How Long Does an Alternator Last?

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In this blog post, we’ll tell you exactly what you need to know about alternators; how long they last and what kind of preventive measures you can take in order to extend their life expectancy. We’ll also cover signs that it may be time to purchase an alternator replacement as well as when professional services are necessary. So if you’re ready, let’s get started on learning more about how long does an alternator last!

What is an Alternator?

An alternator is an essential component of every combustion engine vehicle, providing the energy needed to keep your car running. It converts chemical energy into electrical power so as to charge and rejuvenate the battery in addition to powering any other electric elements in a motorcar.

What Does an Alternator Do?

The alternator functions as a generator and uses the engine to send power to the car’s electrical system. This means that while the battery can provide power initially, once the engine is running it is the alternator that sustains its voltage and will eventually recharge the battery. A malfunctioning or worn down alternator can cause issues with starting and powering accessories like headlights, radios, and blinkers.

Signs of a Bad Alternator

No one wants to be told they need to get their alternator looked at, especially when the signs are still ambiguous. But here are some telltale signs that could point to a bad alternator:

If you’ve noticed your battery warning light is on or that your headlights or interior lights seem dimmer than usual, there might be an issue with your alternator.

Additionally, if you’re noticing a burning rubber smell from under the hood of your car, that’s another sign something is amiss.

Further indicators can include devices not charging when plugged in, a screeching or whining sound after you have started the vehicle, and even being unable to start the engine altogether.

If one of more of these ring true for you, it’s a good idea to get it checked out by a professional soon.

Failing Alternator vs Failing Battery

The signs for a failing battery and a failing alternator can appear to be similar. Both can lead to dim headlights or interior lights, however, the real difference lies in what happens when you try to start your car.

If your battery is on its way out, it won’t have enough energy left to turn the engine over — resulting in no sound or just a clicking noise when you attempt to start it.

On the other hand, if your alternator has failed instead of just your battery, you will still hear the engine turning but it won’t stay running as there isn’t enough power output from the alternator.

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How Long Does an Alternator Last

What Causes an Alternator to Go Bad?

An alternator is a hardworking device and requires regular maintenance to keep it in good condition. Over time components inside the alternator will degrade and wear out from frequent use, leading to an eventual failure.

Some common causes of an alternator failing include:

  • Age or Usage: Most of the time, alternators fail due to age or normal wear and tear.
  • Fluid Leaks: Engine oil or power steering fluid can work its way into the alternator, leading to failure.
  • Driving Habits: Spending a lot of time idling while using many of your car’s accessories can put the alternator under increased stress and cause more wear and tear.
  • Location: If the alternator is located near the bottom of the engine, it can be subjected to water and salt intrusion which can cause malfunction.
  • Loose Wiring or Bad Connections: Incorrect wiring or bad connections can disrupt the flow of electricity and cause the alternator to fail.
  • Broken or Worn-out Internal Parts: Over time, internal components can wear out or break, leading to alternator failure.
  • Lack of Proper Lubrication: Lubrication helps to reduce wear and tear on internal parts, so a lack of proper lubrication can cause the alternator to fail.
  • Corrosion or Build-Up of Debris on the Internals: Debris and corrosion can accumulate inside the alternator, leading to internal malfunctions.
  • Faulty Battery Cell or Diode: A faulty battery cell or diode can short out the system and cause the alternator to fail.”


How Long Does an Alternator Last?

The lifespan of an alternator depends on a few factors, such as the type of car you’re driving and how often you drive it. Generally, an alternator can last anywhere from 70,000 to 150,000 miles (110,000 to 240,000 km).

However, many people find that if they take good care of their cars – regularly changing the oil and performing maintenance checks – they can get more life out of their alternators. If your car is well-maintained then an alternator should last for at least 100 000 miles (160 000 km) or more.

Average Lifespan of an Alternator

When it comes to the average lifespan of an alternator, most mechanics say that they generally last between 60,000 and 100,000 miles (95,000 and 160,000 km). While this is a good estimate for many cars, some vehicles may experience their alternator going out earlier or later than this.

How Does an Alternator Work?

The alternator is a critical part of your car’s electrical system, powering almost all of its electronic components while you’re driving.

Not only does the alternator keep your headlights, steering, windows, wipers, and seats heated, but most importantly it charges your car battery while you’re in motion.

This efficient system provides direct current (DC) power by turning mechanical energy into electrical energy via an attached pulley and drive belt that spins a set of magnets around a coil.

This process generates alternating current, which is then channeled through a rectifier, converting that AC power into DC power and powering your vehicle’s electrical systems.

This means that the drive belt connected to your engine holds the key to successfully driving most cars!

Of course, general wear and tear is inevitable with any part in your vehicle, but heat damage, overuse, water exposure and faulty components are also common culprits of shortened alternator lifespans. 

How to Maintain Your Alternator?

In addition to being on the lookout for any warning signs, there are also some steps you can take to maintain your alternator’s efficiency and keep it functioning optimally in the long run.

  • Avoid an unexpected cost by knowing the correct way to jump-start your car – improper techniques can fry the alternator and leave you with a costly repair.
  • Make sure you don’t add too much tech to your vehicle – a massive upgrade could put serious strain on the alternator. Play it safe with any aftermarket electronics and measure twice before going all-in!
  • Be sure to have it inspected regularly and watch out for any fluid leaks coming from your alternator – it could be a sign that something needs attention!
  • A warning light or dim lighting in headlights may indicate a battery issue that should be addressed immediately. It could even turn out to be the alternator, not just the power source itself!
  • If you must purchase a new alternator for your vehicle, opt for a brand-new one rather than settling for “remanufactured” components.
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How Long Does an Alternator Last

How To Test Your Alternator?

Before testing the alternator, you should always check the battery and make sure it’s in good condition. Make sure to then inspect the serpentine belt, alternator pulley, and belt tensioner.

After this is done correctly, the last step is to use a multimeter to test the actual battery voltage while the engine is running.

It should read out between 13.5 – 15 volts throughout your test and during any engine revving. This will help ensure your alternator is in tip-top shape!

How to test alternators without multimeters?

  • If you need to test an alternator without a multimeter, there is still a simple way to check its functionality – inspecting the drive belt. A damaged or worn out drive belt can prevent the alternator from performing properly and should be the first thing checked. To ensure that your alternator is in good condition, feel the surface of the rubber material and look for any visible signs of cracking, wearing, or deterioration. If you find any such damage and suspect that it may be impairing your alternator, then replacing the drive belt should be enough to get it running again.


  • Understanding how to test an alternator without a multimeter is essential for anyone with a car or truck, even if you don’t consider yourself mechanically inclined. It might come as a surprise, but it can be done by simply performing a visual inspection of the alternator pulley. Check for any rust, accumulated dirt and grease, wear on the belt or any other damage that may have occurred to it over time. If any of these elements exist, this could mean that the alternator isn’t properly working, and needs to be serviced


  • It is important to check the alternator bearings for any excessive play. This can be done without a multimeter through visual inspection and careful listening. While looking at the alternator, ensure that it is securely fastened and there are no signs of damage. 

    Additionally, running your fingers over each bearing should help identify any grinding or catching that may signify too much play in the bearings. When washing an alternator, always be sure not to submerge the component in water as this could potentially cause bearing damage or failure.

  • One way to test alternators without a multimeter is to start the engine and disconnect the battery terminal. When this is done, the engine should continue running without any problems. If there are stalls or unexpected cut-outs, then this probably indicates that the alternator isn’t running at its peak performance, which could lead to more issues down the line if left unchecked.


  • If you want to check the alternator for proper functioning without using a multimeter, one option is to reconnect the battery terminal and then check the voltage at both terminals. If the reading is between 13.5 and 14.5 volts, then it means that your alternator is working fine. However, if the voltage is lower than expected, then it indicates that there’s something wrong with your alternator and it needs to be replaced immediately.

How To Replace Your Alternator?

Replacing an alternator can be a tricky process and requires special tools, so you’ll want to make sure you have the right equipment and know what you’re doing.

Tools you will need:

– Wrench set

– Socket set

– Ratchet (3/8” or ½”)

– Screwdriver

– Pliers

– Replacement alternator

Steps For Replacing an Alternator:

1. Disconnect the negative cable from your battery.

2. Use a wrench to loosen the bolts that secure the alternator in place.

3. Carefully take off the serpentine belt as well as any wiring harnesses connected to it. To ensure peak efficiency, you should replace it with a new one; properly looping and threading it in the same manner that it was removed from your vehicle.

4. Install the new alternator

5. Securely attach all wires, tighten bolts and clamps, then install the new alternator. Be sure not to over-tighten them though; it could cause strain on the belt and damage your machine.

6. Reattach the negative cable to your battery.

7. Test your alternator to make sure everything is working correctly.

Note: Always wear protective gloves when handling the battery to avoid electrical accidents.

What is the Cost of Replacing an Alternator?

The cost to replace an alternator will vary depending on the make and model of your vehicle. On average, it can range anywhere from $300-$700 with labor costs being around $100-200.

If you choose to purchase a remanufactured part, expect to pay less than if you buy a brand-new one. However, buying a new and more reliable component is generally the better option any day!


FAQs about How Long Does an Alternator Last? 

Do Alternators Fail Suddenly?

Yes, alternators can fail suddenly if they are not properly maintained. The most common cause of sudden alternator failure is a faulty or worn-out belt, which can lead to the alternator failing without warning.

Can a Bad Alternator Kill a New Battery?

Yes, a bad alternator can kill a new battery. If the alternator is not providing enough charge to the battery, it will eventually go dead despite being brand-new.

Can a Vehicle Function Without an Operable Alternator?

No, a vehicle cannot function without an operable alternator. The alternator is needed to keep the battery charged and provide power to other electrical components in the vehicle. Without it, your car won’t be able to run.

Can an alternator go bad in 5 years?

Alternators are remarkably durable and can often continue working for the whole lifespan of a car, particularly if it is fewer than five years old. Despite its intricate design, alternators have been known to last up to 100,000 miles or more with proper maintenance.

What wears out alternator?

The most common is poor maintenance, such as not replacing the serpentine belt or failing to check the battery regularly.

Alternators can also be worn out due to overloading, which happens when too many electrical components are running at once in the vehicle.

Excessive heat can also cause damage to the alternator, as can extreme temperatures that cause internal components to expand and contract.

Finally, vibrations from rough terrain or road conditions can also cause wear and tear over time.

When should you replace your alternator?

It is generally recommended that you replace your alternator every 100,000 miles or so. This can vary depending on the make and model of your vehicle, however, so it’s best to consult your owner’s manual for more specific information.


Thank you for reading! We hope this article was helpful in answering the question: “How Long Does an Alternator Last?”

With proper maintenance and care, your alternator can last for many years.

However, if you neglect your vehicle or do not regularly maintain it, your alternator will not last as long.

If you have any further questions about car maintenance or parts replacement, feel free to contact us. We would be more than happy to help!

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