Abstract: In a preferred embodiment, an engine oil change indicator system, including: a combination engine oil pressure sensor and engine oil temperature sensor connected to a port on the engine to which port is normally connected an oil pressure switch; and a microprocessor connected to receive inputs from the combination engine oil pressure sensor and engine oil temperature sensor and to cause a low engine oil pressure warning light to be illuminated when the microprocessor has calculated from the inputs that the engine oil should be changed.

Abstract: In a preferred embodiment, a system of physical measurement and display of a parameter, including: accepting an input signal representative of a value of the parameter, the input signal having an arbitrary shape and amplitude; and displaying the value of the parameter in an arbitrary shape; including the use of analog and digital circuitry and nonvolatile memory.

Abstract: In a preferred embodiment, a sequential high-rate battery charger for charging a battery having a plurality of cell units, the battery charger including a current source; an apparatus to selectively sequentially connect each of the plurality of cell units to the high current source; and an apparatus to sequentially provide high current from the high current source to each of the plurality of cell units for a first selected period of time.

Abstract: In a preferred embodiment, a metering system for measuring and indicating the state of charge of an electrical storage battery, including: apparatus for storing a numerical value indicative of the state of charge of the battery and for providing an output voltage signal representative thereof; apparatus for detecting the terminal voltage of the battery, coupled to the apparatus for storing, and being operable to generate a function of the battery terminal voltage which is a substantially proportional fraction of the terminal voltage and to provide an input to the apparatus for storing if the function is below a threshold variable reference voltage signal; apparatus for receiving the output voltage signal and for generating the variable reference voltage signal therefrom, the variable reference voltage signal being lowered as a function of the output voltage signal as the output voltage signal indicates progressively lower states of charge; and apparatus for measuring the level of current drawn from the batter

Abstract: A motor controller comprises a plug detect circuit which detects "continuous" plug diode conduction during plug braking. The plug detect circuit detects "continuous" plug braking by detecting when a plug diode is or is not conducting current throughout substantially the entire time that a power MOSFET controlling the plug braking is conductive in one pulse width modulated MOSFET switching cycle. Continuous plug detection facilitates the motor controller's controlling a vehicle so that the vehicle has a more constant and smooth plug braking deceleration and subsequent powered acceleration in the opposite direction. According to another aspect of the invention, a motor controller comprises a POT HI and a POT LO driver circuit. The POT HI and POT LO driver circuits allow the detection of faults in throttle devices and the connections of the throttle devices to the POT HI and POT LO driver circuits.

Abstract: In a preferred embodiment, a high-frequency, pulse-width-modulated, power-transistor, DC motor speed controller having current limiting in both drive and regenerative modes, essentially constant ramping rates regardless of whether or not the operator switches to neutral before changing direction, a simple sequencer which controls the timing of four functions--both drive and regenerative current measuring circuits and both drive and regenerative transistors, a highly effective transistor filter capacitor arrangement, and circuitry in which the level of regenerative current is used as an input to control the current under which the direction relays switch.

Abstract: In a preferred embodiment, an inductor excited by a square-wave alternating current to produce a magnetic field in the inductor. A member movable in proximity to the inductor causes losses in the magnetic energy, which losses are directly related to the position of the member with respect to the coil. In another aspect of the invention, there is provided an inductor excited by an alternating current and a moving member which includes a ferromagnetic core having disposed thereon a thin sleeve of high resistivity material. In a further aspect of the invention, there is provided an inductor excited by an alternating current and a moving member, the excitation circuit including an oscillator having a positive temperature coefficient of frequency.

Abstract: A method and apparatus for measuring operations data which uses a commercially available digital multimeter (DMM) as the data receiving and display device. In one preferred embodiment, for example, basic operations data is transduced to digital form and then coded with a width modulator. The width modulated data may represent, for example, total elapsed time or total counts of a measured operation. The full-scale range of the data is encoded as frequency. A technician reads the frequency of the data signal with the DMM to determine the full-scale range of the data and then reads percent-of-range with the DMM as duty cycle. For multiple operations data, peak voltage is used as a parameter identifier. Alternatively, the value of the parameter being measured, the full-scale range, and the parameter identifier may be encoded as any combination of frequency, peak voltage, or duty cycle.

Abstract: A reader device, preferably implemented in solid-state form, is provided as a separate element for connecting to a so-called cumulative operations measurement system. Such a system is, for example, concerned with the measurement of elapsed time, especially in determining how long a particular piece of apparatus may have been functioning; or, on the other hand, measuring events such as the number of times a particular piece of apparatus has been turned on without regard to the elapsed time. The reader device is preferably provided with its own source of power, or it can rely on the power source contained within the operations measurement system.

Abstract: The monitor is a circuit including an integrator for storing a state-of-charge measurement and a charge signal channel and a separate discharge signal channel both arranged for connection to receive a battery terminal voltage signal. The charge signal channel is operable in response to a battery terminal voltage signal above a charge threshold function voltage to produce a charge output signal to change the integrated measurement in the integrator in a first direction to indicate an increased charge. The discharge signal channel is operable in response to a battery terminal voltage signal below a discharge threshold function voltage to produce a discharge output signal to change the integrated measurement in the integrator in a second direction to indicate a decreased charge. Both the charge and discharge threshold function voltages are functions of the stored integrator state-of-charge measurement.

Abstract: The indicator is especially useful for an industrial truck with a steerable wheel which can be turned through a steering arc of as much as one hundred eighty degrees. The indicator includes a potentiometer mechanically coupled to be rotated in synchronism with the steering rotation of the steerable wheel, and a multiple voltage threshold detector circuit connected to receive the variable voltage from the potentiometer and operable to provide one out of N discrete output signals in response to potentiometer voltages which have predetermined voltage level relationships to the respective voltage thresholds. At least N discrete indicator lamps are arranged in an array for indicating steerable wheel direction, and the indicator lamps are connected to receive the discrete output signals from the multiple voltage threshold detection circuit for indicating travel direction.

Abstract: The system includes a battery state-of-charge monitoring circuit which is operable to produce a signal change when there is a change in the battery charge from an acceptable charge to a substantially reduced charge. The signal change from the monitor is connected to control a lock-out relay to disable a control circuit for a load controller for battery powered equipment which is to be locked out. A current detecting device is connected to detect the presence of current in the control circuit of the controller and is connected to hold off the lock-out operation of the lock-out relay while current is flowing in the control circuit to thereby assure that the lock-out of the load occurs after a normal interruption of the load control circuit.

Abstract: The system accurately measures a summation of the operations when an operating voltage is present. The system includes a capacitor charged by a supply voltage and a volatile memory register connected to receive the operating voltage signals to be measured and operable to store those signals as a measure of operations. A nonvolatile memory register is provided having stages corresponding to the stages of the volatile memory register. A store sequencing means is connected to be powered by the energy stored in the capacitor when the supply voltage is removed to transfer the count stored in the volatile memory register into the nonvolatile memory register. A means is provided for detecting when the supply voltage is applied, with a recall sequencing means operable in response thereto to transfer the count stored in the nonvolatile memory register into the volatile memory register.

Abstract: The system includes a plurality of parallel-connected power field effect transistors arranged for connection in series with the traction motor with a common control circuit connected to the gate electrodes of the field effect transistors to control the on-off cycle of conduction through the field effect transistors. A plurality of parallel connected power diodes are arranged for reverse connection in parallel with the traction motor to serve as freewheeling diodes. The diodes are physically positioned apart from one another and distributed in position among the field effect transistors and each diode is positioned in a similar manner with a group of associated field effect transistors for ease of transfer of current flow between the diode and the associated field effect transistors.

Abstract: The system includes a digital integrator having a plurality of digital stages operable to store a numerical value in binary digital form which is indicative of state of charge. A switching circuit is provided for generating a series of voltage pulses on a single output line with each pulse corresponding in length to the binary digital value stored in the integrator to provide a time based resultant indication of the stored binary digital value. A filtering means is included to provide a substantially smooth analog output voltage having an amplitude corresponding to the summation of the pulses.The system preferably includes a delayed high voltage reset feature to set the integrator to a full charge state in response to voltage levels accompanying charging of the battery.

Abstract: The invention relates to apparatus for determining the state of charge of electric storage batteries.The apparatus makes use of known quiescent battery (16) terminal voltage recovery characteristics after a prior energy transfer to predict the ultimate steady state terminal voltage as a measure of state of charge.

Abstract: State of charge is determined for a battery during a quiescent interval with substantially no current flow through the battery by determining the quiescent time interval since the last substantial current flow through the battery, taking a rapid measurement of the battery terminal voltage, and relating the combination of these two measurements to known battery open circuit voltage recovery characteristics.

Abstract: Battery terminal voltage is measured on a continuing basis during both positive and negative voltage excursions with relation to a summed reference value to obtain a measured difference. The resultant measured difference causes the generation of convergence function signals which vary dependent upon the magnitude and polarity of the measured difference and a bi-directional integrator is connected to receive the convergence function signals to integrate in either direction dependent upon the polarity of the convergence function signals. A feedback is provided from the integrator to modify the summed reference value and the output of the integrator is indicated as a measure of the state-of-charge.