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Battery test system, as for smoke detector alarm

  • US 4,251,811 A
  • Filed: 12/26/1979
  • Issued: 02/17/1981
  • Est. Priority Date: 12/26/1979
  • Status: Expired due to Term
First Claim
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1. In a battery powered alarm circuit having first and second battery terminals for receiving a battery potential therebetween, a sensor for detecting an alarm condition, means responsive to said sensor for providing an alarm control signal, an annunciator responsive to said alarm control signal for sounding an alarm, and a capacitor for providing starting current for said annunciator, a test system for determining a high series resistance condition of said battery, said test system comprising:

  • means for drawing a test current pulse from said battery, said means having a test pulse signal indicating said test current pulse;

    switch means having a principal current conduction path, and a control electrode, the potential on said control electrode determining the conductivity of said principal current conduction path, said switch means having its principal current conduction path connected in series with said starting capacitor;

    logic control means responsive to said alarm control signal and said test pulse signal, said logic control means having an output terminal connected to the control electrode of said switch means for conditioning said switch means for conduction at least during said alarm control signal, and for conditioning said switch means for nonconduction at least during said test pulse signal, so that said starting capacitor does not discharge substantial current during said test current pulse; and

    test means responsive to said test current pulse for indicating a high series resistance condition of said battery.

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