Abstract: To eliminate the effect of hysteresis when electrical energy is supplied to an electromagnetic positioning element, for example to an electromagnetic valve, upon change in sign of the electrical energy which is provided from a previously occurring change, additional electrical energy is supplied if the change in energy is counter the direction of the magnetization curve. The extent of the additional energy may be at least as great as the gap between the ascending and descending branches of the hysteresis curves (H1, H2), or may be a quantity obtained by experience or measurement if the gap between the hysteresis curves is known or determinable. If the electromagnetic energy applied is in excess of that for reversal of magnetization, it may be applied for a period of time which is just long enough to permit remagnetization of a magnetic portion of the electromagnetic apparatus (11) but not long enough to cause change in a mechanical output thereof.

Abstract: A battery-condition monitoring operation is performed by connecting a load resistor across the battery terminals for a time interval to draw a definite battery discharge current. A metering unit measures the voltage across the load resistor or that directly across the terminals of the battery. A timing switch sensible to the temperature of the load resistor automatically terminates the time interval, and a start switch is pressed to initiate the time interval; alternatively, the timing switch automatically initiates the measurement at successive time intervals. Latest at the end of the time interval, an arresting device prevents the metering unit from responding further to the metered signal, and the value most recently metered by the metering unit is persistently held, until the next such measurement operation, and constitutes an indication of the remaining capacity of the battery.

Abstract: A difference amplifier compares the sum of a signal corresponding to the voltage across the battery and a signal corresponding to the current through the battery to a reference signal. When the output of the difference amplifier indicates that the sum of the two signals is less than the reference signal, a limiter circuit responds to limit the current drawn from the battery by controlling a current regulator interconnected between the battery and its load. If desired, a temperature signal indicative of the battery of temperature can also be applied to the difference amplifier so that the point at which the regulation sets in varies as a function of temperature.

Abstract: A volt meter is connected across the battery terminals to read output voltage; a standard load, which may be the normally connected or design load for the storage battery is connected thereacross and, when a predetermined load current flows into the standard load, a control means coupled to the volt meter controls the volt meter to then indicate battery voltage as a measure of remaining stored charge.