What is HID?
HID stands for High Intensity Discharge Lighting which is also known as Xenon lights. Unlike conventional headlamps with a filament, HID lights consist of a high voltage ballast and a gas filled Xenon bulb. An electrical arc passing across this gas produces a very bright light very similar to the color, often referred to as temperature, of daylight. HID lights are very efficient, require almost half the energy required to produce more light. HID Xenon lights are used in sports venues for this same reason. This light is very intense and illuminates road signs and markers very well. Drivers in oncoming traffic can be blinded by these HID lights if not properly aligned.
Xenon/HID Conversion Kits
HID lights were once considered a high end option that was only available on high end luxury vehicles from the factory. However, technology and manufacturing efficiency have made them more broadly available. Kits have been available in the aftermarket for several years which allow one to convert their existing headlights to HID units using original headlamp housing. These kits contain a Xenon filled bulb, a starter, an electronic ballast, and a wiring harness. The Xenon bulb fits in place of the original light bulb and connects directly to the electronic ballast, which needs to be mounted remotely in the engine compartment near the headlamp housing. The factory headlamp harness then plugs into the starter which is connected to the electronic ballast. Many kits now integrate the starter and ballast together which makes for a cleaner and more reliable install. The ballast and bulbs must be matched together, since the voltage and power ratings bust be paired together, otherwise the system may fail prematurely or potentially overheat and melt the headlamp housing. The ballast regulates and controls the voltage and current between the starting and the operation phase of the bulb.
HID Temperature and Color
The color of light is measured and expressed in degrees Kelvin (K). The color spectrum ranges from a red to purple. HID headlamps do not have this wide of a range though there are different bulbs that skew toward either extreme. Most are more focused on the center of that range.
4,300K is the temperature that is closest to natural daylight. Factory HID headlamps are setup for this color temperature. Conventional Halogen filament bulbs are yellowish which is equivalent to a 3,300K temperature. 6,000K has a bluish tint and temperatures above that are increasingly blue shifting to a purple tint.