What are the inspection methods for a car generator not generating electricity?
3 Answers
When a car generator is not generating electricity, preliminary inspections can be conducted on the vehicle, followed by further inspections after removing the generator without disassembling it. Inspection methods include: using a multimeter (voltage and resistance modes), a general DC voltmeter, a DC ammeter, and an oscilloscope, among others. You can also create a small test lamp using car bulbs or flashlight bulbs, or detect issues by altering the car's operating state. The car generator serves as the primary power source for the vehicle, functioning to supply power to all electrical devices (except the starter) while the engine is running normally, and simultaneously charging the battery. Based on the three-phase stator windings of a standard AC generator, additional winding turns are added with lead-out terminals, along with an extra set of three-phase bridge rectifiers. At low speeds, the output is provided by the original and additional windings connected in series, while at higher speeds, only the original three-phase windings supply the output.
If I find that the car alternator isn’t generating electricity, I’ll first check whether the battery voltage is normal because if the alternator doesn’t supply power, the battery won’t last. I’ll use a multimeter to measure the battery terminal voltage while the engine is running. If it’s below 13.5 volts, it could be an alternator issue. Next, I’ll check if the belt is loose or broken—a broken belt will directly cause the alternator to fail. I’ll also see if the alternator pulley is spinning; if not, the belt needs to be replaced or adjusted for tension. Then, I’ll inspect the wiring connections, such as the alternator-to-battery cable terminals, for corrosion or detachment. If the terminals are dirty, cleaning them might restore the connection. Finally, I’ll test the alternator output by directly measuring the B+ terminal with a multimeter—if the voltage is below 13 volts at idle, the fault is confirmed. Remember to disconnect the battery’s negative terminal for safety before working. Regular maintenance can prevent these issues—don’t wait until the car breaks down on the road to fix it.
When the generator fails to produce electricity, I immediately pay attention to the vehicle's symptoms: first, I check if the dashboard charging light is on—if it is, it's a preliminary indication of a charging system issue. Then, I quickly inspect the belt tension by pressing the middle section with my hand; if it sinks more than half a centimeter, it needs tightening. Next, I test the battery voltage by starting the engine and measuring the positive and negative terminals with a multimeter—the ideal output should be between 13 and 14 volts. If I don't have tools, I can also infer the problem by observing if the headlights flicker. These steps are simple and efficient, suitable for handling at home. However, if the issue is complex, I take the car directly to the repair shop to avoid wasting time and causing further trouble.
