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BATTERY CHARGING CIRCUIT

  • US 3,867,681 A
  • Filed: 03/20/1974
  • Issued: 02/18/1975
  • Est. Priority Date: 03/20/1974
  • Status: Expired due to Term
First Claim
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1. An improved circuit for charging a battery from a charging source, comprising:

  • a. a voltage regulator adapted to be connected to the charging source, said voltage regulator having a control input for selectively causing said voltage regulator to produce an upper regulated voltage and a lower regulated voltage at its output;

    b. a current regulator connected to said voltage regulator circuit;

    c. a normally open charging path having an input connected to said current regulator, having an output, and having a control input;

    d. means connected to said charging path output and adapted to be connected to the battery to be charged;

    e. a voltage comparator having an input adapted to be connected to said battery to be charged for producing a first charging signal in response to a battery voltage below a selected voltage reference level;

    f. a first timer for producing a second charging signal at selected predetermined intervals;

    g. a power fail and restore circuit for producing a third charging signal in response to failure and subsequent restoral of primary power;

    h. a second timer for producing a fourth charging signal of a selected duration in response to a selected operation;

    i. means connected between said voltage comparator, said first timer, said power fail and restore circuit, and said second timer and between said charging path control input for closing said charging path in response to the simultaneous presence of said first charging signal and either of said second and third charging signals, and in response to said fourth charging signal;

    j. and means connected between said second timer and said voltage regulator control input for causing said voltage regulator to produce said upper regulated voltage in the presence of said fourth charging signal and for causing said voltage regulator to produce said lower regulated voltage in the absence of said fourth charging signal.

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