Battery charger having temperature compensated charge rate

  • US 4,667,143 A
  • Filed: 12/23/1985
  • Issued: 05/19/1987
  • Est. Priority Date: 12/23/1985
  • Status: Expired due to Fees
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First Claim
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1. Apparatus for charging a battery comprising:

  • a switching type voltage regulator having a current sense output wherein said regulator is connected in a series circuit between a power source and a first terminal of said battery, said regulator receiving unregulated dc power from said power source and delivering regulated power to said first terminal of said battery;

    a controller for said regulator operatively connected to provide switching signals to said regulator, said controller having a voltage adjust circuit and a current limit circuit, and having a first external voltage input and a first reference voltage input associated with said current limit circuit, and having a second external voltage input and a second reference voltage input associated with said voltage adjust circuit, said voltage adjust circuit and said current limit circuit being operatively connected to modulate said switching signals in response to the potential applied to said first and second external voltage inputs;

    a current sense resistor having a first terminal connected to said current sense output of said regulator and a second terminal connected to a second terminal of said battery;

    means for connecting a current sense output voltage from said regulator to said first external voltage input of said controller for modulating said switching signals in response to said current sense output voltage;

    a resistive voltage divider network connected across said first and second terminals of said battery;

    a thermistor disposed to measure the temperature of said battery, wherein said thermistor is connected in parallel with a resistor of said resistive voltage divider network;

    means for operatively connecting a node of said resistive voltage divider network to said second external voltage input of said controller for modulating said switching signals in response to said thermistor and the voltage of said battery;

    means for connecting a ground potential to said first reference voltage input; and

    means for connecting a reference potential to said second reference voltage input wherein said reference potential corresponds to the maximum modulation of said switching signals that can be provided by said controller.

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