How Many Miles Will A Car Run Without An Alternator?

While electric cars don’t have alternators, this is an integral part of fuel-powered vehicles.

how long will a car run without an alternator

It ensures that the battery remains charged up so that you can start the engine next time and use other electrical components in the car. It’s like the power plant of your vehicle.

We will share with you details about the alternator in this article. How it works, tips, and tricks to keep it running properly for long. And will answer the question – will a car run without an alternator? Keep reading!

What is Alternator?

Simply, an alternator is a machine that transforms rotational energy into electrical energy. It is the part of your vehicle that keeps your car charged.

This small machine is connected with your engine through the serpentine belt. The belt rotates the internal components of the alternator which eventually generates electrical current. The current then recharges your car battery so that you can start your vehicle, run the headlights, and other electrical components of the car.

How long Do Alternators Last?

Generally, alternators last around 5 to 7 years or 80,000 miles to 150,000 miles. However, the lifespan can vary depending on several factors like the quality of the alternator, weather condition of the place you are driving the vehicle, how much load you are putting onto the alternator, etc.

Alternators in the older models last longer than the modern vehicle models. Because the newer models are equipped with different sensors, electrical components, and other add-ons that consume a significant amount of electricity. So, alternators remain in constant stress producing energy for your car.

On the other hand, older models barely come with any sensors. Those use battery power to run the lights and vehicle computer system only, in most of the cases.

Having said that, many modern vehicles also pass a decade without requiring an alternator replacement. So, it is very difficult to give an exhaustive verdict on this.

How Long will a Car Run Without Alternator?

The alternator generates electricity to power up your battery. So, how long will your car run without the alternator depends on the power remaining in your car battery. You will be able to drive the car for about 2 to 3 hours in the daylight, and about an hour in the night time with headlights on.

Let’s break down things a bit more to clarify the difference-

In the daytime, your car requires less power from the battery to run as the headlights are not in operation.

In night driving, you will need headlights, and interior lights to drive safely. So, the battery drains faster and you will get less time in the road without an alternator installed.

If your car alternator goes bad when you are driving the vehicle, you will get more run time than the situations where you want to start the vehicle without the alternator.

This is because your vehicle requires most power starting the engine. When the alternator is good at the time of starting the engine. And you have driven enough to recharge the battery before the alternator dies, you will get a lot more run time than mentioned above.

How to Know if Alternator is Going Bad?

Although car alternators don’t give many hints before they go bad, you can get an idea beforehand if you are aware of some of the symptoms that appear before the alternator dies. Such as-

1. If you are driving in low visibility condition and the headlight is turned on, then suddenly dimming the headlight is a significant sign of your alternator or the battery is dying.

2. If you are experiencing a delayed battery charge in your vehicle, it’s time to check the alternator. It may be the battery that is going bad or the alternator. Either way, you need to inspect to keep your vehicle up and running.

3. Short circuit or burn in the alternator is a common problem. If you smell electrical burn from the engine bay, act fast, and see if things are okay there.

4. If your alternator has died already, you may see the battery light turned on in the dashboard. The light turns on if the wire is disconnected or the battery dies. So, don’t panic before checking the actual reason for the illuminated battery light.

5. In some cases, you may get a check engine light warning in the gauge cluster because of a malfunctioning alternator. Use an OBD II tool to check the fault code. If you see P0620, it’s your battery or alternator that is malfunctioning.

6. Suddenly started to see the electrical components not working properly? Or maybe the radio or the dashcam stopped working? Either way, check the car power control module (PCM) to see if everything is working properly.

Tips to Keep Alternator in Good Shape

Here are some of the tips that should help you to keep the alternator in good shape-

1. Air-cooled alternators need enough airflow to run properly. Make sure the air vents are clean and open without any external dust and debris.

2. Alternators need to be mounted perfectly. Vibration in the internal components can damage the alternator. So, check regularly if the alternator is firmly in place or not.

3. Dust is an enemy to almost all electrical components. So, keep the alternator clean for a longer lifespan.

4. When we ask people to keep the components clean, they start pressure washing or degreasing the component. Don’t pressure wash or degrease the alternator. It will damage the internals of the alternator.


Without the alternator producing power to the battery, your engine ignition system won’t work. The battery won’t be able to provide enough electric power to the spark plugs to ignite the engine.

Plus, an air conditioner, headlight bulbs, and other accessories that depend on your car’s electrical system won’t work as well.

So, it is mandatory to keep your vehicle’s charging system up and running so that your battery remains in full charge when you start the engine next time.

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