RAPID CHARGING OF BATTERIES

• US 3,597,673 A
• Filed: 06/26/1969
• Issued: 08/03/1971
• Est. Priority Date: 06/26/1969
• Status: Expired due to Term

• Current Assignee: John H. Bigbee, Wilford B. Burkett
• Original Assignee: John H. Bigbee, Wilford B. Burkett
• Inventors: Burkett, Wilford B., Bigbee, John H.
• Application Number:
  US04/836,791
• Time in Patent Office: 768 Days
• US Class Current: 320/129
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process

Abstract

A battery is charged in a very short period of time, for example less than 15 minutes, by applying a charging current that is in excess of the nominal 1-hour rate of the battery with discharge pulses sandwiched between charge pulses, with or without a rest period between the end of the charge pulse and the beginning of a discharge pulse and the end of the discharge pulse and the beginning of a charge pulse. The discharge pulse has a peak value in excess of the nominal 1-hour rate of the battery and the pulse has a short period, for example 1 to 4 microseconds, which time may be related to the time associated with the electrochemical characteristics and construction of the cell or cells of the battery being charged. The frequency of the discharge pulses is increased as the terminal voltage and charge of the battery increases. The charging at the high rate is terminated or converted to a trickle charge when the terminal voltage of the battery exceeds a selected voltage level associated with the desired level of charge in the battery. The disclosure relates to both the method of rapid charge and apparatus for rapid charging.

Claims

1. A circuit for rapid charging a battery having one or more cells, an inductor, a first controllable switch, a source of pulsating direct current voltage connected to the battery through said switch on one side and through said inductor on the other side for providing charging current pulses, a second controllable switch connected across said battery, means responsive to the voltage across said battery and said inductor for closing said second switch, means for holding said second switch closed for a period of time less than the interval between charging pulses, and means responsive to a selected level of voltage across the battery between charging pulses for inhibiting said first switch to terminate the application of charge current through said switch.

2. Apparatus for rapidly charging a battery from a source of charge current pulses, said apparatus comprising a first controllable switch connected between the source and the battery;

a second controllable switch connected across the Battery;

means for sensing the terminal voltage of the battery;

means for sensing the flow of charge current through the battery;

means responsive to both sensing means for controlling the operation of said second controllable switch for discharging the battery; and

means for inhibiting said first controllable switch in response to the attainment of a selected quiescent battery terminal voltage during charge to terminate charge.

3. Apparatus for rapidly charging a battery from a source of charge current pulses, said apparatus comprising a first controllable switch connected between the source and the battery;

a second controllable switch connected across the battery;

means for sensing the terminal voltage of the battery;

means for sensing the flow of charge current through the battery;

means responsive to both sensing means for controlling the operation of said second controllable switch for discharging the battery;

an electrical path connected in parallel with said first controllable switch for providing trickle charge current to said battery, and means to inhibit the operation of said first controllable switch in response to the attainment of a selected quiescent battery terminal voltage during charge to convert from a rapid charge to a trickle charge.

4. A circuit for terminating the high-rate charging of a battery having one or more cells comprising a first electrical path having a first resistance, a second electrical path having a second resistance greater than said first resistance connected in parallel with said first path, a source of charging current connected to the battery through said first and second paths, circuit means electrically connected for monitoring the quiescent terminal voltage of one or more of the cells of said battery, and circuit means responsive to said monitoring means for substantially increasing the resistance in said first path to cause the charge current to flow through said second path at a reduced rate to said battery upon the attainment of a predetermined quiescent battery terminal voltage.

5. A method of terminating the rapid charging of a battery having one or more cells comprising the steps of rapid charging a battery by charging the battery during a plurality of charging intervals, providing discharge intervals interspersed with said charging intervals, and causing the duration of intervals of said charging to diminish as said charge in said battery increases;

monitoring the quiescent terminal voltage of one or more of the cells of said battery during the rapid-charging step; and

terminating the rapid-charging step when the monitored quiescent terminal voltage assumes a predetermined value.

6. A method of battery charging comprising the steps of rapid charging a battery by applying a charging current at a rate in excess of the nominal 1-hour rate of the cells of the battery;

monitoring one of the parameters of terminal voltage, pressure, and temperature of the battery which change as charge progresses; and

intermittently discharging the battery in response to the attainment of a predetermined value of the monitored parameter;

monitoring the quiescent terminal voltage of one or more of the cells of the battery during the rapid-charging step; and

terminating the rapid-charging step when the quiescent terminal voltage assumes a predetermined value.

7. A method of rapid charging batteries having one or more cells comprising the steps of applying charging current pulses having an average value in excess of the nominal 1-hour rate of the cells and discharging the battery for a period of time less than the duration of a charging current pulse with the discharge current having a peak value between 100 and 200 times the nominal 1-hour rate of the cells.

8. A method of rapid charging batteries having one or more cells comprising the steps of applying charging current pulses having an average value in excess of the nominal 1-hour rate of the cells, and discharging the battery for a period of time less than the duration of a charging current pulse with the discharging period being approximately 2 microseconds in duration.

9. A rapid battery charging circuit comprising source means for supplying direct current pulses to a battery when the voltage level of said pulses exceeds the terminal voltage of said battery, a charge current path connected between said source and said battery, a discharge path of a first power transistor controlled by a second transistor, circuit means for sensing the quiescent terminal voltage of the battery, and circuit means connecting said second transistor to the sensing means for applying the discharge path across said battery each time the quiescent terminal voltage attains a predetermined value.

10. The battery-charging circuit of claim 9 further including circuit means responsive to the attainment of a predetermined value of quiescent terminal voltage for preventing charge current flow through said charge current path to terminate the charging of said battery.

11. A method of charging batteries having one or more cells comprising the steps of applying a charging current to the battery whereby the parameters of terminal voltage, temperature, and pressure of the battery change;

sensing the change in one of the parameters;

intermittently, in response to the attainment of a preselected value of the sensed parameter, depolarizing the battery by reversing the current through the battery;

sensing the quiescent terminal voltage of one or more cells of the battery; and

reducing the rate of the charging current in response to the attainment of a predetermined sensed quiescent terminal voltage.

12. A method of charging batteries having one or more cells comprising the steps of applying a charging current to the battery whereby the parameters of terminal voltage, temperature, and pressure of the battery change;

sensing the change in one of the parameters;

intermittently, in response to the attainment of a preselected value of the sensed parameter, depolarizing the battery by reversing the current through the battery;

sensing the quiescent terminal voltage of one or more cells of the battery; and

terminating the application of charging current in response to the attainment of a predetermined sensed quiescent terminal voltage.

13. A method of charging batteries having one or more cells comprising the steps of applying a charging current to the battery in excess of the nominal 1-hour rate of the cells of the battery whereby the parameters of terminal voltage, pressure, and temperature of the battery change;

sensing the change in one of the parameters;

intermittently, in response to the attainment of a preselected value of the sensed parameter, depolarizing the battery by reversing the current through the battery;

sensing the quiescent terminal voltage of one or more cells of the battery; and

reducing the rate of the charging current below the nominal one hour rate of the cells of the battery in response to the attainment of a predetermined quiescent terminal voltage.

14. A method of charging batteries having one or more cells comprising the steps of applying a charging current to the battery in excess of the nominal 1-hour rate of the cells of the battery whereby the parameters of terminal voltage, pressure, and temperature of the battery change;

sensing the change in one of the parameters;

intermittently, in response to the attainment of a preselected value of the sensed parameter, depolarizing the battery by reversing the current through the battery;

sensing the quiescent terminal voltage of one or more cells of the battery; and

terminating the application of charging current in response to the attainment of a predetermined sensed quiescent terminal voltage.