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Sensing ignition by voltage monitoring

  • US 8,393,201 B2
  • Filed: 09/21/2010
  • Issued: 03/12/2013
  • Est. Priority Date: 09/21/2010
  • Status: Active Grant
First Claim
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1. A method of sensing the ignition state of a vehicle engine, comprising the steps of:

  • a) sampling a voltage level of a vehicle electrical system as powered by a vehicle battery without relying on other physical phenomena related to the engine, to obtain a current voltage sample;

    b) determining if said current voltage sample has a sufficient drop from a preceding voltage sample;

    c) determining if said current voltage sample is reliable by determining if a trend of voltage samples preceding said current voltage sample is consistent with said current voltage sample; and

    d) determining if said current voltage sample is below a specified threshold from which an accurate inference is that the vehicle engine ignition is off.

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