Modern Headlight

Your source for information for the latest in automotive headlight technology and trends

Modern Headlight - Your source for information for the latest in automotive headlight technology and trends

Focus On HID Headlights

Have you ever wondered what are HID headlights?  In this segment we’ll focus in on exactly what HID headlights are and how they are different from other types of headlights on the market today.  HID stands for  high intensity discharge.  The great thing about HID headlights is that they produce more light at much lower power consumption when compared to halogen light bulbs.  HID bulbs work by vaporizing metallic salts in the presence of xenon gas.  Similar technology is used mercury vapor street lamps.  The main difference is that argon gas is used in street lamps causing the light output to increase very slowly.  It is the xenon gas that allows the HID bulbs to produce high light output immediately and increase the light output as the headlight comes to full temperature.

HID headlights need to use ballasts with an ignitor.  Some systems have the ignitor integral to the bulb itself while others have a standalone ignitor component or as part of the ballast.

The process the create light in HID headlights can be broken down into three phases.  First high voltage pulse is introduced to create a spark.  This ionizes the xenon gas which allows conduction to occur between the electrodes and current begins to flow between them.

Next, the temperature rises rapidly due to the high power needed to create the electrical arc between the electrodes.  At this point the metallic salts contained in the bulb begin to become vapor.  The resistance then decreases and the ballasts now switch to operate in its continuous mode.

Once continuous mode is reached the arc is in its most stable shape and is operating at peak efficiency.  Depending on the type of system that is being used you will either have an operating voltage of 85 volts alternating current, D1 or D2 system, or, as in D3 and D4 systems, 42 volts AC.

There are several types of burners available for HID headlight systems.  The tend to use about half the wattage required for halogen headlights but offer about two to four times the amount of light measured in lumens.  The various burner categories are designated by a code.  The codes are broken down into components that describe the configuration of it.  For example, D2S would discharge (D), be second generation (2) and have a shielded capsule.  Another example, D4R would discharge (D), be fourth generation and have a reflective capsule.  The main difference between the R and the S is that the reflector ( R ) has ceramic paint around the bulb for use in a reflector headlight housing.

That is a basic rundown of the technical properties of the HID headlight; now let’s discuss some advantages and disadvantages of using this headlight technology.

The most important reason that you would use a HID headlamp is greater night time visibility from the increased light output compared to halogen headlights.  Since xenon headlights create brighter and more usable light.  We all know that more usable light means safer night time driving because you can more easily identify obstacles ahead with less strain on the driver’s eyes.

Another advantaged when comparing xenon headlamps to halogen is the longevity of HID lamps.  On average your xenon bulb is going to outlast a halogen counterpart by 100-400%

The major disadvantage is possibly causing oncoming drivers to have their vision temporarily impacted.  Because of this it is imperative that you have your HID headlights properly aligned to ensure that the majority of your light is being focused on the road ahead rather than into the eyes of oncoming traffic.  I have written an article that explains how to properly focus your headlights for their most safe operation.  Please read that article on how to align your headlights.

There are many HID conversion kits available for cars that did not initial come with HID headlights.  Because many expensive and desirable cards use HID headlights a HID conversion kit is a way for you to give your car a more distinctive look by adding HID headlights.

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