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Advanced Lighting Technology, the HID
The lighting technology for automotive use have come a long way, and 10 years ago, the industry took a major jump with the introduction of HID (high-intensity discharge) lamp systems. Since than, it has become OEM in many cars and have become familiar with many people as "those bright blues on expensive cars." However, with wider use of HID today, the prices have come down to a point where many will consider it as an option to upgrade to them... So in order to assist in making your choice, I wrote this article to better inform you before you jump in... Let's take a look first though, at what makes a good headlight...other than bulbs or lighting systems. HOUSINGS It makes a big difference depending on which type of H4 light "HOUSING" you use, if… you're talking about something that was converted from sealed beam units.
MR2's and retracted light Corolla fit the description here… First, while the bulbs can make a big difference in brightness and color, without accurate focus and reflectivity, the output will not be sharp or bright in directions where you need the light. Many less expensive housings use low-translucency glass or plastic that hinder light output, and many have less than adequate reflector designs. Cheap units also fade in color or become cloudy with age. Hella, Cibie, Stanley, and Koito makes very high quality housings because it’s their business to supply OEM housings as well. Among these, if you like the flat-clear lens look, I can recommend nothing other than Stanley MR (Raybrig MR in Japan). These housings have very accurate focus on the reflector and the lenses are made of high impact and high translucency ABS plastic. It takes a lot to scratch or crack them, is very lightweight, and projects the light of high quality bulbs to perform its best. Though I don’t recommend the color reflector units, the standard chrome reflector is top notch. Traditional Halogen Bulbs PIAA and other near-HID frequency H4 bulbs, while some are colored more for fashion than others, you will want to choose them correctly. It’s important to understand how lighting works. Halogen filament bulbs (all modern standard light bulbs including PIAA, and other makes of ‘colored’ bulbs) use similar filament wires that technologically has the ability to make red to lower blue frequencies generally and 3000~3200K range predominance. It’s the combination of these colors that make them yellowish-white. To mask the predominantly yellow lights of these filaments, many brands use colored bulb surfaces to mask the lower frequencies, thereby making it effectively darker but bluer to ‘simulate’ HID. But the fact is the more blue you go the darker the light gets as filament’s original color isn’t available at that frequencies. You may see 4500K halogen but its actually a 3200K filament with all the light basically filtered off by the glass to give you the little tiny bit of the 4500K light produced by the filament, and way off it's peak light output color rabge. So… when choosing bulbs, get clear bubs to make most use of the limited color output of the halogen (sometimes falsely named xenon, or plasma) filament bulbs. Don't be fooled with these terms, HID and Xenon are used in almost every imposter halogen bulbs made. If it doesn't require a ballast installation, it's not a true plasma lamp system. These tinted glass enclosed halogen lights not only have darker light output, they generate lots of heat, change colors in short time, and are not even close to true Xenon Plasma systems.
High-Intensity Discharge, Plasma Lighting
true HID PLASMA light source, a arc of plasma gas
Traditional Incandescent and Halogen light source, a filament wire
With true xenon plasma ballasted HID units, the filament is non-existent, and light is produced by xenon gas plasma arc. This new technology does not run on standard 12V so conversion ballast is utilized to meet the electrical requirements. The wider range of color from yellow to very high frequencies of blue (predominantly from 4200~6700K makes them appear to the eye bluer than halogens. With the wider color frequencies in these lights, the human eye can perceive more contrast, and depth of field. The true plasma HID therefore can also work with wider range color filters and lenses. Also the actual intensity of light is much higher for given voltage and amperage draws than halogen encased filaments thus are much more efficient as well. You may have noticed on OEM HID equipped cars’ bulbs produce much less perceived heat, due to less infra-red light produced. Less heat means less wasted electrical energy producing light color ranges that human eye cannot see. The HID units generally produce 4-6 times more visible light than halogens for a given electrical draw so it's friendly to battery and alternators too. Most all of HID automotive lighting require 30 to 40 watt draw with equivalent light of a 160~250 watt halogen bulb... Sure, Mice, Owls and Snakes will see the halogen lamps brighter than HID’s but not humans… Another merit to the HID is the fact that it lacks a mechanical filament. What this means is that it's more resistant to vibration and shock of driving conditions and generally have bulb life-span of 10 times the traditional bulbs that use filaments. The price may be steep at near $500 still for the HID conversions but if your drive involves lots of night time activities, it's definitely worth it's cost. The contrast of forward view is unmatched with true HID units. I think its' better money spent than a set of wheels or the TRD wing... Don't you think? All the car makers are switching to HID in OEM applications as cost becomes increasingly less expensive. In Japan, they are almost standard on Corollas! Aftermarket units have come down from $2500 just 5 years ago to $500 today. If you purchase high quality H4 bulbs for $70 or so today, and need replacements every couple of years from color change or filament failures, the HID which lasts over 10 years with no color shift is a very conceivable option. INSTALLATION Since HID bulbs differ in electrical requirements, the main concern is to wire the required ballast converter (usually supplied with aftermarket HID conversion kits). Figure out a safe, dry location that it can reside and secure it so that it can withstand certain amount of heat and is away from water spray. It must also be within reach of all power and switching connections so as not to modify the wire harness too much. The wiring loom of aftermarket HID systems include a switched 20~30Amp power supply, a ground, and a harness to fit your original H4 bulb socket to use as relayed switch source. In other words, the system will use the original lamp's voltage output as a switch to activate the ballast, which is powered by it's own battery source. Once the unit is secured, you may exchange and wire up the bulbs themselves.
Since HID bulbs in conversion kits are available in many standard Halogen based bases, like H4, 9006, etc...You will want to get one that fits your housing properly. Water leaks and ill fitment can mean VERY expensive damage of the bulbs and ballasts where otherwise they would last over 10 years. The H4 lamps are designed with 2 filaments, a high and low beams in one bulb, situated at different distance from the reflector of the housing to project different portions of the reflector. Since the HID bulbs do not have 2 filaments, many newer HID bulbs have solenoids that actually mode the whole bulb from one position to another. Older systems just have to go without high beams, though the light is so bright and well focused that I don't really need the high beams anymore. There's non of this problem with quad-light array used in many cars today. HID aftermarket conversion kits are available from $500~$800 today and is reversible and transferable to other cars (may require new bulbs if base is different at nominal cost) but over the long run, with added visibility, longer life, and efficiency...it's a wise choice at current prices. Lastly, I will mention that this technology is revolutionizing many industries outside automotive markets. It makes divers safer at night with longer battery life and brighter lights. It made indoor photography more in tune with daylight characters. HID's made airliners visible from further distance, and camping and outdoor events more safe and secure. So it's here to stay...