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LED Lights: Small Is Beautiful


In just about every new car that comes out, you’ll find LED lighting somewhere around it, whether it’s in the form of daytime running lights, the tail lights or the interior lighting.  Car manufacturers seem very proud of featuring LED lighting in the designs.  You might be wondering what all the fuss is about.  Is this just the latest fashion or is there some real advantage to having LED lighting in your car?

If you have ever started the day with a flat battery caused by leaving the headlights on or a door slightly open or even the passenger reading light on (i.e. all of us at some point), you will have discovered the disadvantages of the old style incandescent bulbs the hard way.  Ditto if you have ever had a bulb blow on you at a bad moment.  LED lights don’t blow anywhere near as often as incandescents and they also use a lot less power.  And that’s the advantages.

Let’s go back to basics.  What is an LED light, how does it work and why don’t they blow or use as much power as the invention credited to Thomas Edison? (Historical note: Edison didn’t so much invent the lightbulb as improve it and buy out the patent from the other guys working on electric lighting.  The first guy to light a building entirely by electric lights was the UK Joseph Swan. History lecture over.).

LEDs (light-emitting diodes) have been around for quite some time, having been discovered back in the early 1900s when scientists were starting to mess around with this new-fangled electricity stuff.  LEDs are semiconductors made from materials like gallium, selenium and good old silicon.  Skipping complex explanations about how all types of diode only allow electricity to flow in one direction, what’s special about an LED is that with only a tiny bit of electricity flowing through it (2–3 W), they start glowing.

For the best part of 100 years, LEDs weren’t particularly useful as they weren’t very bright. They lit up in dull red and you could see them glowing if it was dark but you couldn’t use them to find your way from A to B.  Other diodes were much more fun in the early part of the 20th century, such as the ones used in crystal (cat-whisker) radios.  In the 1960s, people started tinkering with computers and electronics, and found that LEDs were a good way of showing that a circuit was going.  They were pretty expensive at first but soon became mass produced and became more widespread.  You know those red numbers on timers and other whizz-bang gadgets in movies and TV shows from the 1970s and 1980s?  Ditto green lights?  Those are LEDs at work.

The fun really started when someone found a way to get colours other than red and green.  If the human eye picks up more or less equal amounts of the three primary colours of light (red, green and blue), this is perceived as white.  This means that if you shove a red, a blue and a green LED close together, it will look like a white LEAudi-led-lightD.  Make your semiconductors out of other materials and you get other colours, including actual white.   More tinkering around with refraction by various physicists around the world led to the production of a nice bright white LED bulb and the possibilities really opened up – about 100 years after the initial discovery of LEDs.

There are three reasons why LED lighting is popular for heaps of applications, not just in the automotive world.  Firstly, they use next to no electricity, so if you are in the habit of leaving lights in your car on, this won’t drain the battery overnight.  It also won’t put demands on your car for extra energy, which increases fuel efficiency (and is even better news for hybrid and electric vehicles).  Second, they last for ages.  Thirdly, they don’t waste energy in the form of heat.

There’s a fourth advantage, which is more to do with aesthetics: LED lights tend to be smaller, which means that they can be worked into prettier designs (Audi has some nice ones).  The fact that LEDs come in different colours also means that you can play around a bit with interior ambient lighting, which is also a lot of fun.

Work is still underway.  While LED lights have become bright enough to be used aroundr8-grey-rear-lights the home, as daytime running lights and as tail lights (HSV do this well), they haven’t got bright enough yet to be used as headlights… at least not yet.

LED, Xenon and Halogen Headlights

OK, so how do LEDs stack up against the other big two forms of lighting in vehicles, namely halogen and xenon?


  • Cheap
  • Common
  • Easy to make
  • Eventually blow themselves out
  • Use heaps of watts of electricity
  • Waste a lot of those watts in the form of heat


  • Really, really bright
  • More energy-efficient than halogens
  • Longer lifetime than halogens
  • Expensive to make
  • Take a little bit of time to reach full brightness
  • A tendency to dazzle oncoming drivers, pedestrians and cyclists


  • Don’t use much electricity
  • No waste heat
  • Last for ages if kept at the right temperature (i.e. cool)
  • Small size allows more scope fordesigners to make something beautiful
  • Not bright enough for headlights
  • Need to be kept cool, which can be a problem near a traditional internal combustion engine
  • Still a bit on the pricey side


  1. Sam says:

    You mention that LED lights aren’t bright enough to be used as headlights, yet a number of the major vehicle manufacturers are already using them in their headlights (eg. Mercedes-Benz, Audi, Lexus, and even some of the Japanese manufacturers) and they appear to be even brighter than Xenons.

    July 20th, 2016 at 11:07 am

  2. John says:

    Thank you for the informative articles

    July 20th, 2016 at 11:12 am

  3. Chris says:

    Thanks for the article. I didn’t know the history of LEDs, so your writing was very interesting. Oh, and I like the informality of your touch. I’ve written dozens of reports and books, so it’s not often I get to enjoy the style and language of articles. Thanks again, and Best Wishes.

    July 20th, 2016 at 12:34 pm

  4. Ken Frost says:

    You better tell Audi, BMW and Mercedes and several other car companies that LED are bright enough for headlights. The LED’s in my car are very good – better than the zinion in last car.

    July 20th, 2016 at 3:18 pm

  5. Megan says:

    Looks like I used older material for my research! Goes to show how quickly the field is developing.

    July 21st, 2016 at 8:40 am

  6. John A. Monk says:

    LED’s in my Mazda6 Atenza are” Bright & Beautiful ” and fully automatic ie switching themselves on and off dipping in on coming traffic turning on bends etc.

    July 21st, 2016 at 9:01 am