The long life span offered by LED lighting is one of the major attractions for many people. Unlike conventional Halogen or Incandescent bulbs, LEDs will help rid the need for continued maintenance and the replacements of faulty bulbs. As LEDs do not rely on heating a delicate filament to produce light, they generally do not just stop working as you would expect a traditional bulb to when it fails. Instead, LEDs are said to have reached the end of their usable life when the light output drops below 70% of the original brightness offered when new. This is measured in lumens.
So what exactly does the life span of and LED bulb mean? And how is it calculated?
What is the life span?
The life span of an LED bulb is said to be the amount of time the bulb produces useful light.
LEDs suffer lumen depreciation over time and the bulb will get gradually get dimmer.
The life span is measured up until the lumen measurement depreciates under a certain amount, for most domestic bulbs this can be either 70% or 50%, also read as L70 and L50.
Once the lumens fall under 70%/50% of their initial output they are considered to be no longer useful.
Take note though; the stated life span is not the necessarily guaranteed. Ensure you check the warranty that is sold with the bulb as well as the life span. LEDs contain many components and can be subject to premature failures just like any other electrical product.
How is it calculated?
You may be asking: “If LED bulbs have only been around a short while, how is it possible to claim the LEDs will last 1000’s of hours?”
All LED bulbs are subjected to rigorous testing.
As part of this testing, the LED chips used within a bulb/ lamp are illuminated and under careful observation, the lumens are measured continuously.
The collated data can then be input into a mathematic formula that, based on various patterns formed will calculate and predict the L70/ L50 figures.
For a more in-depth explanation, see this publication by LED manufacturer Cree on their LED testing.
Will they last the estimated lifespan?
Yes. Most customers, when using the LEDs as directed, will experience years of use without failure. Some may even exceed the estimated ‘life span’ and not notice a depreciation of Lumen/ light output. LEDs unlike incandescent bulbs should not just fail at the end of their life. Their lumens/ light output will depreciate over time.
Whilst LEDs do not rely on a delicate filament, this does not make then immune to failure. Whilst uncommon, you may experience a sudden failure with an LED bulb and this can be down to a few factors. Here are a few reasons that may cause an LED to suddenly fail:
Temperature- LEDs may stay cool to touch but it is a myth that they do not create heat. A ‘heat sink’ is built into the back of most LED bulbs and this is used to dissipate the heat created. A good heat sink should allow the heat to escape and keep the LED chips from over heating. If however, an LED bulb has an inefficient heat sink that doesn’t do its job well, the LED chips can overheat and fail prematurely. It is also worth considering the ambient temperature which can affect the bulb. LED chips are sensitive to high temperatures they are in a room that is subjected to increased heat, this will shorten the lifespan and may cause the bulb to fail prematurely.
Insufficient housing- always ensure you are using a sufficient housing unit for your LED. For example if using an LED above a shower unit or outdoors it must be in an IP65 rated fitting. Otherwise moisture can cause damage to the bulb.
Manufacturing- Sometimes a bulb may fail do to a manufacturing issue. Often caused where parts of the LED lamp have not been soldered together correctly this can cause either the power not to run through correctly leading to the LED not working, or it can cause heat to build up within the lamp close to the chips, raising the internal temperature of the lamp, causing the chips to fail.
LEDs on the whole should not fail. Though sometimes this may happen and it may not be obvious at first why but try eliminating reasons that may have caused it. Always check the life span of a bulb to see what life you could expect from it, but remember to check the warranty as well as the life span is not the warranty of the bulb. If you ensure you take the best care of bulbs, ensuring they are in an environment that is not too extreme in temperature and it is a suitable housing then they should last the expected time.