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: 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.

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.