AUTOMATIC TEMPERATURE RESPONSIVE BATTERY CHARGING CIRCUIT

• US 3,667,026 A
• Filed: 12/02/1970
• Issued: 05/30/1972
• Est. Priority Date: 12/02/1970
• Status: Expired due to Term

• Current Assignee: Henry A. Bogut, Leon Jasinski
• Original Assignee: Henry A. Bogut, Leon Jasinski
• Inventors: Jasinski, Leon, Bogut, Henry A.
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): Hickey, Robert J.
• Application Number:
  US05/094,261
• Time in Patent Office: 545 Days
• Field of Search: 320/35,36,22,39
• US Class Current: 320/150
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: Y10S 320/19 Charger status, e.g. voltmeter

Abstract

A charger for charging a battery at a first predetermined rate and automatically terminating said charge rate when the battery temperature rises, in response to the charging current, to a point indicating full charge. The battery has a thermistor mounted therein which changes resistance as the battery temperature changes. The charger includes a charging circuit and silicon controlled rectifier in series with the battery. A sensing circuit, coupled to the thermistor, senses a thermistor resistance indicative of less than a full charge and changes from a first to a second state. If the thermistor resistance indicates a full charge, the sensing circuit changes from the second to the first state. A switch circuit connected to the sensing circuit and the rectifier gate electrode is responsive to changes from the first to the second state to trigger the rectifier into conduction and allow charging of the battery at the predetermined rate. A latch circuit connected to the sensing circuit and rectifier gate electrode operates in response to the sensing circuit changing from the second to the first state to inhibit further conduction of the silicon controlled rectifier. The latch circuit is deenergized, allowing further conduction of the silicon controlled rectifier, by removal of the battery from the battery charger.

Claims

1. A device for charging a battery from a source of alternating current wherein the battery includes a temperature variable resistor in series with the battery which changes resistance and current therethrough as the battery temperature changes in response to charging current, said device including in combination, a charging circuit including rectifier means coupled to the source of alternating current and to the battery for applying a unidirectional charging current to said battery, a first silicon controlled rectifier including a pair of principal electrodes in series with the battery and said charging circuit for passing said unidirectional charging current to allow charging of said battery, said first silicon controlled rectifier having a gate electrode for controlling conduction thereof, first circuit means coupled to said temperature variable resistor and responsive to the current therethrough to develop a first voltage varying in level in accordance with the temperature of said battery, semiconductor trigger circuit means coupled to said first circuit means and responsive to said first voltage exceeding a first predetermined level to change from a first to a second state and responsive to said first voltage decreasing below said predetermined level to change from the second to first state, first switch means coupled to said semiconductor trigger circuit means and said gate electrode for triggering said first rectifier into conduction by said change of state whereby said battery is allowed to charge, and turn-off circuit means coupled to said semiconductor trigger circuit means and said gate electrode and responsive to said trigger circuit means changing from said second to said first state to trigger said first rectifier into non-conduction whereby said battery is no longer charged.

2. The device of claim 1 wherein said first switch means includes, a first transistor coupled to said rectifier gate electrode and to said semiconductor trigger circuit means and responsive to the change from the first to the second state to trigger said first rectifier into conduction.

3. The device of claim 2 wherein said turn-off circuit means includes, a second silicon controlled rectifier having a gate electrode coupled to said semiconductor trigger circuit means and a principal electrode coupled to the battery, said second rectifier being rendered conductive in response to said semiconductor trigger circuit changing from the second to the first state, said first rectifier being rendered non-conductive and further conduction thereof inhibited, in response to said second rectifier conduction, said second rectifier being rendered non-conductive by removal of said battery from said device whereby said first rectifier may be rendered conductive in response to said first switch means.

4. The device of claim 3 wherein said turn-off circuit further includes, a second transistor coupled to said first rectifier gate electrode and to a principal electrode of said second rectifier, said second transistor operative in response to conduction of said second rectifier to render said first rectifier non-conductive and inhibit further conduction of same.

5. The device of claim 4 wherein said turn-off circuit means further includes, a third transistor coupled to said second rectifier gate electrode and to said semiconductor trigger circuit means, said third transistor operative in response to said trigger circuit means changing from the second to the first state to trigger said second rectifier into conduction.

6. The device of claim 5 wherein said semiconductor trigger circuit means is a Schmitt trigger.

7. The device of claim 6 further including, indicator circuit means coupled to said charging circuit and to said battery and responsive to the charging current flowing therethrough to indicate charging of said battery.

8. The device of claim 7 further including second indicator circuit means coupled to said charging circuit and to said second rectifier and responsive to conduction of said second rectifier to indicate completion of charging.

9. The device of claim 8 wherein said first and second indicator circuit means includes, a lamp coupled to said charging circuit for providing said indication, and a silicon controlled rectifier having first and second principal electrodes in series with said lamp and charging circuit, said silicon controlled rectifiers each including a gate electrode for controlling conduction thereof, said rectifier gate electrode in said first indicating means being coupled to said battery and responsive to charging current flowing therethrough to render said rectifier conductive, said rectifier gate electrode in said second indicating means being coupled to said second rectifier and responsive to conduction thereof to render said rectifier conductive.

10. A device for automatically charging a battery having a voltage thereacross from a source of alternating current at a predetermined charge rate and automatically terminating said charge rate when the battery temperature rises to a first level indicating full charge, in response to the charging current, and wherein the device is reset by removal of the battery from the device, said device including in combination, a charging circuit including rectifier means series coupled with said battery and coupled to said source of alternating current for applying a unidirectional charging current to said battery, a first silicon controlled rectifier having a pair of principal electrodes in series with said battery and said charging circuit for passing said undirectional charging current to allow charging of said battery, said first rectifier having a first gate electrode for controlling conduction thereof, first circuit means coupled to said battery and responsive to a battery temperature below said first level to switch from a first to a second state, said first circuit means responsive to a battery temperature above said first level to switch from the second to the first state, first switch means connected to said first circuit means and the first rectifier gate electrode and responsive to a change from the first to the second state tO develop a trigger signal, said first rectifier operative only in response to said trigger signal to conduct whereby said battery is allowed to charge, latch circuit means coupled to said first circuit means and said first rectifier gate electrode and including a second silicon controlled rectifier having a first principal electrode coupled to the battery and a gate electrode coupled to said first circuit means, said second rectifier being rendered conductive in response to said first circuit changing from the second to the first state, and further being held conductive by said battery voltage coupled thereto, said first rectifier being rendered non-conductive and further conduction of same inhibited in response to said second rectifier conduction, said second rectifier being rendered non-conductive by termination of said battery voltage coupled thereto, termination of said battery voltage being effected only by removal of said battery from said device.

11. The device of claim 10 wherein said battery further includes, a temperature variable resistor mounted therein in series with the battery which changes resistance and current therethrough as the battery temperature varies, and said first circuit means includes, bias circuit means coupled to said temperature variable resistor and responsive to the current therethrough to develop a bias voltage varying in accordance with the temperature of said battery, said first circuit means further including semiconductor trigger circuit means coupled to said bias circuit means and responsive to said bias voltage exceeding a first predetermined level to change from the first to the second state, said trigger circuit means being further responsive to said first voltage decreasing below said first predetermined level to change from the second to the first state.

12. The device of claim 11 wherein said first switch means includes, a first transistor coupled to said semiconductor trigger circuit means, and to said first rectifier gate electrode, said first transistor being responsive to said trigger circuit means changing from the first to the second state to trigger said first rectifier into conduction.

13. The device of claim 12 wherein said latch circuit means further includes, second switch means coupled to said first rectifier gate electrode and to a second principal electrode of said second rectifier, and operative in response to conduction of said second rectifier to render said first rectifier non-conductive and inhibit further conduction of same.

14. The device of claim 13 wherein said latch circuit means further includes, a third switch means coupled to said second rectifier gate electrode and said trigger circuit means, said third switch means operative in response to said trigger circuit changing from the second to the first state to trigger said second rectifier into conduction.

15. The device of claim 11 wherein said semiconductor trigger circuit means is a Schmitt trigger.

16. The device of claim 15 wherein said second and third switch means are transistors.