A quick test I've always used is to start the car. Remove the neutral cable from the battery. If the car still runs your alternator is fine.
It can, though it is unlikely -- the alternator and the voltage regulator would both have to be faulty. A faulty alternator will not charge a battery, though, so it may seem normal until the charge put into the battery at the store runs out.
weak or faulty battery, faulty alternator (or slipping alternator belt causing battery not to charge) or faulty starter motor
Faulty Alternator?
As long as the battery is charged
That is typically caused by a faulty alternator. Have the alternator tested; the light is indicating that the alternator is not providing a charge to the battery.
faulty voltage regulator
alternator faulty
Your battery is not charging. It is either due to a faulty battery or a faulty alternator. Get it changed.
It could be battery connection, discharged or faulty battery, faulty alternator or regulator, faulty starter or a loose and corroded connection on the starter.
You can have the alternator tested free of charge at just about any major auto parts store. By the way, a bad alternator will not "discharge" a battery - the alternator's function is to provide the charge to the battery. If the alternator is faulty, then it is not providing the charge necessary to keep other components from discharging the battery. I had the alternator tested and it was charging. If the alternator has a bad diode, it will discharge the battery. I replaced the alternator and everything is fine.
Possible causes,- Faulty battery- Alternator belt missing or loose- Faulty Alternator- Alternator harness is open or shorted- Alternator circuit poor electrical connection
A few causes that will make the Battery Light come on are: 1. Faulty Battery 2. Loose Battery Connection 3. Battery is not Charging, ie. Faulty Alternator