why do some cars have blue headlights

Traditionally, cars have had yellowish headlights. Now, many cars have light blue colored headlights. Some cars come with those headlights from the factory and other times, owners will install similar systems or similar
looking systems. The factory blue headlights are known as HID (high intensity discharge) headlights. Just like the name describes, they re brighter than normal halogen headlights. Traditional lights heat a small metal filament to produce light while HID lights create a plasma discharge arc between two tungsten electrodes. It is this plasma discharge that creates the blue color. But, this technology is not new, it s very similar to the bright lights that illuminate stadiums and roadways. The brightness is the main advantage of these lights. Like, these headlights were popularized in Europe where fog, rain and curvy roads create demanding driving conditions. Because HID lights are brighter, they penetrate fog, rain and snow better than halogen lights an advantage when the conditions are not ideal. HID headlights are also more energy efficient than halogens, which isn t a major concern in vehicles right now, but as we move to battery powered cars that will become very important the less power accessories consume, the further the vehicle can drive on a single charge. If they re better, why don t all cars have them? They re not better in every way, they do cost more. I mentioned that they are similar to stadium lights, except stadium lights require a lot of warm up time before they are really bright. HID lights often reach 75% brightness within a few seconds and achieve 100% brightness after a couple minutes. This quick start-up is made possible by a ballast and ignition control module in the vehicle that provides a 20,000 volt pulse to initiate the arc. В These components along with the bulbs themselves increase the cost for manufacturers to install these types of lights. Vehicle conversion kits are available for many vehicles and they usually begin around $300. But, you can t put these bulbs in any headlight socket. In the US, it is illegal to change the type of bulb that your headlights were originally approved for by the Department of Transportation (DOT) and similar laws exist in most other countries.


Because HID lights are brighter, the DOT pays very close attention to the aiming of these lights. If you see HID lights that are blinding, it s generally because somebody has installed the bulbs in an unapproved headlight fixture that is not designed to focus the light down and away from your eyes. Approved headlight fixtures have a very sharp projection pattern that keeps the light out of oncoming eyes. In some European countries, HID system are required to be auto-leveling so that heavy loads in the rear of the vehicle do not pitch the light up into oncoming traffic. For left hand drive vehicles, the right headlight is actually aimed slightly higher than the left to improve visibility on the right side of the road (street signs, peripheral dangers etc) while the left side is aimed lower to keep it out of oncoming eyes. If you re driving in front of a car with HID lights, it may appear that their right headlight is improperly aimed, but it is likely that it is intended and should still be a reasonable brightness. Many systems calibrate every time the vehicle is started to ensure they are properly aimed and do not blind any other motorists. There are also tinted bulbs available that look similar to HID systems. They are not as bright as HID headlights, but they can often be installed legally. Many bulb manufacturers have introduced to give buyers a reasonably priced alternative to traditional bulbs. Sources:, Photo: Edit 1: I seem to have caused some confusion. There are some cars that have reflectors specific for HID bulbs. They don t blind people. Ie. Nissan, Volvo, some Lexus and Prius. Edit 2: There are halogen projectors too, but they aren t as bright as HID projectors. Do not put HID bulbs in halogen projectors. It s 100 times worse than stock halogen reflectors. Edit 3: A few people just got down voted because I failed to provide a more thorough write up.


I m sorry. I ll try to fix that if I can. Edit 4: Number adjustment. Edit 5: Auto-leveling is another factor. It corrects the aim of the lights if there are any disturbances in the back of the car like a lot of people. I m currently working on implementing it in my car. I know how much people hate those bright blue/purple/greenish headlights. I don t like it either. I had HIDs in my car for a day and it pissed me off because I was blinding people. I did lots of research as to why and how it happens. I also did some modifications on my Civic and purchased some parts that were needed. I will explain how it affects the HID system as well as the colors that they come in. People just throw those Plug and Play (PnP) kits on their cars. They re unsightly and don t play nice with other drivers on the road and can cause confusion and are blinding. is what it looks like. This is Halogen vs. HID. It s brighter and the light goes all over the place like this shows. This is similar to those people in SUVs and trucks that aim their headlights too high. The light bounces off the reflector and shines everywhere. It s considered off-road lighting. HID and stock reflectors in the headlight assembly do not work together. Do not install them in your vehicles. The variety of colors the HID bulbs come in. People assume that there s a correlation between higher temperatures and brightness. The temperature in which the bulbs burn determine the of light. The best and safest color range for visibility is around 5000K (K for kelvin). It s white light. Halogen bulbs are around 4300K. The color of lights you see on luxury vehicles and such are at 5000K. Some people you see driving down the road have those blue colored lights. They are usually higher than 6000K. They aren t recommended because blue light causes strain on the eyes of everyone including the driver of that vehicle. White (5000K) to Yellow (3000K) are easier to see with. They don t create a strain on the eyes. I would recommend 4300-5000K. This is the most important part of this whole post. This is what ties in everything I mentioned before.


Projectors have a built in to prevent glare and redirects the light more efficiently with brighter results. The should be aimed no higher than two feet on a wall from a 20 foot distance. This well prevent you from blinding other people. I would also recommend people to do this with stock halogen setups as well. This will give the light a wider spread for more visibility and increase the range. Installing these onto traditional halogen headlight assemblies is known as retrofitting. Retrofits require part modifications, usually the reflector is cut or mounting needs to be completed. a DYI guide. It s not too hard. I managed to do a harder install on my Civic because I got the larger TSX projectors. I would recommend the Mini H1 projectors as they are easier to install for beginners. There was a lot of math involved for what I did and lots of planning. Even then I made a few mistakes. A few tips while retrofitting. You might have to cut part of the housing if you use larger projectors that aren t meant for your car. I would recommend a nice water-proof sealant if it comes to that. But be warned, aim the lights properly before sealing up the projectors. If it s not aimed right, correct it over and over until it s right and you aren t blinding people. The supplies you might need can be purchased from The Retrofit Source or where every you prefer. Here comes the part with the money. Doing this right means it will cost you something around $300. Even more if you mess up your headlight assembly. I would recommend easier to install projectors if you don t want the hassle of cutting and stuff. It ll be cheaper and the new Mini H1 projectors are better. If you can t put up this kinda of money, then don t even bother putting in PnP HID kits. Because really, you re not getting any more visibility and it doesn t look cool at all. On top of that you re blinding everyone in your path. This is what I used to retrofit my dull headlights into something worth driving in at night. Here s my Sources for images and knowledge base:

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