How Long Should Headlights Last?

Headlights on a car in a field
Headlights all burn out eventually, but if yours keep going out, there might be an underlying problem. konradlew/Getty Images

Question: How long should headlights last?

I don’t know how long the first set of headlights in my car lasted, but it was a long time. Then one burned out, so I just replaced both to be safe, and one of the new ones burned out really fast. Way faster than the originals. Maybe I got lucky with the first ones, or maybe I got some bad replacements. But now I’m wondering if these new replacement headlights are going to burn out fast too. How long are headlights supposed to last?

Answer:

Halogen headlights typically last somewhere between 500 and 1,000 hours, but there are a lot of different factors at work. For instance, replacement halogen bulbs that are significantly brighter than the OEM bulbs usually don’t last as long. Certain manufacturing defects and installation problems can drastically shorten the operational lifespan of a headlight bulb as well. There are also other types of headlights that tend to last longer than halogen.

How Long do Tungsten-Halogen Headlights Last?

There’s a good chance that your car shipped from the factory with halogen headlights, since that’s what most cars use. Halogen headlight bulb capsules, in use since the 1990s, are tremendously widespread, and even sealed beam headlights designed for older vehicles are built around halogen bulbs.

The actual filament in a halogen headlight bulb is tungsten. When electricity passes through the filament, it heats up and glows, and that’s where the light comes from.

In old sealed beam headlights, the headlight was either filled with an inert gas or a vacuum. While this worked fine for many years, the longevity of these pre-halogen tungsten bulbs suffered due to the way that tungsten reacts to being heated up to the point where it emits light.

When tungsten gets hot enough to emit light, material “boils” off the surface of the filament.

In the presence of vacuum inside the bulb, the material then tends to get deposited on the bulb, which effectively shortens the operational lifespan of the headlight.

Modern tungsten-halogen bulbs are very similar to much older sealed beam headlights, except they are filled with halogen. The basic mechanism at work is exactly the same, but halogen-filled capsules last much longer than they would if they were filled with an inert gas or vacuum. This is primarily due to the fact that when the tungsten filament gets hot and releases ions, the halogen gas collects the material and deposits it back onto the filament instead of allowing it to settle on the bulb.

There are a few different factors that can affect the operational lifespan of a halogen headlight capsule or sealed beam headlight, but a typical operational lifespan is somewhere between 500 and 1,000 hours. Brighter bulbs tend to last a shorter amount of time, and you can also purchase bulbs that are specifically engineered to last longer.

What Causes Halogen Headlight Bulbs to Fail?

As halogen bulbs age, and as you use them, they eventually start to give off less light than they did when they were new. This is normal and expected, but there are also a number of factors that can cause a halogen bulb to stop working much sooner than it should.

When you’re dealing with halogen capsules, which most modern vehicles use, the biggest cause of premature failure is some type of contaminant getting on the bulb. This can be as innocuous as the natural oils from the fingers of the person who installed the bulb, or as obvious as dirt, water, or other contaminants present inside the engine compartment of a car.

While it is extremely easy to replace most headlight capsules, and you can do so with very basic tools, or no tools at all, it's almost as easy to damage a bulb during installation. In fact, if any contaminants at all are allows to get on the exterior surface of a halogen bulb, it’s a pretty safe bet that the bulb will burn out prematurely.

This is why it’s so important to be careful when installing a halogen capsule, and to attempt to remove any contaminants that accidentally get on a capsule prior to installing it.

In the case of sealed beam halogen headlights, they are much more robust and harder to damage than capsules. However, breaking the integrity of the seal is still an excellent recipe for early failure. For instance, if a rock hits a sealed beam headlight, cracks it, and allows the halogen gas to leak out, it’s going to fail much earlier than it would have otherwise.

How Long do Xenon, HID, and Other Headlights Last?

Xenon headlights are similar to halogen headlights in that they use tungsten filaments, but instead of a halogen gas like iodine or bromine, they use the noble gas xenon. The main difference is that unlike halogen bulbs, where all the light comes from the tungsten filament, the xenon gas itself actually emits a bright white light.

Xenon can also effectively slow the evaporation of material from a tungsten filament, so tungsten-xenon headlights typically last longer than tungsten-halogen bulbs. The actual lifespan of a xenon headlight will depend on a number of different factors, but it’s actually possible for xenon headlight bulbs to last over 10,000 hours.

High-intensity discharge (HID) headlights also tend to last longer than halogen bulbs, but not as long as tungsten-xenon bulbs. Instead of using a tungsten filament that glows, these headlight bulbs rely on electrodes somewhat similar to spark plugs.

Instead of igniting a mixture of fuel and air like spark plugs, the spark excites the xenon gas and causes it to emit a bright, white light.

Although HID lights tend to last longer than halogen headlights, they don’t usually last as long as tungsten-xenon bulbs. A typical life expectancy for this type of headlight is about 2,000 hours, which can, of course, be shortened by a number of different factors.

What to Do About Broken, Burned Out, or Worn Out Headlights

Although headlight bulbs are often rated to last hundreds (or even thousands) of hours, real world considerations usually get in the way. If you find that a headlight bulb burns out very quickly, then there’s always a chance that you may be dealing with a manufacturing defect. It’s more likely that some type of contamination got on the bulb, but you may be able to take advantage of a manufacturer’s warranty anyway.

Headlight bulbs from major manufacturers are often warrantied for 12 months after the date of purchase, so while you may have to jump through hoops, there’s a good chance you will be able to get a free replacement if your headlights fail within the warranty period.

Before you replace your burned out headlights, it’s also a good idea to check the headlight assemblies. Since any contamination on the bulb can cause it to fail early, a worn out or damaged headlight assembly can definitely be a problem. For instance, if a rock punches a small hole in one of the assemblies, or the seal goes bad, water and road grime may be able to get inside the headlight assembly and drastically shorten the life of your headlight bulb.

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