How to Determine if an Alternator is Good or Bad?
2 Answers
To determine if an alternator is good or bad, simply use a multimeter to measure each wire coming out of the motor. Any two wires must show resistance; otherwise, it indicates the motor is damaged. Below is relevant information about alternators: 1. Composition: An alternator consists of a rotor, stator, rectifier, end cover, pulley, etc. Any abnormal component or part can cause poor generator performance. 2. Function: When the engine is running normally, it supplies power to all electrical equipment except the starter motor, while also charging the battery. The generator is the main power source of a car, and automotive generators are alternators.
I usually enjoy tinkering with car parts myself, and judging whether an alternator is good or bad is actually not difficult. Just use a multimeter: measure the battery voltage before starting the engine, which should normally be around 12 volts; measure it again after starting, and if it rises to 13.5-14.5 volts, it means the alternator is charging and working properly. If the voltage doesn’t change or is too low, the alternator might be faulty. Don’t forget to listen for sounds—if there’s unusual noise or a screeching sound when accelerating, the belt might be loose or the alternator could be worn internally. Also, check the battery light on the dashboard; it should turn off after starting to indicate everything is fine. If you encounter issues, don’t force driving to avoid stalling on the road. After testing it yourself, go to a repair shop for confirmation.
