Quick information on HID for cars
 

Purpose: Understanding and purchasing HID (High Intensity Discharge) technology for your car.

Question: Everyone has been awed by the infusion of those blue headlights found on some popular high end model cars such as BMW, Lexus, Audi, and Mercedes. The question is: How do you get them for your car?

Background: Unlike the popular belief, Thomas Edision didn't develop the light bulb, but he developed a PRACTICAL incandescent light. There's three types of headlight technologies: Halogen, HID and LED (LED we'll leave out for now)

Everyone should know what standard halogen bulbs are. These are the common bulbs that Edison made famous. There are multiple issues with these bulbs. First, they are only allowed to be so bright as to prevent blinding other drivers. Second is their beam pattern. Light is scattered and not really focused on the road in front. Finally is lifespan. Bulbs burn out frequently because they are still filament based.

Then there’s HID (High Intensity Discharge) technology. People has called them Xenon as well but that just refers to the gas they are using. We normally see HID lamps in the form of mercury vapor and sodium vapor lights used as street lamps and as outdoor lighting for stadiums. These lamps are popular because they are efficient. In the case of sodium vapor, they are twice as efficient as normal fluorescent bulbs. The problem with that technology is that there is a long startup time for mercury vapors. Xenon helps solve the start-up problem, as does a special controller (ballast). HID solves the problem of bulb lifespan but what about beam pattern and making the light brighter? I’ll get to that after some more history lesson

...read the full guide with pics here