The latest advances in headlamp technology and a guide to fitting LED daytime running lights.
Light and dark are fundamental to human psychology and physiology. In nature, we have evolved to function during daylight and produce the hormone, melatonin, to promote sleep at night. Producing artificial light has also been essential to our survival, cementing a link between light and safety.
Yet, where ancient civilisations would struggle to keep a fire lit (the latest rash of reality television programmes highlight how critical a fire is for survival), modern man takes lighting for granted, because it is available at the flick of a switch.
Scared of the dark?
In an automotive context, the association between light and safety is promoted heavily but not always correctly. At OEM level, safety is the reason why daytime running lights (DRLS) have become mandatory on new cars, even though some people view them as unnecessary – and even dangerous – in countries outside of Scandinavia. Indeed, the ‘brighter is better’ hymn is sung by many light bulb retailers, implying that their products are superior and safer. This may lead you to buy the brightest bulbs possible, while forgetting, or ignoring, the equally essential safety issue related to dazzling oncoming motorists.
Ring Automotive, the Uk-based vehicle lighting and aftermarket
specialist and our technical partner for this feature, acknowledges that, while its range of high performance headlamp bulbs increase brightness, the engineering both of the bulb and the headlamp optics make the extra light workable and safe.
This is one reason why the MOT test started enforcing legislation, banning HID headlamp conversion kits earlier this year. Brightness should not be the only technical consideration when buying any bulb, let alone an uprated one.
Evolution of bulbs
Using electricity for lighting was suggested by the scientist Humphrey Davy in the early 1800s, after he noticed that electricity arced through the air and produced light when he shorted out terminals. Arc lights had evolved by the mid-19th century, but they were inefficient and the electrodes demanded a complex clockwork mechanism to maintain an adequate gap, because the intense heat eroded them away. As gas would provide a more popular means of domestic lighting, some of the earliest cars used either candles or gas headlights, both of which were fairly ineffective. Electric lighting was not technically viable until the introduction of more efficient dynamos and the filament bulb.
Davy had also noticed that a metal wire heated-up when electricity passed through it. Unfortunately, this was of little use, because it would react with ambient oxygen and melt. Enclosing the wire within a glass tube, evacuating the air and pressurising the void with inert gases (such as nitrogen and argon) offered a solution. Experiments with different filament materials followed, culminating with tungsten, because it possesses the highest melting point of all pure metals. Within the glass, the tungsten is coiled and the tighter the coil is wound, the more heat is generated and the brighter it glows.
Tungsten-halogen bulbs appeared in the 1950s, with minute quantities of iodine, or bromine gases, added at an even higher pressure within the glass envelope, which increased the lifespan of the filament by encouraging any evaporated part of the coil to redeposit itself. As 12-volt electrics became universal, these bulbs produced double the light and lasted twice as long. Developed by Lucas, the H4 twin-filament tungsten-halogen bulb contained one filament each for dipped and main beam lights and became virtually universal in vehicles, although single filament bulbs (H7) have since regained popularity, as they tend to offer superior performance.
More recently, dual performance lamps (such as H15) combine main beam and daytime running light filaments. Some recent cars feature cornering lights, usually located in the foglight apertures beneath the headlights, which are activated by the steering angle sensor, although this can confuse other motorists into thinking that the turning car in front of them has a broken foglamp. Some cars are programmed to cut-out the DRLS, should there be a conflict between indicating a change of direction and marking out the car.
The arrival of HID
Some changes have had a more positive effect. Despite refinements made to their design and construction, tungstenhalogen bulbs remain relatively inefficient, because they waste between 70-90% of the consumed energy as heat. Looking to improve headlamp efficiency, vehicle aesthetics and optics, lamp designers turned to High Intensity Discharge (HID) bulbs to replace the traditional filament-type. This also necessitated a complete redesign of the headlight’s internals.
These HID bulbs – called ‘burners’ – borrow certain elements from energysaving tube lights, themselves based on technology from the wasteful arc light. Known also as ‘strip lights’, the electrodes are placed at either end of a glass tube and, after the air is evacuated, the tube fills with a glowing highvoltage arc. Once the inside of the tube is coated with a fluorescent powder, the dangerous ultraviolet glow is converted to brighter, safer and usable light. HID burners do not utilise fluorescence, but rely instead on a number of different gases and salts within the burner. Like filament bulbs, HIDS produce ultraviolet light that can damage the headlight, although advanced glass technology filters it out. HIDS are sometimes called ‘xenons’, but the nomenclature can be confusing, because certain halogen bulbs can also contain xenon gas.
As HID bulbs do not have tiny filaments at either end of a glass tube to ‘start them up’, they require an igniter to create the, approximately, 2000 volts necessary to vaporise the salts. An electrical ballast – a resistor that limits the current – then takes over to maintain the running power at between 35-85 volts, at which point the total power consumption tends to be much lower than that of an equivalent filament bulb, while the light output is double. The igniter is included on D1, D3 and D5 HID bulbs, but the ballast is always a separate component. The different light output characteristics of the HID burner means that the optics of a filament headlight are incompatible, due to the increase in scatter that affects the beam pattern and heightens significantly the risk of dazzling oncoming motorists. This is a prime reason why HID (and, for that matter, LED) conversion headlight bulbs are illegal to sell, fit and use on the road.
Early D1 and D2 HID burners contain mercury vapour, which is not captured when the car is scrapped. To respond to legislation banning the heavy metal, car manufacturers introduced D3 and D4 mercury-free HID bulbs in 2012, although replacement mercury-containing parts are available. However, the old and new bulbs are not interchangeable. Some new types of extra-efficient 25-watt HID bulbs have been introduced (such as D5S, D6S and D8S) but they are fairly uncommon.
Old HIDS should be disposed as hazardous waste and not simply placed in household rubbish.
As there is no road-legal Light Emitting Diode replacement bulb, certain newer cars with LED lighting have sealed lamp units. The enclosed nature of their construction ensures that the LED module and the optics of the lamp work together accurately. Carmakers prefer LED headlights both for aesthetic reasons, with LED lamps marketed strongly as a premium extra, and for their low energy consumption and the associated reductions in CO2 emissions. Yet, even LEDS do not break the traditional link between light and heat, and some LED headlights contain either considerable heat sinks and/or cooling fans.
While LED headlamps are fitted to some of the newer vehicles on the used car market, do not assume that they offer superior performance over HID, or even filament bulbs. From a DIY perspective, consider also that, should an LED module fail, the complete headlight will need to be replaced and that aftermarket alternatives are unavailable. In the near future, specialist LED headlight repair is likely to be offered by various aftermarket ECU repair businesses.
LED Matrix lighting is becoming popular, where individual LED modules are controlled via a windscreenmounted camera to provide auto-dip, or speed adaption functions, with the latest versions mapping oncoming motorists and switching-off areas of light to surround but not dazzle them. Vauxhall’s Intellilux is one such system, while Audi and Volvo have developed their adaptive headlights to provide individual illumination for pedestrians and animals.
According to Michael Koherr, Ford of Europe’s lighting research engineer, lighting is going to become even more sophisticated: “We are now developing new spot-lighting technology that helps draw the driver’s attention to pedestrians, cyclists and even large animals in the vehicle’s path. This would use an infrared camera to locate and track people and bigger animals up to 120 metres away.”
What goes wrong?
Back in the realms of current technology, filaments can simply snap, but you can detect impending breakage by identifying the blackened remains of evaporated tungsten on the inside of the bulb’s glass. Unlike HID burners, however, filament bulb performance does not drop with time. While your HID bulb may last for more than a decade, its performance deteriorates as the molecules of gases and salts within the burner not only age but also diffuse gradually through the glass. The result is a deterioration in light output and, because the process is gradual (with sodium vacating after the first few months, making the light glow whiter, before dimming gradually) the owner of an older car tends not to notice, because the headlight still works, albeit at a reduced capacity. Ring recommends that HID burners are replaced in pairs every five years.
The main operating condition that reduces HID life is repeated switching on and off. The control gear can fail as well. Should the ballast break, the start-up igniter will not work. If the igniter fails, you may hear a ‘clicking’ sound from the affected headlight. In any case, a flashing dipped beam dashboard tell-tale may be one way of indicating that a fault code has been logged. Most Hid-equipped cars are fitted with self-levelling and headlamp washers. As
certain Japanese models were failing UK MOT tests, such as Mitsubishi Lancer Evolution XIIIS, which had factory HIDS but no washers, the MOT regulations stipulate that, if levellers/washers are fitted as standard, they must work.
While adaptive LED and LED Matrix headlights require periodic adjustment and calibration via diagnostics (general advice on digital calibration was outlined in the October 2018 issue of CM), the headlight will need to be replaced as a complete unit, which will necessitate programming, alignment and calibration. The headlights themselves can suffer from various ailments. Other than stonechip damage, or an impact that breaks the mounts, the internal reflective material can detach. While several specialists offer a resilvering service, this tends to be less successful if the coating is applied to a plastic base. A more common phenomenon on newer headlights, where a glass lens has been replaced by a plastic cover, is the surface becoming opaque. While long-term UV light exposure from the sun tends to be the culprit, inexpensive bulbs can lack ultraviolet blockers, which hastens deterioration.
Low-quality components are a growing problem and bulbs are one of the most popular targets for counterfeiters. You need to be able to place trust in your supplier and its brand.
Ring’s vehicle lighting division has been established for more than 40 years and its test and R&D facilities are located at its West Yorkshire base. “Customers can trust our bulb range,” says Matthew Flaherty, product manager at Ring. “We do not simply print our logo on other people’s bulbs; we partner only with leading manufacturers to produce bulbs that have the highest quality, and liaise closely with our suppliers around both Europe and Asia, many of which we have worked with closely for over 20 years.”
With research revealing that one in four aftermarket bulbs are built to a poor standard, buying dubious items from unknown sources is likely to restrict your vision and increase light scatter, or ‘glare’.
As production accuracy is so critical to road safety, automotive bulbs are one of the few aftermarket parts that must be certified for their performance. This means they should be Type Approved and bear the appropriate ‘E’ mark. The legislation caps various design and performance characteristics, such as filament alignment, power consumption, brightness, colour temperature and base design, making it an offence to use a non-type Approved bulb in an on-road exterior lamp, because of the safety implications. You can use non-approved bulbs (including LED conversions) within the interior, as long as the light output is not directed outside. While you can buy standard non-type Approved lamps, not only are they illegal to use on the open road but they could also be a false economy. The car might fail its MOT on dipped beam alignment and the potential lack of UV light blockers may damage the headlight. Alternatively, lower gas pressures may be used to compensate for the cheaper glass at the expense of durability.
When upgrading filament bulbs, much depends on your needs. As some cars necessitate dismantling of the frontend just to change a headlight bulb, fitting long-life replacements may be preferable. The longer life is attributed to them running cooler, with the tradeoff being a slight reduction in output.
As Ring’s Matthew Flaherty says: “Type Approval demands that an H7 bulb, for example, runs at 1500 lumens, with a tolerance of 10% – so a long-life bulb will run within the lower side of that 10%. A performance road-legal bulb can be up to 10% brighter, while remaining within the Type Approval limits. The filament is wound tighter, too, which ensures a smaller focal point, which places more light on the road where it is needed by the driver.”
While Matthew Flaherty admits that using obviously blue lights at the front of your car is illegal in the UK, he explains why the blue coatings on Ring’s roadlegal upgraded bulbs will not fall foul of the authorities: “When a filament glows brighter, you change its colour temperature. Coating technology, applied to the glass, alters it again, so you can keep the bulb legal but use a white, or bluer light, to replace yellow, which offers better reflection from road furniture, such as signage, without straying from the Type Approval colour and brightness limits. Again, if you are unsure, check that the bulbs are E-marked so they can be used on the road.”
Cost is an another factor. While high-performance bulbs are marketed as premium products, extra and more expensive gases may also be included, such as xenon. Illegal updates While fitting uprated E-marked bulbs of the same light type is acceptable, mixing and matching different technologies is not. For example, placing HID, or LED, bulbs in halogen lamps is technically impossible, because they have different bases to prevent accidental fitting. This has led to the deliberate creation of ‘Frankenstein bulbs’, which have halogen bases but HID/LED tops, so they can be fitted into lamps designed for filament bulbs. Due to their hybrid construction, it is impossible to meet the required safety standards, meaning that they are illegal to sell, fit and use on British roads. Due to the lack of any formal certification, the quality of such bulbs can be questionable. Many of them are available through online marketplaces, where some unscrupulous sellers claim they are legal to use.
You may find such items, especially LED sidelight conversion bulbs, offered for sale at reputable retailers, but statements about their non-legality for on-road use can be hidden away in the small print on the packaging, so look carefully. If you drive an older car, you might have read that you can update its lighting with conversion bulbs, because Type Approval regulations do not apply to various lamps beyond a certain age. Unfortunately, the research is incorrect, because the assumption is based on original parts of the British Road Vehicle Lighting Regulations from 1989, not the later regulations that superseded them.
The replacement headlight bulbs market, in particular, offers great scope for improvements. But buy carefully – make the wrong choice and you could make your car unsafe and illegal.
Headlights have evolved considerably. Pictured are performance comparisons of a 1908 Ford Model T’s gas headlamps against a Ford Anglia 105e’s filament dipped beam and the HID Xenon of a 2016 Ford Mustang.
Filament bulb production is a precise art. Misalignment results in poor output and glare, which is why you must insist on Type Approved bulbs, which are a legal requirement for on-road use.
Pictured are D1 and D3 HID burners with an integral igniter. Note the different moulding used for the plastic connector, because D3 burners (on the left) contain no mercury and have a different electrical ballast specification.
Ring has conducted research into the effects of ageing HID burners. Pictured above is the light output from a new D3 bulb compared to the one below that is 10 years old. The loss in output is quite dramatic, even though the old bulb would still pass the MOT.
HID electrical ballasts tend to be fixed to the bottom of the headlight moulding and replacement should be straightforward. If the igniter is not integrated with the HID burner, a sheathed cable transmits 10,000 volts from the ballast to the burner. Always follow the safety instructions, supplied with the new bulb.
Both bulbs and complete lamp units (including sealed LED lamps) should carry E-marks in order to be road-legal.
LED Matrix front lamps work in conjunction with a camera. This Audi unit can detect and illuminate a safe walkway for pedestrians.
Here's why LED conversion bulbs are a poor upgrade. The image on the right shows the exterior lamp’s optics working with the original filament bulb to create an even, bright halo. The LED’S lightemitting characteristics, shown at left, result in a less efficient lamp.
Pictured is the result of fitting a roadlegal upgraded sidelight bulb, compared with a standard item. The one on the right, made by Ring (Xenon3500k 501), has a blue coating, which acts to remove the yellow/orange light to produce an output that still complies with Type Approval.
Sealed LED central brake lamps have been used for many years. They will fail the MOT if fewer than half of the modules are working. You may be able to break open the seal to repair them – in this case, water had entered the unit, corroding the resistors.