let there be (head)lights!

Automobile Lighting Technology
(Part 2: The New Player)

By P Sanchez
​
Last time, we discussed the traditional types of headlight bulbs, the incandescent bulb of classic cars, halogens – the current global standard, and the high-performance HIDs of the last decade. But there’s a new technology that has been implemented virtually everywhere that needs light generation: from smartphone and flatscreens, to indoor and portable lighting, and of course, headlights. we’re talking about LEDs.

---

The New Kid on the Block.

Light Emitting Diodes are the latest and fastest proliferating lighting technology.  Unlike incandescent and halogen bulbs that heat filaments to glow, and unlike HIDs that need high-voltages to initiate a plasma, LEDs convert electricity directly into light in a low-energy process called electroluminescence. And it’s all part of the modern wonder of semiconductors.

How does it work? Without getting too heavy on the science, the core material in a diode has what’s called a p-n junction. One side of this material has a decidedly electron charge, the other has positive “holes”.  When a suitable voltage is applied to the material, electrons move across to the positive and recombine with the holes. This change in energy states in the particles releases photons – light!

Cool trivia: technically diodes release only high-energy light. In the color spectrum, high-energy (or technically: high-frequency) light is in the range of blues. But how do we get all those different LED color varieties? The diodes are also packed with fluorescent materials that absorb part of the high-frequency light and give off their own light but at a lower-frequency (yellows and reds). By varying the type and amount of fluorescent materials determine the color of the LED.

Currently, LED bulbs for headlights are still more expensive than halogen and HIDs but as global LED production grows, prices continue to drop year after year.

How good are LEDs? For the same brightness that HIDs make (approx 3000 Lumens at 55W), LEDs can do at less than half the wattage consumption, or brighter at 4000 to 12,000 Lumens at the same 50+ wattage consumption. LEDs also have a slightly bluish hue (6000 K) by default but as previous explained, color can be baked-in, with even some LED bulb designs capable of switching between different colors. 

Additionally, LEDs robust design (no fragile filaments or hermetic glass encasing) and high energy-conversion efficiency (low energy requirement, low-heat byproduct) make them the longest lasting of all lighting bulb types.

Other than the cost, current LED bulb replacement has one design flaw. Most headlight housings are designed to reflect light coming from an omnidirectional light source such as halogen bulbs. This is not the case with a lot of current LED bulb designs which the individual lighting units themselves are directional. LED bulb designers attempt to get a more omnidirectional performance from LEDs by orienting multiple units around a shaft. However, there are still a lot of poorly designed aftermarket bulbs that cause uneven and unusual light scattering.

So Many Questions
​
The big question is, which lighting technology is the best for your car, go OEM with halogens, install extra brights with HIDs, or try the latest LEDs? 

Wanting to upgrade to something “fancier” is a personal decision and you can do what you want with your money but if you’re looking for more practical reasons, consider these:

Are your current light bulbs busted or have somehow weakened (just make sure it’s not an electrical problem with your car).

Are you planning to keep your car beyond the service life of a basic replacement bulb?

Do you live in an area where there’s often foul weather and poor visibility?

Do you do a lot of night time driving?

Does the market have bulbs of the type you like but meant exactly for your car make and model?

Are you doing the installation yourself? Consider ease of installation.

Have you checked your local regulations for headlights?

And lastly, just remember: it’s always good to consult with a qualified mechanic at your local car repair. It’s not often you have to change the bulbs of your headlights. In case you do, you may also want it done right.