Battery impedance monitor

  • US 5,773,978 A
  • Filed: 10/25/1996
  • Issued: 06/30/1998
  • Est. Priority Date: 10/25/1996
  • Status: Expired due to Term
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First Claim
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1. An impedance monitor for a battery having positive and negative output terminals across which a DC output voltage is provided, said monitor comprising:

  • an oscillatory loading circuit adapted to be coupled across the battery terminals for periodically loading the battery to produce at the output terminals a time-varying voltage component having a peak-to-peak amplitude superimposed on the DC output voltage, anda measuring circuit adapted to be connected across the battery output terminals for sensing the time-varying voltage component to determine the internal impedance of the battery,said measuring circuit including an impedance portion connected in series with the battery when said detector circuit is connected across the battery terminals and having a finite DC impedance and a substantially zero AC impedance for shifting the level of the DC output voltage without affecting the peak-to-peak amplitude of the time-varying component,said measuring circuit including a peak detector for generating, in response to the output of said impedance portion, an indicating voltage level proportional to the peak-to-peak amplitude of the time-varying voltage component.

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