I'm also very confused about xenon headlights....now are these the ones i see on the new maximas...whenever i'm driving on the highway and i see a maxima or an acura tl or a beemer..and it hits a bump i see the headlights go from like white to purplish and stuff...they look reeli hot r those xenons? if so what r bi xenons...and do all the new ML's come with it? or is it that they just come with the new headlights but not the actual xenon bulbs but just a regular bulb....if someone can answer those questions...ill be less confused about all of this.
There are several things to know about automotive headlights. First, there are incandescent bulbs and high-intensity discharge bulbs. Traditional bulbs are incandescent, just like a standard light bulb in a lamp. They use the 12V electricity from the vehicle to power hard-wired filaments in them which glow. These bulbs are generally filled with halogen gas, which produces a nice bright light, but with a slightly yellowish tint (but less yellowish than older Argon gas bulbs). High-intensity discharge bulbs have no filament. Light is created by passing very high voltage through a Xenon-gas filled bulb, which creates an electrical arc. The high voltage is generated from a transformer attached to the vehicle’s 12V power supply. Fluorescent lighting in you home or office works similarly with a “ballast� to create the high voltage from 110-volt electricity.
Note that you can buy incandescent bulbs filled with Xenon gas, but they are not much whiter or brighter than halogens. Some incandescent bulbs are advertised as looking just like HID/Xenon lighting, even mentioning “color temperature�, but they are really just coated with a purplish tint. This will filter out the yellowish light and make them appear to cast a whiter light, but in reality, they will not be as bright as standard halogens because of this filtering.
Another part of automotive lighting is how the beam pattern is created. Traditionally, the bulb is aimed at a convex reflective surface on the back of the headlight housing. Light is reflected back through the lens on the front of the headlight that would diffuse it into the desired pattern. These are easily identified because you usually cannot see the bulb through the headlight lens because it looks foggy or patterned. Many newer cars don’t use a diffuser, but instead have a totally clear lens, using the shape of the reflector to create the appropriate beam pattern. In these headlights, the bulb can clearly be seen through the lens.
Some cars use projector lighting, which uses a small, thick lens (similar to that of a movie projector) to create the desired beam pattern. ML’s from 1998 through 2001 used a reflector with a diffuser lens. Projector beams are usually identified by small, round lighting lenses that often cast rainbow of light around the edges of the beam. This is likely what you see from oncoming BMW’s and Acura’s. Beginning with 2002, all ML’s use projector beams for the low-beams and clear diffuser reflectors for the high-beams.
While any of these reflector/projector systems can be used with either incandescent or HID/Xenon lighting, you can’t (i.e. legally) just stick an HID bulb in a housing designed for an incandescent bulb, or vice-versa. The reason is that HID lighting is so bright that it requires a different beam pattern to keep from blinding the drivers ahead. Usually, there is a very “sharp� cut-off of light at the top of the beam pattern for HID lighting whereas incandescent lighting has a more gradual “diffused� cut-off. Because of this sharp cut-off and bright light, some HID systems incorporate electro-mechanical leveling system to keep the beam level when vehicle angle changes due to bouncing, uneven loads, road conditions, etc. This is not a requirement in the US, but many manufacturers do implement these systems, as they are required in other countries.
High-intensity discharge bulbs take some time to warm-up before they give off their full lighting. Because of this, they were originally not used in high-beams because it was not convenient to have to wait on this warm-up cycle when you needed your brightest light. The high-beams used standard halogen bulbs. Bi-xenon systems actually use the HID lights for high-beams (although they still have an incandescent bulb for daytime flash-to-pass functions). They use projector lens systems that have a moveable baffle between the bulb and the lens. In low-beam mode, the baffle is lowered to create the sharp cut-off. In high beam mode, the baffle is moved out of the path to give a full beam pattern.
If you want brighter, whiter lighting, I suggest you get a set of bi-xenon headlights for your ML. You should be able to find them for less than $1K. If you have a pre-2002 model, you will need wiring harness adapters (which many sellers include), but otherwise they are an easy DIY. If you have a 2002+ ML, you won’t need any wiring adapters, but after replacing the headlight units, you will need the dealer to enable the HID option before they will work in your truck. I hope this answer all your questions!
- RODNEY
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