Some replacement halogen bulbs are also significantly brighter than the OEM bulbs, and that increase in brightness usually translates to shorter lifespans. Certain manufacturing defects and installation problems can also drastically shorten the operational lifespan of a headlight bulb as well.
How Long do Headlights Last?
There are several different broad categories of headlights, and one of the main differences between them is how long they can be expected to last.
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 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 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 a vacuum inside the bulb, the material then tends to get deposited on the bulb, which effectively shortens the operational lifespan of the headlight.
Changes in Halogen Headlight Technology
Modern tungsten-halogen bulbs are 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 inert gas or vacuum. 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.
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 arc is normal and expected. 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 problem 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 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 allowed 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 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 example, 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. 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 example, 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.
