1. Halogen BulbsThe principle of halogen light bulb is to turn enough current to heat the filament incandescent state, will emit light. Injection of iodine or bromine bulb halogen gases etc. at higher temperatures, evaporation of tungsten and halogen chemical effect, the evaporation of tungsten in tungsten will be re-solidified, forming a balanced cycle, to avoid premature rupture tungsten.
Most commonly used automotive halogen lamps models: H1 H3 H4 H7 H11 9004 9005 9006 etc.
H4 is a two-wick lamp, by changing the lightbulb light switch focus to achieve the distance, commonly use for high beam and low beam all together, that is only one reflector of car headlights. The high beam light and low beam light can not switch on at the same time, switch on the high beam light, the low beam light is off.
H1 H3 H7 H11 are single-wick lamp, only one wick to provide long distance or short distance light. For example: H7 are usually used in the low beam light, H1 is used in the high beam which is widely used for double headlight model, that there are two reflectors, one for low beam, one for high beam.
H3 H11 are usually used for automotive front fog lights.
2. OEM Xenon HIDXenon HID, full name is the gas discharge lamp, the same principles as nature lightning.
HID light principle: in the quartz tube, filled with a variety of chemical gases, of which a majority of Xenon with iodide and other inert gases, then through the ballast (commonly known as the AC adapter) to the vehicle 12 volt DC voltage instant boost to 23,000 volts, through the high amplitude excitation of xenon gas inside the quartz tube electronics free, between the two electrodes to produce light, this is called the gas discharge. When you carefully watch the light bulb, you will find the middle of a spherical glass ball on the inside is filled with xenon gas, and yellow is rare it! When the ballast to give 23000V high pressure, the xenon gas on the breakdown, after being ionized, the light output will beyond imagination.
Most common type of original car HID bulbs are D series. Such as D1S D2S D2R D3R D3S D4R D4S etc.
3. Aftermarket HID conversion kitsAdvantages: Easy installation, xenon lamp type selection corresponding to the original halogen bulbs.Cheap Price, between £30 to £120, depends on the quality and brands.
Disadvantages: As the aftermarket xenon conversion lamp can not take into account the design of each car lens and reflector which originally fit around a halogen filament bulb, so the beam pattern is bound to be inaccurate, to cause light divergence, there will be glare in some places and not enough light in other places within the beam pattern, even if you are using low beam light will affect the opposite carriageway.
Thanks for reading my guide!