Can a Car Run Without an Alternator? Risks of Driving with a Bad Alternator

Can a car run without an alternator? What are the risks of driving with a bad alternator?

If you’re wondering what the risks of driving with a bad alternator are or if a car can even run without one, then this is a post you need to read to the end.

Before we go into answering this question, I think it’s necessary that we know exactly what an alternator is and the role it plays in a car.

You see, a car requires a few things to run and one of those requirements is electrical power. Your battery provides the car with that electrical power, and as your car drains the battery of its electrical power, the alternator – which is an essential part of a car’s electrical system, does the work of recharging or replenishing that power being drained as you drive.

A car alternator can go bad as a result of overcharging or undercharging. One of the most common issues that affect it is insufficient battery charging. An alternator that provides poor charge to the battery will destroy the vehicle’s electrical components as time goes on.

Also, overcharging can affect an alternator even though it’s less common. It damages the battery and electrical system more if it is not fixed on time.

can a car run without an alternator

How Can You Tell When You Have a Bad Alternator?

1. Dimming of The Interior and Exterior Lights

As I mentioned above, an alternator recharges the battery which provides electrical power to the vehicle. If your alternator is not recharging the battery, then the battery won’t have enough power to actually keep your car’s interior and exterior lights bright enough.

If you notice that your car lights are dim, there are a few possible reasons for this but a bad alternator is a very common cause.

2. Dashboard Warning Light that is Associated With whe Alternator in Your Car

This would depend on the car because different cars use different dashboard warning lights. But I would recommend consulting your owner’s manual to see which dashboard warning light goes hand in hand with an alternator that’s going bad, or that is already bad.

With that being said, if you see that dashboard warning light, look into it further to see if it’s indeed the alternator because sometimes, dashboard warning lights can appear because there’s a problem with them reading the actual component. So they think the component is broken but in reality, it’s just the signal between the component and the light that’s broken.

This is why you need to look into it further before you automatically assume that the dashboard warning light means that you have to go replace your alternator.

3. Frequently Needing a Boost with Your Battery

Your battery provides your car with electrical power. So, let’s say you come to your car and realize that you need to boost the battery before you can start the car, and the boost powers your battery enough to start the car. But as you drive, your alternator is unable to charge the battery.

The next time you go to start your car, you need another boost because the alternator did not recharge the battery the previous time. If you constantly need a boost whenever you want to start your car, that’s a sign that your alternator is bad or is going bad.

4. Weird Electrical Issues

If you have any moving electrical parts of the car that suddenly start moving slower, this could be a result of a bad alternator or an alternator that’s going bad.

The reason for this is simply because, with these moving parts, if they don’t have enough power to move at full speed, they’ll move slower and this should let you know that you likely need to change your alternator.

5. Your Car Stalls or is Difficult To Start

If your car is stalling, that means there’s something that’s causing it to stall. There could be different reasons for this but your car basically needs a few things to run. These things include fuel and electricity. If your car can’t get that electricity, then it might be a problem with the alternator.

Can a Car Run Without an Alternator?

The answer to this question is yes. A car without an alternator or a bad alternator can run for a short period when it has a failed or bad alternator. And this is because the alternator is what charges the car battery when the engine is on and running.

Once the battery gets depleted, your car will die and will not restart until the battery is charged or you jumpstart the car with another battery.

Is it Safe To Drive a Car Without an Alternator?

When your alternator begins to fail and it has not entirely gone bad, then it’s okay to still drive your car for some time with a failing alternator.

However, when the alternator has completely stopped working, you’ll only be able to drive your vehicle for a short time before the vehicle stalls. Your car will not be able to ignite at all because your car battery would be dead due to the bad alternator.

Risks of Driving with a Bad Alternator

Driving with a bad alternator can lead to a number of issues such as battery drain, difficulty in starting the car, and damage to your car’s electrical components. We advise that you take your car in for repairs the moment you notice that the alternator is beginning to malfunction.

If your car has complete electric power steering, driving the car could be dangerous to you and those around you. It would be better to tow the vehicle to the mechanic.

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What Happens If You Drive Your Car With A Bad Alternator?

1. Loss of Power Steering

When driving with a bad alternator, it can cause your vehicle to lose power on the power steering wheel, which would mean you lose control of the vehicle. This is dangerous for you and other drivers.

This one is common if your vehicle is a newer car that comes with electrical power steering, and it means that a failed alternator while driving simply makes it lose all power steering.

In cases like this, please do not keep driving the car. It is best to look for where to park the car and seek a mechanic’s help.

2. Engine Overheat

Continuous driving with a bad alternator can cause your engine to overheat. This would in turn cause severe damage to your engine and other parts of the car.

Where’s the Alternator in a Car?

In order to find the alternator, you need to find the belt on the side of the engine because it functions when the engine is revolving. Once you find the belt attached to the engine, you should be looking out for a metal cylindrical component with some see-through spots on it that allow you to see copper coil inside.

How to Test a Bad Alternator

To test your alternator, you have to set your multimeter to DCV (DC Volts), and you’d want to set it to something above 15. Make sure the terminals on your battery are clean so you can get a reading when you do the test. Attach the multimeter’s black cable to the negative battery terminal and the red cable to the positive battery terminal.

Once this is done, you should be seeing a reading of 12.6 volts or something around that figure on the multimeter. It could be a little bit lower or a little higher.

With this in place, you can then start the car. If your alternator is running correctly and charging the battery perfectly, the multimeter should be reading between 14.2 volts and 14.7 volts. If you get a reading that is over 14.7 volts, it means that your alternator is overcharging the battery and that could cause damage to the battery. You don’t want that.

If the reading is below 14.2 volts, let’s say around 13.2 volts, that means the alternator isn’t charging the battery well enough. It might still charge it because it’s above the 12.6 volts magic number but it’s not going to be able to charge it when you run accessories like the headlights and radio. The lower the multimeter reading goes below 14.2 volts, the worse the alternator condition.

How to Tell Which is Bad Between the Alternator and the Battery

If you jump start your car and it comes on, but refuses to come on the next time you try to start the ignition, your alternator is likely the culprit. But on the other hand, if you try to jump-start the car and it refuses to start, then you may have a dead battery.

How Long Can You Drive With A Bad Alternator Bearing?

How long you can drive with a bad alternator bearing is really dependent on how far gone the problem with the bearing is or not. If the faulty bearing is in the early stage, you might drive for days, weeks, or longer even though there are risks you should have in mind as I have explained above.

If the bad alternator bearing is at its advanced stage, your vehicle might not even be able to drive at all because you may have already overstretched your early-stage driving warning limit.

And if you continue to drive the car in this condition at this advanced stage, it is very risky. It can lead to engine overheating, smoking, and finally, permanent damage to the alternator. This will prevent the car from powering.

Bad Alternator FAQs

What Happens if Your Alternator Fails While Driving?

Your radio system and lights will shut off. Your brake light, airbag, ABS, and EML lights will all show up on the dashboard. Even your turn signals will stop working if you try to use them. Within a few seconds, your car will start misfiring really badly and then stall.

How Far Can You Drive if Your Alternator is Bad?

You can only drive as far as your available battery power can take you. If the battery was well charged before the alternator failed, it may get you far enough to a mechanic as long as you don’t put off the car at any point.

Can a Bad Alternator Affect Transmission?

Yes, a bad alternator can affect your transmission. Once your alternator fails, it stops charging the battery and as a result, you’ll notice that your transmission gears will fail to shift correctly. This can also cause other serious symptoms.

How Does a Bad Alternator Sound?

A bad alternator makes a whining sound that almost sounds like a power steering pump going out. Another telltale sign you’ll get is the burning smell.

Can a Bad Alternator Drain Battery?

Yes, a bad alternator can drain your battery if the diode that converts the electricity going into the battery from AC to DC goes bad and causes the electricity to flow back into the alternator instead of its usual one-way flow into the battery.

Can a Bad Alternator Cause Misfire?

Yes, a bad alternator can cause a misfire if the failure happens while driving. It is one of the major symptoms of a bad alternator.

Will a Bad Alternator Cause a Loss of Power?

Yes, a bad alternator will cause your car to lose power while driving. This will be followed by warning lights like your brake light, ABS, and airbag showing on your dashboard.

Can a Bad Alternator Damage the Engine?

If left for a really long time, a bad alternator may cause your engine to develop problems. However, this would be an extreme case.

Can a Bad Alternator Cause Stalling?

Yes, a bad alternator can cause stalling if the failure happens while driving.


So, can a car run without an alternator? The simple answer is yes. But not for long. It is also a very risky thing to do especially if it’s a car with an electrical power steering.

A car with an electrical power steering would lose its power if it has to run without an alternator, and this would be dangerous to the driver and people around.