Electric battery charging apparatus
First Claim
1. Means for terminating the charging of an electric storage battery, or a phase of such a charge, including:
- means for producing a battery signal dependent on battery voltage, a progressively increasing ramp signal, and a shiftable bias signal;
signal combining means producing a combined signal comprising a combination of the battery signal, the ramp signal and the bias signal, which combined signal increases with increase of battery voltage, but decreases with increase of ramp signal, or increase of bias signal; and
means for increasing the bias signal whenever the combined signal exceeds a higher predetermined value, to decrease the combined signal by a predetermined amount to a lower predetermined value, and means to terminate the charge, or a phase of the charge, when the combined signal falls below a value lower than the said lower predetermined value.
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Accused Products
Abstract
For use in an automatic electric battery charger, a charge controller which monitors the rate of rise of battery voltage, and terminates the charge when the rate of rise falls below a predetermined value, typically 11 mV per cell in 45 minutes for a lead-acid battery. The battery voltage is monitored by combining with it a ramp signal which changes, in the opposite sense to the rise in battery voltage, at a rate just sufficient to offset a rise in battery voltage of the said predetermined value. In the preferred embodiment, the combining step is performed by a summing amplifier, and a bias signal is also fed to the summing amplifier; this bias signal is shifted, in one direction only, to hold the output of the amplifier between narrow limits as long as the rate of rise of battery voltage is greater than the predetermined value. As soon as the rate of rise of battery voltage is no longer sufficient to offset the ramp signal, the amplifier output shifts outside the said limits, and this shift is used to terminate the charge.
18 Citations
18 Claims
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1. Means for terminating the charging of an electric storage battery, or a phase of such a charge, including:
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means for producing a battery signal dependent on battery voltage, a progressively increasing ramp signal, and a shiftable bias signal; signal combining means producing a combined signal comprising a combination of the battery signal, the ramp signal and the bias signal, which combined signal increases with increase of battery voltage, but decreases with increase of ramp signal, or increase of bias signal; and means for increasing the bias signal whenever the combined signal exceeds a higher predetermined value, to decrease the combined signal by a predetermined amount to a lower predetermined value, and means to terminate the charge, or a phase of the charge, when the combined signal falls below a value lower than the said lower predetermined value.
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2. Means for terminating the charging of an electric storage battery, or a phase of such a charge, including:
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a first input line which is connected to a source of a signal dependent on battery voltage; a second input line which is connected to a source of a ramp signal; signal combining means having an output line, and being arranged to produce, on the output line, a signal comprising a combination of the signals on the two input lines, which combination signal changes in one sense in response to a rise in battery voltage, and in the opposite sense in response to the rise of the ramp signal; combination signal monitoring means arranged to monitor the combination signal on the output line, and including shiftable bias signal storing means connected to the output of the signal combining means and arranged to store the extreme value which the combination signal has so far reached in the said one sense; and comparing means connected to the storing means to receive the stored extreme value, and to the output of the signal combining means, and arranged to compare the stored extreme value with the actual value of the combination signal, and to terminate the charge, or a phase of it, when the combination signal changes in the said opposite sense by more than a predetermined amount from the stored extreme value. - View Dependent Claims (3, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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4. Means for terminating the charging of an electric storage battery, or a phase of such a charge, including:
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a first input line which is connected to a source of a signal dependent on battery voltage; a second input line which is connected to a source of a ramp signal; a third input line which is connected to a shiftable bias signal storing means; signal combining means having an output line, and being arranged to produce, on the output line, a combination signal comprising a combination of the signals on the three input lines, which combination signal changes in one sense in response to a rise in battery voltage, and in the opposite sense in response to the rise of the ramp signal; and combination signal monitoring means arranged to monitor the combination signal on the output line, and connected to stored bias signal modifying means arranged, when the combination signal reaches a predetermined value, to modify the stored shiftable bias signal in such a sense as to prevent the combination signal from shifting in the said one sense beyond the said predetermined value, the combination signal monitoring means also being arranged to terminate the charge, or a phase of it, when the combination signal changes in the said opposite sense by more than a predetermined amount from the said predetermined value. - View Dependent Claims (5, 6, 7, 8)
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Specification