Vehicle battery diagnostic device

  • US 4,719,427 A
  • Filed: 08/07/1986
  • Issued: 01/12/1988
  • Est. Priority Date: 06/20/1983
  • Status: Expired due to Term
First Claim
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1. A battery diagnostic device comprising:

  • voltage detecting means for detecting the terminal voltage of a battery charged by a generator, and for producing a first output signal proportional to the detected terminal voltage;

    current detecting means for detecting the charge and discharge currents of said battery, and for producing a second output signal, I1, proportional to the detected battery current;

    specific gravity detecting means for detecting the specific gravity of the battery electrolyte, and for producing a third output signal St proportional to the detected specific gravity;

    microcomputer data processing means, responsive to said first, second and third output signals, for calculating and then outputting signals indicating the battery charge condition, said microcomputer data processing means including,means for calculating the battery internal resistance rB from the difference between said first output signal when the battery terminals are in an open circuit condition, V1, and said first output signal when the battery terminals are in a closed circuit state, V2, and said second output signal, I1, from the relationship, ##EQU4## means for calculating a temperature corrected specific gravity S from the third output signal St and the temperature t°

    C. of the electrolyte at the time the specific gravity was detected from the relationship, S=St +0.0007 (t°

    C.-20),means for calculating the amount the battery has discharged ID (Ah) from its rated capacity (Ah) from to the relationship, ##EQU5## means for calculating the percent of discharge DC from the relationship, ##EQU6## and means for producing signals proportional to the calculated resistance rB, temperature corrected specific gravity S, discharge amount ID and percent of discharge DC ; and

    means for displaying the charge condition of the battery determined from at least said signals proportional to said calculated internal resistance rB and percent of discharge DC.

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