LED headlights ready for prime time

My trucking job mostly involves night driving between Toronto and Montreal, in all weather conditions. So I’m keenly aware of the importance of a good headlight system. And commercial drivers obsess about lights all the time – just leave your fog lights on after the mist has cleared and you’ll hear about it on the CB. Don’t get me wrong. The halogen bulbs in my dedicated Volvo do a pretty good job illuminating the road. But recently I’ve noticed that the clearest and brightest low beams belong to Freightliners, specifically Penske-owned Cascadias, as they slide past me on the Big Road.

I recalled seeing a news blurb somewhere about Penske outfitting its tractor fleet with LED headlights, and was genuinely thrilled when editor James Menzies asked me to test drive one of the retrofits. So one April night my godson Zak and I booked a newish 10-speed Freightliner Cascadia with a 425-horse Cummins ISX engine, and went looking for “the darkness on the edge of town.”

Truck lighting has come a long way since 1896 when Karl Benz mounted candles on his prototype truck. From lanterns to acetylene lamps to sealed beams, to halogen, HID-Xenon and finally LED headlights, it’s always been about seeing and being seen. Over the years, lighting solutions have paralleled – and sometimes lagged behind – other aspects of the automotive trade. But occasionally something new comes along that significantly moves the bar several notches.

The round two- and four-headlight sealed beam systems that we’re all familiar with were standard for 50 years or more, and rectangular headlights, mostly found on trucks, became more common after the 1970s. A major step forward came in the early 1980s when bulbs could be changed separately from the lens and reflector, followed in 1983 by the halogen bulb. By replacing the vacuum lamps with halogen (a combination of several gases) the tungsten filaments burned brighter.

Halogen remains the mainstay among trucking fleets but that could be changing. It tends to yellow with age and grow dimmer, and the bulb life is only about 1,000 hours. You often notice the difference when replacing a burned-out headlight. The new one burns much brighter. Depending on the manufacturer, halogen headlights can lose 20% of their luminosity in only 160 hours. Compare this to the “new generation” LED low beams which might eventually lose 7% of their output, but would take 20,000 hours to do so.

At 16 years of age, Zak is a physicist-in-training, and patiently explained to me the difference between candle power and lumens, photons, neutrons and electrons, as we spent several hours trundling the back roads between Toronto and Georgetown looking for dark stretches of highway. This is the time of year when a lot of animals are moving around and getting struck, so we were actually hoping to see some wildlife darting in front of the truck.

This didn’t happen, but the directional fluting of the beams onto the shoulders of the road was excellent. “Sixty degrees,” Zak announced when we stopped, measuring the sideways flaring of the headlights with his protractor.

This is an intentional design feature, according to Brad Van Riper, chief technology officer at Truck-Lite, which produces the solar charger.

By comparison, no one flashed their high beams at me while test driving the Penske Cascadia, but I personally think the intensity of both systems is about the same, though they have slightly different penumbras, and they are both brighter than that to which Joe Highway is accustomed. I was nervous about the amount of light the LEDs were emitting. But to the credit of the Truck-Lite engineers, the horizontal cut-off of the LED’s beam lined up just below a car’s trunk lid at a stop light. LEDs are monochromatic and narrowly focused. To fill out the rest of the light spectrum Truck-Lite used a blue chip that is coated with a phosphor.

“There are many ways of doing this,” says Van Riper, “but the most effective way is by coating the top surface of the LED with a phosphor and when the blue wave length light sees the phosphor, it releases photons that fill the rest of the spectrum, giving you white light.”