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WAM is right. (more) (archive)

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Posted by DHoang on January 15, 2000 at 06:45:52:

In Reply to: Re: Xenon-type headlights posted by WAM on January 15, 2000 at 04:31:35:

: The xenon bulbs are not the same as gas discharge xenon bulbs.
These disco bulbs selling for $30-40 have xenon gas filled inside of a regular tungsten or halogen type lamp that operates off of your regular 12v. THe Xenon changes the color temperature from 1700-3500Kelvin up to 5000kelvin giving the bluish tint.

: They are filled with xenon gas and are claimed to be 30% brighter than stock halogen bulbs.

Unless you have actual lamp data to compare to, I would pass this off as snake oil. THe perception is that because the color temp has now shifted to the blue /white spectrum, instead of the ordinary yellow / white spectrum, that there's an increase in light output. In almost all cases, there are NO CHANGES in light output, measured in Lumens or Candelas.

I fitted them to my mom's car, just for the extra brightness. There is a slight difference when you look at the headlights, one with halogen and the other with xenon, but probably not 30%.

Chances were that the slight differences you perceived came from comparing an OLD lamp against a fresh & NEW lamp. One problem with Halogens & incandescents is that (with the very short lamp life hovering at around 500 hours), at 200 hours, or 40% of its life, your light output drops by 50%. So a used lamp is not producing the maximum light output but rather only 1/2 light output at that juncture. So depending on whether your lights had been used as daytime running lights or not, YOu're burning up your lamp hours far quicker than if you are using your lights only at night. ANd light output for tungsten halogen as a function of time has an almost linearly descending slope curve

: The 'real' xenon bulbs are gas discharge type, ie. they do not have a filament but an arc is created between the two electrodes, thereby providing the illumination.

Absolutely. The gas discharge type requires more than just a neg. and pos. wire connected to the prongs of the lamp. In between the metal halide lamp is an ignitor to step up the 12v to
a very very high voltage (I don't recall the value off hand) to zap ignition between the arc, a transformer then takes over to maintain the desired voltage (and this will not be 12v, but a designed voltage) for thermal efficiency, and a capacitor to stabilize the entire circuit in case there's power demand elsewhere in the circuit.

: I am afraid that you are going to have to change the whole ballast system. The $1000 seems a little low, people have quoted something like $2200 on this board but that may have been E39 prices.

: : I have a 91 M5 and I am wanting the Xenon headlights. Someone told me you need to change the whole ballast to get the Xenon lighting.. but Pep Boyz or Track will sell Xenon bulbs. What is the difference in changing the whole Ballast?
: : Has anyone ever tried these Xenon bulbs? Changing $40 worth of bulbs beats doing $1000 worth of ballast work.
: : Thanks!
: : Matt
: : 91 E34 M5

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