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I wanted to provide something for the members here that would explain a little more about HIDS in general. Todd came through for me, more then I could have asked for.
Thanks to Todd (RSX-CT) for putting together this awesome detailed thread on HIDS - I hope this helps everyone learn more about hids and what they need to do, etc. I also hope it's answers any questions you guys might have.
Please keep all comments/questions ON TOPIC and in relation to HIDS - others will be deleted out. Thank you!
The objective of the following is meant as a one stop source of information regarding the use, technology, and purpose to the use of high intensity discharge (HID) xenon lighting systems. There is a LOT of misinformation and myth mixed in with the true information on the forums. The following information is meant to quell the myths and half-truths as much as possible as well as provide a basis for the uninformed to learn about HID. It is meant specifically to be a very easy read, in lay language. If some parts seem vague, it is to avoid confusion. Any diagrams here are just representations that are not necessarily to scale.
PART 1: The Basics (“Knowing is half the battle”)
What is it and why is it better?
I think just about everyone knows HIDs were first used by car manufacturers as OEM and that is where their increasing aftermarket interest comes from. But what is the drive for a manufacturer to use them as OEM? Quite simply they realize the benefits of using the new technology to create better vehicle lighting systems with a much higher level of equipment longevity. Be aware that 90-99% of the aftermarket “kits” out there do not fall into the same qualifications as the OEM equipment, so comments about quality and specification may not apply.
OEM HID arose out of the need for better lighting and alleviation from the limitations of older incandescent halogen bulb technology. Halogen technology has its limitations in achieving increases in output. Minor increases in luminous output (brightness) require a decrease in longevity of the bulbs and the byproduct of heat. Anyone that has used aftermarket higher wattage bulbs knows that they typically do not last very long. However, today’s newer cars that are still equipped with halogen systems the apparent focus has been on improving the optics rather than increasing the output of individual bulbs. Halogen’s major drawback is the fact that it requires a thin filament to produce light to convert electrical current to heat and light. Cars take some abuse in performing their task and bulb filaments eventually fail in part due to vibration.
HID alleviates the filament issue, because, as I will cover later, they do not use filaments at all. The HID bulb (appropriately called a capsule or a burner) has the benefit of producing approximately three times more lumens without the drawbacks of using a filament. The issue of vibration is therefore removed from the equation allowing the bulbs to be incredibly hardy as a light source. OEM bulbs and ballasts are meant to perform as “life of car” parts, meaning they should not experience failure under normal use for the natural life of your car. In most cases they will last until after you trade, sell, or junk your car.
There is also a benefit in the color of the light produced by HID lamps over that of conventional halogen bulbs. A couple things need to be said about correlated color temperature first, as it is rather difficult to explain in lay language. The degree Kelvin that color hue is correlated with does not indicate in any way to the operating temperature of our source. The correlated color temperature scale simply relates the color hue of light produced from different sources to one benchmark, a super heated block of carbon. What is important to know is that we can relate the scale to daylight and familiar color hues. Typical daylight is about 5000k, pure yellow is around 3000k, white is around 4000k, and blues become apparent around 5500-6000k. I say apparent because most people think of natural daylight as white, where it really has some blue hue to it. Most unfiltered/uncolored halogen bulbs put out around 3500-3700k light, and as they age they go down the color scale becoming more yellow. All OEM HID comes with 4100k bulbs (there are also OEM 5000k and 6000k) and as they age they go up the color scale becoming bluer.
Those values only indicate where most of the light produced by the source falls in the color spectrum. In actuality, there is light all over the scale being produced. Without getting too much into Human physiology and the realm of sensation and perception, our physiology dictates that our eyes see better in natural daylight. Millions of years of evolution have adapted them to be that way. The closer to natural daylight your output, the more “useable” light there is for you to see. Each color is made up of a combination of intensity from each wavelength, and the 4100k color hue has spectra most heavily weighted in wavelengths around 505nanometers, where our eyes are uniquely most sensitive. A value too low or too high on the scale skews everything to that one side and decreases the intensity in our sensitive range. Therefore the 4100k produced by OEM HID bulbs is beneficial over the typical halogen output.
There is a gimmick among aftermarket kit producers to advertise 8000,10000, 12000, and yes even 30,000k kits, which completely negates all the benefits of using HID in the first place. The fact is these are cheaply made bulbs and the manufacturer does not even know what color temperature the output really is. The equipment to measure color hue is very, very expensive and not something a manufacturer of illegal kits would want to waste money on. In addition, anything that high on the color scale would produce almost no spectra in the sensitive range of visible light, 10000k is better suited for insects that see in the ultraviolet spectrum.
The color output is also subject to scattering of light; certain wavelengths will scatter more from interference than others. Diffraction occurs through interference with the water vapor in air, more so when there is a lot of it such as in inclement weather. It is the same effect that causes the sky to be blue! We perceive different wavelengths of light as different colors of the visual spectrum (rainbow). In order of large to small wavelength the major colors are red, orange, yellow, green, blue, indigo, violet. Smaller wavelengths are subject to diffraction more than larger ones because of simple physics. As you go towards blue hues, the more subject it is to scattering due to interference, meaning it creates what we would call glare and difficult visibility in bad weather. Yellow or orange-yellow has the combination of the least scattering and a majority of output still inside of the sensitive visible range, making it optimal for inclement weather. This is why you see yellow fog lights and honking big yellow lights on some rally cars.
The diffraction of blue light also lends to the phenomenon of “eye fatigue.” Eye fatigue refers to the phenomenon in which shortest wavelengths of blue actually are incorrectly focused by the eye simply because of physical design of our anatomy. Briefly, very short wavelengths in the blue spectrum cause some blurring of our field of vision, which can become worse over the time of exposure. Maybe you won’t notice when you get in your car, but an hour down the road you may start having difficulty with visual acuity.
Now you know why it is better, but how does it work?
HID bulbs produce light by using an electrical arc between two electrodes across a void rather than resistance across a filament as with halogen bulbs. The void is filled with a mixture of mercury vapor, sodium salt, scandium salt, and xenon gas. Just a note, OEM bulbs no longer use mercury for reactions, they use something that is hopefully more environmentally friendly and less dangerous should a bulb break. The high luminous output is due to the mixture being heated to a gaseous phase and ionizing, and a continuous reaction ensues until the source arc is turned off. The exact ratio of elements within the void also determines the correlated color temperature of the output. Let’s just say the formulas of OEM bulbs are closely guarded secrets of Osram and Philips. Aftermarket kit bulbs are generally cheap knock-offs, I wouldn’t be surprised to find that they still use mercury as part of their formulations. Poor quality control over the ratio of elements is what leads to premature and drastic color changes, decrease in luminous output, and failure.
HID bulbs age, and over time, they gradually lose luminous intensity and climb up the color temperature scale. However, this occurs in a logarithmic fashion. Within the first several hundred hours of use the bulbs will undergo a quick color change; this is commonly called “burn-in” or “color shifting.” The end result is that a yellow or very white looking 4100k bulb will probably end up being in the proper 4100-5000k range most of its useful life. Here is a not to scale representation of that process:
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Actual 5000k OEM bulbs are meant as replacements for older 4100k bulbs should one fail or fall victim to a read bumper of another car. That way the newer bulb will more closely match the older bulb in the other headlamp.
HID also requires the use of a ballast and igniter to power the bulbs. Some ballasts are physically packaged as an all inone unit with an integrated igniter, others have separate packaging of the ballasts and igniters. The igniter is responsible for converting the 12volt DC supply from your battery to the 20,000-24,000 volts AC required to initially light the bulb by creating a sufficient arc. Once the bulb is lit, the ballast is responsible for supplying the appropriate 85volts AC, and phasing to maintain the electric arc. More importantly, it controls the amount of current flow to the bulb, much like a resistor. Without the current limiting control of the ballast, the reaction within the bulb would burn out within a second.
An important thing to note here is that the distance between the igniter/ballast and the bulb should never be altered. Wire, just like a filament, has resistance, and this is taken into account with the design of a ballast. Change it, and you change the operating parameters. Should you have a ballast with a separately packaged igniter, it is possible to lengthen the distance between the two if required.
Using HID on a halogen equipped vehicle requires the use of a relayed wiring harness to bypass the stock wiring. The stock wiring was chosen based on the electrical requirements of halogen system, not HID. HID will draw more current at start up than a halogen system will, but once lit the HID does use less power. Changing a fuse to meet the current draw of ballast is a very bad idea, which will tax the capacity of the wiring and cause it to excessively heat up. That, of course, is very rare, but other problems can occur as well. The most common being that only one ballast will be able to draw enough power to produce a sufficient arc, leaving the other one flickering in a desperate attempt to light. This is not something you want to happen, as it will decrease the life of your ballast and bulbs by doing so. A relay is a very simple device that closes a separate circuit when power is applied to its coil. The idea here is to use your stock wiring to power the relay’s coil to close a circuit directly connecting the battery to the ballasts.
All ballasts are not created equal. The general consensus is aftermarket ballasts face the same problems as knock-off bulbs; they will not stand the test of time like OEM will. Most aftermarket kit ballasts are based off inferior designs from companies that no longer exist. As a matter of fact one specific design that is common to at least 50% of kits out there is based off a design from a company that went under years ago. The reason the company went under is because the design had so many failure problems that every OEM that used them on their cars dropped them. They sold the design and since then it has been copied to death and is relabeled under every name imaginable. According to one source it took Philips over 5 years to invent the first automotive HID ballast that worked, so skimping on a properly designed ballast is not recommended. An improperly made ballast can prematurely destroy a bulb and it would appear as if it was the bulb itself.
Thanks to Todd (RSX-CT) for putting together this awesome detailed thread on HIDS - I hope this helps everyone learn more about hids and what they need to do, etc. I also hope it's answers any questions you guys might have.
Please keep all comments/questions ON TOPIC and in relation to HIDS - others will be deleted out. Thank you!
The objective of the following is meant as a one stop source of information regarding the use, technology, and purpose to the use of high intensity discharge (HID) xenon lighting systems. There is a LOT of misinformation and myth mixed in with the true information on the forums. The following information is meant to quell the myths and half-truths as much as possible as well as provide a basis for the uninformed to learn about HID. It is meant specifically to be a very easy read, in lay language. If some parts seem vague, it is to avoid confusion. Any diagrams here are just representations that are not necessarily to scale.
PART 1: The Basics (“Knowing is half the battle”)
What is it and why is it better?
I think just about everyone knows HIDs were first used by car manufacturers as OEM and that is where their increasing aftermarket interest comes from. But what is the drive for a manufacturer to use them as OEM? Quite simply they realize the benefits of using the new technology to create better vehicle lighting systems with a much higher level of equipment longevity. Be aware that 90-99% of the aftermarket “kits” out there do not fall into the same qualifications as the OEM equipment, so comments about quality and specification may not apply.
OEM HID arose out of the need for better lighting and alleviation from the limitations of older incandescent halogen bulb technology. Halogen technology has its limitations in achieving increases in output. Minor increases in luminous output (brightness) require a decrease in longevity of the bulbs and the byproduct of heat. Anyone that has used aftermarket higher wattage bulbs knows that they typically do not last very long. However, today’s newer cars that are still equipped with halogen systems the apparent focus has been on improving the optics rather than increasing the output of individual bulbs. Halogen’s major drawback is the fact that it requires a thin filament to produce light to convert electrical current to heat and light. Cars take some abuse in performing their task and bulb filaments eventually fail in part due to vibration.
HID alleviates the filament issue, because, as I will cover later, they do not use filaments at all. The HID bulb (appropriately called a capsule or a burner) has the benefit of producing approximately three times more lumens without the drawbacks of using a filament. The issue of vibration is therefore removed from the equation allowing the bulbs to be incredibly hardy as a light source. OEM bulbs and ballasts are meant to perform as “life of car” parts, meaning they should not experience failure under normal use for the natural life of your car. In most cases they will last until after you trade, sell, or junk your car.
There is also a benefit in the color of the light produced by HID lamps over that of conventional halogen bulbs. A couple things need to be said about correlated color temperature first, as it is rather difficult to explain in lay language. The degree Kelvin that color hue is correlated with does not indicate in any way to the operating temperature of our source. The correlated color temperature scale simply relates the color hue of light produced from different sources to one benchmark, a super heated block of carbon. What is important to know is that we can relate the scale to daylight and familiar color hues. Typical daylight is about 5000k, pure yellow is around 3000k, white is around 4000k, and blues become apparent around 5500-6000k. I say apparent because most people think of natural daylight as white, where it really has some blue hue to it. Most unfiltered/uncolored halogen bulbs put out around 3500-3700k light, and as they age they go down the color scale becoming more yellow. All OEM HID comes with 4100k bulbs (there are also OEM 5000k and 6000k) and as they age they go up the color scale becoming bluer.
Those values only indicate where most of the light produced by the source falls in the color spectrum. In actuality, there is light all over the scale being produced. Without getting too much into Human physiology and the realm of sensation and perception, our physiology dictates that our eyes see better in natural daylight. Millions of years of evolution have adapted them to be that way. The closer to natural daylight your output, the more “useable” light there is for you to see. Each color is made up of a combination of intensity from each wavelength, and the 4100k color hue has spectra most heavily weighted in wavelengths around 505nanometers, where our eyes are uniquely most sensitive. A value too low or too high on the scale skews everything to that one side and decreases the intensity in our sensitive range. Therefore the 4100k produced by OEM HID bulbs is beneficial over the typical halogen output.
There is a gimmick among aftermarket kit producers to advertise 8000,10000, 12000, and yes even 30,000k kits, which completely negates all the benefits of using HID in the first place. The fact is these are cheaply made bulbs and the manufacturer does not even know what color temperature the output really is. The equipment to measure color hue is very, very expensive and not something a manufacturer of illegal kits would want to waste money on. In addition, anything that high on the color scale would produce almost no spectra in the sensitive range of visible light, 10000k is better suited for insects that see in the ultraviolet spectrum.
The color output is also subject to scattering of light; certain wavelengths will scatter more from interference than others. Diffraction occurs through interference with the water vapor in air, more so when there is a lot of it such as in inclement weather. It is the same effect that causes the sky to be blue! We perceive different wavelengths of light as different colors of the visual spectrum (rainbow). In order of large to small wavelength the major colors are red, orange, yellow, green, blue, indigo, violet. Smaller wavelengths are subject to diffraction more than larger ones because of simple physics. As you go towards blue hues, the more subject it is to scattering due to interference, meaning it creates what we would call glare and difficult visibility in bad weather. Yellow or orange-yellow has the combination of the least scattering and a majority of output still inside of the sensitive visible range, making it optimal for inclement weather. This is why you see yellow fog lights and honking big yellow lights on some rally cars.
The diffraction of blue light also lends to the phenomenon of “eye fatigue.” Eye fatigue refers to the phenomenon in which shortest wavelengths of blue actually are incorrectly focused by the eye simply because of physical design of our anatomy. Briefly, very short wavelengths in the blue spectrum cause some blurring of our field of vision, which can become worse over the time of exposure. Maybe you won’t notice when you get in your car, but an hour down the road you may start having difficulty with visual acuity.
Now you know why it is better, but how does it work?
HID bulbs produce light by using an electrical arc between two electrodes across a void rather than resistance across a filament as with halogen bulbs. The void is filled with a mixture of mercury vapor, sodium salt, scandium salt, and xenon gas. Just a note, OEM bulbs no longer use mercury for reactions, they use something that is hopefully more environmentally friendly and less dangerous should a bulb break. The high luminous output is due to the mixture being heated to a gaseous phase and ionizing, and a continuous reaction ensues until the source arc is turned off. The exact ratio of elements within the void also determines the correlated color temperature of the output. Let’s just say the formulas of OEM bulbs are closely guarded secrets of Osram and Philips. Aftermarket kit bulbs are generally cheap knock-offs, I wouldn’t be surprised to find that they still use mercury as part of their formulations. Poor quality control over the ratio of elements is what leads to premature and drastic color changes, decrease in luminous output, and failure.
HID bulbs age, and over time, they gradually lose luminous intensity and climb up the color temperature scale. However, this occurs in a logarithmic fashion. Within the first several hundred hours of use the bulbs will undergo a quick color change; this is commonly called “burn-in” or “color shifting.” The end result is that a yellow or very white looking 4100k bulb will probably end up being in the proper 4100-5000k range most of its useful life. Here is a not to scale representation of that process:
Actual 5000k OEM bulbs are meant as replacements for older 4100k bulbs should one fail or fall victim to a read bumper of another car. That way the newer bulb will more closely match the older bulb in the other headlamp.
HID also requires the use of a ballast and igniter to power the bulbs. Some ballasts are physically packaged as an all inone unit with an integrated igniter, others have separate packaging of the ballasts and igniters. The igniter is responsible for converting the 12volt DC supply from your battery to the 20,000-24,000 volts AC required to initially light the bulb by creating a sufficient arc. Once the bulb is lit, the ballast is responsible for supplying the appropriate 85volts AC, and phasing to maintain the electric arc. More importantly, it controls the amount of current flow to the bulb, much like a resistor. Without the current limiting control of the ballast, the reaction within the bulb would burn out within a second.
An important thing to note here is that the distance between the igniter/ballast and the bulb should never be altered. Wire, just like a filament, has resistance, and this is taken into account with the design of a ballast. Change it, and you change the operating parameters. Should you have a ballast with a separately packaged igniter, it is possible to lengthen the distance between the two if required.
Using HID on a halogen equipped vehicle requires the use of a relayed wiring harness to bypass the stock wiring. The stock wiring was chosen based on the electrical requirements of halogen system, not HID. HID will draw more current at start up than a halogen system will, but once lit the HID does use less power. Changing a fuse to meet the current draw of ballast is a very bad idea, which will tax the capacity of the wiring and cause it to excessively heat up. That, of course, is very rare, but other problems can occur as well. The most common being that only one ballast will be able to draw enough power to produce a sufficient arc, leaving the other one flickering in a desperate attempt to light. This is not something you want to happen, as it will decrease the life of your ballast and bulbs by doing so. A relay is a very simple device that closes a separate circuit when power is applied to its coil. The idea here is to use your stock wiring to power the relay’s coil to close a circuit directly connecting the battery to the ballasts.
All ballasts are not created equal. The general consensus is aftermarket ballasts face the same problems as knock-off bulbs; they will not stand the test of time like OEM will. Most aftermarket kit ballasts are based off inferior designs from companies that no longer exist. As a matter of fact one specific design that is common to at least 50% of kits out there is based off a design from a company that went under years ago. The reason the company went under is because the design had so many failure problems that every OEM that used them on their cars dropped them. They sold the design and since then it has been copied to death and is relabeled under every name imaginable. According to one source it took Philips over 5 years to invent the first automotive HID ballast that worked, so skimping on a properly designed ballast is not recommended. An improperly made ballast can prematurely destroy a bulb and it would appear as if it was the bulb itself.
