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Driving lights for 4x4 vehicles

By Dean Mellor, 07 Mar 2011 Electronics & Gadgets

Tech: Driving lights

The market is packed with a huge variety of driving lights. Before you spend your hard-earned, make sure you know what lights will best suit you and your vehicle.

The market is packed with a huge variety of driving lights. Before you spend your hard-earned, make sure you know what lights will best suit you and your vehicle.

No matter how good they are, your 4X4’s standard headlights just don’t cut it when you’re driving in the Aussie bush after sunset.

Even top-spec vehicles fitted with HID headlights can be improved upon when it comes to lighting, so it’s fortunate that there’s a huge range of quality driving lights on the market from a number of manufacturers that can help you see your way safely through the night.

You don’t have to spend thousands of dollars on a quality driving light set-up, but a pair a cheapies from the auto section of your local Kmart won’t deliver the lighting output that you need, nor the quality of construction to handle the rigours of back-road driving.

Important considerations when choosing a set of driving lights include the brightness of the lights, the shape of the light output and the quality of construction. And always make sure the lights will physically fit where you intend to mount them to your vehicle. This last point may sound like an obvious one, but the design of many frontal-protection bars severely limits the size and the shape of the lights that can be fitted.

When it comes to lighting output, the ‘shape’ of the light projected is just as important as the light output itself. The best shape will light up as far as possible down the centre of the road, but also illuminate to the sides of the vehicle where the wildlife is lurking.

In an ideal world you’d fit a pair of powerful spotlights to light up as far as possible into the distance, and rely on your vehicle’s standard headlights on high-beam to look after illumination to the sides of the road. The trouble with this solution is that your vehicle’s standard headlights are likely to be inadequate, limited by their built-to-a-price wiring, not-so-powerful globes and poor lens optics.

Some years ago, many vehicles were fitted with standard-shape round or rectangular headlights that could be easily replaced with aftermarket headlights offering superior lens optics and light output; these replacement headlights could then be complemented by a pair of powerful spot-beam driving lights to offer the ideal lighting arrangement. But modern vehicle design has resulted in the demise of standard-shape headlights, so replacement items are no longer a possible option.

On many modern 4X4s with stylised headlights, you can replace the standard 55-watt globes with more powerful 100-watt items but, according to Alan Johnson at Piranha Off Road Products, this will offer minimal improvement in overall light performance; as little as three to five percent. Match higher-wattage globes to a better wiring loom, however, and Alan says you will see a more significant improvement in light output. But bear in mind that overall lighting performance will still be limited by the quality of the standard headlights’ lens optics.

One popular lighting solution for modern vehicles is the combination driving-light kit, with one spot beam and one spread beam. The spot beam lights up as far as possible down the centre of the road, while the spread beam complements the vehicle’s standard headlights, offering much better illumination of each side of the road. Most driving-light manufacturers now offer combination driving-light kits.

As mentioned, light performance is not completely dictated by the power of the globes in your driving lights. A quality driving light with good optics and a 65-watt globe can easily outperform a poorly designed driving light with a 100-watt globe. Simply fitting more powerful globes to your existing driving lights will not in itself improve their performance by a great margin and can, in fact, have a negative effect. The more powerful the globe, the more heat it will generate, and, in extreme cases, this can result in discoloured glass lenses or melted polycarbonate lenses.

If your budget allows, the ultimate lights currently on the market use high intensity discharge (HID) technology instead of traditional halogen globes. Without going into too much technical detail, HID lights essentially emit light via an arc of electricity passing through a gas, as opposed to halogen globes in which electricity is passed through a filament, causing it to glow and therefore emit light.

HID lights offer several advantages over halogen lights. Where halogen lights are only about five percent efficient, HIDs are closer to 20 percent efficient and, as a result, the average HID light is only around 35 watts compared to the average halogen light which is around 100 watts. HID lights also emit a brighter and whiter light than halogen lights that is much closer in appearance to daylight. Finally, HIDs last longer than halogen globes.

On the downside, HID lights require an electronic ballast which adds weight, they can take a second or two to ‘warm-up’ and they cost significantly more than halogen lights.

Once you’ve decided on the best lighting solution for your specific vehicle, you’ll need to examine the design and construction of the driving lights to make sure they’ll go the distance on the front of your rig.

Traditionally, the construction of quality driving lights has consisted of plastic or metal housings, with smooth reflectors on the inside, complemented by glass lenses with specific shapes in them designed to direct the light into specific patterns. These fluted lens optics are very important in light design as they shape the way the light is projected in front of the vehicle, and good optical design can significantly reduce light-scattering losses and therefore increase the efficiency of illumination.

Traditional driving lights with plastic housings are generally lighter than those with metal housings, but not as robust. However, the problem with a heavy pair of lights is the stress they can place on their mounting brackets, and the point at which they’re attached to the vehicle. Thick glass lenses add to the overall weight of the driving light and they also require protection in the form of lens covers or grill guards to prevent stone damage, adding even more weight.

Despite heavy-duty construction of the housing and lens assembly, driving lights can be let down by insufficient mounting brackets which succumb to fatigue from mile after mile of corrugated roads. Have a good look at the mounting system on any set of lights you intend to purchase – they should be sturdy yet also allow easy adjustment of the lights.

Some driving lights can be fitted with optional stays to support the top of the light and therefore minimise stress on the mounting bracket. If you decide to fit stays, make sure they allow for easy adjustment of the lights and never attach them to the body of the vehicle; the movement between your vehicle’s bar where the lights are mounted and the body of the vehicle is enough to quickly destroy the lights.

There’s at least one heavy-duty driving light on the market that features a mounting system that supports the light at several points around its housing via a metal ring, yet can be quickly adjusted without tools.

Finally, make sure that the point of the vehicle where the lights will be mounted is sufficiently strong to handle the weight of the lights. We once had a pair of quality driving lights fitted to an original equipment alloy bar. The design of the bar didn’t provide a completely flat surface for the lights and, after only 500km of gravel-road driving, the lights started wearing through the mounting point of the bar, one of them falling off altogether and leaving a big oval hole in the bar.

New lightweight materials and technologies have resulted in major steps forward in driving light design. Composite materials, new ABS plastics and polycarbonate lenses have given light manufacturers a newfound freedom in light design. These materials are very light yet also very strong, and less overall weight means that there is less strain placed on the lights’ mounting brackets and on the point to which they’re attached to the vehicle.

Another recent innovation is free-form reflector technology, which has allowed light designers to replace heavy patterned-glass lenses with clear polycarbonate lenses that are tough and light. With free-form reflectors, light optics are completely controlled by the shape of the reflector surface in the body of the light, not by a pattern in the lens. And tough polycarbonate lenses are less likely to succumb to stone damage than glass lenses, virtually eliminating the need to fit covers or grille guards.

Another point to consider is a light’s ability to stray dry. Have a look at what claims the manufacturer makes in regards to waterproofing, especially if you’re likely to be doing a lot of water crossings. Some manufacturers offer driving lights that are specifically designed to handle water submersion.

Before you fit a set of driving lights to your vehicle, make sure you check out your relevant state’s rules and regulations pertaining to objects protruding from the front of your vehicle. In NSW, for example, it’s illegal to have driving lights that sit forward of the vehicle’s frontal-protection bar. It can also be illegal to mount driving lights on the roof of your vehicle.

Another consideration when fitting driving lights is the light that can be reflected off shiny surfaces back into the driver’s eyes. Highly polished alloy bars or lightly coloured steel bars are the worst offenders, and you may need to apply a coat of matte-black paint to some reflective surfaces.

Finally, wiring up a set of driving lights is a task beyond many of us. Narva offers a brilliant ‘plug and play’ wiring loom designed to simplify installation but, if you’re not confident, get an expert at your local four-wheel drive service centre to do the job.