What is the lifespan of LED strip lights?

Your interest in LED strip lights may stem from their asserted longevity. What is their actual duration? What is the definition of lifetime? If you harbour scepticism, continue reading to discover the circumstances and timing of potential failures in your LED strips, as well as the methodology manufacturers employ to substantiate their longevity assertions.

LED longevity and the 70% criterion (L70)

In contrast to incandescent bulbs that fail abruptly and fluorescent lamps that exhibit flickering, LEDs exhibit a gradual decline in light output over time. Consequently, excluding any "catastrophic" failures resulting from power surges or mechanical damage, one can anticipate that the LEDs on your LED strips will remain functional until they are deemed insufficiently bright for use.
What constitutes "too dim for use"? Numerous answers exist, corresponding to the variety of lighting applications. The industry has somewhat arbitrarily determined that a 30% light loss, or 70% light retention, constitutes the threshold. The L70 metric refers to the duration, in hours, required for an LED to reduce its light output to 70% of its initial level.

What is the method for calculating L70?

Numerous factors affect LED longevity, including material selection, durability, and quality. Generally, elevated temperatures and increased drive currents both result in a more rapid decline in light output.
Due to the significant variability in materials selection across different LED types and manufacturers, a testing methodology known as LM-80 was established to serve as the primary standard for evaluating light longevity. LM-80 mandates the evaluation of sample specimens at specified temperatures and drive currents, with variations in light output assessed at 1000-hour intervals, extending to 10,000 hours.
LM-80 assessments are generally performed at independent laboratories to guarantee impartial outcomes, with the findings disseminated in a report format. All reputable manufacturers conduct this test on their LEDs, and a credible LED strip supplier should readily provide this information, especially for wholesale purchases.
The challenge of LED longevity testing is its protracted duration. Despite the LEDs being illuminated continuously, a 10,000-hour test necessitates approximately 14 months. This constitutes an eternity in the rapidly evolving LED lighting sector. To validate a product's full 50,000-hour claim, nearly six years of uninterrupted testing would be necessary.
Consequently, an extrapolation algorithm known as TM-21 was formulated. The algorithm analyses the performance of the LM80 samples over the initial several thousand hours and produces an estimated lifetime figure. This is the figure commonly presented on specification sheets and warranties.
 

Three reasons your LED strip longevity assertion may be erroneous.

The LM80 test and the associated TM-21 methodology encompass various conditions and stipulations for lifetime assertions. If your LED strip supplier did not adhere to these instructions, their longevity assertions may be questionable.
You may claim a maximum of six times the number of hours that were actually tested. Thus, if the LM80 test duration was limited to 5,000 hours, even with impeccable LED performance, the maximum lifetime that can be asserted from this data is 30,000 hours. This is to prevent hasty conclusions based on insufficient data.
The drive current and case temperature parameters for the LM80 tests must exceed those utilised for the LED strip. Temperature and drive current are the principal factors influencing LED longevity. If your LED strip is set to operate at an elevated drive current and is often utilised in a hot attic, your actual usage conditions may surpass those of the LM80 tests. Consequently, the initial lifetime projections would be an overestimation.
LM80 and TM-21 do not constitute an infallible lifetime assurance. Additional factors excluded from the testing methodology, such as humidity or volatile organic compounds present in potting compounds for waterproof LED strips, may also influence LED longevity. There are limited regulations regarding the materials that can be substituted in an LED's construction while utilising the same LM80 test report. Consequently, a manufacturer aiming to reduce costs may employ higher-quality materials for the samples used in LM80 tests, but resort to inferior, less expensive materials for mass production.
The issue extends beyond mere brightness reduction; your LED strip may also experience a colour shift.
Besides diminishing in brightness over time, if materials degrade at varying rates, an LED may also experience a shift in colour throughout its lifespan. The magnitude of the colour shift is documented in LM80 test reports, yet it is infrequently referenced in LED strip specifications. Consequently, locating documentation regarding acceptable standards for both your application and the industry at large will prove challenging.