RAPID CHARGING OF BATTERIES

• US 3,614,582 A
• Filed: 07/13/1970
• Issued: 10/19/1971
• Est. Priority Date: 07/13/1970
• Status: Expired due to Term

• Current Assignee: John H. Bigbee III, Wilford B. Burkett
• Original Assignee: John H. Bigbee III, Wilford B. Burkett
• Inventors: Burkett, Wilford B., Bigbee, John H. III
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): Gunther, John M.
• Application Number:
  US05/054,244
• Time in Patent Office: 463 Days
• Field of Search: 320/2,4,5,9,11,14,20-22,39,44,45
• US Class Current: 320/129
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: Y10S 320/17 Sensing of "gassing" voltage

Abstract

A battery is charged in a very short period of time by applying a charging current in excess of the nominal 1-hour rate of the battery, with the charging current decreasing as the battery becomes charged. The charging current is intermittently interrupted in response to the attainment of a predetermined voltage by integrating the battery terminal voltage, and the battery is discharged at a high rate for a short period of time. The frequency of the interruptions is increased as the terminal voltage and charge of the battery increases. The disclosure relates to both the method of rapid charging and apparatus for rapid charging.

Claims

1. A method of rapidly charging a battery comprising the steps of alternately charging and discharging a battery during alternated charging and discharging intervals to impose an increasing charge on said battery;

and maintaining the duration of each said charging intervals by integrating the battery terminal voltage.

2. A battery-charging circuit comprising a source of charging current coupled to a battery through a selectively operable electrical connection;

a discharge path;

circuit means for developing a control signal by integrating the terminal voltage of said battEry, with said battery terminal voltage increasing as charging of said battery progresses; and

circuit means responsive to said control signal for connecting said discharge path.

3. A method of rapidly charging batteries for one or more cells comprising the steps of applying charging current to the battery during a charging interval, integrating the battery terminal voltage which increases as charge progresses to provide a control signal at a selected threshold voltage to end each charge interval and to start a discharge interval and discharging the battery during each discharge interval after a charge interval.

4. A method in accordance with claim 3 comprising the further step of terminating the rapid charging when a predetermined average discharge current is reached.

5. The method in accordance with claim 3 wherein the charging current exceeds the nominal 1-hour rate of the cells of the battery and the average discharge current averaged over the time of discharge current flow exceeds the value of the charge current.

6. Apparatus for rapid charging a battery comprising a first controllable switch, a source for supplying charging current coupled to said battery through said first switch, a second controllable switch, a discharge path coupled to said battery through said second switch, circuit means for integrating the battery terminal voltage, and circuit means responsive to a selected threshold voltage in the integrating means for closing said second switch to apply said discharge path.

7. An apparatus in accordance with claim 6 wherein the controlling means includes a relay winding, the first controllable switch is a pair of normally closed contacts associated with the relay winding and said second switch includes a pair of normally opened contacts associated with said relay winding.

8. An apparatus in accordance with claim 6 wherein the first controllable switch is a silicon-controlled rectifier.

9. An apparatus in accordance with claim 6 wherein the second controllable switch is a silicon-controlled rectifier.

10. An apparatus in accordance with claim 6 wherein the closing means includes a relaxation oscillator.

11. An apparatus in accordance with claim 6, further comprising a thermal-responsive switch for opening the current path from the source to the battery, the heat element of said thermal-responsive switch being in the discharge path of said battery.

12. An apparatus for rapid charging a battery having one or more cells comprising transmission means operable to transmit charging current to said battery, a discharge path, means for integrating the terminal voltage of the battery, and means responsive to a selected voltage across the integrating means for applying the discharge path to the battery.

13. An apparatus in accordance with claim 12 wherein the applying means is controllable to provide a selected period of time for the application of the discharge path.

14. An apparatus for rapid charging a battery having one or more cells comprising an integrating circuit connected across the battery, the integrating circuit including a capacitor having a charge rate responsive to the terminal voltage of the battery, a discharge path, a first switch responsive to a selected threshold voltage across the capacitor, and circuit means controlled by said first switch for applying said discharge path across said battery.

15. An apparatus for rapid charging a battery having one or more cells comprising a source of charge current, a normally closed contact or an electromechanical relay connected between said source and said battery, a discharge path, a normally open contact of said electromechanical relay connecting said discharge path across said battery, a voltage divider circuit connected across said battery, an integrating circuit including a capacitor connected between a junction in the voltage divider network and the negative terminal of said battery, an electromechanical relay having a capacitor connected across its winding, a silicon-controlled rectifier being connected in series with the relay winding between a source of voltage and the negative terminal of the battery, and means for connecting the capacitor of the integrating circuit between the gate and cathode of said silicon-controlled rectifier.

16. An apparatus for rapid charging a battery comprising a source of alternating-current voltage, a transformer having two secondary windings, a first silicon-controlled rectifier, means for connecting one secondary winding across said battery through said first silicon-controlled rectifier, a second silicon-controlled rectifier, means for connecting said battery to said second winding of said transformer through said second silicon-controlled rectifier, a third silicon-controlled rectifier connected in series with a resistor between one terminal of said second winding and the negative terminal of said battery, an integrating circuit including a capacitor in parallel with a voltage divider network and connected across said battery, a fourth silicon-controlled rectifier connected between one terminal of said capacitor and the gate terminal of said silicon-controlled rectifier, means for connecting the gate terminal of said fourth silicon-controlled rectifier to a junction of said voltage divider and means for connecting the gate terminal of said first silicon-controlled rectifier to the junction between the series resistor and said third silicon-controlled rectifier.

17. A method of rapidly charging a battery comprising the steps of alternately charging and discharging a battery during alternating charging and discharging intervals to impose an increasing charge on said battery;

sensing a condition by integrating the terminal voltage of said battery;

maintaining the duration of each of said charging intervals as a function of the time integral of battery terminal voltage;

interrupting said charging of said battery at the ends of said charging intervals, with said battery terminal voltage increasing as charging of said battery progresses;

limiting said discharging intervals such that the difference between maximum and minimum battery terminal voltages during discharging intervals diminishes as charging of said battery progresses;

diminishing the level of current applied to said battery to effect said charging as charging of said battery progresses;

effecting said charging with charge current exceeding the nominal 1-hour rate of the cells of said battery;

causing the frequency of the intervals of the discharging to increase as said alternate charging and discharging progresses;

causing the duration of intervals of said charging to diminish as said alternate charging and discharging progresses; and

causing the quotient of the duration of a charging interval divided by the duration of an immediately succeeding discharging interval to diminish as said alternate charging and discharging progresses.

18. A method of rapidly charging a battery comprising the steps of alternately charging and discharging a battery during alternating charging and discharging intervals to impose an increasing charge on said battery;

sensing a condition by integrating the terminal voltage of said battery;

maintaining the duration of each of said charging intervals as a function of the time integral of battery terminal voltage;

interrupting said charging of said battery at the ends of said charging intervals in response to said sensed condition, with battery terminal voltage increasing as charging of said battery progresses;

limiting the duration of said discharging intervals such that the difference between maximum and minimum battery terminal voltages during discharging intervals diminishes as charging of said battery progresses;

diminishing the level of current applied to said battery during said charging intervals as charging of said battery progresses;

effecting said charging with charge current exceeding the rated hourly capacity of said battery;

effecting said discharging with discharge current exCeeding the charging current applied during the initial charging interval of said battery;

causing the frequency of the intervals of discharging to increase as said alternate charging and discharging progresses;

causing the duration of intervals of said charging to diminish as said alternate charging and discharging progresses; and

causing the quotient of the duration of a charging interval divided by the duration of an immediately succeeding discharging interval to diminish as said alternate charging and discharging progresses.

19. A battery-charging circuit comprising a source of charging current;

a load;

means for generating a control signal;

said generating means including a means for integrating the battery terminal voltage;

circuit means for alternately connecting said battery to said source and to said load;

said circuit means being responsive to said control signal;

said control means being operable to cause the difference between maximum and minimum battery terminal voltages, during the periods of time that said battery is connected to said load, to diminish as charging of said battery progresses;

said circuit means being operable to impose a charging current on said battery which decreases as charging of said battery progresses;

said circuit means being operable to connect said load with said battery with a frequency which increases as charging of said battery progresses, with battery terminal voltage increasing as charging of said battery progresses;

said circuit means being operable to connect said source with said battery, with the duration of periods of connection between said battery and said source becoming shorter as charging of said battery progresses; and

said circuit means being operable to cause a quotient equal to the duration of a period of time during which said source is connected to said battery divided by the duration of an immediately succeeding period of time during which said load is connected to said battery to diminish as charging of said battery progresses.

20. A battery-charging circuit comprising a source of charging current;

a load;

means for generating a control signal;

said signal being an integral function of the terminal voltage of a battery, with said battery terminal voltage increasing as charging of said battery progresses;

circuit means for alternately connecting said battery to said source and to said load;

said circuit means being responsive to said control signal;

said control means being operable to cause the difference between maximum and minimum battery terminal voltages, during the periods of time that said battery is connected to said load, to diminish as charging of said battery progresses;

said circuit means being operable to impose a charging current on said battery which decreases as charging of said battery progresses;

said circuit means being operable to connect said source with said battery, with the duration of periods of connection between said battery and said source becoming shorter as charging of said battery progresses, and with current applied to said battery exceeding the hourly rated capacity of said battery;

said circuit means being operable to connect said load with said battery with a frequency which increases as charging of said battery progresses, and with current discharging from said battery at a level which exceeds the current applied to said battery when said source is first connected to said battery; and

said circuit means being operable to cause a quotient equal to the duration of a period of time during which said source is connected to said battery divided by the duration of an immediately succeeding period of time during which said load is connected to said battery to diminish as charging of said battery progresses.