Led Lifespan

[techen]

I was reading up a few things and noticed that a LED lifespan can be quite quick. It's mostly pointed to Steveo but how is it possible for an LED to last 20 years? The heat made from a LED would shorten its life very quickly and drives have issues failing as well. Is there any proof to suggest they have a large lifespan?

 

[bodge99]

Hello.

Welcome to the world of "accelerated testing"... Real world LED lifespan depends on several things, the most important being sufficient cooling and strictly controlled maximum drive current.

Excessive heat will kill LEDs very quickly. The quality of the current regulation in the power supply is important...
Transient voltage spikes in the power supply (if not properly suppressed) can also shorten LED life.

Also, the quality of the manufacturing process has an overall effect on reliability.

See https/www.roodmicrotec.com/fileadmin/user_upload/pdfs%20Presse/pdfs_Publications/microtec_LED-Test_e_01-08.pdf

In essence, you get what you pay for...

Some people design and build their lighting systems to maximise LED life.. i.e. provide more LEDs, but underrun them slightly.
This means that the LEDs run cooler and should therefore have a greater lifespan.

Other electronic techniques can be used.. (current waveform shaping etc.).

Bodge99

 

[techen]

Cheers, I get it now. Am still quite interested in Steveo pushes his LEDs or lets them run underpowered.

 

[Ps3Steveo]

No mine are run on constant current drivers made for the exact amount of LEDs the drivers specify. They run very cool on my heat sinks as well as the standard recommended ones, the ones I build on aluminium hollow bar have a much larger surface area for cooling too as the bar is the heat sink. Mine could last longer than the time the company specifies as they run cooler. Also if one did burn out I'd replace it .

 

[techen]

No mine are run on constant current drivers made for the exact amount of LEDs the drivers specify. They run very cool on my heat sinks as well as the standard recommended ones, the ones I build on aluminium hollow bar have a much larger surface area for cooling too as the bar is the heat sink. Mine could last longer than the time the company specifies as they run cooler.

Also if one did burn out I'd replace it

.

Ah so you have like a warranty? That's alittle bit more of a relief haha, Sounds good to me. I just saw a few forums speaking out LEDs burning out and loosing there brightness.

 

[bodge99]

Hello,

It sounds like Ps3Steveo a.) knows what he is talking about and b). obviously has practical experience. You could do far worse than listen to this guy!

Believe me, the two do not always come together. I've seen some commercial designs that "will do the job" but have significant design shortcomings. The ease of led replacement is one consideration that is often poorly implemented.. but (IMHO) substandard controller design is inexcusable in a commercial product (fault tolerance etc.).

I'd guess that some DIY solutions fail early due to insignificant LED cooling. High power LEDs are manufactured to very close tolerances.. a lot of development work has gone into them. If the operating parameters of these LEDs are ignored, then it is no surprise that they fail.

You will find that all electronic devices have a specified failure rate (normally a percentage failure rate per x hours "run time").
This is true for every electronic device from the humble light bulb upwards.

"Over engineering" in LED cooling allows the device to run at its maximum brightness, but at a lower temperature.
Overall reliability and life should be increased..

Bodge99

 

[techen]

Thank you Bodge, seems you know your stuff in LEDs.

 

[Ps3Steveo]

It's like the new design I'm working on at the moment Techen, I won't build it for anyone till I know it's running at least the same temps as with standard heat sinks, if not it won't be built.

 

[techen]

Sounds good. I just want the best

 

[ian_m]

There was an article in EDN magazine (Electronic Design News) and that the main area of unreliability of LED products is now not the LED, as designers are now aware of the heat issues, but the capacitors used in the LED drivers. Basically not enough care (and cost) is being taken in LED drivers leading to early life failures.

 

[Adam_Sciberras]

In testament to Steveo, I run one of his hollow bar led units (which I will post about in the next couple of days mate) and they run very cool, and it's enclosed!

 

[Ps3Steveo]

Not had trouble with mine and been building them for years. Plus if a failure happens I replace the part providing its not the fault of the user.

 

[Zikofski]

this has been a good post and has given me a question to ask for steve and what is the maximum operating temp of the LED's heat sink in a normal environment that you are testing them in, and what would be the inpact if that normal environment became hotter, only reason i am concerned with this, is i am moving to Brisbane the temp out there rarely drops below 30c, would this increase in average air temp, increase the temp and lack the cooling abilities, and there for reduce the life of the LED or its driver, is it possible you can inform me of the operating temps for the LED's they get to a MAX in the uk and maybe i can run a few tests out in Australia to see if there is any difference? and if so make changes to my cabinet design and it may help you out with designing your LED's units, and give you an in site into non uk temps if you decide to expand your business overseas and may prevent some future failures if say the UK got a long period of hot weather

who knows haha,

from what you showed me when i picked my unit up i was highly impressed with the build quality and the time and effort you have put into the LED's and the cooling looks really good compared to the branded versions, my only issue i think in hooter conditions as its passive cooling will i need active cooling?

 

[Ps3Steveo]

They will run at 75c comfortably in our climate you wont see anywhere near that, mine got too 57c in the summer when it was baking hot outside so you wont have trouble. The drivers have a 5c lower safety cut off than the LED's run at so before the LED would get too hot the driver would trip out first. If you then switch off the power and turn on it resets it and powers back up. We put the driver in a small 1 inch thick wooden box with no cooling space mid summer and it ran fine mate. They wont need extra cooling.

 

[Zikofski]

sweet

that is perfect,57c is still hot tho

haha wouldn't wana touch them after a days running