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Battery capacity estimating method and apparatus

  • US 8,004,243 B2
  • Filed: 04/08/2009
  • Issued: 08/23/2011
  • Est. Priority Date: 04/08/2009
  • Status: Active Grant
First Claim
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1. A method for estimating battery capacity of a battery, the method comprising the steps of:

  • reading CACPrior, wherein CACPrior is the last determined computed amp-hour capacity of the battery;

    monitoring battery current of the battery using a current sensor;

    determining SOCbyAhFirst time at a first time, wherein h SOCbyAhFirst time is the state of charge of the battery calculated by amp-hours at said first time;

    determining SOCbyOCVFirst time at said first time, wherein SOCbyOCVFirst time is the state of charge of the battery calculated from the battery open circuit voltage (OCV) at said first time;

    determining SOCbyAhSecond time at a second time, wherein SOCbyAhSecond time is the state of charge of the battery calculated by amp-hours at said second time;

    determining SOCbyOCVSecond time at said second time, wherein SOCbyOCVSecond time is the state of charge of the battery calculated from the battery OCV at said second time;

    calculating Δ

    SOCbyAh, wherein
    Δ

    SOCbyAh=SOCbyAhFirst time

    SOC
    byAhSecond time calculating Δ

    SOCbyOCV, wherein
    Δ

    SOCbyOCV=SOCbyOCVFirst time

    SOC
    byOCVSecond time;

    calculating a weighting function, W, defined as

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