Halogen, HID & LED Lighting - Turning Darkness To DaylightPosted in How To on July 1, 2010
Ever since the electric light bulb was conceived in the early 1800s, inventors have sought to improve on its design to provide greater light output, better power efficiency, and increased longevity. Humankind has been fascinated with its ability to expand our means to explore remote places and illuminate our environment in darkness. When the sun drops below the horizon, we continue to work and play, and quality lighting affords us that ability.
In the off-road world, nighttime exploration and racing is a common situation. Luckily, we've got lots of choices when it comes to modern lighting for our vehicles. There are lights with beam patterns to cover fast and slow driving, and wide and narrow fields of view.
Flood or fog light patterns typically spread the light over a large area to illuminate a wide berth up closer to the vehicle. These allow you to see best around the front and sides, but don't illuminate far outward. In contrast, long range or driving light patterns focus light over a narrower beam angle but project the light out much further ahead. As such, these are more appropriate for high speed driving. Often, a vehicle has a combination of beam patterns strategically mounted to provide a full blanket of light from side to side, and near and far, as needed.
There are three major varieties of common off-road lights today: Halogen, high intensity discharge (HID), and light emitting diode (LED) sources. We spent some time with Michael Dehaas, president of KC Hilites (www.kchilites.com), to get the skinny on differences in the various lighting types. KC sells all three varieties and each has its place in the off-road world. We'll discuss briefly how each of these works, and the benefits and drawbacks of using one over another.
Vehicles for years have come from the factory with halogen headlights. These bulbs have all but replaced the older standard sealed beam headlights whose light shone a more yellowed hue when compared to halogen versions.
|LAMPS AT A GLANCE|
|LAMP TYPE >>||HALOGEN||HID||LED|
|COST||Lowest||Medium to high||Highest|
|LIGHT OUTPUT||~25 lumens/watt||~100 lumens/watt||~100 lumens/watt|
|ILLUMINATION||Slightly yellow||White-blue||Varying whites,|
Just how much current does an off-road light use? You'll want to have an idea on current consumption when you get ready to wire in a set of aftermarket lights to determine the toll on your battery and alternator, and to know what size switches and/or relays you'll need to handle the juice needed to power the lights.
Use this simple formula to estimate the current draw for each light:
I (current draw in amps) =
P (light power in watts) / 12 volts
So, for a 130 watt light we would find that the current consumption is about 10.8 amps for a single lamp, or about 21.6 amps for a pair.
Next on our lighting list for comparison are HID lamps. A high intensity discharge (HID) light uses high internal voltage in a gas filled bulb to form an intense plasma to create light. These lights offer more illumination with less power consumption when compared to a halogen lamp. They typically offer lighting output similar to that of a 150W halogen but are typically rated at only 35 watts. That translates to HID units being about 300 to 400 percent more efficient than halogen lamps.
Light emitting diode (LED) units typically come in light bar sizes ranging from 4 inches to about 50 inches long. Each light consists of two rows of high intensity LEDs, each sitting in a small optic or reflector assembly that measures about one inch square.
LEDs are composed of semiconductor materials and when a current is passed through the formed junction, they emit light. Various colors are possible depending on the characteristics of the material used to build the diode. A big advantage of LEDs is their efficiency. They can produce far more light for a given amount of input power than conventional bulbs. They also have high service lifetimes (typically in excess of 10,000 hours). LEDs are much less sensitive to shock and vibration damage than traditional glass bulbs, which is especially useful for off-road applications.
Consider a halogen light rated at 150 watts. This translates to a battery current draw of about 12.5 amps per light. A step up in improvement (and cost) is a comparable 35W HID light that would draw about 3 amps of current. A LED light bar of similar light output might only consume about 2-3 amps of current.
The Future Of Leds
Light emitting diodes may well be the real future of multi-purpose and off-road lighting. For applications where the light is made "to be seen" (tail lights, brake lights, etc.) they offer excellent visibility in signal colors. But, in applications where they are used to "see" they can't yet match the sheer illumination power of HID lights.
Looking forward, RGB LEDs can be used to provide hues of red, green, or blue and can be used to offer combinations of lighting with the array of individual diodes. The color of each element could be programmed individually or strobed to provide a variety of colored patterns.
A Lighting Comparison
In general, halogens offer the least expensive option for basic lighting. HID lamps offer the brightest long-range lighting if you want to see the farthest and drive the fastest, while saving on power consumption (as compared to halogens). LEDs offer a bit of several advantages in that they offer good light output with excellent efficiency, and they come in a unique looking package. The choice is yours, and thanks to the lighting companies of today we have some excellent options.