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Is it the Battery or is it the Alternator?


Imagine getting into your car turning the key and the car fails to turn over. For most of us, there need be no imagination as it’s already happened a time or two. But then the age-old question pops into your head, is it the battery or is it the alternator?

What do the alternator and the battery actually do?

The battery supplies an electric charge that travels through the starting system and turns the gears to start the car. When the car turns over, the alternator then sends the current back to recharge the battery as you drive. The alternator supplies the power for your car’s electronics when you are driving and makes sure the right amount of charge is sent back to the battery.

So, if your car won’t start it could be loose or corroded connection cables, a dead or dying battery, an issue with the starter or a bad alternator. Here are a couple of ways to tell if it is the battery or the alternator:

  • The symptoms of a dead battery are most notable when you try to start your engine. If the vehicle is difficult to start or it starts inconsistently, it could indicate that your battery is about to die. If you start to see corrosion on the connection cables or the terminal, that is a key indicator that there is probably damage to the battery.  If a jumpstart works that is the final sign it is your battery!
  • If the battery is dead it could be the result of some underlying issues such as a bad alternator, or it could just be that the battery is at the end of its life.
  • Since the alternator and the battery perform similar functions, some of the failure symptoms are the same. If the car fails to turn over or it is delayed, it could be the battery or it could be the alternator. However, if the car starts but stalls while you are driving, it could be a problem with the alternator and that would mean the battery is not receiving enough return in the electrical current which causes your car to stall. A squealing sound when the sound system or the heater are on could indicate faulty alternator bearings. A final test you can perform is turning your AM radio to a low number without music and rev the engine. If you hear a whine or the sound goes fuzzy when you hit the gas, your alternator could be failing. 

If the alternator is bad it will likely damage the battery and shorten its lifespan due to overcharging or overuse. However, if the problem exists with the battery nothing should happen to your alternator. If you still have questions after performing the recommended tests above, feel free to leave the problem to the professionals! We are always here to service your needs and answer any questions you have to help maintain the integrity of your vehicle and extend its life.

Collierville Auto Car Experts
Collierville Auto Car Experts
At Collierille Auto, we are true car experts with decades of knowledge and experience. Let us guide you through the ins and outs of the car buying journey. Your ride is waiting, and we're here to help you find it!

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