What Is the Lifespan of an Alternator? | Autance

Here’s where all that juice comes from.

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What Is the Lifespan of an Alternator? | Autance © What Is the Lifespan of an Alternator? | Autance

You probably realize that your car’s battery is an important component. Your car’s battery is responsible for all of the Inspector Gadget-approved devices in your ride. There’d be no tunes, no fancy safety mechanisms, and no headlights without a battery to power it all. What you might not know, however, is that the battery is only half of the equation with your car’s electrical system. The alternator plays just as important of a role as the battery’s, if not more so.

The alternator is slightly harder to diagnose and replace than a battery, but not by much. Car Autance’ editors have had their fair share of both battery and alternator problems and are here to help you get started with as few shocks as possible.

Let’s get rolling.

An alternator. Depositphotos

What Is an Alternator and How Does It Work?

Once the battery provides starting power for the vehicle, the alternator recharges the battery to provide power for the vehicle’s electrical components using energy from the engine. The alternator itself is a component that’s a little bit bigger than a softball in most vehicles. It has electrical coils and a rotor inside the housing to generate electrical flow. It is typically run by a pulley and the serpentine belt.

The alternator’s job is also to provide charge to the battery. Because batteries are only able to output power, they aren’t very good at staying charged while powering everything else on the vehicle.

How Long Do Alternators Last?

In general, alternators last a long time, but that’s not always the case. Depending on how the vehicle uses its electrical components and how much juice is required to operate everything, the alternator could last as long as 100,000 miles or more, or may start to fail at 40,000 miles. That’s why it’s important to be aware of how a failing alternator behaves.

Symptoms, Causes, Issues of a Failing Alternator

As your car’s alternator starts to exit the building, a few things will start to happen:

  • Various electrical components may start to lose power.
  • The vehicle may not start, or may not stay running after a jump-start
  • Headlights may dim
  • tereo systems may not work.
  • Climate systems may stop blowing.
An alternator. Depositphotos

The Car Autance Glossary of Alternator Terms

Welcome to Autance School.


Batteries provide power to start vehicles, as well as for all of the electrical components that are needed to keep them running and performing safely. Traditional internal-combustion vehicles use 12-volt batteries.


When a vehicle’s battery loses its charge for one reason or another, a jump-start can help it gain enough power to start the vehicle. Jump-starting requires the use of another vehicle and its battery and a set of jumper cables. Once the vehicle is jump-started, the alternator might be able to recharge it back to normal use.


Voltmeters measure electrical potential and can help identify power issues in a vehicle’s electrical system.

  • OBD-II

OBD, or on-board diagnostics, is the system through which a vehicle monitors itself and reports issues. The OBD system generates codes that correspond to specific problems, which can be read using a code tool.

The Car Autance Questionnaire

Car Autance answers all your burning questions.

Q: Is It Dangerous To Drive With a Bad Alternator?

A: Assuming it’s even possible to keep the vehicle running, it’s extremely dangerous to drive with a failing alternator. Driving a vehicle with headlights that blink on and off, or one that has trouble stopping properly because the braking and steering components don’t have any power is less than ideal.

Q: How Much Does It Cost To Replace an Alternator?

A: Remanufactured alternators are much more affordable than brand new ones. In general, they can be swapped in to replace a failing alternator for $300 to $500. Your mileage may vary wildly, and it’s important to remember that the price includes labor, which is generally the most expensive part of the process.

Q: Can I Change the Alternator Myself?

A: Absolutely! Just make sure you’re comfortable working with belts and that you have a good sight line on the alternator’s location. Many vehicles’ alternators are easy to see with the hood up, but some are buried under various other components.

Video on Alternators

It can be hard to figure out the best tools and products to help you diagnose and repair your car’s alternator problems. That’s why Car Autance’ editors have grabbed a few of their favorites to get you started. They include Mechanix Work Gloves, Veepeak OBDCheck Scanner, and the Crescent 170-Piece Tool Kit.

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