If you’ve ever driven off-road or through remote areas at night, you’ve probably found your vehicle’s stock headlights woefully inadequate. Enter driving lights. They’re entirely illegal on any public road in this country, and poorly understood as a result. But man, get them right, and they may be one of the most empowering modifications you make to your truck. Here’s how.
What Are Driving Lights?
Let’s start by defining the job you need driving lights to perform—forward facing illumination. There’s a few factors involved in achieving that.
Distance: The reason your stock headlights may feel inadequate is because they only enable you to see 300 or 400 feet ahead. At 65 MPH, that means those stock lamps are, at best, giving you four seconds to see and react to stuff. That stuff may be mundane—a curve in the road—or it may be something dangerous—a deer. By increasing the distance at which you can see ahead in the dark, driving lights then increase your reaction time.
Color Temperature: Very blue lights appear brighter to the human eye. That’s not necessarily a good thing. Cool to cold color temperatures are also harder to look at. This can cause eye fatigue during long nighttime drives and, if that light is bounced back to your eye by reflective road signs, or airborne precipitation, it can actually limit vision. Warm color temperatures may not appear as bright, but are easier to look at, and facilitate better vision. But, skew to warm, and you lose the ability to accurately render colors. The brown hide of that deer may begin to blend in with the green of background foliage, canceling out the safety added by increased reaction time.
Color temperature is measured in Kelvin. The color temperature of mid-day sunlight is about 5,000 Kelvin. To work best, you want lights to be within about 500 K of that number.
Beam Pattern: While you want a light to give you as much reaction time as possible, you want to be able to see and react to stuff across a broad swath of the road, shoulders, and surrounding areas too. And don’t forget vertical spread. As you drive along an undulating road, the orientation of your vehicle relative to the road ahead will constantly be in flux. A broad vertical spread of light will illuminate stuff above and below the horizontal axis of your vehicle. As light is produced, gathered, and reflected inside the light, it doesn’t always project forward evenly. Producing an even spread of light, free of hot spots, and shadows, can prove challenging, but is key to facilitating good visibility.
By The Numbers
The performance of driving lights can be defined in several ways. Let’s look at what those numbers mean.
LED Versus HID
A Light Emitting Diode is a small semi conductor that emits light when electricity passes through it. Because they’re entirely electrical, LEDs provide their entire illumination potential as soon as they’re powered. LEDs are also very small, opening up new possibilities for packaging them.
Inside a High Intensity Discharge bulb, pressurized xenon gas is excited by an electrical current arcing between two diodes. That electricity heats the gas, which then glows. But, that heating process takes a few seconds to reach its full potential, so HID’s grow in brightness. The large size of HID bulbs—they’re a couple of inches long—is actually helpful to light makers. A single bulb is able to produce considerably more light than a single LED, and designing and producing a reflector for a single, large source, is much easier than doing the same for multiple small ones. So, lights made with HID bulbs tend to be capable of projecting light further than similarly-sized lights made using LEDs.
And while LEDs create a ton of heat at their semiconductor junctions, they don’t project infrared radiation, as HID bulbs do. So, the lens of an LED light will remain cool to the touch, even while its large heat sink may grow very hot. In contrast, the lens of an HID light does heat up. This can be useful for keeping snow and ice from accumulating on the lens of a driving light in winter conditions.
LEDs typically last about 50,000 hours. An HID bulb last about 9,000. Either offers years, and years of life. When an LED burns out or suffers a fault, the entire light it’s housed in must be replaced. With an HID, you can just replace the bulb.
Raw Lumens: LEDs and HID bulbs aren’t produced by the brands you buy driving lights from, but rather large industrial companies who sell their technology to those consumer-facing brands. And those LED makers need a performance metric to communicate to those light brands. Enter raw lumens.
Raw lumens are the level of brightness an LED is capable of producing in ideal laboratory conditions. But laboratory conditions do not represent the real world. LEDs typically can’t be driven to their maximum power without overheating them. So, light makers can only power them to a fraction of their theoretical performance potential. And, even then, a portion of that power is still lost to heat. This typically reduces potential light output by at least 10 to 25 percent before the LED is even installed in a reflector, and protected by a lens. No reflector is 100 percent efficient, reducing power even further. And, a portion of the light that then gets projected forward will reflect off the inside of the lens, causing further losses.
Raw lumens have little to no bearing on the actual output of a driving light.
Effective Lumens: Now we’re talking. Effective lumens are an actual measurement taken by a light maker. But, that measurement occurs 3.3 feet (one meter) in front of the driving light, which isn’t terribly useful. Effective lumens measure the real output of the LEDs or HID bulbs inside a driving light, but do nothing to quantify the performance of the reflectors, and therefor the ability of the light to actually project light forwards.
Lux: A measurement of the intensity of light. One lux is equivalent to one lumen of light spread across one square meter (or 10.8 square feet). If that sounds complicated, it’s equal to the amount of light it takes to comfortably read book or newspaper-sized text. Measuring the distance at which a light can produce a certain amount of lux is then a realistic portrayal of the light’s performance. The width at which that performance is achieved also gives you a factual description of the beam pattern.
The industry standard performance metric is to quote light performance by the distance at which a pair of lights can project one lux, and the width at which that beam continues to provide that 1 lux. Since driving lights are typically sold and used in pairs, this creates an easy, transparent way in which you, the consumer, can then compare them. If a $1,000 pair of lights projects 1 lux to 4,000 feet, you can understand why you may want to pay more for those versus a $500 pair that projects 1 lux to 2,000 feet. A pair of lights that achieves superior performance at that distance will also be a pair of lights that achieves superior performance at any other distance.
Best Practices
There’s some practical considerations to mounting, using, and selecting lights we’d be remiss not to cover.
Location: Positioning the lights out in front of your truck, where no reflections will be able to bounce back into your eyes, is the most effective place to put them. Mounting lights to your roof, or worse, the trailing edges of your hood, tends to bounce the light off that hood, back into your eyes, causing eye fatigue and reducing your ability to see through that reflection, then out into the night. In conditions where there is precipitation or dust in the air—and off-road, there is almost always dust in the air—then lights mounted on your roof, or worse, the trailing edges of your hood, will illuminate those airborne particles right in front of the windscreen, creating an impenetrable shield of light through which you will be unable to see. Lights mounted out in front of your vehicle minimize these reflections.
But, mounting lights in an appropriate location is often more challenging than mounting them some place stupid. Aftermarket bumpers should give you the ability to mount a quality pair of lights in the ideal location. License plate brackets may be strong enough to mount a small pair of lights. Hidden light mounts, which provide a mounting bracket within the front grill, may provide a very stable mounting option, but the shape and size of the driving lights becomes an important consideration, the grill slats may limit or obscure light performance, and airflow to the radiator can be disrupted.
Wiring: A quality pair of driving lights should include a wiring harness which makes it easy to install the lights. That harness should include a switch which will enable and disable the lights, and connect to your vehicle’s high beam switch, enabling you to operate them as you would your standard high beams.
How Many Lights Do You Need? Two. A single pair of driving lights should be capable of illuminating everything you need to see as you drive, including close up ditches, far away distance, and everything in between. With an appropriate color temperature and versatile beam pattern, those lights should work as well while crawling through rocks at a walking pace as they do while driving down a remote paved road at expensive ticket speeds. Running more lights is not a flex, it is a prominent visual indication that you have selected inadequate products.
Just Tell Us Which Lights To Buy
The cheapest viable product if you hope to achieve a meaningful upgrade in visible distance at night is likely a $450 pair of Lightforce Strikers. Those include all the wires and switches you need, and project one lux of light out to 2,460 feet with a beam that’s 302 feet wide.
A solid upgrade from there would be a pair of ARB Solis 21 or 36s. With those, you’ll want to select a spot pattern light for the driver side, and a flood pattern for the passenger, in order to create a versatile, high performance beam pattern. Wiring harnesses and switches are included, and a pair of 21s configured like that will provide one lux of illumination at 3,346 feet, a beam width of 105 feet, at just $525. The 36’s increase that distance to 4,796 feet for $730.
The highest performing pair of lights currently available in the United States is the Lightforce HTX2. They use a combination of LEDs and HIDs to deliver 1 lux at 5,906 feet (yes, that’s over a mile), at a width of 367 feet for $1,300.
Need help selecting and installing your lights? The shop where you got your GFC installed will be able to point you in the right direction, and wire the lights up so they operate correctly.
Tell us about your current setup and feel free to ask any questions in the comments section!