Abstract: An in situ self-diagnostic automotive alternator battery charging system is disclosed. Included are: a battery; voltage regulator sensing battery voltage and generating an excitation signal; and an alternator driven by a vehicle engine provide a rectified electrical signal to charge the battery in response to the excitation signal. Electronic circuit status detectors, variously coupled to the battery, voltage regulator and alternator, maintain a first logic state when a corresponding signal characteristic is within a predetermined range and a second logic state when the corresponding characteristic is outside the predetermined range. Combinatorial logic means respond to a logic state sequence from the detectors to identify predetermined sequences of the logic states resulting in the identification of faults in the charging system.

Abstract: A detector monitoring the voltage ripple in the rectified electrical output signal of an alternator in a multiphase alternator battery charging system is disclosed. A circuit monitors the undulating alternator output signal and produces a signal level in response. To correct the detector operation for various magnetic phenomena present in the alternator, a first circuit measures the rotational speed of the rotor and produces a proportional signal. A second circuit determines the excitation current supplied to the field coil. The measurement and determination are separately weighted and combined to form a corrected comparison threshold value. A variable threshold circuit combines the signal proportional to the rotational speed of the rotor and the determined field coil excitation current to produce a combined signal level.

Abstract: A detector monitoring the operational status of the field coil circuit in a multiphase alternator and voltage regulator battery charging system is disclosed. Circuit means monitor a first signal at a first terminal of the field coil circuit. Means generate sampling intervals on a repetitive basis. Circuit means interrupt the excitation signal supplied to the field coil by the voltage regulator during the sampling intervals. A second signal is measured during sampling intervals at a second terminal of the field coil circuit. Comparator means compare the first and second signals and produce an output signal when the comparison varies from a predetermined value.