output circuit comprising;

1. input terminals and output terminals;

2. means connecting said output circuit input terminals to said control circuit output terminals for producing a high control signal at said output circuit output terminals in response to said battery temperature being within a predetermined region relative to said ambient temperature, for producing a low control signal at said output circuit output terminals in response to said battery temperature being above said predetermined region, and for producing a low control signal at said output circuit output terminals in response to said battery temperature being below said predetermined region;

3. and means connecting said output circuit output terminals to said charging circuit control terminals.

2. The improved battery charging circuit of claim 1 wherein said first temperature sensitive resistor is connected to said first input terminal and said second output terminal of said control circuit at the time the battery to be charged is connected to said first and second input terminals of said control circuit.

3. a first resistor of predetermined magnitude connected between said first input terminal and said first output terminal;

4. a second resistor of predetermined magnitude connected between said first output terminal and said second input terminal;

5. a first temperature sensitive resistor arranged to sense the temperature of a battery being charged, said first temperature sensitive resistor being connected between said first input terminal and said second output terminal;

6. and a second temperature sensitive resistor of the same type as said first temperature sensitive resistor for sensing the ambient temperature of said control circuit, said second temperature sensitive resistor being connected between said second output terminal and said second input terminal;

c. means connected to said first input terminal and said second input terminal of said control circuit for connection to a battery to be charged;

d. and an output circuit comprising;