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How long do LED strip lights last?

Home /  Blog /  Home & Residential /  How long do LED strip lights last?
You may have become drawn to LED strip lights because of their long lifetime claims. But how long do they actually last? How is lifetime defined? If you're feeling skeptical, keep reading to find out how and when your LED strips may fail, and how manufacturers arrive at their lifetime claims.

 

LED lifetime and the 70% rule (L70)


Unlike incandescent bulbs which burn out and fluorescent lamps which begin to flicker, LEDs behave differently in that over time, they slowly and gradually lose their light output. Therefore, barring any "catastrophic" failures caused by things like power surges or mechanical damage, you can expect the LEDs on your LED strips to be usable until they are considered too dim for use.

But how dim is "too dim for use"? Well, there are as many answers as there are lighting applications. The industry, however, has somewhat arbitrarily decided that 30% light loss, or 70% of light remaining, should be that line in the sand. This is commonly called the L70 metric, and is defined as the number of hours it would take for an LED to diminish to only 70% of the original light output.

How is L70 calculated?


There are many factors that influence LED longevity such as materials selection, durability & quality. The general rule, however, is that higher temperatures and higher drive currents both lead to faster light output decline.

Because materials selection can vary widely among LED types and manufacturers, a test methodology called LM-80 was developed to dictate the primary standard for light longevity tests. LM-80 prescribes testing of sample specimens at predetermined temperatures and drive currents, with changes in light output measured in 1000 hour intervals, up to 10,000 hours.

LM-80 tests are typically conducted at third-party laboratories to ensure objective results, and the results are published in a report format. All reputable manufacturers will have this test performed on their LEDs, and a reputable LED strip supplier should have no issue providing this to you, particularly if you are buying wholesale quantities.

The difficulty with LED longevity testing is that it takes a long time. Even if the LEDs are illuminated 24/7, a 10,000 hour test requires 14 months or so. This is an eternity in a fast-moving industry like LED lighting.  Testing a product to the full 50,000 hour claim would, in turn, require nearly 6 years of continuous testing.

As a result, an extrapolation algorithm called TM-21 was developed. The algorithm takes in the performance of the LM80 samples over the first several thousand hours and spits out an estimated lifetime number. This is the number that is typically reported on specification sheets and warranties.

 

3 reasons why your LED strip lifetime claim may be inaccurate


The LM80 test and corresponding TM-21 methodology have multiple conditions and requirements for lifetime claims. If your LED strip supplier did not follow these instructions, their lifetime claims may be problematic.

1) You may only claim up to 6x the number of hours that was actually tested. In other words, if the LM80 test duration was only 5,000 hours, even if the LEDs performed flawlessly, the longest lifetime you can claim from this data is 30,000 hours. This is to ensure that premature conclusions are not drawn based on limited data.

2) The drive current and case temperature parameters for the LM80 tests must be higher than the drive current and case temperatures used on the LED strip. As mentioned above, temperature and drive current are the primary factors that affect LED longevity. If your LED strip is configured to run at a higher drive current and is frequently used in a hot attic, your actual use conditions may exceed that of the LM80 tests. As a result, the original lifetime predictions would be an over-estimate.

3) LM80 and TM-21 is not a perfect, foolproof lifetime guarantee. Other factors that are not included in the test methodology, such as humidity or VOCs found in potting compound for waterproof LED strips can also affect LED lifetime. There are also few rules on what materials can be substituted in an LED's construction while applying the same LM80 test report, so a manufacturer looking to cut corners may use superior materials for the samples used in LM80 tests only, and for mass production use inferior, cheaper materials.

 

It's not just about brightness decline - your LED strip may shift in color!


In addition to dimming over time, if materials degrade a different rates, an LED can actually begin to shift in color over its life. While the extent of the color shift is reported in LM80 test reports, this is rarely mentioned in LED strip specifications. Correspondingly, you will be hard pressed to find documentation on what is an acceptable level for both your application and the industry as a whole.

If you can get ahold of either the LED manufacturer's LM80 test reports, or a metric called "delta u'v'" - you can get a sense of color stability by keeping in mind that a delta u'v' over 0.003 is considered noticeable to the human eye. Generally, delta u'v' under 0.006 over the LED strip products' lifetime is considered acceptable for most indoor lighting applications. However, for more demanding applications such as museums and lighting up artwork, you may wish to select a product with better color stability over time.

 

LED strip lifetime is not just about the LEDs!


Although LED longevity is the most discussed aspect of LED strip lifetime, it is actually the adhesive and power supply that are just as likely to fail, and when they do, fail catastrophically.

The adhesive backing on the LED strip may be subject to a variety of environmental conditions such as dust, humidity and sunlight exposure, which can degrade the adhesive over time, resulting in the LED strip falling off of its installed surface.

At Waveform Lighting, we use 3M VHB double sided tape for our high CRI LED strips - some of the most durable and heavy-duty material available on the market.

Secondly, the power supply unit is an electronic component assembly that is also a potential failure point in the long run. A reputable power supply manufacturer will publish a mean-time-before-failure (MTBF) metric, which should give you a sense of how long the manufacturer expects the product to last. Unlike the LEDs themselves, when the power supply fails, it will fail catastrophically and will cause the LED strip to flicker or go completely dark.

Waveform Lighting offers high quality power supplies.

One simple way to extend the lifetime of your power supply unit is to keep it as cool, dry, and away from dust. Be aware of the LED strip power draw vs power supply capacity as well. Exceeding it would lead to immediate damage, and getting close to the upper capacity limit can also cause premature failure. We recommend that you aim to never exceed 80% of a power supply's rated power capacity.



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