What Does the Alternator Warning Light (Battery Warning Light) Mean?

The alternator on your vehicle uses the rotational power of the engine to generate electricity and keep the car running. The alternator needs to maintain a certain voltage in order to keep the battery at sufficient charge while driving. As the alternator ages, it won’t be able to maintain a constant voltage and any fluctuations will be detected by the car’s computer.

What the alternator warning light means

When you start the engine, the car will check to make sure the alternator is outputting the correct voltage. This warning light will shut off after a few seconds if the computer has determined that the alternator is functional. When the light stays on, it indicates that the computer has detected an issue with the charging system.

If this light illuminates, try to use only necessary accessories like windshield wipers or headlights so as to avoid excessively draining out the battery. An alternator that is on its way out may cause this warning light to flash when there is a high demand on the battery. You can always save yourself a lot of trouble by paying attention to warning signs like this and trying to conserve your car’s battery.

What to do when the alternator warning light is on

As mentioned before, if this light is on, it means that your engine cannot produce enough power to keep itself running. Turning off all non essential accessories will help increase the distance you will be able to travel with a poorly charged battery. Keep in mind that issues with the battery can also cause the light to come on so if the battery is old, it should be tested as well.

It is better that you have a certified technician inspect and test your charging system to diagnose the problem in order to minimize any chance of permanent damage to your car.

Is it safe to drive with the alternator warning light on?

When this light is illuminated, your car is still somewhat safe to drive as you will have enough battery power to run the engine. However, it is still dangerous to continue driving for long distances or at high speeds as the battery will run out of juice and the car will be harder to stop without the assistance of the engine. If you are on the freeway and this light comes on, you should pull off the freeway and move to lower speed areas as soon as possible.

As always, our certified technicians are available to come to you to help you diagnose any issues with your car’s battery.


The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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