Facts About Headlights

In the beginning, cars and trucks used incandescent or “sealed beam” headlights. Similar in design and function to your typical screw-in light bulb, they used a tungsten steel wire – or filament - sealed in a glass lens. When electricity passed through the filament it became so hot that it produced a steady and reliable source of light. As with home lighting, sealed beams had limitations. The brightness was limited and the light produced was not clean, natural-looking but a dingy tainted or yellow color. They also weren’t very efficient. The energy used to light the bulb actually produced 95% heat and only 5% light.

Next came the Halogen headlight. Around 1978, a brighter longer-lasting headlight hit the market. Although still an incandescent bulb, it was filled with an inert gas known as halogen which allowed it to burn brighter and last longer. This is still the most common style headlight in the industry. Early halogen headlights were sized and shaped like the old sealed beams which were either round or rectangular. This was convenient if you wanted to upgrade your lighting to the new halogens, but eventually the bulb and the headlight capsule or lens became two separate items. This allowed manufacturers to design the smooth streamlined headlights that are common today. The halogen bulb merely snaps into the back of the unit to provide the light source and is actually self-contained.

The latest technology regarding headlights deals with eliminating the tungsten steel filament that has been the common component of lighting since Thomas Edison. Such is the case with vapor lamps. Mercury and sodium vapor lamps are used in streetlights and at sports stadiums. But for automotive applications Xenon gas is the way to go. Xenon gas headlights produce a brilliant bluish light three times brighter than a halogen bulb, while using 65% less energy. The automotive industry has dubbed these style headlights “High Intensity Discharge” or HID headlights. While very bright, they use a special controller or ballast to create an arc between two points which excites the gas and creates light. To accomplish this, the ballast steps up the voltage from 12volts that the vehicle runs on, to 20,000 volts to ignite the xenon in the bulb.

Unfortunately, all of this high-tech magic adds to the price of having HID lighting. HID bulbs and ballasts can run hundreds of dollars to replace while a halogen bulb is twenty dollars or so. And don’t be fooled by imitations – HID produces a blue light but not every blue light is an HID.