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Methods of controlling the application and termination of charge to a rechargeable battery

  • US 5,600,226 A
  • Filed: 10/13/1993
  • Issued: 02/04/1997
  • Est. Priority Date: 10/13/1993
  • Status: Expired due to Fees
First Claim
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1. A method of charging a rechargeable battery having a voltage characteristic that varies in a predetermined manner with a charge state of the battery and for terminating said charging of the battery in response to the charge state of the battery when the battery has attained a full charge, comprising the steps of:

  • supplying electrical energy to the battery for charging of the battery;

    monitoring said voltage characteristic of the battery as said electrical energy is supplied to the battery;

    differentiating a variation of the monitored voltage characteristic with time as said electrical energy is supplied to the battery to provide a slope characteristic that decreases as a function of time to a bottom peak followed by a top peak followed by a decreasing slope;

    identifying in said slope characteristic a minimum slope of said bottom peak as said electrical energy is supplied to the battery; and

    terminating said supplying of electrical energy to the battery when said slope characteristic equals said minimum slope as said slope characteristic decreases following said top peak.

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