Alternators are used for the purpose of charging the battery in the vehicle. They are also used to power the electrical system located within the vehicle when the engine is running. The alternator is constantly spinning thousands of rotations within one minute, so they can wear out.
If your headlights are dimmer than usual, your alternator might be bad. If the car will not crank, or you have to charge the batter every single time you need to crank it, it could be that the alternator has malfunctioned and is not charging the battery correctly. If you experience starter problems, it could be that the battery isn’t being charged correctly and actually have nothing to do with the starter itself.
If you experience a whining or growling noise when you try and crank your car, you may need to get the alternator checked. The smell of burning rubber or burning wires is also a sign that the alternator is no longer in good working condition. The “GEN” light or a light shaped like a battery pops up on the dashboard and you automatically know somethings up with the battery. Buying a new battery may not fix the problem, because it may be that the alternator has malfunctioned and the battery isn’t getting the charge it needs. Diagnostic testing can be performed to determine what is causing the problems and the mechanic can let you know what repairs are needed and the cost of fixing that particular problem.