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Symptoms Of A Bad Alternator

Table of Contents

Cars are one of the common modes of travel for people all around the world.

Each vehicle may differ in the make, model, and driver, but they all have certain parts in common.

One of those parts is an alternator. Not a lot of people know what the alternator is, let alone the symptoms of a bad alternator.

Now for all the rookies out there, the first question that comes to mind may be what is an alternator?

The alternator is a generator for the car.

It distributes electricity throughout the vehicle by recharging the battery. 

All cars with a standard internal combustion engine will always have an alternator.

This device is small, around the size of a healthy coconut, and is mounted in front of the engine with a belt around it.

Now that you know what an alternator is, you may think, how do you know if you have a bad alternator?

To be able to tell when your alternator isn’t working at its best, keep reading. 

Symptoms Of A Bad Alternator

Like we’ve said before, an alternator is one of the critical components of a car.

It makes sure that the whole car system is working smoothly.

If it starts failing or a problem with the alternator arises, it could cause the car to shut down gradually.

This works like a domino effect, where the failing alternator can be the trigger for other problems. 

So how can you tell whether your alternator is failing?

Below we’ve listed certain signs of a bad alternator that you should keep an eye out for. 

The second you see any of these symptoms, take your car to the auto repair shop.

The alternator is very important to your vehicle running smoothly, and it is certainly not a paranoid reaction to go to a professional at the first sign of trouble. 

1. The Indicator Light

Symptoms Of A Bad Alternator

One of the first signs of a failing alternator is the flashing indicator light.

The flash of the indicator is a warning sign.

You might find it on the dashboard with the words “ALT” or “GEN.” ; but many cars now will show a battery symbol.

The second you see this warning signal on your dashboard, know that it is time to take the car for repair.

That would be the best thing you could do for your car – stop the problem from exceeding in the first pre-stages. 

2. Dim Or Flickering Headlights 

The alternator provides energy to every part of the car, including the headlights.

So, if your headlights are flickering or have become dim for no reason, you should take this as a symptom of a bad alternator. 

3. Electrical Failures

Like the first two points suggest, electrical failures as a whole are a significant symptom of a bad alternator.

All the systems and devices that are powered through your alternator start to act up when it is failing. 

They might either completely break down, start malfunctioning, or work at a lower capacity.

These systems can include power windows, power locks, air conditioners, dashboard lights, the car radio, and more. 

It is very possible that there is another issue causing these electrical failures, but it’s always better to be safe than sorry.

Take your car to a trusted automotive shop and suggest a look at the alternator.

4. Weird And Strange Noises

Your car should purr like a tiger when driving.

It should not be emitting weird noises, rattling sounds, and splutters from the engine.

If it is, you should prop up the car hood and take a look at the engine, more specifically, the alternator. 

If you have no experience with cars, a better idea would be to take it to a professional.

You never know what is causing the strange noise.

This symptom might not seem so dire and may sound quite vague, but it could very well indicate a bad alternator.

5. Stalling Cars And Difficult Start-Ups

Cars today have multiple sources of energy, including gasoline and electricity.

The alternator in the vehicle is the spark that lights the flame of gasoline, which powers the engine.

If the alternator fails, you’ll find that the spark is not ignited, and so the engine does not start. 

The second this starts happening, you should know that there is something wrong with your alternator.

The bad alternator is the reason your engine is stalling and not starting up your car.

If you ignore this problem and keep trying to kick start the engine, there will come a time where your car won’t start at all. 

6. Dead Batteries 

signs of a bad alternator

Another symptom of a bad car alternator is a dead battery.

Yes, batteries often fail on their own.

However, bad alternators can be a contributing factor as well. 

A bad alternator can fail to recharge the car battery.

If this happens a lot, the battery will die, and you’ll end up needing to spend a lot of money to replace it.  

7. Burning Rubber Or Wire Smell

A common sign of a bad alternator is a foul odor.

This bad smell is of burning rubber or wires.

It indicates that parts of your alternator are wearing out because the alternator’s belt is under constant tension and friction.

The smell can also arise when a worn-out alternator belt is too close to the hot engine.

This odor resembles that of an electrical fire, as an overworked alternator pushes too much electricity into the car.

This causes the wires to heat up too much.

The damaged wires can cause excess heat, which can cause a car system to fail.

This is a very dangerous problem that requires immediate attention.

8. Broken Or Loose Connections

When checking your car for problems, you may find that your car battery is dead.

When this happens, it indicates that the wires and connections that make sure the car runs smoothly are either burning up or have burnt out. 

Any problem with the wires can stall different systems within the car, reduce electricity output and dim the car lights.

A common indicator of this is if your AC is not working because it indicates that it is not getting proper electricity through the alternator via the wires.

9. Bad Alternator Belts

We’ve already talked about how the alternator is surrounded by a belt.

This belt is essential for the smooth functioning of an alternator.

So, belt problems are one of the most common symptoms of alternator issues. 

When you open the engine hood, and the belt is either missing, loose, hanging off the engine block, or flapping around, you have a bad alternator belt.

These problems will be very obvious and the minute you see one, go to a professional for alternator belt repairs. 

10. Weak Systems

Last but certainly not least, a symptom of a bad alternator is weak car systems.

As we’ve explained above, the alternator powers most, if not all, the different systems of the car.

So, once you start noticing that any system in your vehicle is not working entirely well, it is time to get your alternator checked out. 

What Next?

Now that you know the 10 main symptoms of a bad alternator, you can pay more attention to when your car stops functioning properly.

Knowing the symptoms of a bad alternator is essential.

It means you won’t dismiss any small sign of trouble that could later cause major problems. 

From flickering lights to strange sounds and smells, keep an eye on it all.

Any or all these symptoms can indicate a bad alternator.

Luckily, the sooner you get your car checked, the more money you can save on repairs.

Can A Car Run With A Bad Alternator?

Bad Alternator

Yes, a car can run with a bad alternator but not for very long.

On average, you can probably drive your car 3 to 4 miles after your alternator has failed. 

In some cases, your car might be able to go farther, but it all depends on how badly your alternator is damaged.

Although yes, it is possible for your car to run on a bad alternator, it is not recommended as this can further exacerbate problems.

Risks Of Driving With A Bad Alternator

There are plenty of risks of driving with a bad alternator.

The first one is that you don’t know when the car will break down.

You could be in the middle of a highway, with no repair shop or help insight, and your car just shuts down completely. 

It is also possible that your alternator overheats, and a small explosion could occur, which could potentially put you in harm’s way.

Since alternators power cars, overheating can lead to other mechanical problems as well that you might not be equipped to deal with alone. 

Driving with a bad alternator exacerbates problems in your cars and can lead to more costly repairs later on. 

How Do I Know If It Is The Battery Or The Alternator?

testing a failed alternator

Problems in the car boil down to two things. You either have a dead battery or a bad alternator and, in some cases, both. 

If your car engine starts but dies immediately after, this means that you have a bad alternator.

However, if your car refuses to start, this means that the battery is dead.

In this case, you’ll need to jump-start the car. Once it turns on, it should run smoothly. 

Since we have already understood how to spot a bad alternator, let’s now talk about how to spot a bad battery so you can see the difference. 

There are three symptoms that you should look for:

1. Dim Dashboard Lights

The first indicator of a dying battery is dim dashboard lights.

The dashboard has an icon for a battery gauge, and you should always keep an eye on that.

The minute it goes dim, it means that there is something wrong with the battery.

2. Check For Battery Corrosion 

Prop open the hood of the car and take a look at the battery.

If you find any kind of corrosion on it, that is probably the reason the car isn’t starting. 

Take a rag and carefully wipe away the corrosion and then try jump-starting it.

Run the motor for a while, turn it off, and then attempt to restart the car.

If you can’t restart it, the alternator is working, but the battery isn’t being receptive to the electrical charge.

3. Old Car Battery

All things have a lifespan, and batteries are no different.

As batteries age, their ability to retain electrical charge decreases, and eventually, the metal starts to corrode from the inside. 

A car battery, on average, can live up to 2 to 5 years, after which it won’t be able to hold any power. You can recondition car batteries of course, but that’s a different story.

If it’s been more than 2 years since you got your battery, the problem could stem from an old battery.

What Does A Bad Alternator Sound Like?

A bad alternator sounds like a series of rattling and grinding noises, which are pretty strange.

You’ll probably also feel like there is something wrong with the car and that it is about to fall apart. 

The rattling and grinding sounds can be due to a loose alternator belt or overheating of the alternator itself.

The second you hear these noises, make sure to take your car to a professional and get the alternator checked out before any other misfortune happens. 

How Can I Test My Alternator At Home?

If you’re worried about having a bad alternator, you’ll be glad to know that it’s possible to test your alternator at home, and here is how! 

All you need is a multimeter, which is readily available.

After you’ve acquired this, just follow the steps given below. 

However, before you begin following any of the steps, be sure to turn your engine on.

Step 1

Open the hood and locate the battery.

Make sure that you have clear access to it.

Next, locate where the alternator is and check the belt to see whether it is loose.

Step 2

Turn your multimeter to a setting of 20 volts and then start the engine.

Step 3

Once you’re done with step 2, you have to make sure that the alternator belt is spinning properly without slipping or flapping.

Step 4

Next, you have to check the voltage coming from the alternator.

If you can easily access the alternator without any mishap, take your multimeter and place its positive red probe to the red terminal connector on the alternator. 

Now take the negative black probe and attach it to any metal part of your car that is easily accessible.

Don’t connect the negative probe directly to the alternator.

Once done, you should be getting a voltage reading on the multimeter display screen. 

If, however, you do not have proper access to the alternator, connect the positive red multimeter probe to the positive terminal of the battery and the negative probe to the negative terminal of the battery.

Either way, the results will be the same.

Step 5

If your alternator is working smoothly, your multimeter will give a reading between 13.8 to 14.2 volts.

If the reading is higher than 15 volts, the alternator’s voltage regulator may be faulty.

So, you need to get the alternator checked out.

If the reading is lower than 13 volts, your engine’s idle speed may be too low, and there may not be enough power.

In this scenario, try revving the engine speed up to 2000 RPM or higher, and then check readings on the multimeter. 

Before checking the reading, make sure all connections are tight, the belt isn’t slipping, and there is no corrosion on the battery.

If all is well, your readings should be within the normal range.

If not, get your car checked out by a professional as your alternator has probably gone bad.


An alternator is an integral part of the car.

It powers almost every other system within the car, and without it, the car won’t start.

So, it is imperative to keep an eye on your alternator’s health. 

At the first sign of trouble, rush your car to the repair shop.

It’s also a good idea to make contingency plans and ensure that you prevent future damages by acting pre-emptively.

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