Condition responsive battery charging circuit

• US 4,209,736 A
• Filed: 07/27/1978
• Issued: 06/24/1980
• Est. Priority Date: 07/27/1978
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Reidenbach, Stanley G.
• Primary Examiner(s): Hickey, Robert J.
• Application Number:
  US05/928,705
• Time in Patent Office: 698 Days
• Field of Search: 320/22-24, 320/31, 320/32, 320/35, 320/36, 320/37, 320/38, 320/39, 320/40, 320/43
• US Class Current: 320/152
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: Y10S 320/28 Regulating transformer, e.g. high leakage, ferro-resonant

Abstract

A battery charging circuit includes a ferroresonant transformer having a rectified output for providing a constant output voltage to be supplied to a battery to be charged. Battery temperature is sensed providing an input to a control circuit which operates a shunt regulator associated with the ferroresonant transformer to provide battery charge voltage as a function of battery temperature. In response to a high battery temperature the controller functions to lower the output voltage to the battery, and in response to a low battery temperature, operates to provide a higher output voltage, with suitable control for any battery temperature between minus 10° and plus 150° Fahrenheit. As the battery approaches full charge and battery acceptance current falls below a predetermined level, a charge cycle termination control allows charging to continue for a period preset by the operator, at the end of which period, line voltage is removed from the charger thereby terminating the charge cycle.

Claims

1. Apparatus for charging a storage battery, comprising:

input means for connection to a source of AC electrical energy;

means connected to the input means for providing a constant output voltage for charging the battery;

output means for connecting the constant output voltage providing means to the battery to be charged;

means for automatically varying the level of the constant output voltage as a function of battery temperature; and

means for automatically terminating battery charging a predetermined time after current being supplied to the battery drops below a predetermined level.

2. The apparatus of claim 1 further comprising:

means for manually adjusting the level of the constant output voltage for a given battery temperature.

3. The apparatus of claim 1 wherein the constant output voltage providing means includes a constant voltage transformer and means for rectifying the output thereof.

4. The apparatus of claim 3 wherein the means for automatically varying includes:

means for sensing battery temperature;

means for producing a temperature variable reference voltage as a function of the temperature sensed by the temperature sensing means; and

means for sensing the rectified output voltage being supplied at the output means.

5. The apparatus of claim 4 wherein the means for automatically varying further includes a shunt regulator operatively associated with the constant voltage transformer.

6. The apparatus of claim 5 wherein:

The constant voltage transformer is a ferroresonant transformer having a tapped ferroresonant winding, the distal ends of which are interconnected through a capacitor;

the shunt regulator including as SCR bridge of the type having a pair of SCR'"'"'s whose cathodes are interconnected and a pair of diodes whose anodes are interconnected, the two interconnections being connected together and to circuit common, the interconnections of the diode and SCR pairs being connected, respectively, to the tap of the ferroresonant winding through current limiting means and to one of the distal ends of the ferroresonant winding.

7. The apparatus of claim 5 wherein the means for automatically varying further includes means for controlling operation of the shunt regulator, the means for controlling including comparator means for comparing the temperature variable reference voltage with a portion of sensed output voltage being supplied to the battery by the constant voltage transformer, the means for controlling acting to control the shunt regulator for adjusting the level of the constant output voltage to be a predetermined multiple of the temperature variable reference voltage.

8. The apparatus of claim 7 further including means for manually adjusting the level of the temperature variable reference voltage thereby to change the level of the constant output voltage for a given battery temperature.

9. The apparatus of claim 1 wherein the means for automatically terminating includes:

termination control means including means for sensing current being supplied to the battery being charged;

the control means providing a signal when the sensed current drops below a predetermined level; and

timing means connected to the input means and responsive to the signal from the termination control means to become operation for removing AC electrical energy from the providing means a predetermined time after becoming operational.

10. The apparatus of claim 4 wherein the means for sensing battery temperature is a temperature variable linear resistor.

11. The apparatus of claim 4 wherein the means for sensing output voltage is a voltage divider connected across the output means.

12. A circuit for charging a storage battery, comprising:

means for providing constant output voltage to the battery being charged;

means for automatically varying the level of the constant output voltage as a function of temperature of the battery being charged; and

means for automatically terminating the supply of constant output voltage to the battery a predetermined time after current being supplied to the battery drops below a predetermined level.

13. The circuit of claim 12 further including input means for connecting the providing means to a source of AC electrical energy and output means for connecting the providing means to the battery to be charged.

14. The circuit of claim 12 wherein the means for providing a constant output voltage includes a ferroresonant transformer and means for rectifying the output thereof.

15. The circuit of claim 12 wherein the means for automatically varying includes:

means for sensing battery temperature;

means for producing a temperature variable reference voltage as a function of the temperature sensed by the temperature sensing means; and

means for sensing the output voltage being supplied by the providing means to the battery.

16. The circuit of claim 15 wherein:

the means for providing a constant output voltage includes a ferroresonant transformer and means for rectifying the output thereof; and

the means for automatically varying further includes a shunt regulator operatively associated with the ferroresonant transformer and means for controlling operation of the shunt regulator.

17. The circuit of claim 16 wherein the means for controlling includes means for comparing the temperature variable reference voltage with the output voltage being supplied to the battery, the means for controlling acting to control the shunt regulator for adjusting the level of the constant output voltage to be a predetermined multiple of the temperature variable reference voltage.

18. The circuit of claim 13 wherein the means for automatically terminating includes:

termination control means including means for sensing current being supplied to the battery being charged, the termination control means further including a switch which becomes operational when current being sensed drops below a predetermined level; and

timing means connected to the input means and responsive to actuation of the switch to become operational for removing AC electrical energy from the providing means a predetermined time after becoming operational.

19. A control circuit for a battery charger, the charger being of the type having a ferroresonant transformer and means for rectifying the output voltage thereof for producing a constant output voltage for charging the battery, the control circuit controlling the charger as a function of temperature of the battery being charged and as a function of acceptance current of the battery and comprising:

means for automatically varying the level of the constant output voltage produced by the charger as a function of the temperature of the battery being charged; and

means for automatically terminating operation of the charger a predetermined time after the acceptance current being supplied to the battery by the charger drops below a predetermined level.

20. The control circuit of claim 19 further comprising:

means for manually adjusting the level of constant output voltage for a given battery temperature.

21. The control circuit of claim 19 wherein the means for automatically varying includes:

a shunt regulator operatively associated with the ferroresonant transformer;

means for sensing the rectified output voltage being supplied to the battery;

means for sensing temperature of the battery being charged;

means for producing a temperature variable reference voltage as a function of the temperature being sensed; and

control means including a comparator for comparing the level of a portion of the output voltage being sensed with the temperature variable reference voltage, the control means acting to control the shunt regulator for adjusting the level of the charger output voltage to be a predetermined multiple of the temperature variable reference voltage.

22. The control circuit of claim 21 wherein:

the ferroresonant transformer includes a center-tapped ferroresonant winding, the distal ends of which are interconnected through a capacitor;

the shunt regulator including an SCR bridge of the type having a pair of SCR'"'"'s whose cathodes are interconnected and a pair of diodes whose anodes are interconnected, the two interconnections being connected together and to circuit common, the interconnections of the diode and SCR pairs being connected, respectively, to the center tap of the ferroresonant winding through current limiting means and to one of the distal ends of the ferroresonant winding.

23. The control circuit of claim 21 further including means for manually varying the level of the temperature variable reference voltage thereby to change the level of the constant output voltage for a given battery temperature.

24. The control circuit of claim 21 wherein:

the means for sensing output voltage is a voltage divider connected across the rectified output of the ferroresonant transformer; and

the means for sensing the temperature of the battery is a temperature variable linear resistor.

25. The control circuit of claim 19 wherein the means for automatically terminating includes:

timing means including means for removing operating electrical energy from the ferroresonant transformer a predetermined time after the timing means becomes operational;

a switch for turning on the timing means;

means for sensing acceptance current being supplied by the charger to the battery; and

means responsive to acceptance current sensed below a predetermined level to turn on the switch thereby to turn on the timing means.

26. The control circuit of claim 25 wherein:

the timing means is a timer actuated switching mechanism which becomes operational to open thereby to remove electrical energy from the ferroresonant transformer, the mechanism incorporating adjustment means for manually selecting a period of operation of the timer after which the switching mechanism opens.