Battery charger
First Claim
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1. A battery charging circuit comprising:
- means for providing a direct current source at a voltage above the terminal voltage of batteries to be charged;
a pair of output terminals to which a battery to be charged may be connected coupled to said last mentioned means;
means for sensing the level of current flowing between direct current source providing means and said pair of output terminals;
a first active voltage regulator for establishing voltage at said output terminals at a predetermined low charge rate voltage above the said desired battery terminal voltage;
a second active voltage regulator for establishing a voltage at said output terminals at a predetermined high charge rate voltage above both said desired battery terminal voltage and the voltage set by said first active voltage regulator;
voltage reference means for establishing a value approximating the desired terminal voltage of a fully charged battery;
means for sensing the voltage across said output terminals;
and means for comparing the level of said voltage references means and said voltage sensing means and for applying a signal to both said first and second active voltage regulators indicative of a deviation of the output terminal voltage from said voltage reference means voltage;
said current sensing means operating to enable said second voltage regulator means when current sensed thereby exceeds a predetermined level.
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Abstract
A battery charging circuit employing three operational amplifiers, one to sense charging current and two to regulate constant voltage charging, one for low rate or float level and one for high rate charging. A resistance element acts as part of the current sensing circuit and also limits charge current. A Zener diode provides a voltage reference and aids in sensing deviations of actual terminal voltage from desired terminal voltage to provide feedback control to the voltage regulating operational amplifiers.
13 Citations
8 Claims
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1. A battery charging circuit comprising:
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means for providing a direct current source at a voltage above the terminal voltage of batteries to be charged; a pair of output terminals to which a battery to be charged may be connected coupled to said last mentioned means; means for sensing the level of current flowing between direct current source providing means and said pair of output terminals; a first active voltage regulator for establishing voltage at said output terminals at a predetermined low charge rate voltage above the said desired battery terminal voltage; a second active voltage regulator for establishing a voltage at said output terminals at a predetermined high charge rate voltage above both said desired battery terminal voltage and the voltage set by said first active voltage regulator; voltage reference means for establishing a value approximating the desired terminal voltage of a fully charged battery; means for sensing the voltage across said output terminals; and means for comparing the level of said voltage references means and said voltage sensing means and for applying a signal to both said first and second active voltage regulators indicative of a deviation of the output terminal voltage from said voltage reference means voltage; said current sensing means operating to enable said second voltage regulator means when current sensed thereby exceeds a predetermined level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification