LED headlights are pretty common, but some new cars still come with older tech. So, what is an LED headlight, and should you replace your old ones?

LED is an acronym for Light Emitting Diode. They are very common all over the place, from kitchen cabinet lighting to torches and car headlights.

The big advantage is that for the same brightness (measured in Lumens), LEDs are more energy efficient than regular light bulbs and also last longer. We’ve known this for a long time, but until recently they couldn’t produce sufficient amounts of light for use in either automotive or general household lighting applications.

LED headlights 101:

  • LED headlights are replacing traditional light bulbs in cars due to their energy efficiency and longevity.
  • LEDs work by passing an electric current through a semiconductor, producing light through a process called electroluminescence.
  • LEDs offer benefits such as brightness, energy efficiency, minimal heat production, and natural-looking light.
  • LED headlights originated in motorsport, with Audi being one of the first to adopt them in road cars.
  • Retrofitting LED headlights to a vehicle not originally equipped with them is most likely not legal, but in some instances if it keeps within ADRs it might be. LED light bars and driving lights are also legal options if installed correctly.

How does an LED headlight work?

Light Emitting Diodes (LEDs) don’t contain a filament, like an incandescent lightbulb, that can burn out, and they don’t heat up much. Having been around almost 50 years, you would think they’d have taken over traditional bulbs long ago, but it is the recent ability to use them to produce white light that has pushed them into use beyond basic electronics.

Due to the lack of bright light applications for the last 40-odd years, LEDs were introduced as brake lights and indicators on vehicles before they could be used in headlight or household applications.

To keep it simple, an LED creates light when an electric current is passed through a p-type semiconductor to an n-type semiconductor. This p-n junction is where the magic occurs. Essentially, as the electrons move from one post to the other (and they can only move in one direction) they lose energy, becoming photons of light. Thus, the more energy that’s lost in the transfer, the more light (photons) that’s produced. This production of light is called electroluminescence. The colour of the light produced also depends on the semiconductor material used. Each material has a unique ‘colour recipe’ determined by its bandgap, which decides the energy needed for electrons to jump from one level to another. This jump emits light of a specific colour.

The great thing about LEDs is the lifespan is around 50,000 hours, they require little energy to power them and they don’t produce any heat. And the light produced is very white.

To road cars via motorsport

Like a lot of automotive innovations, the arrival of LEDs as headlights in road cars came via motorsport. The ability to create white light with an LED was discovered in 1995 and Audi became the first manufacturer to make use of the lighting innovation on its R18 endurance racer in 1997. This development eventually filtered down to the R8 Coupe supercar, becoming the Matrix Bean LED lights.

Since then, the popularity of LEDs for taillights, indicators and headlights has boomed. And motorsport continues to be a testbed for LEDs. In 2017, BMW announced it would be using special glasses fitted with blue LEDs to enhance its endurance driver’s alertness and boost their concentration. This stems from the fact that blue light messes with the circadian rhythm by tricking the body into thinking the blue light is early morning light and so it should be awake. We know tablets emit blue light which is why makers have now created blue light filters to ensure the circadian rhythm of those using tablets to read at night aren’t being ‘stimulated’.

What are the benefits?

LEDs produce much brighter, cleaner light than other types of lighting, they’re smaller, they don’t produce heat as a by-product of light, and they require much less energy to power them than conventional lighting sources. Thus they offer energy and fuel efficiency gains.

More than this, the white light produced by LEDs is very close to natural light causing less eye strain/fatigue, and in fog they produce less glare. And the projection of the light beam exceeds that of conventional lighting sources.

LED headlights in the real world

More and more carmakers are beginning to fit LED lighting to their vehicles, but it was Audi that led the charge. The 2004 A8 offered LED daytime running lights, the 2008 R8 had all-LED headlights, but it was the 2013 Audi A8’s Matrix LED headlights that hinted at the potential of the technology. This set-up sees LED clusters set inside reflectors and controlled by a camera mounted on the windscreen.

Flick the headlight controller to ‘automatic’ and with the high-beams on, the system will activate beyond 30km/h. According to Audi, “As soon as the camera on the windshield detects other vehicles or city limits, the controller switches off individual LEDs or dims them in 64 stages, creating several million possible light patterns. The Matrix LED light masks out other vehicles while continuing to fully illuminate the zones between and adjacent to them.

“The LEDs in the Matrix LED headlights also assume the function of cornering lights, shifting the focal point of the light along the curve. This occurs shortly before the wheel is turned, based on predictive route data provided by MMI navigation plus.”

The latest generation Audi A8 which was recently launched in Australia heralded the latest-generation of the system, called HD Matrix LED high beam. In each headlight, there are 32 LEDs that can be controlled individually. The LEDs are arrayed in two rows with the low beam also offering variability.

Can you fit LED headlights to your vehicle?

Most likely not. If your vehicle didn’t come with LED headlights from the manufacturer, then you’re out of luck. This hasn’t stopped LED conversion kits from flooding the market in Australia with the fine print on just about all of these websites and catalogues reading, “the LED retrofit light cannot legally be installed in on-road vehicles”. That won’t stop them from selling them, though, and there have been instances of driver’s being booked after having retro-fitted LED headlights to their vehicles.

However, you can fit things like LED light bars and additional LED driving lights, but they must be fitted in particular spots on your vehicle to be compliant, and they must only be able to be turned on when high beam is activated and they must automatically switch off when high beam is turned off. You can read more about LED lightbars HERE.


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Practical Motoring

The team of journalists at Practical Motoring bring decades of automotive and machinery industry experience. From car and motorbike journalists to mechanical expertise, we like to use tools of the trade both behind the computer and in the workshop.

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