Apparatus for measuring internal resistance of wet cell storage batteries having non-removable cell caps

  • US 5,047,722 A
  • Filed: 04/17/1989
  • Issued: 09/10/1991
  • Est. Priority Date: 04/17/1989
  • Status: Expired due to Term
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First Claim
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1. Apparatus for measuring the total internal resistance of a multicell battery having spaced apart positive and negative terminals comprising:

  • first transistor means having an input circuit and an output circuit and having mutually exclusive conductive and non-conductive electric states;

    second resistance means connected in series with the output circuit of said first means to form a network, said network being connected between said positive and negative terminals;

    an operational amplifier having an output circuit connected to the input circuit of the first means and first and second input circuits, the first input circuit of the amplifier being connected to said network at a point connected to both of the first and second means; and

    third means including an oscillator to apply an alternating voltage to the second input circuit of the amplifier, the alternating voltage changing polarity on alternate half cycles, the first means being in the conductive state when the alternating voltage is of one polarity and being in the non-conductive state when the alternating voltage is of the other polarity, said network conducting no current when the first means is in the non-conductive state and conducting a current of constant value when the first means is in the conductive state, the voltage appearing between the positive and negative terminals as a result of the current flow in the network being monotonically related to the internal resistance of the battery.

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