What are xenon and LED car lights?

Many modern cars come with xenon or LED lights, and, in some cases, both. But what are they?

Words by: First published: 1st October 2018
In the world of headlight technology, things move pretty quickly, but people don't really notice. Traditionally, you got halogen headlights and nothing else, but today, there are loads more options, including xenon and LED lights.
What are xenon lights?
Despite the name, these aren’t actually ‘xenon lights’. Technically, they’re metal-halide lamps that also contain xenon gas. When you turn them on, they take a little while to reach full brightness, and the xenon shortens that time by giving a minimum light straight away.

You may also read about Bi-xenon lights, but the only difference between those and plain xenon lights, is that bi-xenons use xenon lights for both full and dipped beam.
How do xenon headlights work?
In contrast to traditional bulbs, in which a filament glows in a gas when an electric current passes through it, xenon lights have two electrodes, and they ‘charge’ the gas between them. That’s what gives off the light. And, that’s why you may also see lights such as these referred to as HID (High Intensity Discharge) lights.

The result is a white-blue light that is between two-three times brighter than a halogen bulb. That means not only does it light the road further ahead, it also gives better visibility in the dark and in poor weather conditions.
What are the advantages of xenon?
As well as the better light, xenon lights also use less energy, and because they have no filament to wear out, they are longer-lasting. In some cars, they also come with automatic height adjustment to align the lights to suit the load the car is carrying.
Are there any disadvantages to xenon?
Xenon lights are more costly and complex than traditional halogen bulbs, and that means they tend to be limited to more expensive, top-end cars. They can also only be replaced by a qualified technician, whereas a traditional halogen bulb can be changed by anyone.
What are LED lights?
We’ll spare you the full scientific details about how LEDs work – it’s something to do with electrons, photons and electroluminescence – but the result is a unit that produces a very white light.

However, each LED itself is very small, so what looks like a single bulb on a car is made up of many small LEDs. For that reason, car designers can also sculpt the necessary array of LEDs into fancy shapes, which is giving them scope to create exciting looks for their cars, especially with daytime running lights (which are lights automatically on when a car is driving to increase visibility).
What are the advantages of LED lights?
As well as producing a whiter light than a halogen bulb, LED lights use much less energy (which leads to better fuel consumption and lower emissions) and last much longer, because there are no internal parts to wear.

However, as with HID lights, one of the main issues with LEDs is that they cost more than halogen bulbs.
Related topics:
Car jargon explained