Symptoms Of Bad Alternator | What You Should Know About

By Max Anthony •  Updated: 03/16/21 •  6 min read

Many of you may not know what is an alternator, and what does it do for your car? Similarly, some people know about it , but they don’t know its bad signs. If you are any of these people, it’s time to learn thoroughly about the alternator as well as the symptoms of bad alternator. So, let’s start by figuring out what an alternator is?

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What is an alternator?

Symptoms Of Bad Alternator
Alternator on display | via Amazon

An alternator is an essential part of your car or vehicle that charges its battery for smooth performance. If the alternator fails to charge the battery of any vehicle, your vehicle will stop moving.

As a result, you wouldn’t be able to move anywhere on your vehicle that would ruin your day and mood. Therefore, having a good performing alternator is very important for your car. Now that you know about what an alternator is, let’s learn about the symptoms of a bad alternator. 

Symptoms of Bad Alternator

It is crucially important to understand the symptoms of bad alternator to avoid issues later on. Moreover, by knowing them, you would be able to make the necessary repairs on time for your vehicle. As a result, you would be able to keep your car in a good state and always going for you with an incredible performance. So, let’s learn about the following common symptoms that your alternator may show at any time. 

Overly bright or dim lights of your car

One of the most common symptoms of bad alternator is the overly bright lights of your vehicle. Not only excessively bright, but if your car shows dim lights, it might also be due to the alternator issues. When the alternator of your vehicle is not performing as required, it fails to provide enough voltage to your car’s lights. As a result, the lights fail to turn on entirely and produce a dim light due to receiving fewer voltages.

On the contrary, the alternator sometimes starts to supply excessive voltages to the lights due to any issue with them. At that time, the lights turn on overly bright and may affect the life of the car’s battery.

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Slow or underperforming accessories

Your car includes several accessories that are linked with the performance of the alternator too. For example, the rolling up and down of your car door’s windows are linked with the alternator. Similarly, the movement of car wipers at the front screen is also associated with the alternator.

Similarly, the charging of accessories inside the car and car’s AC and seat warming processes are all linked with the alternator. When you observe that these processes are not responding as they are expected, it means that something is wrong with the alternator.

For example, when you turn the door mirrors down, and they go down very slowly or not smoothly, it is a sign that the alternator is not working properly. All these things need the proper supply of electricity or energy to work, but they fail to work properly if they don’t get the required energy from the alternator.

Bad alternator vs bad battery

In case of any issues with the alternator, it would fail to charge the car’s battery. When it fails to get a charge, you will fail to start up your car or drive it properly. Sometimes, the alternator is working, and the battery is also charging, but both of them are underperforming.

In these cases, when you start the car, it may result in a jump-start or may turn off again and again before getting started. This is also a symptom that your car’s alternator is not performing appropriately and must be checked. 

Frequent Trouble starting
symptoms of bad alternator
Alternator on display | via Amazon

If your car has frequent trouble starting, it is definitely due to the malfunctioning of an alternator. It is alright if you face trouble starting very rare. This is normal and might not be linked with the issues of the alternator.

However, if the car has everyday trouble starting, then you must ask a mechanic to check its alternator or battery. By checking the issues at the right time without any delay, it would save the car parts from damaging and enhance your car’s alternator and battery life. 

Unwanted noises from the car

When car start producing unwanted noises such as whining noises, these are symptoms of bad alternator. Not only during starting the car, but your car may also show bad noises when it is running.

A car with a perfectly working alternator and battery don’t produce the whining or grinding sounds. Therefore, if you notice any of these sounds in your car, make sure to take your car to the mechanic shop for proper examination. 

Battery warning lights are on

At the front dashboard, there are several indicators about different parts and functions of the car. Among these there are the battery warning lights that turn on if there is something wrong with the battery.

These lights probably turn on when the battery is not receiving the required voltages from the alternator. Whenever you see that the battery warning lights are on or blinking at the dashboard, make sure to check the alternator as well as your battery on time to avoid any major damages later on.


For enjoying a smooth ride, it is important to have your car’s parts performing smoothly and efficiently. When your car has issues alternator that charges your car’s battery, you will face several issues with your car.

Even your car may stop working if the alternator of your car fails to charge your car’s battery. Therefore, it is important to have deep knowledge about the car’s alternator as well as the symptoms of bad alternator.

Knowing these things would help you get the necessary repairs and fixes on time so that you wouldn’t face any issues with your car. Besides, checking and fixing the issues with the alternator would result in extending the life of your car’s battery and let it go in the long run.

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Max Anthony

Max is a gizmo-savvy guy, who has a tendency to get pulled into the nitty gritty details of technology and cars. He attended UT Austin, where he studied Information Science. He’s married and has three kids, one dog and a GMC truck and a Porsche 911. With a large family, he still finds time to share tips and tricks on cars, trucks and more.