Alternator Charging Issue

An alternator is an electromechanical device that converts mechanical energy to alternating current electrical energy. Most alternators use a rotating magnetic field but linear alternators are occasionally used. In principle, any AC generator can be called an alternator, but usually the word refers to small rotating machines driven by automotive and other internal combustion engines Resource : en.wikipedia.org/wiki/Alternator Basically this means that an alternator is what charges the car's battery and also provides power to operate the engines computer, lights, radio, etc. So, if the alternator quits functioning then all of these electrical devices will try to run off the car's battery. The problem with that is, once the battery starts to loose power ( since it is no longer being recharged ) the will start to function poorly and will eventually stop running all together. Generally when the alternator starts to fail a Battery light will illuminate on the dash board. This means the battery is no longer being charged , this does not mean the battery has a problem. Testing : Using a multi-meter set to DC volts, connect the positive and negative leads to the same on the battery with the car's engine running. You should see from 13.2 - 14.7 volts. If you see less than this and confirm it is the same when the engine is running or not, then you know the alternator is not charging.