CHARGE CONTROL MEANS FOR MOTIVE POWER BATTERY CHARGER

• US 3,864,617 A
• Filed: 07/12/1973
• Issued: 02/04/1975
• Est. Priority Date: 07/12/1973
• Status: Expired due to Term

• Current Assignee: Exide Electronics Corporation (Exide Electronics Group, Inc.)
• Original Assignee: Howard A. Smith, William E. Renick
• Inventors: Smith, Howard A., Renick, William E.
• Primary Examiner(s): Beha, Jr., William H.
• Assistant Examiner(s): Hickey, Robert J.
• Application Number:
  US05/378,788
• Time in Patent Office: 572 Days
• Field of Search: 320/32,37,38,39,40,48,22-24
• US Class Current: 320/159
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: Y10S 320/17 Sensing of "gassing" voltage

Abstract

A battery charger is equipped with a current adjusting device. A current sensor continuously measures the current output from the charger and feeds the readings to a current comparator. The terminal voltage of the battery is also continuously read and the readings are fed to a voltage comparator. A voltage reference feeds a constant reference voltage to the voltage comparator. The voltage comparator compares the battery voltage with the reference voltage and feeds a signal dependent upon the voltage difference and in accordance with a preselected program to a current reference. The current reference delivers a signal dependent on the output of the voltage comparator and in accordance with a preselected program to the current comparator. The current comparator to the the signal received from the current sensor tothe signal received from the current reference and provides an output signal to cause the current adjusting device to adjust the charging current to the values called for by the preselected program. A typical charge program which can be selected is a first charging mode at the initial charge rate of the battery until the battery voltage rises to a preselected value slightly below the gassing voltage. This is followed by a second charging mode wherein the charging current is gradually diminished so as to hold the voltage constant at the preselected value. When the charging current drops down to the finishing rate of the battery, a third mode commences wherein the current is held at the finishing rate regardless of further increase of the battery voltage. The charge can be terminated by a timing device set for total charge time or alternately for a predetermined charge period at the finishing rate.

Claims

1. In a battery charging device having an input and an output, the input being connectable to a source of power and the output being connectable to a storage battery for supplying a charging current thereto, the improvement which comprises:

a. a voltage reference having an output;

b. a voltage comparator having a first input, a second input and an output, the first input being connected to the output of the voltage reference, the second input being connected to the output of the charging device, the comparator comparing the voltage of the battery with the voltage of the voltage reference and producing a first reference signal at its output as a result thereof;

c. a current reference having an input and an output, the input being connected to the output of the voltage comparator the current reference supplying to its output a second reference signal whose magnitude is related to the signal received by the input thereof in accordance with a preselected charge program relating a desired battery charging current to the battery voltage, said second signal being proportional to the desired charging current;

d. a charge current sensor having a current input, a current output and a sensing output, the current input thereof being connected to the output of the charging device, the current output thereof being connectable to the battery to be charged, and the sensing output providing a third reference signal, the magnitude of which being proportional to the magnitude of the battery charging current;

e. a current adjusting device for adjusting the magnitude of the battery charging current, the device having a power input, a power output and a control input, the power input and the power output of the current adjusting device being connected in the charging device so as to provide current thereto, the control input controlling the adjustment of the device; and

, f. a current comparator for supplying a control signal to the current adjusting device, the current comparator having a first input, a second input and an output, the first input being connected to the output of the current reference, the second input being connected to the output of the current sensor, and the output being connected to the current adjusting device, the current comparator comparing the third reference signal received from the current sensor to the second reference signal received from the current reference and supplying the control signal as a result thereof, the control signal causing the third reference signal to continuously equal the second reference signal.

2. A charging device as defined in claim 1 wherein the voltage comparator is an operational amplifier having two inputs and one output, and the current comparator is an operational amplifier having two inputs and one output.

3. A charging device as defined in claim 1 including:

a. a line contactor for providing power connections between the power souRce and the battery charging device, the contactor including a contactor closing means;

b. a timer for measuring a time period having a normal starting means, the timer being operatively connected to the closing means of the line contactor so as to cause the contactor to close when the timer is started and cause the contactor to open when the time period measured by the timer is completed.

4. A charging device as defined in claim 1 including:

a. a line contactor for providing power connections between the power source and the battery charging device the contactor including a contactor closing means;

b. a manually initiated means for energizing the contactor closing means;

c. a timer for measuring a time period and for de-energizing the contactor at the end of the time period the timer including a timer start means and d. means operatively connecting the timer start means and the current reference so that the timer will be started when a selected point in the charge program is reached.

5. a charging device as defined in claim 1 wherein the means for adjusting the charging current is a magnetic amplifier.

6. In a battery charging device having an input and an output, the input being connectable to a source of power and the output being connectable to a storage battery for supplying a charging current thereto, the charger supplying the battery with a charge current demanded by a preselected charge program, the charge program including a first mode at a first preselected fixed current until the battery voltage rises to a first preselected value, a second mode wherein the current is gradually reduced so as to hold the preselected voltage value and a third mode wherein the charge is completed at a second preselected fixed current lower in value than the first preselected current and the voltage limitation is removed, the improvement which comprises:

a. a voltage reference having an output;

b. a voltage comparator having a first input, a second input and an output, the first input being connected to the output of the voltage reference, the second input being connected to the output of the charging device, the comparator comparing the voltage of the battery with the voltage of the voltage reference and producing a first reference signal at its output as a result thereof;

c. a current reference having an input and an output, the input being connected to the output of the voltage comparator the current reference supplying to its output a second reference signal whose magnitude is related to the signal received by the input thereof in accordance with the preselected charge program relating a desired battery charging current to the battery voltage, said second signal being proportional to the desired charging current;

d. a charge current sensor having a current input, a current output and a sensing output, the current input thereof being connected to the output of the charging device, the current output thereof being connectable to the battery to be charged, and the sensing output providing a third reference signal, the magnitude of which being proportional to the magnitude of the battery charging current;

e. a current adjusting device for adjusting the magnitude of the battery charging current, the device having a power input, a power output and a control input, the power input and the power output of the current adjusting device being connected in the charging device so as to provide current adjustment thereto, the control input controlling the adjustment of the device; and

, f. a current comparator for supplying a control signal to the current adjusting device, the current comparator having a first input, a second input and an output, the first input being connected to the output of the current reference, the second input being connected to the output of the current sensor, and the output being connected to the current adjusting device, the current comparator comparing the third reference signal received from the curRent sensor to the second reference signal received from the current reference and supplying the control signal as a result thereof, the control signal causing the third reference signal to continuously equal the second reference signal.