let there be (head)lights!

Automobile Lighting Technology
(Part 1: Standard Bearers)

By P Sanchez

​There was a time when the only kind of light bulb that automobiles had was the incandescent.  Yes, the incandescent light bulb, the same kind that you now only see as an emoji icon for “idea”. Modern production methods of the last century made the incandescent light bulb cheap and reliable enough for the masses and it enjoyed decades of ubiquity as a primary electrical lighting source, including headlight bulbs for cars of yester-years

But its design changed little since the days of Thomas Edison and even with its last iteration, the incandescent light bulb is still relatively inefficient in converting electricity to light, with most of the energy wasted in heat. By today’s standard, the typical incandescent light bulb’s soft yellow-tinted glow is only good for setting a romantic ambiance to an indoor space, and not so good for lighting the evening highway.

But it’s almost 2020 and we’re closer to the perfect evening driving vision with the advancements in headlight bulb technology. We got choices now, three types of lighting, in fact, differing in performance and cost. We’ll go through each of them and by the end, you can hopefully determine which is best for you.

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Crash Course

Just a needed quick explainer on how modern lighting works: With incandescent bulbs, electricity runs through a filament which is a metal conductor, usually made of tungsten, that had been drawn thinner than a human hair. This is important because the thinner the conductor is, the easier it is to heat-up with electricity and the brighter it’ll go. 

To prevent the filament from burning out, it’s either sealed in a vacuum chamber or filled with an inert gas such as those in the household light bulb. But incandescent bulbs don’t last because the filament eventually breaks due to fatigue from prolonged exposure to rapid temperature changes, as well as gradual vaporization of the metal filament because of the high heat.

Hot Halogens

Needing a brighter and more reliable light source, automobiles have adopted the halogen type light bulb.  In fact, halogens have been the standard for road vehicles for at least the last 50 years. 

Halogens are technically under the incandescent family as they still heat up a filament to produce light. The difference is that the special filament used gets even hotter and brighter than regular bulbs. So hot that a lot of the material of the filament vaporizes. To keep the filament intact, it’s encased in a halogen gas environment like bromide and iodide using a quartz crystal capsule. In this environment, the vaporized metal redeposits back to the filament.

How good are halogens? We’ll have to talk about Lumens, the standard unit for brightness, Watts (W), a measure of energy, and color temperature (K). To put it in simpler perspective, a 100 W incandescent bulb which is bright enough to light a large-sized bedroom is rated at 1600 Lumens. A halogen bulb can do the same brightness at only 72 W. Typically halogen light bulbs for automobiles consume around 55 W and do about 1100 to 1500 Lumens at best. 

Halogens are more expensive than incandescent bulbs but cheaper than the two other new lighting technologies that are to be discussed. 

Like regular incandescent light bulbs, halogens exhibits a yellow-hue light (3000K) and though they last longer and shine brighter than ordinary incandescent bulbs, they still don’t compare in performance and reliability as with the next two lighting designs.

HIDs, They’re Intense!

Sometimes referred to as Xenon bulbs or arc, HIDs (High-Intensity Discharge) lights don’t use any metal filaments that could burn-out, like those in incandescence and halogen lights. Instead, HIDs make high voltage electricity jump between two electrodes (not unlike a sparkplug). The electrical arc energizes the encased inert gas (usually xenon gas) into a glowing plasma, resulting in a more efficient light production compared to halogens. 

How good are HIDs? For the same wattage of a typical halogen bulb for cars (55 W), HIDs can easily double the Lumens to 3000. They have a cooler bluish-white hue (5000-8000K) and cooler operation, therefore longer service life than halogens. Most HIDs have service lives rated around 2000 hours.

HIDs are more expensive the halogens but they are more expensive too. They also take time to warm-up making them incompatible for high-beams, require special ballasts to run on higher voltage, and their blinding brightness has had some states ban their use.

Next Time

For the last installment of this two-part series, we’ll take-on what’s becoming the new standard in automobile lighting: LEDs. How do they work differently from Halogens and HIDs and are they worth upgrading to? And hopefully, we’ll be helping you make an informed choice on your next car part purchase.