How Long Does an Alternator Last?

Your alternator is a vital component in your car. It recharges your battery, using engine power, and it also delivers power to your car’s electrical components. Essentially, it keeps the battery from losing charge, and of course if your battery dies, your car is simply not going to work.

You ask a lot of your alternator these days. In times gone by, it didn’t have to do much more than just power your headlights, and a few accessories like your radio. But think about all the accessories your car comes with today – entertainment systems, for instance, use up a lot of power, and then you probably also have on-board navigation, power windows, power mirrors, and perhaps even heated seats. All these “extras” need to receive power from your alternator. So, your alternator works every day, from the moment you start up your car until you turn it off. And if your alternator is failing, you will need to replace it.

Many factors can affect the life of your alternator, so it is difficult to say how long you can expect it to last. It will not usually last the life of your car, though. For one thing, the alternator’s rotor spins on a needle bearing, and this is a component that can break due to wear, or a buildup of dirt. The diodes in the voltage regulator can also fail, and engine heat puts strain on the alternator. Generally speaking, you can expect your car alternator to last anywhere between 40,000 and 100,000 miles.

Signs that your alternator is wearing out include:

Loss of power to various accessories when your car is idling
Dimming headlights
Dimming dashboard lights
ALT or GEN light is on
If you notice any of these symptoms, you should have your alternator checked. A professional mechanic can diagnose the problem with your alternator, and replace it if necessary.