TRS Tech

Technology: HID Bulbs Explained

HID bulbs have a capsule filled with a mixture of noble gasses and metal halide salts. The ballasts send a startup current through the bulb, which arcs across two electrodes on each side of the capsule, creating light. HID bulbs have a very long lifespan of around 2500+ hours, compared that to a standard halogen bulb, which generally only lasts around 300 hours.

HID headlight bulbs are available in a number of different types and kelvin ratings that we will describe below.

Types

D2S

Used for projector-based HID headlight setups. The most common type of HID bulb. (S stands for Shielded, as in the "cutoff shield" inside the projector)

D2R

Used for older reflector-based HID headlight setups. (R stands for reflected)

D2C

"Universal" HID bulb that can be used in reflector or projector based HID headlights. Only produced by aftermarket manufactures.

D1S/D1R

Similar to the D2 series bulbs in that "S" denotes for projector use, and "R" denotes for reflector use. The main difference compared to the "D2" series is that the igniter is integrated into the base of the bulb. The igniter is built into the bulb here instead of being part of the ballast system. Newer than D2S/D2R, but still not as common.

D4S

An entirely new generation of more environmentally safe HID bulbs. These bulbs are 100% mercury free, and are marginally brighter than their predecessors. They require special ballasts designated for use with D4 style bulbs. Designated as "XenEco" bulbs by their manufacture; Philips.

Kelvin Ratings

3000K

Has a golden yellow output perfect for use in fog lights. The yellow light penetrates through snow, rain, and fog more effectively than white or blue light.

4300K

Has a slightly off-white output similar to that of sunlight. All cars that come equipped with HID headlights from the factory use 4300K bulbs. If you want the most usable light, 4300K is the kelvin rating for you.

5000K

A pure white output, no tinge of yellow, and no tinge of blue.

6000K+

As you move into the higher kelvin ratings, your light output will appear more bluish-purple in hue, but the bulbs wont be physically as bright.

As HID bulbs age, they go through what is known as "color-shift". When the bulbs are brand new, the output is whitish-yellow and as physically bright as it will ever be. As the bulbs age with use, their output turns more pure white/bluish and also starts to dim a bit. That's why cars with factory 4300K bulbs that are 5+ years old look like they're running 5000K or higher bulbs.

We commonly get customers looking for high kelvin [ie 6000K] bulbs because they want their headlights to be "brighter". There is a huge misconception here. As the Kelvin rating of a bulb increases, its Lumen rating decreases. Simply put: 4300K bulbs will put more usable light on the road compared to 6000K, 8000K, 15,000K bulbs. Period, end of story. TRS refuses to sell anything higher than 6000K because 1) We don't cater to obnoxious "enthusiasts" who want their headlights to look like a Christmas tree, and 2) it starts to defeat one of the main purposes of the headlight upgrade: better light output.

Furthermore, choosing a high-kelvin bulb doesn't guarantee you'll get the exotic color flicker effect that everybody lusts after. The effect is produced entirely by the projector and lens combination. Visit TRS Tech for more on Clear Lenses.

When choosing a bulb from TRS, it does not matter whether you are using low beam or bi-xenon projectors. Unlike halogen headlights, with bi-xenons, nothing happens to the bulb when the high beams are activated. It does not get any brighter or shift positions. Simply put: you don't need "low beam" or "bi-xenon" specific bulbs. Our S2K-R low beam projectors and FX-R bi-xenons both use "D2S" bulbs.

It is also important to note an important difference between OEM and low quality aftermarket bulbs. The positioning of the capsule inside the projector is crucial to get a focused beam pattern without any uneven hotspots. All OEM bulbs have precision-set glass tubes to ensure the output will be in focus, whereas the aftermarket ones without the metal support structure are often mis-aligned inside the projector, causing a blurry cutoff line and other awkward shadows in the beam pattern. Here, our high-end Morimoto bulbs perform on par with the quality Philips units with their aligning metal base frame.

Our recommendation for retrofitters

The Morimoto D2S bulbs offer the most bang for the buck. They're available in a variety of K ratings to suit everybody's tastes, they're precision aligned for a nice crisp beam pattern, and they use a special mixture of halide salts to give them intensity and longevity on part with the OEM's. 35w Philips 85122+ D2S bulbs are the standard today for most OEM applications from auto makers such as Infiniti or Acura. They have the most lumens, great reliability, and you can still get a ton of color flicker with them despite their 4300K color temp. No question the Philips bulbs are extremely high quality, but ultimately you end up paying more for the brand name in the end versus a real marginal increase in quality.