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Method for evaluating capacity of secondary battery using mathematical calculation of specific resistance components of equivalent circuit model fitted from impedance spectrum

  • US 7,062,390 B2
  • Filed: 07/01/2003
  • Issued: 06/13/2006
  • Est. Priority Date: 07/02/2002
  • Status: Expired due to Fees
First Claim
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1. A method for evaluating a capacity of secondary batteries of a same group produced under same conditions, the method comprising:

  • (a) partially charging the secondary batteries to have a charge capacity of at least 60% with a voltage less than a full charge voltage;

    (b) measuring an impedance spectrum for the batteries partially charged;

    (c) determining specific internal resistance components from an equivalent circuit model fitted from the measured impedance spectrum to perform a numerical operation; and

    (d) comparing the numerical operation value of the resistance components with an initial discharge capacity graph of the batteries to evaluate an initial discharge capacity of unknown batteries of the same group.

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