How long do alternators last? When and how to have them replaced?

Updated Mar 11, 2021 | Same topic: Automotive FYIs

So, how long are alternators good for? Well, it depends. 

In a more general sense, an alternator is defined as a generator that converts mechanical energy to electrical energy. In relation to cars, an alternator is used to charge the battery and power the numerous electrical components inside a modern car. Contrary to what many believe, a car’s battery isn’t the primary electrical power source, instead, it is the alternator.  

How Alternators Work - Automotive Electricity Generator

With that said, the alternator is one of the most important parts of a car. Without it, the car will instead tap the ultra-limited supply in the battery. And guess what, a car without an alternator cannot charge the battery, and therefore cannot start once again after shutting off.

A picture of a car's alternator.

A typical car's alternator

So, how long do alternators last?

To answer the question of how long alternators are good for, be aware that the alternator is a more “solid” or more “permanent” piece of equipment than a car’s battery. According to many sources (mechanics), a typical alternator’s life expectancy can last you somewhere between 5 to 8 years. Then again, this depends on how one uses the vehicle. The more you drive, the more wear and tear is incurred after all.

A picture of a Toyota Corolla.

Most older cars will have older parts so take this into consideration as well 

While that might be the case, there are some other components that might affect the alternator’s performance. Say for example the wires leading to the battery from the alternator and vice versa. These are somewhat exposed to the elements and might get damaged in the long run, especially for heavy car users. There’s also the fusebox and the hundreds of terminals that might need cleaning, replacement, etc. When these go bad, they can affect the alternator’s effective operation.

>>> Related: 5 simple steps to get your car alternator checked in proper way

What are the factors that affect alternator longevity?

As we’ve said, there are many things that will affect how long alternators will last. The biggest of course is the usage of the car. If you live in places like Metro Manila, Cebu, Davao, etc., and drive daily, then your car’s parts including your alternator will get wear and tear faster. 

A picture of heavy traffic

Regularly driving through heavy traffic can incur heavier wear and tear on a car

Another, of course, is the quality of the parts making up the alternator. Also, cars from reputable brands with large and accessible dealership networks are able to properly service their customer’s vehicles and supply individual parts that will certainly have longer lifespans. 

When should you have your alternator replaced?

If you’re the type of car owner who has experienced starting problems before, then you’ll know that it can be tricky to tell whether it’s the battery or it’s the alternator that’s going bad. They have the same symptoms when they fail after all. As we’ve said before however, batteries tend to go bad before alternators. But if your car won’t start and you know your battery’s still good, here are the most common symptoms of a failing alternator:

  • Check alternator light. Usually presented as “ALT” or “GEN” icons. 
  • Flickering headlamps when idling and are brighter when revving. 
  • A dead battery.  
  • Strange sounds from the engine bay. Have another person rev the car while you determine the source of the noise.  
  • Also, strange smells can indicate burning alternator components, wires, and belts. 
  • Car runs fine after push-start – your alternator’s good. Car starts fine but eventually shuts off – it might be your alternator. 
  • Remember that a car also won’t start if something’s wrong with the starter. 

A picture of a car's starter.

Don't forget to consider that your starter might be the real culprit

>>> Related: Will a dead and dying battery destroy your cars’ alternator?

How does one replace an alternator?

Before talking about actual parts replacement, do note that most mechanics with “formal” and “standardized” training will say that one cannot repair and service an alternator’s individual parts. Here in the Philippines however, our “manong” mechanics are essentially mechanical necromancers who are able and skilled enough to restore a diode pack or even entirely rewire an alternator stator. If not, the guy might have lots of spare parts just lying around. So yes, do approach these mechanics first before buying an entire alternator. It might just save you some money.  

To start, make sure that you brought the right alternator for your car. There are many resources for these online, but if in doubt, you can always consult your car’s dealership or a mechanic for the proper price in the market, how long the alternator will last, etc.

A picture of a pile of alternators

There are a lot of alternator types with varying specifications out there

>>> Related: How to test an alternator without a multimeter

Next, make sure to park your car in a flat and well-lit area. Please remember to allot some time for the car to cool down, and remember to use wheel chocks (kalso) and to set your park to “park.” 

After that, disconnect the car battery. Remember to start with the negative side first. If possible, wear a pair of gloves. 

Locate the alternator. Usually, it’s around device with a fan, pulleys, and a belt. It is also positioned close to the engine. If you found it, we advise you to loosen the belt first, then the alternator bolts afterward.  

After disconnecting the alternator from its mounts, you can then remove the electrical connections positioned behind the alternator. After that, set it aside. This can get confusing so we advise you to label these connections.

A picture of the rear of a car alternator

The wires behind a typical car alternator 

Also, if you’re replacing the alternator, it might be a good idea to replace the alternator belt with a new one as well. 

Finally, just reverse these steps to install the new alternator. Don’t forget to tighten the alternator belt. You can then test your new alternator by reconnecting the car battery starting with the positive side and then start the car. If you hear any weird noises or if it doesn’t start at all, recheck your work, especially the wiring behind the alternator, and see if you forgot anything. 

Now you know how long your alternator will last, how to know if it needs replacing, and how to replace it. For more handy car maintenance tips, keep reading here on   

Cesar G.B. Miguel

Cesar G.B. Miguel


Cesar Guiderone B. Miguel was born and raised in Iligan City, Lanao Del Norte. He graduated in 2010 with a Bachelor of Arts in English degree from Mindanao State University - Iligan Institute of Technology. He previously worked as a freelance writer for various websites, as a member of the Iligan City Disaster Risk Reduction Management's training staff, and as a medical sales representative.


View more