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Can You Drive With A Bad Alternator?

Can You Drive With A Bad Alternator?

When your car has a bad alternator, you’re taking your chances if you continue driving it here and there. 

After all, the last thing you want is to get stuck with a car that won’t start. Can you drive with a bad alternator, and what happens if you do? Here’s all the information you’ll need.

If your car is starting to experience alternator problems, you can still drive it wherever you need to go. However, you are doing so at your own risk, since it’s likely that sooner rather than later your car won’t start.

When an alternator begins going bad, this results in your car’s battery draining at a much faster pace. 

Thus, even if you know your battery still has plenty of life left in it, the bad alternator in your car will do all it can to kill the battery.

If your alternator has already stopped working entirely, you may be surprised to learn that you can still drive your car, albeit for probably only a short distance. 

Since the alternator and battery go hand-in-hand, having an alternator that isn’t working means you will soon have a battery that is not working. 

Is It Safe to Drive with a Bad Alternator?

Technically, it is safe for you to drive your car if it has a bad alternator. However, you’ll only be able to do so for as long as your car battery still has power stored within it. 

Once the alternator quits working on your car, your vehicle will then start relying on the battery alone to power its various systems, which is why your car battery drains so much quicker without a working alternator.

Unfortunately, there are other things that result from having a bad alternator that could put you at risk when on the road.

First, your car’s engine will become extremely unreliable. This can include not only being difficult to start, but also stalling out on you in the middle of rush-hour traffic.

Also, if you are driving after dark with a bad alternator, you may begin to notice your vehicle’s headlights will start to get much weaker, making it more difficult for you to see and others to see your vehicle. 

A bad alternator can also lead to your dashboard and other electronics within your car malfunctioning, which won’t be a good feeling when you’re behind the wheel. 

Last but not least, expect to start smelling rubber burning or other chemical-type smells emitting from your car. 

If this happens, this usually means wires are burning or the alternator belts are becoming overheated, both of which are probable causes of your car’s electronics going haywire.

How Long Can You Drive with a Bad Alternator?

As to how long you can drive your car if it has a bad alternator, the bad news is there is no set answer regarding how many miles you can go before your car stalls out for good.

The best we can do to answer this question is to tell you that your car will last as long as its battery still has power. Remember, when your car does not have an alternator that can recharge power that’s taken from the car battery, your vehicle then becomes completely dependent upon the battery’s power. 

Once your car battery becomes the sole power source for all of your car’s systems, it will drain at a very fast rate. 

Before you know it, your car will stall out, no matter where you happen to be at that moment. 

To get the maximum distance out of your vehicle when you have a bad alternator, we suggest you shut off functions that are not absolutely necessary to operate your vehicle. 

This can include shutting off the air conditioning, radio, and anything else that is non-essential for your vehicle’s operation. By doing this, you can probably get your vehicle back home or to a mechanic for evaluation.

Will a Car Still Run with a Bad Alternator?

Yes, your car will still run with a bad alternator, but for how long is debatable. 

Depending on how bad your alternator’s condition is at that moment, you may be able to drive your car for as little as 30 minutes before it stalls out and won’t restart.

If the alternator problem has just started, your battery has plenty of power stored in it, and you shut off all non-essential systems for your vehicle while driving, most experts agree you can probably drive your car for up to two hours before it will die. 

One very important thing to remember is that should you need to start your car when it does not have a working alternator, make absolutely sure that you do not turn off the car’s engine once your car starts. 

Since starting your car takes quite a bit of energy from your car battery, there is always the chance you may not get a second chance to start your car again under these circumstances.

How to Tell if an Alternator is Bad

If your car’s alternator starts to go bad, there are several signs you should look for that will confirm your suspicions.

The most common sign is a dead car battery. Since the alternator charges the battery while suppling the systems of your car with electricity, a bad alternator won’t charge your battery as efficiently as usual.

Also, you’ll smell burning wires or chemical smells that indicate alternator belts are burning or overheating. 

As you start noticing these smells, you most likely will simultaneously start to hear strange sounds underneath your hood, such as grinding or whining sounds. When these sounds emerge, this means your alternator’s bearings are bad.

Since wires may be burning, this plays havoc with your car’s electronics. 

As a result, your headlights will get either really dim or really bright, your dashboard warning lights may start to go crazy, and you may or may not be able to operate power windows, power locks, a sunroof, or other electronic systems on your vehicle. 

As a final blow to you and your vehicle, you’ll notice your vehicle stalls out far more than it ever did previously. 

If you are constantly starting your vehicle due to stalling out, get it started and head straight to your mechanic to get your alternator examined.

Alternator Replacement Cost

When you do need a new alternator for your vehicle, you won’t need to panic at the thought of having a repair job that will cost thousands of dollars. 

In most situations, having an alternator replaced is one of the most reasonable repairs you can have made to your vehicle. Typically, you can expect to pay as little as $100 to as much as $400 to get your alternator replaced.

Of course, this assumes that no other parts need to be replaced. If you have tried to drive as much as possible with a bad alternator or no alternator, it is always possible your car may have suffered additional damage, especially if you noticed rubber or chemical smells that indicated wires or belts may have been burning.

Fortunately, most alternator replacements tend to involve replacing only the serpentine belt.

If your vehicle needs a new serpentine belt, you can expect the repair bill to increase by about $25-$50. 

What Makes an Alternator Go Bad?

Since the alternator is so important to keeping your car on the road, you may be wondering what makes it go bad in the first place.

Most alternators go bad simply due to age or being used extensively. In other words, the more you drive, the shorter the lifespan for your alternator.

Another reason your alternator may fail is due to fluid that is leaking onto the alternator itself.

Most often, this will be either power steering fluid or engine oil. If either of these leak onto the alternator, a malfunction or complete failure of the alternator will occur.

Once you begin to think your alternator is experiencing problems, you’ll be smart to take your car to a mechanic right away. 

Since it could lead to other problems with your vehicle and possibly put you at risk when on the road, solving the problem right away will help both you and your car.

Frequently Asked Questions (FAQs)

Can You Jumpstart a Car with a Bad Alternator?

Yes, you can jumpstart a car if it has a bad alternator, and chances are it will run long enough to get you home or to the nearest mechanic. However, if you leave the jumper cables attached longer than needed, this could damage your vehicle’s electronics.

Can I Drive 20 Miles with a Bad Alternator?

It may be possible for you to drive 20 miles with a bad alternator, and in fact you may be able to drive far beyond 20 miles. By turning off the non-essential electronics with your car, such as the A/C and radio, you can drive as many miles as the power within your car battery will allow.

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Zach Reed

Hi, I'm the founder of! Having owned a wide variety of vehicles in my life, I was astounded at how hard it can be to find answers to common automotive questions. Rather than sit idly, I decided to create this website to help others!