How Long Does a Car Battery Last Without an Alternator?

The alternator is a generator in a car. In general, it distributes electricity to the car and recharges the battery. This tool is essential for a car battery. Without such, a car battery won’t last long. Now, the question is:

How long does a car battery last without an alternator? In general, the duration of your car depends on the capacity and condition of the car battery. For instance, if your battery isn’t ultimately charged, your car can run from 5 to 30 minutes. The runtime will be longer if you have a fully charged battery.

In this article, we’ll cover the essential things you need to know about the car’s alternator. This way, you can understand how it works and how to tell if it’s about to go out.

Without further ado, let’s get into it!

How Long Does a Car Battery Last Without an Alternator

How Long Will a Car Battery Last Without Alternator?

As I said earlier, the alternator is an essential tool for your car, and it won’t last long without it.

In general, your car would last only for around 5 to 30 minutes if your battery isn’t fully charged. It can be longer otherwise, but it won’t make much difference.

An alternator is that it provides power to the spark plugs that ignite the gas in the engine.

Its primary purpose is to keep the battery charged when the vehicle is running. Thus, any car won’t go far without it.

Another thing is that it helps the battery keep the electrical components charged.  Such things include the windshield wipers, headlights, and others.

In short, your car won’t likely have a chance to run long without the alternator.

Can a Car Run With a Bad Alternator?

A car may run with a bad alternator, but it’s not likely to run well and long.

As I said earlier, the alternator plays an essential role in the performance of the car’s power. Thus, if your car runs in a bad one, it won’t take long for a bad alternator to disrupt it.

For instance, a bad alternator won’t do well in charging the batteries and the accessories. Without these components, your car wouldn’t continue to run.

Thus, you’ll only have a few more minutes remaining if your alternator starts to break down.

Can a Bad Alternator Destroy a New Battery?

There is a high chance that a bad alternator can damage a new battery.

If you run your car with a bad alternator, it won’t do well even if you have a new battery.

This kind of alternator will cause a battery to lose its power because it charges the battery while a car is running. Thus, it will disrupt all your electrical systems in your car.

If it continues to give a disrupted performance, it will lead your new battery to wear out sooner rather than later.

To avoid such things from happening, you need to know the signs that your alternator is going out. This way, you can remedy the situation before it gets worse.


What Are the Signs Your Alternator Is Going Out?

Below are some signs that your alternator is about to go out:

Warning light indicator

Most vehicles have a warning indicator light on the dashboard with the label ‘ALT’ or ‘GEN.’ It usually has an icon with a battery shape. If it lights up, you may have an issue with your alternator.

If you see this logo light up, you shouldn’t ignore it. Doing so may result in an issue going worse if left unsolved. Thus, it may cost you more in the long run.

The alternator is easy to fix in the first stages. If you continue to ignore it, you may get yourself in a complicated situation.

Dim/Flickering headlights

Issues with the headlights can also be a sign of a failing alternator. If you see the lights brighten as the RPMs pickup and dims as it falls, then it’s a sign that you have alternator issues.

While it may genuinely be a problem with the lights or the bulb, it would be better to consider the alternator in checking to be sure.

Battery draining and dying

A dead battery can also be a sign of a failing or an already failed alternator. Still, it’s not always the case.

Thus, if you have a dead battery, it would be best to have the alternator checked as you replace the battery. This way, you can see if your problems aren’t linked.

Strange sounds in the car

Although strange sounds can be a sign of many car problems, it can often be hard to determine their origin.

Still, if you hear strange sounds with the issues above, it might be a sign of an alternator failure. 

Strange smell

Another sensible sign of a failing alternator is a strange smell under your hood. You can smell a few different things, but it may all be due to the alternator working too much and is about to overheat.

A smell of a hot wire or electrical fire smell probably comes from an overheated alternator. Whatever that smell is, be sure to check it out.

Slowed or bad performance from accessories

If you experience alternator problems, the accessories which rely on electricity often fail. Thus, a slow or inadequate performance of electronic accessories may tell you that your alternator is failing.

It is often possible to notice a pattern with this failure of equipment. You can do so with specific systems only, not working when you switch them on.

It’s all because they work in conjunction with other systems which draw on electrical power.

Regular stalling/difficult starting

If you often struggle with starting your car and if it stalls more often than before, then it might be a sign that your alternator is going out. Or worse, it’s already gone out.

When the alternator is failing, people usually notice that the car struggles to start. Or, it may even stall often.

Since the alternator does not charge the battery correctly, the battery doesn’t have enough power to start the car smoothly.

Frequent stalling may be a result of the spark plugs not getting enough power from the alternator. Thus, it fails to keep the engine going. 

While the car battery is not yet dead, it might as well be on its way.


In this article, you have seen the importance of the alternator. Moreover, you get the idea of how essential it is to the performance of a car. Without it, your car wouldn’t last for an hour running.

Another thing to note is that the alternator is quite simple to fix in its first issues. However, if left unchecked, it can lead to worse and complicated issues.

For these reasons, you must always check the signs of a failing alternator. Also, always include it in your things to check if you see some indications of it failing.

This way, you can avoid the situation from getting worse. Moreover, you can maintain your car’s health and performance up and well.


Image credits – Canva

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My name is Hank, and I've been in the automotive industry for 27 years. I've been working in my own auto repair shop for the last 13 years, and now I want to help you here, on my blog. Let me know if you have any questions. Read more