loading Loading please wait....

UNDERSTANDING LED LIGHTING

UNDERSTANDING LED LIGHTING

by Ed Evans, 15th June 2016

LED lamps give improved lighting, but how do we choose the best for our application? Ed Evans visits UK manufacturer Lazer Lamps.


LED lighting is prolific on new vehicles and it’s rapidly gaining popularity on all vehicles for improving the standard lighting and adding daytime driving lamps. There are good reasons for this trend, including improved driver vision, lower power consumption, robustness, and compact size allowing easier installation – everything we want, really. The trick is knowing how to select and buy the best lamps for the application and how to choose a quality product that provides good value. To do that, we need to know what’s inside an LED lamp, how it works, and what gives it longevity, quality and the right type of illumination for our needs. I visited the Stevenage factory of UK specialist manufacturer, Lazer Lamps, where their technical team was happy to provide all the inside information that we could possibly need.

>HOW THE LED LAMP WORKS
LED is the acronym of Light-Emitting Diode. The LED is mounted on a circuit board inside the lamp unit, and gives off light when an electric current is passed through it. The light produced by the LED is directed and shaped into the required beam by lenses and reflectors. Electrical power to the LED is controlled by an LED driver to ensure a stable light output, despite fluctuations in the vehicle’s voltage supply. To ensure the circuit board components run at their most efficient temperature without overheating, Lazer Lamps’ products incorporate a microprocessor-based thermal management system which modulates the output from the LED driver controlling power input. Lazer, and other well-engineered lamps, use additional circuit board components, including inductors to control electro-magnetic interference, a transient voltage suppressor to filter out voltage spikes from vehicle systems such as the alternator, plus resistors and capacitors. To maximize heat dissipation, Lazer uses an aluminium substrate circuit board which is installed in an aluminium finned heat sink which helps remove heat from the board and forms the main structure of the lamp unit.

>LED PERFORMANCE
LED lamps give more illumination for less energy and, while vehicle manufacturers take advantage of providing good lighting for less power, we can select LED lamps with a view to gaining maximum illumination for similar or less energy consumption. Lazer Lamps’ director, Ben Russell-Smith explains: ‘LEDs produce around 100 lumens per watt when driven at high current, whereas halogen lamps produce around 12 lumens per watt and High Intensity Discharge (HID) lamps give around 50 lumens per watt.’ But there’s more to this than lumens. Beam penetration and spread affect how far we can see down the road, and also the amount of side vision available to show pedestrians and, in country areas, wildlife and road/trackside debris. Lazer Lamps’ dual optic hybrid system combines a long beam range for road use with a broad beam closer to the vehicle for off-road driving, giving both flood and spot lighting in the same unit.

^ Compared to standard headlamps (left), LED lamps can provide a more penetrating beam with a longer and wider illumination (below).

^ The photometric diagram shows actual illumination. This lamp has maximum intensity (in Lux) up to 170 metres ahead of the vehicle.

> INSTALLING LED LAMPS
Another benefit of LED lamps is their relatively compact shape which allows a greater choice of location on the vehicle. Physical mounting is a matter of simple bracketry to fix on to the vehicle. And wiring up involves the proven and simple system of running power from the battery and switching that power via a relay linked to the full beam circuit so that the lamps extinguish when switching to dip beam. Lazer Lamps’ kits include a relay and waterproof connectors for splicing into the existing circuits. The rear of the lamp needs air space to allow heat to dissipate, but it also needs to be clear of mud spray which could clog the cooling fins on the heat sink.



^ STEP 1

Lazer Lamps’ four-lamp wiring kit includes 6 metres of cable, comfortably reaching roof-mounted lamps and most other locations.



^ STEP 2

Driving beams and daytime running lamps are combined here in a Lazer Lamps unit set into a Devon 4x4 Defender bumper.





^ STEP 3

LED lamps are easily mounted on the bumper top (first), or on an external roll cage (second) or a roof-mounted lamp bar.

LED LIFESPAN

LEDs are tested by their manufacturers over 50,000 hours, though if a lamp assembly were to fail earlier, it’s probably down to other components. So the quality of the component parts and assembly method is critical to reliability and longevity. The LED requires careful temperature management, and the light it emits has to be focused and transmitted using reflectors and lenses. The efficiency of the temperature control, the quality of the hardware and electronic components, and the optical efficiency of the lenses and reflectors has a significant effect on the life-span of the lamp, and on the quality and amount of light projected to the point where it’s needed. Lazer Lamps tackle these issues by using a high thermal conductivity heat sink, ceramic capacitors and a robust fully-sealed construction.

The temperature of the circuit board and its components is closely controlled to maximize the LEDs’ output, otherwise a light of 20,000 lumens might only produce, say, 16,000 lumens if the system runs too hot. Excess heat reduces the lifespan of the components, and the LED can be damaged if run at high temperature for extended periods. LEDs do not fail in the way conventional bulbs do, but they do degrade with normal use, and this will be accelerated by poor temperature control in the unit. Ingress of grit, sand and especially moisture all reduce the unit’s lifespan, so the sealing is critical. Lazer Lamps are claimed to be watertight to 1 metre depth and, to prevent sudden temperature changes damaging the seals when immersed, Gore-Tex breathers allow pressure changes inside the unit – the equivalent of axle breather pipes.

UNDERSTANDING LED LIGHT
• The number of lumens is the total light emitted from the LED source and does not account for the efficiency of the reflector, or the heat management. Up to 30 per cent of the light can be lost through poor heat management, and inefficient optics.
• Lux is the unit for the actual amount of light arriving at a specified distance from the source LED, such as the point the driver is focusing on down the road or track.
• The combination of spread and reach associated with LED lamps means there is no need for separate lamps to be angled to the road ahead and to the side, nor for critical directional adjustment.
• The compactness of LED lamps means they suffer less from vibrational movements when driving, especially off road.

LASER LAMPS TEAM
||||||||||



DIRECTOR Ben Russell-Smith designed and developed lighting systems with Nissan and Ford before forming Lazer Lamps Ltd in 2010 in response to the growing demand for LED systems. The company manufactures a range of BSI-approved and Euro E-marked lamps for road and off-road use, plus daytime running lamps. Their systems are fitted to Defender Challenge vehicles and are widely used in motorsports.