LED headlights becoming more popular

If you're lucky enough to encounter a parked Audi R8 supercar, after you've finished ogling its exotic shape, take a close look at the headlights.

You're looking at a full array of LED driving lights - high and low beams and a line of daytime running lights that curl up below the main lights like a smirk.

Although light-emitting diodes have come into common use for brake and signal lights, only a handful of pricey cars and trucks offer LED headlights, including a couple of Lexus hybrids, the top-line Cadillac Escalade SUV and - as an option - the relatively cheap Toyota Prius.

But like almost every automotive technological breakthrough, LEDs are expected to become available on more affordable rides.

They're especially desirable for hybrid and full electric vehicles, says Viren Merchant, electronics engineering manager for exterior lighting at Visteon Corp., a major supplier to the world's auto makers.

"With electrification of the vehicles, where power generation or power storage costs money, using less power gives you less storage (requirement) or more range," Merchant says.

"That's what's driving it and there's a lot of interest in (manufacturers) in that regard."

Maybe a headlight primer is in order here.

In the beginning, cars groped their way through the dark with headlamps lit with acetylene gas. Then for decades, the tungsten-filament sealed beam - essentially a road-going old-school light bulb - ruled.

Halogen bulbs, a big leap over sealed beams, visibility-wise, arrived from Europe in the 1970s and now are the main light source for cars.

More recently, we're seeing more cars equipped with high-intensity discharge (HID) lamps, identifiable by their bluish-white light. They work by passing electricity through xenon gas.

Merchant estimates about 15 per cent of the world's vehicles now are equipped with HID lights, which car buffs have been retrofitting to their rides for years and are increasingly offered as original equipment.

Now come LEDs, which have been used since the 1960s for readouts on electronic equipment and more recently on things like Christmas lights.

Development of the technology has produced increasingly powerful white-light LEDs that are turning up in home lighting and flashlights.

Merchant says automotive engineers and designers love LEDs mainly for three reasons: long life, low power consumption and new styling and function possibilities, with LEDs stacked or arrayed in different patterns.

"With a bulb you have a single light source and there's only so many things you can do with it - a certain size, a certain area and a certain cone that you have to play with," says Merchant.

"LEDs give you a styling differentiation with many points of light, so to speak, that bulbs don't allow you to do."

But looks probably won't drive the spread of LED headlights.

"LED takes 70 or 80 per cent less power compared to incandescent sources. The power savings is a significant driver," says Merchant.

On conventional cars, that means less load on the charging system, and for electric vehicles and hybrids perhaps smaller battery packs.

And there's a good chance they'll never need replacing.

"You don't go to an auto-parts store and buy bulbs," says Merchant. "They can typically last the life of a vehicle."

Rainer Neumann, a researcher at Visteon's Germany division, says HID bulbs last about 3,000 hours, while LEDs offer a 15,000-hour lifespan.

So why aren't all vehicles equipped with these paragons of luminosity?

There's a clue in the fact they're only found on high-buck cars for now. You're paying for more than just a bulb. They require electronic controls and a cooling system because excessive heat can lead to premature failure.

"With a bulb you put 12 volts from a battery and you turn it on," says Merchant.

The LEDs themselves - produced by semi-conductor manufacturers - aren't cheap.

"So when you add the two together, it's a highly engineered product," says Merchant.

"You have expensive sources; you have expensive controls.

"(With) usage increases there will be an economy of scale on controls, as well as on LEDs, and that should bring the price down, at least to HID levels or lower in the future."

A damaged LED headlight will also cost more to replace because, ironically, it's a sealed unit just like the old-fashioned sealed-beam.

But Merchant notes that HID lights, with their built-in washers and motorized self-levelling projector lenses, have already been pushing up prices.