[Sowellman]

Quote: Originally Posted by popey (original)

I thought Bi-Xenon's where better than Xenon's????????????

They should be better. Bi-Xenons use a shutter that on low beam moves between the bulb and the lens to block off a portion of the light. On high beam, the full intensity gets used.

Regular Xenon lamps only work on low beam. When the high beams are switched on, the system reverts back to a halogen bulb.

Rather than using a filament, Xenon produces light through a gas. It requires the use of alternating current rather than DC. That requires the use of a ballast and a high-voltage start up to transform the DC into AC, providing additional power for lighting. The light spread is greater and the output is about doubled.

Xenon and bi-Xenon lamps put out a "whiter" light that is closer to daylight and is supposed to be better for folks who have more trouble driving at night.

A halogen bulb is still required, though, to allow for the flash function.

[Tigger, Eeyore & Roo]

Quote: Originally Posted by Sowellman (original)

A halogen bulb is still required, though, to allow for the flash function.

That's what I thought, so where is it on the R56?

Tigger.

[mikeythemini]

Never saw one, wonder if they wil flash the fogs instead???

[Tigger, Eeyore & Roo]

Quote: Originally Posted by mikeythemini (original)

Never saw one, wonder if they wil flash the fogs instead???

Aren't they mounted so low as to be illegal for that purpose?

Tigger.

[Bilbo Baggins]

Quote: Originally Posted by Sowellman (original)

Any ideas on whether bi-Xenon headlights provide any better cutting power in fog vs. conventional lamps?

Cutting thru fog has nothing to do with higher power, or "whiter" light, and everything to do with light pattern. A proper fog light has a very flat topped pattern that is very wide to help you see the sides of the road in dense fog. When I say dense fog I mean fog that severly limits your visibility to under 50 meters/yards. This is when fogs should be used.

Under these conditions the high beam light pattern disperses too much light up and generates more reflection from the fog or even snow and extremely heavy rain thus causing more glare, reducing your ability to see. Real fog lights are placed low, usually below the bumper, as popey correctly pointed out. The wavelength of light also plays a part in the amount of reflection. The shorter the wavelength the greater the preceived reflection. Whiter light and colors approaching blue are progressively shorter and shorter. During the 1950s ralley drivers discovered that light in the yellow range had less reflection in fog thus the yellow fog lights.

The use of high beams in fog is never a good idea. The added power and poor pattern cause greater glare.

The low/dip beam of the Xenons has a much flatter topped pattern than the halogen and should be somewhat better. The added power and whiter light should not interfer. But all said, the fog lights set below the bumper are better.

[Deutsch]

Quote: Originally Posted by Olly. (original)

Agreed Xenons are £700 on the golf GTI

Funny, they're std. here on U.S. models.

[Sowellman]

Here's a good explanation on bi-xenons:

http://murmini.com/articles/2006/12/13/xenon-headlamps