Abstract: A power control system for a DC electric motor includes a control power regulating means which selectively connects either the armature of the motor, the field winding of the motor or both in a series current path with a DC power source permits operation of the motor in either an armature current or field current control mode using a single regulating circuit. In the field current control mode a contactor connects the armature of the motor directly across the power source and the regulating circuit controls the field current to regulate torque developed by the motor. The armature circuit and field circuit are interconnected by a diode which permits electronic switching between armature current control and field current control modes of operation.

Abstract: Apparatus for providing a continuous indication of battery state-of-charge under load in a system in which the battery is subject to varying load conditions. The apparatus stores a value representative of battery open circuit terminal voltage and reduces the stored value while the battery is loaded at a rate proportional to the difference between the stored value and a scaled value of actual battery terminal voltage. If the scaled value exceeds the stored value, the stored value is increased to a value corresponding to the scaled value.

Abstract: A circuit for indicating the charge state of a battery supplying discharge current to its load circuit under actual load operation during which battery discharge current is subject to magnitude variations and interruptions, having means for storing a stored signal whose value is representative of battery state-of-charge, means for rapidly increasing the value of the stored signal to the scaled value of the battery terminal voltage when its scaled value is below that of the battery terminal voltage, first means for decreasing the value of the stored signal at a slow rate preestablished such that the stored signal decreases from a first value representative of a fully charged battery to a second value representative of a discharged battery in a time period approximating the average time required during normal operation of the load circuit for the fully charged battery to become discharged, and second means, operative only during intervals when the battery supplies no discharge current to the load, for decreasin