What is the Voltage of a Car Generator?
2 Answers
The normal voltage range of a car generator after starting the engine is "15.3V-12.8V"; below is relevant information about car generator voltage:1. Normal generator voltage conditions: When the vehicle's air conditioning is operating and other electrical devices are used excessively, the generator voltage may drop below 12.8V. At this point, the vehicle draws current from the battery and cannot charge the battery. After starting, the battery voltage is essentially equal to the generator voltage, minus the voltage drop due to line loss from the generator to the battery. When the engine is not running, the normal battery voltage range is 13.8V-12.8V. 2. Introduction to the generator: The car generator is the main power source of the vehicle. Its function is to supply power to all electrical devices (except the starter) while the engine is running normally (above idle speed) and simultaneously charge the battery. Based on the three-phase stator winding of a standard alternator, additional winding turns are added with lead-out terminals, and an additional three-phase bridge rectifier is included. At low speeds, the output is from the series connection of the original and additional windings, while at higher speeds, only the original three-phase winding provides the output.
I've been driving for twenty years and have repaired countless engines. The generator voltage usually ranges between 13.5 and 14.5 volts because a 12-volt battery needs a slightly higher voltage to charge. In cold winter weather, the voltage tends to stabilize, but in hot summers, it can drop easily. If the reading falls below 13 volts, it's troublesome—the battery won't charge fully, starting becomes difficult, and even the lights can be affected. Once, I worked on an old Santana with a voltage of only 12.8V—the owner kept complaining about hard starts. It turned out the generator coils were rusted. After the repair, the voltage rose to 14.2V, and everything was fine. Everyone should remember to use a multimeter for regular checks—don’t wait until you’re stranded to panic. Newer cars have monitoring systems, but with older cars, you need to stay vigilant to ensure safe driving.
