Battery charging system

• US 4,035,709 A
• Filed: 04/30/1975
• Issued: 07/12/1977
• Est. Priority Date: 04/30/1975
• Status: Expired due to Term

• Current Assignee: GNB Batteries, Inc. (Transdigm Group Incorporated)
• Original Assignee: Gould, Inc. (Transdigm Group Incorporated)
• Inventors: Seider, Gene J., Freund, Michael C.
• Primary Examiner(s): Hickey, Robert J.
• Application Number:
  US05/573,080
• Time in Patent Office: 804 Days
• Field of Search: 320/23, 320/24, 320/30, 320/31, 320/37, 320/38, 320/39, 320/40, 320/22
• US Class Current: 320/158
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: Y10S 320/22 Line impedance, e.g. resistor
• CPC Class Codes: Y10S 320/28 Regulating transformer, e.g. high leakage, ferro-resonant

Abstract

A battery charging system for charging a battery from a conventional a.c. power source has a leakage reactance transformer connected between the power source and the battery for reducing the voltage of the power source for application to the battery. The power source is connected directly across the primary winding of the transformer to charge the battery at a high rate until it is charged to about 90% of the final capacity. A voltage sensing circuit is activated when the battery reaches about 80% of the desired final voltage, and this circuit energizes a timing motor which maintains the connection of the source directly across the primary winding of the transformer for a period of one hour, which is the normal time required for the battery charge to be increased from the 80% level to the 90% level. At the end of the 1 hour period, a cam driven by the timing motor operates a switch to connect a resistor, which is external of the transformer, in series with the primary winding of the transformer. This sharply reduces the charging current and the charging of the battery is completed at relatively low current levels which vary over a very narrow range. This "finish" charging is continued for a 6 hour period determined by the timing motor. At the end of the 6 hour period, additional cams driven by the timing motor disconnect the power source from the transformer to terminate the charging cycle, and de-energize the timing motor. The system is automatically reset for the next charging cycle.

Claims

1. A battery charging system for charging a battery from a conventional a-c power source, said system comprising the combination of

(a) a leakage reactance transformer connected between the power source and the battery for reducing the voltage of the power source for application to the battery,

(b) means in circuit with the transformer for initially charging the battery at relatively high current levels to achieve a relatively high charging rate,

(c) means for automatically connecting an additional impedance, external of the transformer, in circuit with the transformer after a first predetermined time interval following the charging of the battery to a predetermined voltage, whereby the charging current is sharply reduced and the charging of the battery is completed at relatively low current levels which vary over a very narrow range,

d. and means for terminating the charging of the battery at the end of a second predetermined time period following the sharp reduction in the charging current.

2. A battery charging system as set forth in claim 1 wherein said predetermined voltage is about 80% of the final voltage to which it is desired to charge the battery and said first predetermined time interval is about one hour.

3. A battery charging system as set forth in claim 1 which includes means for connecting said additional impedance in circuit with the transformer when the battery is charged to about 90% of the final capacity to which it is desired to charge the battery.

6. A battery charging system as set forth in claim 1 which includes a transformer that is continuously connected between the a-c power source and the battery without any switching between different taps on said transformer.

4. A battery charging system for charging a battery from a conventional a-c power source, said system comprising the combination of

(a) a leakage reactance transformer connected between the power source and the battery for reducing the voltage of the power source for application to the battery,

(b) means in circuit with the transformer for initially charging the battery at relatively high current levels to achieve a relatively high charging rate, said initial charging means including

(1) a plurality of cam-operated switches,

(2) a high speed motor for driving the cams that operate said switches,

(3) a low speed driving motor for driving said cams,

a battery charging circuit connected to said transformer,

(5) means for energizing the high speed motor via one of the cam-operated switches in response to the connection of the a-c power source to the battery charging system,

(6) means for energizing the battery charging circuit via one of the cam-operated switches in response to a first predetermined movement of said cams, and

(7) means for de-energizing the high speed motor in response to a second predetermined movement of said cams,

(c) means for automatically connecting an additional impedance, external of the transformer, in circuit with the transformer after a first predetermined time interval following the charging of the battery to a predetermined voltage, said automatic connecting means including

(1) means for energizing the timing motor in response to the charging of the battery to a predetermined voltage, and

(2) means for sharply reducing the charging current in the battery charging circuit in response to a third predetermined movement of said cams whereby the charging of the battery is completed at relatively low current levels over a very narrow range,

(d) and means for terminating the charging of the battery at the end of a second predetermined time period following the sharp reduction in the charging current, said terminating means including

(1) means for de-energizing the battery charging circuit in response to a fourth predetermined movement of said cams,

(2) and means for de-energizing the timing motor in response to a fifth predetermined movement of said cams.

5. A battery charging system as set forth in claim 4 which includes means responsive to disconnection and re-connection of the a-c power source after de-energization of the high speed motor for re-energizing the high speed motor to return the cams to the positions they had when the high speed motor was previously de-energized.

7. A battery charging system for charging a battery from a conventional a-c power source, said system comprising the combination of

(a) a leakage reactance transformer connected between the power source and the battery for reducing the voltage of the power source for application to the battery,

(b) a plurality of cam-operated switches,

(c) a high charging rate circuit connected to said transformer and enabled by a first one of said cam-operated switches for initially charging the battery at relatively high current levels to achieve a relatively rapid charging rate,

(d) a finish rate charging circuit enabled by a second one of said cam-operated switches for automatically connecting an additional impedance, external of the transformer, in circuit with the transformer after the battery has been charged to a predetermined voltage, whereby the charging current is sharply reduced and the charging of the battery is completed at relatively low current levels which vary over a very narrow range,

(e) a motor driving the cams for operating said switches, and

(f) means responsive to said predetermined voltage for energizing said motor to drive said cams,

(i) the cam for said first switch enabling the high rate charging circuit for a first time interval following energization of the motor and then disabling the high charging rate circuit,

(ii) the cam for said second switch enabling the finish rate charging circuit for a second time interval following disabling of the high charging rate circuit and then disabling the finish rate charging circuit.

8. A method of charging a battery from a conventional a-c power source, said method comprising the steps of

(a) connecting a leakage reactance transformer between the a-c power source and the battery to initially charge the battery at relatively high current levels to achieve a relatively high charge rate,

(b) connecting an additional impedance, external of the transformer, in circuit with the transformer after a first predetermined time interval following the charging of the battery to a predetermined voltage to sharply reduce the charging current and completing the charging of the battery at relatively low current levels which vary over a very narrow range,

(c) and terminating the charging of the battery at the end of a second predetermined time period following the sharp reduction of the charging current.