Xenon Headlights

  • At a minimum, replace the "Xenon" bulbs with Halogen bulbs.

    The so-called "Xenon" bulbs aren't really Xenon.

    They're just regular bulbs coated so that the light looks more blue.

    Soapbox mode on:

    As a lighting designer I have to chime in after having seen the above quote one time too many.
    Firstly, Xenon is a halogen gas (one of eight if I remember my periodical table correctly, I may be wrong).
    Anyway, the point here is that the reason for using halogens in a filament ("Edison type") lamp is to allow a higher current and thereby a higher filament temperature together with heat resistant quartz glass bulbs.
    This higher temperature gives more light in the visible spectrum with more blue and less red.
    This goes for ALL halogen bulbs.
    Btw, it also gives a shorter lamp life span.

    "Xenon light" is the (slightly misleading) vulgar name for a metal-halide discharge lamp (HID type) as used in many high-end cars lately.
    These operate through the creation of an arc as the actual light source.
    This gives very much higher light output, both visible and some UV too.
    They are started by a strike of high voltage, then the voltage drops to 20-50 volts.
    The standard wattage for car arc lamps is 35W (thereby saving some power as well) but the light output can be compared with a 200W halogen bulb.

    Normally such a lamp 1) cannot be turned on while hot, and 2) takes a few minutes to light up to full strength from cold state.
    These problems are "bugfixed" with a special gas inside the bulb that "glows" during the first cold minute (that's why they change color after the first minutes) and by using a very high (25-50,000 Volts) strike voltage to light the hot lamps "no matter what".
    Also these lamps need high-precision reflectors since the light source itself is very small.
    This in turn, together with the high luminous flux, makes for the need for a self-levelling system to avoid blinding everybody you meet.
    All pretty expensive stuff even in high volume production, but great for the lighting factories.
    Great also for those of us who have these lamps on our own car.

    The problem with these systems is
    1) the environmental issues (the lamps contain mercury, cadmium and other heavy metals in gas form to light the bulb especially while cold)
    2) the problem of lens edge aberration due to the fairly cheap lenses used on most Xenon arc car lights.

    The "bluish" color (actually just daylight white) comes from the higher temperature in the short arc lamps compared to halogens, but also from the crappy lenses used.
    Cleaning of the lens is also an important issue unless it's sealed.

    What's my point? All this makes the short-arc Xenon-lights 1) expensive and 2) easy to identify.
    Those who cannot afford them naturally want to appear as if they had them anyway.
    In recognition of this market, some manufacturers (GE, Sylvania/Osram etc) make "fake" bluish color standard halogens (these bulbs are mostly Xenon filled anyway) with a dichroic color coating on the bulb glass.
    For an amateur they look like short-arc lamps (= expensive car = more girls on Saturday night).
    The luminous output is slightly higher than standard halogen lamps (+20% according to Osram) but it's a matter of perception (the eye is more sensitive to green light than to red).
    In short, the "blue Xenons" are just a sales trick aimed at young male drivers.
    For a more mature alternative, the new H7 lamps are a better choice - cheaper and with great luminous output.

    OK, I see now why my quote reproduced above is not strictly accurate.
    The fake Xenon bulbs are "standard halogens," but standard halogens have Xenon gas inside them.
    So speaking literally, the fake bulbs are "Xenon bulbs.
    " But as Mr.Holm points out, the fake bulbs are just bulbs.
    So even if you install them, your car will lack the electrical equipment needed to provide a "strike of high voltage [25,000 - 50,000 Volts] then [a constant voltage of] 20-50 volts.
    " In short, you may have Xenon BULBS, but you won't have a Xenon headlight SYSTEM.
    And the light generated by your headlights will LOOK brighter, but that's only an optical illusion.PMB

    There is a new very nice solution coming up, a retrofittable short-arc device with the strike unit and drive electronics built into the bulb base.
    Read all about it at http://www.sylvania.com/aboutus/pressrel/press/02212001.html and http://www.sylvania.com/prodinfo/auto/arckit.htm .
    I haven't seen the sealed retrofits in Europe.
    Who will be the first to fit them on an E31 in the US? I think they might fit instead of our 100W(?) front-grille lights which of course would look very cool.

    For anyone wanting to read more about lighting and bulbs, check out the best info site on the web that I've seen so far: http://www.misty.com/people/don/light.html

    Soapbox mode off .


    For those of you who have joined our number lately,
    you should know that Mr.Holm's knowledge of electrical circuit design and theory is unsurpassed.
    So he knows where of he speaks when he exposes the fake Xenon bulbs as the fraud that they are.PMB

    Magnus Holm

  • Now, that was verry intresting.
    What I wonder is this.
    I was at the IAA in Frankfurt 2003 and saw some pretty nice cars.
    Now, at the place where Audi was I took alot pictures from the Nuvolari and the Audi Le-Mans. Now the Audi Le=Mans had a really nice tail lights.
    What I was wondering is this. Is there any company in the world, that could redesign the taillights for a E31 for example using the same things and same huge led like the Audi Le-Mans has? Or if like new cars have those small leds? There should be something i guess. Costs doesn't mather, I am about to buy a E31 but I do that pure for modifications. Things like new cars have, Xenon lights, Led tail lights etc.
    So any info about this and URL's where to find info or redesigners would be really nice.


  • I seem to recall some posts from a guy on Roadfly that was investigating LED rear lights for his 850. Does anyone else remember that...it was maybe 6-9 months ago. I think it was maybe Fauxfont, but I wouldn't swear to it.

    Post a question on roadfly and see what you get.

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