How LED Headlights Illuminate the Road Ahead
Photo courtesy of iStockphoto.com
LED headlights have gradually become a commonplace addition to new-vehicle models, taking over for halogen headlights. But this transition is more than just a technological evolution. It has had benefits for the way drivers are driving during and after business hours in low-light level situations. Improvements include better illumination and beam focus.
Improved illumination is the most apparent difference from halogen lights. LED headlights can illuminate dark roadways 25% farther than their halogen counterparts, and high-beam settings on LEDs offer a significant improvement over low-beam settings, according to a study from AAA.
How an LED headlight projects the beam illustrates how it is an improvement over halogen headlights, according to Greg Brannon, director of automotive engineering and industry relations for AAA.
“LED lights are much better at their ability to project the beam where it needs to go and deal with light scatter, where halogen reflector lights don’t have as clear a cutoff in terms of the way they distribute the light,” said Brannon.
Whether an LED headlight — which consists of multiple LEDs — is set to low beam or high beam is dependent on the number of lights that are shining. When set to low beam, the individual lights of the LED will adjust to create a defined line so there is no light coming out above the beam.
However, despite the technological improvements they bring to the table, LED lights still face an issue that is common with automotive headlights in general, which is not being able to light the road to an unlimted distance and susceptibility to wear and tear.
Despite the brightness improvement over halogen lights, LED headlights failed to fully illuminate roadways while traveling at highway speeds.
“The LED lights absolutely do a much better job of illuminating the roadway, particularly in the low-beam application versus a halogen reflector at 150 feet more in our testing. But, still, that brings the max vehicle speed to about 52 miles an hour, so its still falling short of highway speeds,” said Brannon.
To compensate for this limitation of headlights in general, Brannon said that high beams should be used more regularly.
“In general, our advice to other drivers is that if you are on an unlit roadway and there is no oncoming traffic within a reasonable distance you should really be driving with your high beams on. If you have an auto high-beam setting on your vehicle make sure that it is activated. Because, really, at highway speeds on unlit roadways the light systems are really not able to pick up non-reflective objects,” said Brannon.
Brannon noted drivers transitioning from halogen headlamps to LED headlights will immediately notice a difference in how much they can see. However, this does not necessarily mean that everything in the light’s beam is immediately observable. What the driver is seeing more of with the LED light are the reflective objects in the road.
As with any headlamp, an LED headlamp that is on a vehicle operating in areas with hotter temperatures will face a gradual deterioration of its UV shield. This results in a cloudy headlamp, which reduces light output and increases scatter, which results in glare.
“Whenever that deterioration takes place, light scatter becomes more of a problem. Less light can get out of the lens as well as its not directed in the place that it needs to go,” said Brannon. “We’ve found that lens restoration can actually result in about 60% less light scatter.”
Restoration is highly encouraged as well as proper cleaning of the head lamp for safe operation of the vehicle.
“The headlamp should be cleaned regularly, and a UV protectant is a good idea for any lamp assembly,” said Brannon.