How to Determine if the Generator is Faulty?
3 Answers
Distinguishing whether the generator is faulty can be done by: 1. Starting the engine, keeping the generator running, and using a multimeter to test the battery voltage; 2. If the battery voltage is between 13 to 14.8v, it indicates the generator is in good condition; 3. If the battery voltage remains unchanged after turning off the engine and stopping the generator, it means the generator is damaged. The car generator is the main power source of the vehicle, functioning to supply power to all electrical devices while the engine is running normally, and simultaneously charging the battery. Reasons for the generator not producing electricity include: 1. Diodes being broken and not rectifying; 2. Brushes stuck in the brush holder; 3. Rotor's magnetic field winding not receiving power; 4. Stator windings short-circuited or grounded; 5. Rotor's claw poles becoming loose.
As someone who frequently tinkers with cars, I've found the signs of a failing alternator to be quite obvious. First, check the dashboard: if that battery-shaped warning light comes on, it's definitely an alarm signal. Then listen to the engine sound: if there's strange rattling or squeaking noises, it might be worn-out bearings inside the alternator. My most common method is testing battery voltage: with the engine running, use a voltmeter to measure across the battery terminals. The ideal reading should be around 14 volts - if it drops below 12 volts or fluctuates wildly, the alternator is probably failing. Don't forget to inspect the belt too: look for cracks or looseness, as inadequate tension can prevent the alternator from spinning. Never ignore minor issues - prolonged neglect will completely drain your battery, leaving you unable to start the engine and requiring a tow truck. I recommend regular checks; buying an inexpensive voltmeter allows DIY testing, and prevention is always cheaper than repairs.
After driving for a long time, I have my own experience to judge generator problems. First, pay attention to the car's performance: if it takes a long time to start and is particularly difficult, or if the lights noticeably dim during the day, it's dangerous. It's even more obvious when the air conditioning or stereo is on: if the generator can't supply enough power, these electrical devices will flicker. Secondly, if the battery indicator on the dashboard lights up, don't delay—turn off unnecessary electrical equipment like the radio or headlights immediately. Find a parking spot and manually check if the generator belt in the engine compartment is broken or loose. For older cars, frequent long-distance driving can cause the generator brushes to wear out, leading to unstable power supply. I also recommend using a phone mount to glance at the dashboard lights while driving. If you notice anything unusual, slow down and address the issue. Taking care of these small things can save you a lot of money on repairs.
