can some one tell me why my xenon headlights charge to a bright blue 3 sec after starting the motor and dim to a very pale yellow after about 15 sec. i cant see any thing at night without high beams. thank you.

 

You probably need a new bulb(s), I doubt it'sa ballast. I believe the are the d2s model.

 

ya what year is the car..model...be specific mine goes from nice blue the yellow...but i can still see....mabe your bulbs are bad...i think 4300k is stock lightbulb.. and they don't come cheap if your gonna buy new..upgrade to higher level..idk...6000k, 8000k make sure they are streetlegal color temps in your state, before you buy them though..DO NOT TOUCH THE BULB'S GLASS PART WHEN INSTALLING NEW ONE'S

[IMG]local://upfiles/24882/B96B3C9471494A379D202D98DE30F200.jpg[/IMG]

 

The stock 4300 d2s bulb is brighter that a 6000 or 8000 the lower the k the brighter the light
the highter the k the more color but less light

 

Right if you wanna get some new bulbs and want them a little bit more blue go with 6000k's they almost have the same range as the stock 4300k but IMO they look better.
You can actually get a pair of new ones for $25!!!! These come from China but i know several people that have them and hasn't really had any problems, and you can't beat the damn price!
http://www.vvme.com/catalog/list-s-10145-10147.html

 

This site doesent have DS2 bulbs for the 5 s4 are the listed as something else

 

Funny, my neighbor is using the H7 bulb on his 01 S4

 

H7 is a halogen bulb normally. Retrofit H7HID kits are availableThe high beams may take H7 I'm unsure. D2S HID style are for projector (ellipsoidal) housings and D2R HID are for reflector(free-form) housings. Is it possible your neighbor has aftermarket housings that use halogen bulbsor a retrofit HID kit?

 

not true... its liek a bell curve... the most output of light is just under 5000k. The temp (kelvin, k) is how bright it burns showing different colors..

 

i have OEM xenon german made d2s bulbs for sale.... see my sig.