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Device for controlling the charging and discharging of a storage battery

  • US 4,194,146 A
  • Filed: 08/11/1977
  • Issued: 03/18/1980
  • Est. Priority Date: 08/11/1976
  • Status: Expired due to Term
First Claim
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1. A device for monitoring the charging and discharging current of a storage battery and for controlling a charger connected to the battery, the device comprising:

  • a current sensing resistor adapted to be connected in series with a battery, the voltage across said resistor being proportional to the current through the battery and being referred to hereinafter as the input voltage;

    at least one chopper amplifier stage providing an amplified voltage with an absolute value proportional to said input voltage;

    a voltage to frequency converter providing a train of pulses at a frequency proportional to the absolute value of said amplified voltage;

    a counter responsive to said pulses and to the polarity of the input voltage, the counter being incremented or decremented by said pulses in accordance with the polarity of said input voltage, the state of a logic output of the counter being representative of the state of charge of the battery; and

    a decoding circuit responsive to the logic output state of said counter and adapted to be connected to the charger for limiting the charge rate of said charger to no more than a trickle charge when the counter output state corresponds to full charge of the battery, characterized in that said chopper amplifier state comprises;

    an oscillator;

    a first analog gate controlled by said oscillator and which converts said input voltage into a periodic voltage with an amplitude equal to the absolute value of the input voltage and whose phase is shifted by π

    each time the polarity of the input signal changes;

    an amplifier and associated filter providing an amplified alternating voltage in phase with said periodic voltage and with an amplitude proportional to that of said periodic voltage; and

    a second analog gate controlled by said oscillator converting said amplified alternating voltage into a direct current voltage with an absolute value proportional to the amplitude of said amplified alternating voltage.

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