Doug2.7

Anyone try using xenon fog lamps by tapping into xenon headlight ballast?

Said J. Macias

I can almost assure that if you do that, you'll burn the ballasts...

captainbilly

Ballasts are almost certainly designed to run just the bulb in the headlight. If you try to load them with 2 bulbs or the wrong bulb then they will be overloaded and fail or just not light the bulbs properly. It could be bad for the bulbs also.

You probably could use the ballast to light the same type bulb as the one in the headlight but not at the same time as when the headlights are on.

Doug2.7

so how could it possibly burn out the ballast unless I used both low beam and fogs at the same time? That is why I posted the question. I did short splice the fogs so they can work at the same time or separatly from the low beams so if I watch to ensure only the fogs are on, I do not see a problem but I do see saving about $425 by not buying the complete set, only the bulbs...

Said J. Macias

...those available at the stores are just normal ones (12v) with a blue coating in the glass that gives them that color; the real xenon bulbs doesn't have any filaments on the inside and won't work with 12v, instead they use ballast and transformers to achieve 20,000v at a very low current (they use only 1/3 of the current of a same luminosity halogen lamp). The ballasts included with them are perfectly matched to those bulbs in wattage, intensity, frequency and even temperature.

It's almost impossible, anyway, to find xenon fog bulbs without the bundled ballasts and, in the case you'd find them, hooking them to your low beam's ballasts and transformers could only result in a tragedy, a very sad one with your whole electrical system involved.

Best Regards and take care,

Said J. Macias

duodallas

There may be enough igniter voltage for the extra lamps, but immediately after there is a large current drain which would be greater than what the ballast was design for. You'll need another ballast to run the fog lamps, probably.

Bollinger

I think having long wires between the ballast and the bulb would cause problems. This is necessary for one ballast to service multiple bulbs.

Also, there is some kind of feedback from the bulb to the ballast which is used when lighting it up from cold, and that won't work if you have two bulbs hooked up, as they will confuse it.

2.7tDallas

Listen to him, he is "Mr. Lightsource"