Abstract: A bidirectional integrator is described comprising first and second programmable pulse-forming channels (20, 40), a bidirectional counter (60) and an output display (78). Each pulse forming channel provides means for making both continuous and discrete adjustments in the repetition rate of the pulses formed thereby. In the preferred embodiment, each pulse forming channel comprises an integrator (26, 46) for forming a pulsed output signal, means (24, 44) for varying the pulse repetition rate of the output signal by varying the input signal to the integrator, and a programmable digital divider circuit (30, 50) for dividing the repetition rate of the output signal by any power of two from one to 4096.

Abstract: A method and apparatus are disclosed for measuring the state of charge of a battery. The apparatus comprises threshold means for sensing reductions below a threshold level in the output terminal voltage of the battery and for producing a signal in response thereto and means for integrating said signal over a plurality of such reductions. The output of the integrating means is indicative of the state of charge of the battery. In a preferred embodiment the signal comprises a series of pulses whose number is proportional to the time that the terminal voltage is below the threshold value and the integrating means counts such pulses. Alternatively, a single pulse may be produced and counted for each time the output terminal voltage is reduced below the threshold level. In another embodiment, the signal from the threshold means is integrated directly to develop a representation of the state of charge of the battery. Circuits are also disclosed using a plurality of threshold means connected in series or in parallel.

Abstract: A coulometric device for performing integration or timing functions with precise end-state detection comprises a coulometer; serially connected to the coulometer, a source of pulsed d.c. current representative of one or more quantities to be integrated; and a pulse height discriminator for detecting a reduction in the voltage drop across the coulometer. One variable to be integrated can vary either the duty cycle of the pulsed d.c. current source or the peak current, and the product of two variables can be time-integrated by using one variable to vary the duty cycle and the other to vary the peak current.

Abstract: The disclosed method and apparatus make three connections to a pair of conductors: two at spaced-apart points on one conductor and the third on the other conductor. Using the power available in the conductors, a differential amplifier produces an output signal representative of current flow through the first conductor by sensing the voltage difference between the first and second connections to the first conductor. Temperature-induced changes in the resistance of the first conductor are compensated by a thermistor. The output signal is used to drive one or more displays of amperes, ampere-hours or watt-hours.

Abstract: An integrator system is disclosed which incorporates a feedback control loop to vary the linearity of the integrator's response. In the preferred embodiment an electrochemical coulometer is used which stores the integral of a current that is passed through it. Control is achieved by feeding back a control signal from the integrating circuit output to vary the rate at which current is passed through the coulometer.

Abstract: The apparatus comprises means for sensing reductions in the output terminal voltage of the battery due to varying load conditions and producing a signal in response thereto during the time that the terminal voltage is below a threshold value. The apparatus further comprises integrator means such as an electronic counter or a stepping motor for integrating said signal and means for displaying the integral accumulated by said integrating means.

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.

Abstract: An integration system is disclosed including a reversible integrating device having an integrating capacity between its upper and lower limits of integration which is at least twice that which is required for a desired application. Circuitry is provided for reading the integral stored in the integrating device and producing a voltage proportional to that integral. Circuitry is also provided for sensing which of the limits of integration is closer to said integral and a switch is provided for selecting the direction which integration will proceed so that the period of integration can always be at least half that of the integrating capacity of the device. To determine the integral during the period of integration, a variable resistor is first adjusted to store a reference voltage corresponding to the integral stored in the integration device at the start of the period of integration.

Abstract: A coulometer signaling device is disclosed which indicates when a particular machine has been used for a predetermined amount of time. The device comprises a mercury coulometer which includes an electrolyte whose color changes when the mercury deposited on the anode of the coulometer has been depleted. The end of the tube near the coulometer is somewhat enlarged and a lens is placed over this end in order to make the color change more visible.

Abstract: A method and apparatus are disclosed for reading a coulometer by sensing the temperature of the electrolyte. A preferred embodiment comprises a pair of temperature sensitive elements spaced apart along the coulometer and connected to a bridge circuit.

Abstract: Systems are disclosed for reading the integral stored in a coulometer by sensing the thermal properties of the electrolyte. A preferred embodiment comprises at least one temperature sensitive element and a heat source placed adjacent the coulometer positioned in such a manner with respect to each other that the heat conduction path extends through a portion of the coulometer. The thermal conductivity of the path is changed by the migration of the electrolyte into that portion of the coulometer that includes the conduction path.