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Method and device for estimating charge/discharge electricity amount of secondary cell

  • US 7,557,584 B2
  • Filed: 07/26/2004
  • Issued: 07/07/2009
  • Est. Priority Date: 07/29/2003
  • Status: Active Grant
First Claim
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1. A method for estimating a charge/discharge electricity amount of a secondary battery comprising:

  • a step of measuring a pair of data consisting of a current flowing through the secondary battery and a terminal voltage of the secondary battery corresponding to the current, thus obtaining a plurality of pairs of data,a step of, when specific selection conditions are satisfied, the specific selection conditions including (i) the current in charging and discharging the secondary battery is within a first predetermined range, (ii) a number of the plurality of pairs of data is greater than or equal to a predetermined number, and (iii) a charge/discharge electricity amount during collection of the plurality of pairs of data is within a second predetermined range, calculating a no-load voltage as a voltage intercept at a current of zero in a straight-line approximation obtained by statistical processing with respect to the plurality of pairs of data,a step of, when the specific selection conditions are not satisfied and one of specific current conditions and voltage conditions continue to be met for a certain amount of time, calculating an open circuit voltage from the terminal voltage of the secondary battery, the component resistance of the secondary battery and an average current,a step of calculating a change (Δ

    Vb) in the no-load voltage or the open circuit voltage over a predetermined period of time, anda step of calculating an estimated charge/discharge electricity amount (Δ

    Qe) of the secondary battery based on the change in the no-load voltage or the open circuit voltage.

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