Do leds lose strength?

[Jaeger6978]

My leds in the beginning were super bright but after a week or so they seem to have lost the initial brightness also my cousin purchased the led upgrade for the jbj nano and he seems to be experiencing the same problem is this a common occurence?

 

[ming]

LED's lose strength over time, but a week seems drastic. Their life expectancy can be greatly shortened if it isn't probably cooled with a heatsink though.

 

[NanoPerson67]

leds are kinda new to the reefing industry. there are more and more being made and more improvements are being made. I dont think they should lose brightness. if so i would if ya still can swap them for some classic t5's or mhs... call the manufacturer.. idk if its common or not but loss of brightness is not good what so ever.

ps: did they happen to be marineland leds?.. also sometimes when you first turn on leds it might seem super bright but you get used to it.. maybe thats what heppened to u and u just think they lost brightness but not really..

i had marineland leds but i didnt want future complications because none of my lfs people knew anything bout leds.. the safest is to go with t5's

 

[Jaeger6978]

They actually are mounted on a heatsink at what temperature do they start to lose it and what temperature should they be kept should i add a fan to help cool them off, also will they regain strength if cooled off or are they pretty much shot?

 

[reefman]

i asked that same question to wingo.
1st year=12% loss
years after=3% or less

 

[Jaeger6978]

Maybe it is just me but the same thing happened to my cousin i dont think its a coincidence his also seem to have lost their brightness.

 

[ming]

It really depends on the manufacturer.
From what I recall with the Cree XRE's, they were around 140+F off the top of my head.
It doesn't regain because the higher temperature is speeding up the life expectancy a lot on the bulb. Not even LED's can get any younger.

 

[Aqua Pro Builder]

i asked that same question to wingo.
1st year=12% loss
years after=3% or less

The numbers are HIGHLY dependent on implementation. It is not a general characteristic of LEDs. Those numbers are based on couple LED diode I tested over 3 years. This is by no means a reflection of other people LED light setup. What this means is the same LED bulb (adequate heat sinking or not) will change the numbers greatly when used with different heat sink.

However, the general method in measuring the LED light output is usually after 2 hours of the led is turned on when the performance is stabilized. LED will gradually degrade in output over years but you should not see a difference in 2 weeks with your naked eyes. This indicates something is wrong, most likely due to over driven or over heating. Each brand(model) of LED has their own junction temperature therefore, when over driven or simply overheating due to insufficient cooling, the light output will drop permanently. If this is the case to your problem, the light will not gain back the brightness after cooled. Think of the LED diode as many tiny individual light emitting units in one small space, when over driven more light are output at the beginning but eventually, they burnt out one by one. When more and more tiny units got burnt, your eyes can see the difference in the total light output.

So take note that we are talking two different things: 1)LED Light degradation and the 2)LED burning out.

 

[Jaeger6978]

Their actually the cree XP-G R5 LEDs i guess im gonna have to replace the bulbs and add some fans to keep them cooler thnx for the info.

 

[batt600]

Led fixtures with no fan the leds do not last that long the average led fixture in 5 years should only loose 25% of it life depenging on how it it used leds are like stars it will heat up and blow its self up fan play a big roll in leds

 

[lfsmarineguy]

I'm looking at some new LED units for an install I have coming up and after talking to the company about them I was told that a 30% drop in luminance is considered "failure" or a dead LED. That's where the quality LEDs get their 50,000 hr rating, because that's where the 30% drop occurs (roughly). Cooling plays a huge role in this though so if the LEDs are run at a significantly higher temp. than expected it can shorten their useful life by a lot.

 

[Aqua Pro Builder]

I'm looking at some new LED units for an install I have coming up and after talking to the company about them I was told that a 30% drop in luminance is considered "failure" or a dead LED. That's where the quality LEDs get their 50,000 hr rating, because that's where the 30% drop occurs (roughly). Cooling plays a huge role in this though so if the LEDs are run at a significantly higher temp. than expected it can shorten their useful life by a lot.

Many industry people use a term of L75 which means the life time for led to drop to 75%.