Types and functions of automobile alternators

Automobile alternator can be divided into DC alternator and AC alternator. Since AC alternator is superior to DC alternator in many aspects, DC alternator has been eliminated. At present, all automobiles adopt AC alternator. The motor alternator is also based on electromagnetic induction.

If the stator winding is connected to the electrical load, the motor will output alternating current, then be converted to direct current by the rectifier bridge of the alternator, and output direct current from the output terminal.

The alternator（AC）is part of your charging system. Its main role is to provide power in your car to spark plug and all the electronic accessories. If the alternator starts to fail, you may notice your headlights and dashboard lights start to dim. If the instrument lamps or headlights are dim, it is a clear sign of a potential alternator failure. The performance in decline may result in other electronic accessories, such as power windows, power seats, power locks, these items will operate more slowly than usual.

The signs of a failing alternator - The battery voltage test 

When the car does not start, use the multimeter to measure the voltage of the battery and record it, then start the car, use the multimeter to measure the voltage of the battery and record it. If the car's alternator is not broken, the voltage of the measured battery will be higher than of the car started, around 13.5V. In the previous article (How to test an alternator),we have given the details, you shouldn’t miss it. Well,  if the car's alternator fails, the battery's voltage will be lower than before. The most obvious sign is that if the alternator breaks down and the car doesn't last long, the battery will lose its power and the car won't be able to start.

The signs of a failing alternator - Warning indicator light on dashboard

As an alternator warning light flickers in a dashboard. Normally, the light is shaped like a battery, but some people might say ALT or GEN. This lamp may only be triggered when you use excessively electrical equipment. Under this circumstance, the car runs 30 to 50 kilometers at most, the vehicle can stall, flameout gradually. If it is a diesel car, basically does not affect the engine running, but  exception of the vehicle with oil solenoid valve. So you should reduce utilization of the electrical equipment on the car, except for the brake lamp, turn signal. If it occurs, you’d better to find a automobile mechanic to fix this problem.