This is what many companies publicite. Does anybody know about studies with real number of tested hours and not the common test of few hundred hours and then extrapolated in a log plot for more than 3 orders of magnitude? What is the weakest link of most real LED lamps? chip, encapsulation, lens, driver, housing...
I would be grateful for links and published material that can shed some light on this.
It would be virtually impossible to do such “real” test, for a question of simple mathematics. I mean, if we work out the numbers, 100 000 hours corresponds to about 11 years of 24h/day operation. So we will only have the real, and thus totally reliable, results in over ten years!
So considering these estimates can be tricky and of course LEDs can fail (or fade considerably) well before that expected time. The solid state element (i.e. semiconductor p-n Juntion) is very stable and resistant, but the whole LED is made of many other components which may limit the lifetime.
Common weak points known are the poor heat dissipation, packing degradation (particularly for near UV energies) and components such as capacitors that fail before the actual LED fails. I guess the bottleneck will depend from the producer but I know that encaplulation was an issue some years ago.
Companies are trying to improve these components and heat sinking issues to actually extend the real lifetime of the LEDs. However all is based on estimates and extrapolations since we cannot really wait for over 10 years to see if the engineering worked or not. So companies do have some margin to just provide an estimate which may not be very realistic..
I still have some old LEDs from my youth bricolage age, and they still work, but as Sergio mentioned, the light intensity faded substantially (not just some few percent, for some elements its hard to see that they are really lighted!).
And I have made the experience with intense white light LEDs, that their intensity substantially decreases over time periods of say one year, if they are intensively used!
Regards to all, Dirk
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