2012年4月10日 星期二

On And Off-Road Lighting Tips And Tricks

Nothing changes your perspective on nighttime wheeling or even just driving down paved roads like a good set of lights. And unless you're driving a brand new $50,000 4x4, your factory lights suck in comparison to what is available. There are multiple ways to put more light in front of your 4x4, including off-road lights and headlight upgrade kits. But these can range from $40 to over $500, so it pays to know a little bit about the technology before whipping out the platinum credit card.

In most vehicle lights, electricity flows through a thin piece of metal called a filament just like the soon-to-be-outlawed (in some areas) incandescent light bulbs in your house. The metal heats up almost to the point of melting, and the resulting glow puts the light in your lights. The reflector in the housing focuses the light in one direction, making it more intense.

Headlights are rated in watts, and the most basic way to get a brighter light is install higher watt bulbs. These have larger filaments and sometimes different types of metal that handles higher amperage without melting. However, the filament is held in a gas chamber, and the type of gas affects the light output. Really old sealed beams were incandescent, and they use an inert gas.

These lights give off a very warm, yellow glow. The filament starts to decay from the first time it is used, becoming dimmer and dimmer until they finally give up. The two most common gases used today for automotive headlights are halogen and xenon. Halogens produce a primarily white light, and the halogen gas causes a chemical reaction that redeposits separated parts of the filament back on the metal when the light is turned off, extending the life and maintaining the brightness of these lights over their life. Xenon is another gas that can be used in lights that have filaments, producing either a pure white or a blue tint.

The color is caused by a different temperature at which the filament glows. Both halogen and xenon bulbs produce brighter light with longer life. To add some confusion, xenon is also often used to describe High Intensity Discharge (HID) lights.

These lights have been used for decades by pro off-road racers for ultra-bright systems that operate at a moderate amp draw and lower temperature. An HID light doesn't use a filament at all. Instead of heating a filament to the point of glowing, an HID uses electrodes that do not touch. When the gas in the tube heats up to the point of evaporation, an arc of light connects the electrodes.

They use xenon gas in the tube, but don't confuse a xenon light bulb with an HID. In addition to special bulbs – which some companies call a burner to distinguish them from filament-type bulbs – these systems also require a transformer to increase the voltage and create the arc, as well as a starter which literally starts the arc.

While a halogen or xenon light attains its full brightness as soon as you turn it on, an HID has a warm-up period. A knock against HID lights has been the expense, but there have been several affordable off-road lights and headlight conversion kits introduced in the past few years.

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