Showing papers on "State of charge published in 1975"
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07 Mar 1975TL;DR: In this article, the phase angle between the A.C. voltage across the battery terminals and the current through the battery (measured as a shunt voltage) is continuously monitored.
Abstract: Several embodiments for determining the state of charge of a cell or battery are disclosed. In accordance with one method of this invention, an A.C. voltage is applied to a cell or battery through a shunt. The phase angle between the A.C. voltage across the battery terminals and the A.C. current through the battery (measured as a shunt voltage) is continuously monitored. This phase angle is converted to an analog voltage which represents the A.C. component that is phase shifted by the impedance of the battery. The impedance and thus the phase angle changes with the state of charge of the battery. The analog voltage can be coupled to a meter that provides a phase angle reading or a state of charge reading. Further, the analog voltage can be used to control charge and discharge circuitry. In accordance with a second method, the state of charge of a battery is determined by taking phase angle readings based on input and output A.C. voltages.
144 citations
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11 Feb 1975
TL;DR: In this article, a function generator is constructed to simulate the characteristic curve of the battery relating the internal resistance to the percent charge, and feedback is provided from the output of the indicating circuitry to the bias point of the function generator for causing the generator to produce a signal related to the actual internal resistance.
Abstract: A circuit for detecting and indicating the actual state of charge of a storage battery in response to signals sampled from various points in the circuit powered by the battery. Such circuit is adapted to calculate the open circuit voltage of the battery, it being realized that the open circuit voltage is directly proportional to the battery state of charge. A function generator is constructed to simulate the characteristic curve of the battery relating the internal resistance to the percent charge. Feedback is provided from the output of the indicating circuitry to the bias point of the function generator for causing the generator to produce a signal related to the actual internal resistance of the battery. The circuit is adapted to provide a reliable indication of the amount of usable energy remaining in the battery, irrespective of the conditions under which the battery was discharged.
142 citations
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03 Jan 1975
TL;DR: In this article, a system for monitoring the state of charge of batteries in a fleet of electrically powered vehicles is described, where the battery is associated with an integrator module which registers both the depletion and charging of the battery.
Abstract: A system is disclosed for monitoring the state of charge of batteries in a fleet of electrically powered vehicles Each battery has associated with it an integrator module which registers both the depletion and charging of the battery While the battery is in use in the vehicle, a portion of the current flowing from the battery is sent to the integrator module which registers the current depletion A readout circuit is also coupled to the integrating device for indicating the condition of the battery while it is in the vehicle When the battery reaches a predetermined low state of charge, circuitry provided for detecting this condition provides a prewarning signal and on further discharge disables nonessential auxiliary functions in the vehicle, leaving only those systems working which are necessary in order for the driver to be able to return to a battery charging station At the charging station, the integrator module and the battery are removed from the vehicle and connected at the charging station During charging, the integrator module is coupled to the charger and a portion of the current leaving the charger passes through the integrator module providing continuous display of the state of charge and information to regulate the charge rate and terminate charge when appropriate ampere hours have been returned to the battery
71 citations
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02 Oct 1975
TL;DR: In this paper, an electric battery is continuously tested for its state of charge by a bridge circuit in parallel with a voltage stabilizer such as a Zener diode which forms part of a voltage divider connected across the battery terminals, the other part of that divider being a resistance circuit.
Abstract: An electric battery, such as that of an automotive vehicle, is continuously tested for its state of charge by a bridge circuit in parallel with a voltage stabilizer such as a Zener diode which forms part of a voltage divider connected across the battery terminals, the other part of that divider being a resistance circuit. The bridge circuit has an output diagonal with one corner connected to the battery terminal which is tied to the resistance circuit so that a reduction of battery voltage unbalances the bridge in one sense, a compensatory change in the opposite sense being brought about by a sensor responsive to the load current drawn from the battery. The current sensor may be a small resistor inserted between two adjoining bridge arms. An integrating operational amplifier connected across the output diagonal of the bridge controls a pulse generator which steps an associated pulse counter whenever the amplifier output passes a threshold indicating a predetermined degree of depletion of the battery; the counter, after measuring a cumulative time interval during which this depletion condition is present, triggers a switch which generates an alarm signal, e.g. by eliminating certain options in the operation of the vehicle. The operational amplifier and/or pulse generator also work into visual charge indicators. The resistance circuit of the voltage divider may include a transistor designed to compensate changes in battery current due to the de-energization of a switching relay. A feedback connection between the counter and the pulse generator causes continuing stepping of the counter after the switchover to maintain the alarm signal until the counter resets itself after an extended period, such resetting also occurring upon reclosure of the load circuit after a prolonged interruption.
52 citations
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06 Nov 1975
TL;DR: In this paper, a battery charger receives electrical power from an external source of direct current electrical power through a first inductor which supplies it to a second node and a capacitor which is connected to the third node so that the second switching means can switch the capacitor between series and parallel circuit configurations with respect to the first and second inductors.
Abstract: A battery charger receives electrical power from an external source of direct current electrical power. The power is received through a first inductor which supplies it to a second node. First switching means receives the power from the second node and supplies it to a third node. A second inductor receives the power from the third node and supplies it to the battery to be charged through output connector means. Second switching means are connected to the second node and to a capacitor which is connected to the third node so that the second switching means can switch the capacitor between series circuit and parallel circuit configurations with respect to the first and second inductors. A safety circuit is connected to temperature sensing means positioned to sense the temperature of the battery to be charged, to the first node and to the first switching means. The safety circuit causes the first switching means to become nonconductive upon detection of unsafe conditions which may occur when charging. A control circuit is connected to the first node, to the second switching means, and to the output of the battery to be charged. The control circuit is also connected to the temperature sensing means and supplies control signals to the second switching means to repetitiously cause the capacitor to be first charged in parallel circuit through the first switching means and discharged in series circuit with said first and second inductors to pulse charge the battery to be charged and thereafter cause a brief pulse discharge of the battery to be charged with the repetition rate and magnitude of the pulses varying based on the state of charge of the battery to be charged.
26 citations
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22 Sep 1975
TL;DR: In this paper, a camera incorporating a light-meter and a battery-powered lamp for indicng when the level of incident light is so low as to be unsuitable for photography also includes means for determining the state of charge of the battery.
Abstract: A camera incorporating a light-meter and a battery-powered lamp for indicng when the level of incident light is so low as to be unsuitable for photography also includes means for determining the state of charge of the battery. The possibility of making an erroneous determination of the state of charge of the battery as the result of failing to cover the photosensitive element during the determination of the state of charge is eliminated.
3 citations