Light Duty: Lighting the Way

Ever since man learned about light, the perception has been ‘more light is better.’ More light, more light, more light! But what we have found lately is that the correct amount of light with the correct spectral content of light is better light.”

So says Mahendra Dassanayake, technical leader and lighting specialist with the Ford Motor Company. According to Dassanayake, the concept of “quality of light” is relatively new to the automotive lighting field, but it’s becoming a bigger issue every day.

“It’s just like sound,” he explains. “You have sound with medium, low and high-band frequencies, or you can have a certain amount of compressed sound. And when you do that it’s the perception that you need to address: you tune the visual perception based on how I see light in a more meaningful light—not just spilling a lot of light and saying you have good visibility.

“There’s a lot coming up with light sources and using LED (light-emitting diode) light,” he says, “so it’s a broad brush discussion if you say ‘LED light.’ At the lowest common denominator, it is a diode, but how do you use that light out of the diode in a more energy-efficient, smarter, more intelligent way? There are 1,500 ways of going at it.”


The good news is that fleet maintenance managers don’t have to deal with 1,500 different approaches to vehicle lighting—yet. But the days of the simple plug-in, electric-filament halogen bulb are fading fast as LED and HID (high-intensity discharge) lighting technologies migrate from Cadillac and Lexus models to lower-priced, fleet-appropriate vehicles.

“We are moving towards different light sources for lamps,” says Michael Larsen, bill of material family expert—in other words, a lighting expert—at General Motors.

“The LED is the new light source that’s out there,” Larsen says. “You see it in a lot of signal lamps. I know the heavy-duty industry has really adapted to these requirements where, depending on the state, if a bulb burns out, you can’t drive the vehicle. You have to fix the bulb. So, the trucking companies have figured out that if they spend the extra money on these LEDs then they don’t have to worry about whether a driver’s going to be stuck somewhere for an hour or two while he’s trying to get some stupid 10-cent bulb while he’s trying to get his truck on the road!”

Larsen says that automakers are using more LED lighting for the same reason, but that light-duty vehicles also benefit from the longer life, lower power consumption, and, yes, enhanced styling opportunities afforded by LEDs.

Surprisingly, LED lighting also promises what Larsen describes as a “fairly significant” improvement in fuel efficiency, simply because it draws so little power.

“LEDs are such low-power consumption,” he says. “Take a stop lamp: If you use a standard bulb, you’re probably at 21 watts, and if you do it in LED you’re at five watts. Most of the LED lamps on a vehicle, you can easily run them on a 9V battery. In a standard stop lamp, you would use a 150 milliamp LED, so if you use 10 of them that’s one and a half amps at four volts.”

According to Jayson Ryan, senior manager, OEM sales & product marketing for Philips Automotive Lighting North America, the watts used by headlights are directly proportional to fuel consumption.

“Typically if you look at a halogen bulb, it uses 55 to 60 watts per side. When you implement HID technology, HID runs at about 35 watts per side. So you can immediately see a dramatic improvement in power consumption from your lamps, which is directly translated into mileage. You don’t have to spec’ out as big an alternator, which affects weight, which will improve gas mileage.”


There are other good reasons to consider switching from incandescent vehicle lighting, chief among them safety. We’ve already touched on the “quality of light” issue; as Dassanayake says, “...the correct amount of light with the correct spectral content of light is better light.”

In the case of HID headlamps, that translates into a larger and deeper field of vision for the driver; the more you see ahead of you at night, the safer you’ll be. It also reduces the driver’s eye strain, hence reducing fatigue and keeping the driver more alert and aware.

“The sleep cycle of a human being is defined by the melatonin secretions in the brain,” Dassanayake explains. “In literature, people have found that certain wavelengths of light help better secretion of melatonin, and it keeps (drivers) awake and alert... and helps keep their attention and reduce their fatigue.

“Fatigue comes from the amount of work you have to do to be in control and be aware; in other words, it’s tied to the cognitive loading that someone has to go through,” he says. “So, the visible input is one aspect of that cognitive loading. The visible aspect can be impacted by proper lighting with the correct spectral content.”

Indeed, a study conducted on German drivers by TÜVRheinland®Group, a global compliance and testing company, finds that the number of new cars in Germany with HID lighting has been increasing dramatically, and suggests that there may have been up to 18 percent fewer fatalities on German roads as a result of the increased use of Xenon (HID) car lighting. The study also finds that up to 1,200 road fatalities in Germany could be avoided every year if all cars had Xenon lighting.

“You get a lot more light down the road in a wider beam pattern with HID, so he’s able to see more area,” says Ryan. “Then there’s also color temperature: HID is perceived as a whiter light, and it more closely resembles daylight than its halogen counterparts. So, it’s more natural for the eyes to see in this environment, there’s less strain on the eyes, which can result in less fatigue for the driver.”

The safety factor extends to the rear of the vehicle as well. Cars and trucks equipped with LED brake lights have a clear safety advantage over vehicles with incandescent brake lamps.

“Tail lamps with LEDs come on very fast, (in) twelve nanoseconds; for halogen or incandescent it’s about 200 milliseconds,” Dassanayake says. “So, with LED it comes on immediately... and that instantaneous change triggers your direct view and your peripheral view. If you’re driving at about 60 mph, it’s a good nine or 10-foot advantage.”


So far, LED headlamps have barely registered in the marketplace, but that may soon be changing, according to GM’s Larsen.

“Lexus now has an LED headlamp, and we’ve announced that we’re going to have an LED headlamp on the Escalade by the end of this year,” he explains.

“The LED headlights have a few things going for them,” he says. “One is styling; our stylists always want to set our vehicles apart, and LEDs give you that opportunity. The second benefit is that very soon, within the next couple years, power consumption of LED headlamps is going to be the same as or lower than halogen (55 watts) or even HID (35 watts). LEDs could be down to 25, 20, maybe even 15 watts, and with fuel prices the way they are in America, that’s becoming a big issue, as LEDs may be a big fuel-saver.”

LED headlights also take the “quality of light” issue a quantum leap ahead of HID headlights, which are already pretty good.

HID headlights already put out more light, and a whiter light, than halogen bulbs, Larsen explains, “So you get that perceived benefit of a lot more light.”

The step up from HID to LED headlights will offer that same perceived benefit, in spades. “LED headlights will offer performance equivalent to an HID, but the light from an LED headlamp is going to be a lot whiter, more like sunlight,” Larsen says. “So, your perception of the light output when you go to LED is that it’s even more light than an HID, even though it’s the same.”


Of course, as with any maturing technology, it’s not all sunshine and roses; LED and HID lights have their own maintenance issues.

“The one drawback of an LED lamp is that if it does burn out, you’ve got to replace the whole thing,” Larsen says. “They’re not serviceable; there are actually legal requirements about serviceability of LEDs and what you can and can’t do. So, if your LED stop lamp goes out, you have to replace the unit.”

And here’s something that could dull the shine of those HID headlights: “We typically see that HID bulbs are in the neighborhood of 10 to 15 times more expensive from a replacement standpoint than halogen bulbs,” says Ryan. “But, when you look at how long you can run an HID bulb on a vehicle, you have to take into account how often you would have to change a halogen bulb.”

Whether or not those are compelling issues for your fleet, there is another maintenance concern that affects any fleet technician working on newer light duty vehicles: how do you replace a light—either a lamp or an entire fixture—if you can’t get at it?

Tighter underhood areas can make it all but impossible to replace a headlight, daytime running light (DRL), foglamp or front turn signal, says Larsen. “In the past, you’d pop the hood and there’d be a mile between the headlamp and the radiator; I mean, you could stick your leg in there and it wouldn’t be a problem,” he says. “Well, today, it’s very difficult to see where to get access to the bulbs, and that’s the thing that the maintenance person is going to have to deal with when the bulbs burn out.”


Fortunately, relief from cramped engine compartments is coming from Europe. Larsen describes a new legal requirement in the EU says that any lighting unit on a vehicle that may need to be replaced by the consumer must be serviceable with the use of simple tools in a simple procedure that’s detailed in the owner’s manual.

“Because my company does global vehicles—the Malibu that sells here also sells in other countries—we have to meet that requirement,” he explains. “So, for our vehicles, you will be able to get at those replaceable bulbs without having to do a major tear-up on the vehicle. Maybe you need a screwdriver to pop it open, but that would be the extent of it. So, American and Canadian consumers are going to benefit from the European regulations, at least on these global vehicles, which is what most of ours are. So we, and our competitors, are really focusing on designing in this serviceability.”

Another maintenance improvement you can look forward to is PWM control, or pulse width modulation.

“Whereas on past vehicles, when the battery’s charging, the alternator really kicks up the voltage to the battery; well, that voltage goes throughout the vehicle,” Larsen says. “A bulb might see 14 volts, when it’s designed for 12.8. That greatly reduces the life of the bulb.

“With our new electrical architectures, with pulse width modulation, we can control that; we can cap the voltage,” he explains. “So a 12.8 volt bulb is only going to see 12.8 volts—no more than 12.8 volts—and that’s a big help in life. That’s available on future GM vehicles.”


For the last word in lighting maintenance and serviceability, we turn to the folks who design and engineer the lighting systems on your light-duty vehicles. What do they see as the most pressing issues in vehicle lighting today?

“A regular halogen bulb has between 600 and 1,000 hours of life; an HID bulb would be around 2,000 hours, or even more,” says Ingolf Sischka, product manager-aftermarket, Philips Automotive Lighting North America. “That already gives a very strong indication on how fleet managers could look into reduced costs for fleet maintenance.

“To get a taste of what these lifetimes really mean, an average consumer in North America drives his or her car about 200 to 250 hours a year with the lights on, or about 40 percent of the time,” he says. “For commercial applications, the number of hours with lights on in a year is on average about 50 to 70 percent higher, so you would be looking at lights on during a year of 350 to 400 hours. So, a halogen bulb would last one-and-a-half, two-and-a-half years, but with an HID bulb, that time doubles. And of course, if there is a FedEx truck that is running at night only, this is a significant difference.

“We do recommend looking for solutions that require less maintenance, and HID definitely could be one option,” Sischka says.

“If you’re in an area where you’re going to have a lot of obstacles to potentially knock off your lamps, if we can get a lower profile on a lamp that is also very rugged and dependable, then these products should last a lot longer,” says Mark Paul, business development and marketing manager for Grote Industries, LLC.

But the fuel-saving issue is one that the company would rather downplay. Yes, LED lighting will save you fuel, says business development manager-forward and interior lighting Mike Grote, but the savings is difficult to quantify and depends on the application of the vehicle.


Mike Grote still sees some applications where incandescent lighting continues to make the most sense. A fleet that operates in tight spaces and is constantly having lights knocked off is not going to invest in LEDs, nor is a fleet that only operates its vehicles during the day and whose drivers never turn on the lights. “I’m going to have a hard time telling them they should be buying LEDs,” he says with a chuckle.

Nonetheless, for most fleets LEDs are worth a serious look. “Actually, incandescents are going to be going up in price, as we make fewer of them,” says Grote, underscoring the point. “You just don’t get your economies of scale.”

“If an individual is going to look at an incandescent light bulb because it’s a cheaper product and I can get my vehicle back on the road faster, when you drill down behind the maintenance side, including all the shop time, LEDs are actually more practical over the longer term,” Paul says. “The cost of LEDs has come down significantly, it’s no longer a massive chasm between incandescent and LED pricing. So, I think we’re going to see a lot more moves to LED technology, as long as we can get that message out that it’s a longer-term strategy as opposed to an impulse buy.”

In other words, think it through. Switching to newer lighting technology has a ripple effect throughout the maintenance operation, Paul explains.

“Regardless of what Grote does from an engineering or design point-of-view, if, in the field, people don’t practice proper installation and care, then that’s a problem that you can’t blame on the LED,” he says. “If you’re going to invest in LED technology, don’t forget to invest in training your maintenance guys.”