How to detect whether the voltage of a car alternator is abnormal

To detect whether the voltage of a car alternator is abnormal, the following methods can be used:
Using a multimeter for testing: First, turn the multimeter knob to the DC voltage position, such as 30V or 50V, and connect the red probe to the "armature" terminal of the alternator, while the black probe is connected to the outer shell of the alternator. Run the engine above medium speed, and the reading displayed on the multimeter is the alternator's generation voltage. For a 12V electrical system, the standard voltage should be around 14V; For a 24V electrical system, the standard voltage should be around 28V. If the measured value is not within this range, there may be an abnormality in the voltage of the alternator.
Observe the brightness of the headlights: Before and after starting the engine, carefully observe the changes in the brightness of the headlights. If the headlights turn on significantly after the engine starts, it indicates that the alternator is working properly; If the brightness of the headlights does not change significantly, it may indicate a problem with the alternator.
Using an oscilloscope for detection: This method determines the working status of the alternator by measuring the waveform of the main voltage B+terminal. If the power generation is normal, the oscilloscope will display the corresponding waveform; If there is no waveform, it may indicate that the alternator is not generating electricity.
It should be noted that the above operations need to be carried out according to the correct steps to ensure the accuracy of the measurement results. Meanwhile, there may be differences in the electrical systems of different vehicles, so when conducting measurements, it is necessary to refer to the specific situation of the vehicle for judgment. If abnormal voltage is found in the alternator, it is recommended to seek the help of professional maintenance personnel in a timely manner to ensure the normal operation of the car.