Todd Heller is an expert on digital signs.  He’s VP of Digital Products at Formetco with over 30 years experience in the outdoor business.  Insider caught up with Todd after Todd’s recent trip to China to review some frequently asked questions on digital billboard purchases.  You can reach Todd at  ToddH@formetco.com or 678-360-1941.

Todd, what does it mean when a LED manufacture states that LED’s are rated for 100,000 hours?

This is a very common statement.  It means that the manufacture has performed accelerated aging testing and has mathematically calculated the brightness loss over time.  Typically the 100,000 hours is qualified to a percent of original brightness of either 50% or 30%.

So does this mean every LED Digital Billboard will last 11.42 years?

No, the testing is in a laboratory under constant voltage, controller temperature and humidity.  It does not replicate real life operating conditions.   The number one factor effecting how fast an LED’s loses brightness is heat operating at high temperatures.  LED Digital Billboards with inefficient LED’s use a lot more power and run at a much higher temperature than LED’s that use more efficient LED’s that generate more light with less power and generate less heat.  Less efficient hotter operating LED’s have a much shorter useful life.  This is a watts per lumens (light output) equation.  Other factors are the quality of the UV protection, humidity, over driving the current to the LED’s, and the thermal design of the system, will affect the actual useful life of the LED.

Then how do I know what LED Digital Billboard will provide the longest useful life?

Good question. Today every LED Digital Billboard supplier has their story about useful life.

• First compare power usage.  A sign that uses less power generates less heat and will operate at a lower temperature.   Ask for the total connected electrical load with a full White image at 10,000 Nit.  You need to know the brightness to compare power because lower Nit output LED signs should operate at lower power.   This is typically stated in Watts or Kw (kw= 1,000 Watt).  Then, to compare one LED Digital Billboard to another, you need to know the screen size without the trim.  Then calculate the Watts per Square Foot or Square Meter.  Today a safe power number is 30 Watts per Square Foot or 310 Watts per Square Meter.

• Next is the thermal design; how the LED Digital Billboard is cooled.  Modern more advanced designs today operate efficiently without forced air cooling fans. A LED Digital Billboard that requires fans for cooling is a maintenance problem waiting to happen.  Fans blow in moisture; contaminants, filter clogs, and failing fans quickly cause corrosion and overheating issues reducing the useful life of an LED Digital Billboard.

• Another consideration are the power supplies.  One way to compare is by the manufactures specification data sheet that states the mean time between failures (MTBF).  Quality power supplies cost more but are easily offset by lower maintenance cost.  Power Supplies with a 500,000 MTBF or higher are available today.  One telling factor is that if the Power Supply has a fan, its rated life is typically 50,000 hours or less.  Ask to see the manufactures product specification sheet.

What about image quality of the LED screen, why do some LED Digital Billboard develop uneven colors faster than others?

The biggest factor again relates back to heat.  The power to individual LED’s in some LED Digital Billboards can very by 30% or more.  The LED’s running at the higher power run hotter and discolor faster than the ones operating at lower power and temperature.   In the manufacturing process, all LED’s do not product the same brightness.  The LEDs are sorted by brightness levels and grouped together in bins.   One bin can have a brightness variance of 20%. Multiple bins will be a multiple of that number.   LED manufactures like to sell their entire production run so they offer groups of bins for sale to the LED Digital Billboard Manufacture at much lower prices thus lowering the cost of the LED screen.  The LED Digital Billboard Manufacture typically purchases several Bins and physically mixes them together.  To make the sign look acceptable they use a process called Calibration.  Calibration takes the brighter LED’s down to the level of the dimmer LED’s thus causing the large operating temperature range.   To minimize color degradation over time, the best solution is to find a LED Digital Billboard Manufacture that offers singe bin LEDs.

Do warranties offered between suppliers vary?

Yes.   Read the warranty.   The devil is in the details.  See what is excluded from the warranty.  Even some of the larger LED Digital Suppliers exclude parts not specifically manufactured by them.  Some have a shorter warranty on certain parts like power supplies. On top of that, the power supplies are not readily available or even worse, custom-made, making them only for that manufacture.  So you are stuck with a single source for power supplies for the life of the LED Digital Billboard.  Then what is the term of the warranty for parts, labor, and do they offer a LED brightness warranty or guarantee?

What was the food like in China?

A picture says a thousand words.