FOR something as mundane as headlamps, I have quite a few words to write. It all started during a night fishing trip when my friend’s Toyota Estima blew a headlamp. Then another friend mentioned his BMW’s LED lamps once conked out as well. Let’s have a look-see.
Let’s not mention acytelene lamps or gas lamps here. Those old tungsten filament sealed beams will also get bypassed since they were superseded by H4 halogen headlamps quite some time ago. Very little innovation ensued until the HID headlamp emerged in the early 90s and subsequently LED headlamps.
One point to note is that headlamps are made specifically to suit left-hand drive (LHD) or right-hand drive (RHD).
The reflectors and lenses are designed to suit various countries and you simply cannot fit a LHD headlamp to a RHD car. The beams would not point in the correct direction. Something to ponder when you trawl the local “potong kereta” for new headlamps. However, some cars have a switch to cater for both LHD and RHD countries.
Reflector headlamps are what you normally find on cars. The bulb in the centre will reflect light off the sides to project its light onto the road. Projector beam headlamps do not need reflectors. Their light is projected straight from the bulb to the road via a lens. All HID lamps use projector lenses but not all projector lamps use HID. Some just use the special H1,H7 or H15 light bulbs.
Halogen headlamps (H)
Halogen lights contain a gas, usually a combination of nitrogen and argon, and a tungsten filament encased in a glass tube. The glass is extremely resistant to high temperatures.
When the light bulb receives the electrical current from the car, this heats the tungsten filament creating light, just like the bulbs in your house.
As many as 80 per cent of all cars are fitted with halogen headlamps. Halogen headlamps come with various wattages and sizes and immediately switch on (unlike xenon lights). It is cheap to replace and lasts a very long time.
However, halogen is inefficient and dim in comparisons to other available light options.
A standard halogen bulb will produce just around 1,300 lumens. A further downside is that it is extremely sensitive to substances, even the natural oils from your bare hands on the glass will alter the heat distribution and lower the bulb’s lifespan drastically. It also creates a lot of heat which, being a form of energy, is only wasted.
HID (high-intensity discharge)
HID lights are also known as xenon lights, and have been gradually adopted by increasing numbers of manufacturers for various models, usually for luxury cars. HID lights contain a mixture of gases and rare metals that are heated to generate a bright white (or blue) glow. HID lights generally produce around 3,000 lumen, roughly two to three times brighter than standard halogen lights. However, this has led to complaints about the level of glare these lamps produce.
HID lights actually require more power to start up but once they are on they operate at a much lower power usage than halogen. This low wattage makes HID lights more efficient than halogen and makes them last longer and produce less heat.
However, HID costs a lot to install, thus they are mostly found on high-end cars. They are also not cheap to replace due to the rare metals used in their construction. The headlamp housings need to be specially constructed to house HID lights.
Simply retrofitting HID lights to normal halogen housings will result in excessive glare (see complaints above). In some countries, doing this will result in an automatic failure during annual vehicle inspection.
HID lights also require a short period of time to attain full brightness.
On most car models using HID lights, it is only used for the low beams while the high beam lights are an entirely separate set of halogen lights. This is primarily because high beams need to be turned on and off instantly, which HID cannot fulfil.
LED (light-emitting diode)
LED lights have been around since 2004 but have only just begun to gain popularity recently.
One of the advantages of the LED bulb is that it is the most energy-efficient. LED lights draw 15 to 18 watts of power whereas halogen bulbs draw 55 to 65 watts and HID lights draw around 30 to 42 watts.
This also contributes to their incredibly long lifespan which potentially could see out the entire lifetime of the car.
Another advantage is they have the shortest rise time (the time it takes to turn on) at one millisecond, making them extremely useful as a brake or indicator light.
LEDs also do not contain mercury and their small size enables them to be arranged into any design, thus making them a favourite of car designers and custom freaks.
In terms of illumination, they fall in-between HID and halogen for brightness.
However, although LEDs do not produce heat like halogen or HID headlamps, they do however create a small amount of heat at the emitter. If the emitter is close to sensitive cables and other electrical components, this creates the possibility that other parts may become damaged.
However, through careful design of cooling in the form of fans and heat sinks, this can be eliminated. LED cooling systems are generally positioned in the engine bay and limit the ability to make lights for some models with limited space.
Cheap LED kits online use poor quality aluminium heat sinks and these significantly shorten the bulbs’ lifespan. Conversely, LED daytime running lights and tail lights don’t need heat sinks. The current running through them is not enough to create any sort of problem.