How to Determine if the Generator is Broken?
2 Answers
Methods to determine if the generator is broken: 1. The charging indicator light on the dashboard will illuminate, and the battery power will deplete quickly; 2. The generator may produce abnormal noises or emit a burnt smell when running; 3. After starting the generator for a few minutes and then turning it off, touch the generator. If it is very hot, it may indicate a short circuit, requiring replacement. The car generator is the main power source of the vehicle, functioning to supply power to all electrical devices (except the starter) and charge the battery when the engine is running normally (above idle speed). Based on the three-phase stator winding of a standard AC generator, additional winding turns and lead-out terminals are added, along with an extra set of three-phase bridge rectifiers. At low speeds, the output is from the original and additional windings in series, while at higher speeds, only the original three-phase winding provides the output.
I've had ten years of experience fixing cars, and diagnosing a bad alternator is actually quite straightforward. First, check if the battery warning light on the dashboard stays lit—if it's on, it means there's an issue with the charging system. Second, listen to the car's sounds; if the belt near the alternator is squealing or making a humming noise, it’s likely due to worn bearings. Third, touch the battery casing—if it feels extremely hot, it indicates the alternator isn’t regulating voltage properly. Fourth, use a multimeter to measure the voltage: with the engine running, the voltage between the battery’s positive and negative terminals should stabilize around 14 volts. If it’s below 12 volts or above 15 volts, there’s a problem. The simplest method is to rev the engine hard with the headlights on—if the brightness doesn’t change, the alternator definitely isn’t charging. By the way, the most direct effects of a faulty alternator are the car not starting or stalling while driving. If this happens, pull over immediately and call a tow truck.