Battery Light Keeps Coming On

If battery warning light keeps coming on while driving, it indicates a slipping alternator belt or failing alternator.

The reason why battery light keeps coming on
(1) Slipping alternator belt
(2) Failing alternator

First, let's get some background information. An alternator is a belt-driven device that does two things.

1) it recharges the battery and,
2) it provides electricity to accessories while the engine is running.

So, if the battery light is on, it means the alternator isn't generating any electricity to,
1) charge the battery or,
2) power the accessories.

With that said, we have the following two possibilities...

Slipping Alternator Belt - If the belt occasionally slips, the alternator won't generate any electricity during the slippage. This will trigger the battery light to flicker.

Failing Alternator - If the alternator occasionally fails/dies, it won't (of course) generate any electricity during the failure. This will trigger the battery light to flicker. Although rare, it's possible that wire coming off the alternator may have become loose. If this is the case, each time the loose wire breaks contact with the alternator, the battery light will come on.

What to do?

Please take the car to a reputable car repair shop and ask the mechanic to inspect the alternator and its belt. Hopefully, all you'll need is to have the belt adjusted or replaced.

Have this problem taken care of soon. If you don't, you can be sure that one day the battery light won't just flicker but rather it'll come on steady. When that happens, you will have roughly 20 minutes of driving left before the engine conks out.

How to Test an Alternator with A Multimeter

How to test an alternator with a multimeter can be easy if you just know the proper way to do it. Just follow the simple procedure mentioned. Read more » How to Test an Alternator

If the mechanic says you need a new alternator, don't be surprised if tells you that he'll have to replace something called the "voltage regulator" as well. Why? Because, on many vehicles, its necessary to replace both the alternator and voltage regulator at the same time.