Re: Halogen to HID
let me try to share a little of wat i know:
2 methods of generating light: from bulb:
1. filament
2. arcing
1 filament
this is like the orange bulb we use at home. most headlight bulbs used in cars now have halogen gas filled to generate better lifespan, and brighter light from the burning filament, thus giving it the name: "halogen bulb". Light color usually is yellowish due to its basically a filament burning
2 arcing
uses 2 electrodes and form a high voltage to cause 'arcing' (works a little like lighning) thus the light is very intense. very white in color. this give it the 'high intensity discharge' (HID) name. the gas used in such bulbs is xenon, which explains also that these are usually referred to as 'xenon bulbs'.
the good thing abt these bulbs is that there's no filament, so nothing reali wears out much, so putting it onto automotive use is good, since the road vibrations has no effect on the light, unlike filament (halogen) bulbs where there is mechanical vibration stress that slowly wears out the filament, over and above the 'burning' of the filament.
another obvious good thing abt the xenon lights (or HID lights) is that its veri nicely bright n superduper cool looking.
however this type of lighting requires a combination of specific reflectors (and sometimes lenses) to focus the beam to form the proper lighting pattern \__ \__ (in case of right-hand-drive cars).
It is this reason that the reflector/housing/lense assembly for the xenon/hid lights are very different from those used for filament (halogen) bulbs,. due to these have very differnt light dispersion (due to their nature of light generation...)
also due to its high intensity, its mandatory for cars throughout the world to have auto-levellers built-in to avoid the light angle to be too high to blind other road users.
so, xenon/hid bulb inside a halogen housing is definitely not legal, nor recommended, as your light is very likely scattered all over the place, and you're not getting proper illumination. if mixing xenon/hid buldb in halogen housing, the illum pattern (especially how far the light can throw) might actually be even worse off than using halogen...
just my 2 cents...