Halogen Headlights vs Xenon Headlights: To DIY or Not to DIY
Seeing as NAPA KnowHow is a DIY auto repair blog, you might find it downright bizarre to read that you absolutely should not DIY something on your car, especially something as simple as upgrading your halogen headlights.
How can upgrading to xenon headlights be that big of a deal?
Halogen Headlights vs. Xenon Headlights: Theory of Operation
While “halogen” and “xenon” refer to the gas that is injected into the headlight bulb, how they operate is significantly different. Halogen bulbs are incandescent bulbs, and light is produced by heating a tungsten filament with electricity. A halogen gas, such as iodine or bromide, serves to protect the filament, so the bulb lasts longer. They aren’t particularly expensive — you can usually find a pair for less than $30 — which is why they are the standard for automotive headlights.
Still, halogen isn’t particularly efficient, and it generates a lot of heat for the amount of light produced, which translates to lost energy. A number of automakers have adopted xenon headlights, actually metal-halide with xenon gas, also known as HID headlights. Xenon headlights are more efficient, produce whiter light and are more comfortable for night driving.
HID stands for high-intensity discharge, which is the key to how xenon headlights work. Using a high-voltage ballast, peaking at up to 30,000 V, an arc bridges the gap between two tungsten electrodes. The arc heats the xenon gas and vaporizes metallic salts, at which point they become a light-emitting plasma, and the ballast switches to a lower voltage, typically 80–100 V, to maintain the plasma temperature.
Xenon Headlight Upgrade: “Not” an Option
Aside from how these two kinds of headlights operate, the way they are constructed is a barrier to possible upgrade options. First, HID headlights require a ballast, which is why so-called HID “upgrade” kits include ballasts and wiring with new HID bulbs. Installation, on its own, isn’t particularly difficult, and the only thing you really need to know is basic electrical skills. On the other hand, there is one very good reason why you should never install xenon headlights in a car that wasn’t designed for them in the first place: the position of the light source inside the bulb itself.
Halogen headlights position the filaments very specifically, including light shields and secondary filaments, to optically interact with the reflector and refractor elements in the headlight housing. The idea is to put light exactly where you need it without blinding oncoming drivers. Few aftermarket HID headlight upgrade kits include any kind of shielding or optimized light source placement, excepting those that also replace the headlight unit as well. The result is light that is blinding to oncoming drivers, even when using low beams. Ultimately, the best course of action is to only use headlight bulbs that are designed for your vehicle.
An Upgrade Compromise
If you are looking for better night vision and the HID headlight look, then there is a “xenon” headlight upgrade for you, but it has nothing to do with HID headlights. Marketed as “Xenon Headlights,” these halogen headlights come with blue-filtered glass, which produces a blue-tinted light for better night vision. Because they are engineered to match standard halogen bulbs, they are also optically correct, so you won’t blind oncoming drivers.
Although you can’t technically upgrade your existing halogen bulbs to xenon safely, as with most things, there is an alternative that will get you the boost in performance you’re after.
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Photo courtesy of Foter.