STORAGE BATTERY MONITORING APPARATUS

• US 3,680,072 A
• Filed: 01/26/1971
• Issued: 07/25/1972
• Est. Priority Date: 01/26/1971
• Status: Expired due to Term

• Current Assignee: Gerard Charbonnier, Gerard Gauthier
• Original Assignee: Gerard Charbonnier, Gerard Gauthier
• Inventors: Charbonnier, Gerard, Gauthier, Gerard
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Partridge, Scott F.
• Application Number:
  US05/109,918
• Time in Patent Office: 546 Days
• Field of Search: 320/43,48 324/29.5 136/182 340/249
• US Class Current: 320/164
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: Y10S 320/21 State of charge of battery

Abstract

An apparatus for monitoring the charge of a storage battery which gives an indication of the state of the charge. The charge is monitored by placing a current pulse through the internal resistance of the battery and monitoring the change in voltage at the terminals of the battery. The apparatus also includes a recharging circuit for recharging the battery when its charge falls below a predetermined level and a control circuit for stopping the recharging of the battery when the battery becomes fully charged.

Claims

1. Apparatus for monitoring the state of charge of a storage battery, comprising:

a. first and second terminals connected to the poles of said storage battery while said storage battery is connected to a load circuit;

drive circuit means connected across said first and second terminals for applying current pulses of predetermined duration to said storage battery at predetermined regular intervals;

b. sensing circuit means connected across said first and second terminals for sensing the voltage across said first and second terminals and for generating a first signal indicative of the difference between said voltage before and during each said current pulse;

comparator circuit means connected to receive the first signal and for comparing it with a reference signal generated by a reference circuit means, the output signal of the comparator circuit means during each current pulse being indicative of the state of charge of said storage battery.

2. Apparatus as claimed in claim 1, further comprising indicator circuit means for receiving the output signal of said comparator circuit means and for providing an indication of the state of charge of said storage battery.

3. Apparatus as claimed in claim 1, wherein the sensing circuit means includes a first operational amplifier having a first input connected to said second terminal and a second input connected to a voltage storing element, a first switching element, said first switching element connected between said voltage storing element and second terminal, said first switching element being closed between current pulses whereby the voltage at said second terminal is applied to first and second iNputs of said first operational amplifier and to said voltage storing device, and said first switching element being open during each current pulse whereby the voltage at said second terminal is applied to said first input of the first operational amplifier and the stored voltage is applied to said second input of said first operational amplifier.

4. Apparatus as claimed in claim 3, wherein the voltage storing element is a capacitor comprising a third terminal connected to said second input of said first operational amplifier and a fourth terminal connected to ground.

5. Apparatus as claimed in claim 1, wherein said reference circuit means is connected to said first terminal for receiving said storage battery output voltage, said reference circuit means comprising a voltage regulator means for providing a constant output voltage and a voltage divider whereby the output of said regulator is applied to said voltage divider, the output of said voltage divider being applied to one input of a second operational amplifier.

6. Apparatus as claimed in claim 1, wherein said comparator circuit means comprises a third operational amplifier means for operating as a saturated comparator.

7. Apparatus as claimed in claim 1, wherein said drive circuit means includes a second switching element closed at moments coincident with the start of each successive current pulse, said second switching element energizing a first monostable circuit whose output pulse is applied to a third switching element, said third switching element connecting a shunt resistance between said first and second terminal for the duration of the output pulse of the first monostable circuit, said first monostable circuit thereby defining the current pulse duration.

8. Apparatus as claimed in claim 1, further comprising logic circuit means including:

a. delay circuit means connected for receiving signals coincident with the start of each current pulse and for providing successive trigger signals delayed with respect to the current pulse by an amount less than the current pulse duration;

b. a second monostable circuit means triggered by each trigger signal for providing an output pulse whose duration is such that the sum of the delay of the delay circuit means and the duration of said output pulse is less than the current pulse duration; and

gate circuit means for receiving the output of said comparator circuit means and the output of said monostable circuit means and for producing an output only when both said comparator circuit means and said second monostable circuit means produce a simultaneous output.

9. Apparatus as claimed in claim 1, further comprising control circuit means for controlling the state of charge of the storage battery, said control circuit including a recharging device connected to receive the output of said comparator circuit means, said recharging device operating when said comparator circuit means indicates a predetermined state of charge;

and a storage battery charge sensor means for detecting when said storage battery is fully charged and for stopping the operation of said recharging device when said storage battery is fully charged.

10. Apparatus as claimed in claim 9, wherein said storage battery charge sensor means compares the voltage at said first terminal with a reference voltage.

11. Apparatus as claimed in claim 10 wherein the reference voltage is generated by a circuit including a voltage regulator means for receiving the storage battery output voltage and for providing a constant output voltage, a voltage divider circuit, a fourth operational amplifier, said fourth operational amplifier having a heat-sensitive resistance connected between its output and its first input, said heat-sensitive resistance being surrounded, during use of said apparatus, by an electrolyte of said storage battery wherein said voltage regulator means is connected to said voltage divider circuit, and the output of said voltage divider circuit is connected to the first input of said fourtH operational amplifier and wherein a second input to said fourth operational amplifier is connected to ground.

12. Apparatus as claimed in claim 10 wherein a fifth operational amplifier means for operation as a saturated comparator compares the output voltage of said storage battery and the reference voltage.