Advances in manufacturing are bringing down LED light prices while extending their uses and improving their performance

The benefits of LED (light emitting diode) lamps in truck and trailer applications are widely acknowledged. Used as stop, marker, clearance, and other types of warning lights, LED lamps last far longer and produce more consistent light throughout their life than incandescent bulbs while drawing far less power.

According to the latest research from FLEET OWNER's Aftermarket Monitor, LED marker and stoplights are currently installed in 31.1% of all heavy-duty trucks. Although current trailer numbers aren't available, total installation percentages should be similar. In medium-duty trucks, the LED-use numbers are 35% for marker lights and 33.2% for stoplights.

As large as those numbers may be, the gap between fleets using LEDs and those that would like to make the switch is even larger. The survey found that the trucking industry would like to use LEDs in 68.5% of heavy-duty equipment. When it comes to medium-duty trucks, the preference for LEDs grows to 71.7%.

If there's one thing holding fleets back from making the LED switch, it's their high initial cost. Until recently, for example, a 4-in. LED stoplamp cost 10 to 12 times more than an incandescent lamp. But barring impact damage or theft, that LED lamp would last 10 years or more, in effect more than offsetting its higher initial cost by eliminating replacement labor and downtime costs.

Advances in technology, however, have begun to reduce the initial cost of LEDs and promise to cut prices even further, in some cases allowing them to approach the cost of an incandescent fixture.

What's happened is that diode manufacturers have found ways to increase light intensity, allowing lamp makers to reduce the number of diodes needed to meet federal lighting requirements.

Fewer diodes translate into lower cost. "The 4-in. LED stoplamp that used to cost 10 to 12 times as much as an incandescent now costs only four to six times as much," says Brad Van Riper, vp-research and development for Truck-Lite Co. "And new diodes will let us get that (cost differential) down to three times the initial cost of an incandescent."

"When we introduced our 4-in. LED round stoplight, it had 39 diodes," says Jay Gilliam, manager of heavy-duty sales for Peterson Manufacturing Co. "Today it has 10, which has allowed us to cut the price by 30%." Reducing the diode count also cuts power draw from 0.7 amps to 0.35 amps. (By comparison, a similar incandescent stoplamp draws 2.5 amps.)

Advances in diode technology also mean new applications for LED lamps. For example, higher light intensity has allowed development of single diode marker lamps that are narrow enough to fit inside the top rail of a van trailer, protecting them against impact damage, says Dominic Grote, marketing manager at Grote Industries Inc.

Not only has the diode light gotten brighter, but it's also changing colors. LEDs were limited to red lamps when they were first introduced in 1989. Although it took a while to solve cost and brightness problems, practical amber LEDs are now widely available.

The next color frontier is pure white, and the first white lamps are already being shown by some manufacturers. Grote, for example, has developed a license-plate light and a daytime running light that have both appeared on all-LED show trucks. Following the model set by red and amber diodes, the cost for white should begin to drop as they enter volume production, and white LED lights should begin making their way into fleet vehicles.

While LEDs last far longer than incandescent bulbs, that longevity has created some new problems. "When we moved from incandescent to LED, the weak link (in a light) moved from the lamp to the lens," says Van Riper.

Since LED lamps will produce light for 10 years or more, the lenses covering those lamps have to be upgraded to resist damage from ultraviolet rays, wash chemicals, and other types of environmental degradation over that longer life. LED lights are also exposed to more impacts simply because they see more miles over their extended life.

Most LED light makers now use a high-quality polycarbonate or acrylic to produce lenses that can better resist impacts, and coatings have been developed to protect against UV or other environmental damage. Changes in lens optics - the way the lens disperses the light generated by LEDs - are also allowing development of flush-mount products that are more protected against both impact and environmental harm yet still meet federal regulations that specify warning lamp visibility.

The increased life has implications for the back of LED lights as well. To take full advantage of the maintenance-free lamp technology, wiring connections have to be improved to eliminate corrosion and vibration damage. Most LED makers have developed wiring plugs that provide positive connections while sealing out moisture, and those "plug interfaces," as they're called by some engineers, continue to see improvements.

As for future LED developments, fleets should look for new applications that extend their use beyond straight replacement for standard incandescent bulbs. Peterson, for example, has already released LED strobe lamps that can be used in place of fragile, power-hungry xenon light strobes. Since the diodes are small and solid-state, LEDs can also be expected to evolve into new forms and shapes that would be impossible with any type of gas-filled bulb.