Over the years the off-road lighting industry has evolved. One of the companies leading that evolution is California-based Baja Designs, thanks to years of testing and doing research and development on the dirt as well as the race track.
Here is a lighting primer from the Scientists of Lighting at BD.
Light Sources
Halogen Lights have a filament bulb filled with pressurized gas to prolong the life of the filament and allow it to burn brighter. They have a warm yellow color temperature of around 3200K and have an expected life span of about 200 hours.
HID (High Intensity Discharge) lighting was a quantum leap forward in illumination. HID lamps produce a daylight quality light (4200K-5000K) and brightness (3200 lumens). A single HID produces the equivalent of 250 watts of Halogen lighting power while only consuming about 45 watts. Instead of a filament, HID bulbs fire a charge between two electrodes encased in a Xenon gas-filled bulb. Since the bulb has no filament, vibration does not affect its operating life of approximately 2000 hours.
LED (Light Emitting Diode) advances have finally made it possible to produce high-output LEDs capable of reaching the performance and pricing of HID lighting. The dies have an extensive life (approximately 50,000 hours) and are very resistant to vibration. Other benefits of LED lighting include smooth, even light patterns and the ability to make light assemblies in many varying sizes and shapes.
Because high output LEDs are fairly new, consumers have been inundated with marketing hype but not as many facts as they may want. Here are a few areas that consumers should be aware of.
- Heat Management: High output LEDs generate a lot of heat. If the heat is not properly managed, the lumen output and life span of the LED is severely affected. There are four ways to migrate the heat away from the LED. First and foremost the heat sink acts like a radiator to cool the LEDs. Next, the circuit board which is generally made of aluminum or copper is directly linked to the LEDs and transfers the heat to the heat sink. The circuit board can be mated to the heat sink with thermal paste, a thermal pad or nothing. A thermal pad is the most efficient at transferring the heat and also adds a layer of vibration isolation. Lastly, a thermistor can be put on the board to measure the temperature of the LED and control the current to the LED in the extreme circumstance that there is no airflow to the heat sink. Most lighting manufacturers cut costs in this area by using aluminum boards with no thermal paste or thermal pads and by not having an active thermal management circuit on the board.
- Binning: When LED manufacturers categorize and price LED dies they use two primary performance factors: Luminous Output (brightness) and color temperature. All LED manufacturers sort their bulbs for luminous output and color temperature using a practice called “binning.” In general terms, bulbs measured with the highest luminous output and the most desirable color temperature are put in the highest rated “bin.” Each subsequent bin has lower performance ratings and/or less desirable color, until they get to the last bin with the lowest performance ratings.
- Lumen Claims: The technology for white LEDs has evolved quickly. White LEDs are now available anywhere from 1 watt to 45 watts per LED with varying lumen/watt efficiencies. Newer, higher wattage LEDs have allowed LED light designers to create lights that offer increased performance but require fewer LEDs. In 2014 the CREE XML2 is one of the most efficient LED dies available and depending on power input achieves approximately 140 lumens/watt. Unfortunately, many LED light manufacturers don’t divulge what LED they are using and what percentage they are running the LEDs at, all of which makes it challenging for the consumer to verify lumen claims. A rough calculation of watts per light divided by number of LEDs will at least tell the buyer how many watts they are putting to each LED. Remember that heat management and the bin also affect lumen/watts. Adding to the confusion, no matter how many watts of power you put to an LED, at a certain point you don’t get a complete lumen return per watt. In other words a CREE XML2 is not capable of producing 1400 lumens per LED. Bottom line, buyer beware about lumen claims, especially from less reputable sources.
- Color Temperature describes the color of white light and is measured on the Kelvin (K) scale. Temperatures below 4000 degrees K produce “warmer” or yellow-tinged light. Temperatures above 6000 degrees K produce “cooler” or bluish tint light. And 6000 degrees K and greater make it harder for the human eye to perceive color variations and depth of field—especially as you get older. Meanwhile, 5000 degrees K-5500 degrees K closely mimics bright sunlight and greatly reduces eye strain and driver fatigue.
- Optics: Optics are crucial. It doesn’t matter how many lumens you have if they aren’t where you need them. LEDs are particularly hard to properly focus because there are multiple LED light sources as opposed to a single HID or halogen bulb. Unfortunately, this is particularly hard for a consumer to compare apples to apples because it is notoriously hard to convey light output without actually seeing the light at night. Pictures can help but it takes a highly skilled professional photographer to accurately capture light that is hundreds of feet away. Good optics make all the difference when comparing two lights even if they use the same LED die.
(Baja Designs, the first company to offer an HID light for a motorcycle and the first company to develop an off-road LED light, can be reached at 760-560-2252 or www.bajadesigns.com. For more information about their many exclusive features or products, contact the company at the number listed or on the web.)
