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Elysia
03/17/2011, 12:08 PM
I have a question about the reported life of LEDs. Has anyone actually experienced a LED lasting for tens of thousands of hours? When the LED moonlights went out on my combo compact fluor. hood, I though that the heat of the other lights was to blame. I purchased one of the Marineland LED lights and used it for about 4 months, for a maximum of 2,000 hours. Only to notice the other day that the "blue" LEDs are no longer lit. While the white LEDs still work, I feel that they are very yellow, so the entire fixture has little use anymore.
Do LEDs typically only last a fraction of their reported lifetime? I seem to have the same luck with CFL bulbs in regular fixtures -- I swear I have changed more CFL bulbs than incandescent, despite the fact that they are suppose to provide light for many more hours than an incandescent.

bamf25
03/17/2011, 12:18 PM
With the CFL's it is becoming widely reported that they are way under performing with regards to lifespan.

Dadekster
03/17/2011, 02:09 PM
Has anyone owned one long enough to know if they last as long as they say they are rated for? Isn't five years of moderate use considered normal? I am curious about this as well tbh. I have also read about issues with the CFL's and hope that this is not standard across all LED lighting. I doubt it is, but you never know these days.

Anemonebuff
03/17/2011, 03:17 PM
They are rated to last from 30,000 to 100,000 hours of use under optimal circumstances. Cooled properly and assuming that they were quality LEDs and mounted and powered properly, they will all fall into those ratings. These are electrical components and they are subject to failure due to normal numbers of defective parts/craftmanship. You also must remember that they are degrading during this time, just much slower than other forms of lighting. There are quite a few people in the 1,2,3+ years of LED use so far and I would guess there are some that have used them longer. However, they are not the same LEDs produced in the last year or so. CFLs are way over rated and the global warming crowd refuses to drop them and adopt LEDs and I do not know why, particularly because LEDs do not have mercury in them and last many years longer. I would say that todays LEDs, used properly will get you at least 5 years of good use.

nanojg
03/17/2011, 04:02 PM
I think the OP was asking for actual experience, what you described is basically predictions (kinda like the CFL predictions). I hope you are right though, as I am sold on leds myself, even if they dont last the full 5 years or longer.

Shard
03/18/2011, 03:24 PM
I think the OP was asking for actual experience, what you described is basically predictions (kinda like the CFL predictions).

What he is describing are not just wild 'predictions'. The expected life data is based on actual testing to generate a degradation curve. As long as the LEDs are mounted properly so they do not overheat and are applied the proper power profile, they will last as long as the datasheet says they will. It is really based in science, not opinion.

As for the OPs experience with his fixture, the white LEDs look yellow, because most fixtures tend to use ~6500k white LEDs. The light at that kelvin is yellowish, which isn't necessarily bad, because it is more conducive to coral growth than higher kelvin light. The blues offset the color to give it a 10-20k look.

nanojg
03/18/2011, 03:37 PM
What he is describing are not just wild 'predictions'. The expected life data is based on actual testing to generate a degradation curve. As long as the LEDs are mounted properly so they do not overheat and are applied the proper power profile, they will last as long as the datasheet says they will. It is really based in science, not opinion.

As for the OPs experience with his fixture, the white LEDs look yellow, because most fixtures tend to use ~6500k white LEDs. The light at that kelvin is yellowish, which isn't necessarily bad, because it is more conducive to coral growth than higher kelvin light. The blues offset the color to give it a 10-20k look.

So are you saying that the CFL life spans were "wild predictions" and NOT based on actual testing? Also I disagree that in a reef environment that they will correspond with the datasheet, the datasheet specs were tested under optimal conditions, without daily on/offs and dimming.

widmer
03/18/2011, 03:52 PM
I purchased one of the Marineland LED lights and used it for about 4 months, for a maximum of 2,000 hours. Only to notice the other day that the "blue" LEDs are no longer lit.

There are a couple things going on here.

1. It is quite possible that only one of the LEDs went out, and that either opened the circuit, or caused the rest of them to be overdriven and fried.

2. I question a lot of the manufactured LED fixtures that don't necessarily specify the characteristics of the LEDs that are built into them, or don't even name the manufacturer of the LEDs that were used. Like any other product, you can buy a quality-manufactured item that was built to last, or you can buy one that's "flimsy" and has a short lifespan.

Especially now with marineland's stealth heater catastrophe, I'm not saying that marineland must make poor quality products, but rather, this manufacturer is clearly capable of making something that will prematurely fail.

But truly not all LEDs are created equal. Just like incandescent bulbs, some were manufactured in such a way that they will last two or three times longer than others...

ufoman420
03/18/2011, 04:10 PM
I built my DIY led light for my 170gal reef tank about a year and half ago and i love it. I have not changed anything i have about 1" 1/2 growth on my monipora and zoes spreading like crazy, my candy cane split from 4 heads to about 16 and my pipe organ doubled its size. I have 144 3 watt leds and my hard corals are about 6" below the water surface and no problems at all. My plate coral is at the bottom of the tank 24" and it has a great pink color and doing great.

Pink_n_Purple
03/18/2011, 04:20 PM
All light sources ie compac flores, mh, hps, leds, no-ho-vho flores are all tested and rated in optimal conditions. Humidity, temp, balast, and even source of power 120'240 volts, electrical and magnetic interferance can all come into play when discussing effiency and life of your light source. Imo leds are still a new tech and havnt been around long enough in these situations (horticulture, aquariums) to even know how long they will last or perform. Not the to mention the mixing of parts, and poor building practice of these unheard of manafactures, buying a power supply made by a different company than the light source itself! like buying a hortilux 60hz bulb and running in on a lumitek ballast @ 22,000hz, expect it not to perform optimaly. All in all LED's r unpredictable, imo

BFG
03/18/2011, 05:32 PM
As far as I can remember back in the day when led was breaking into the hobby, manufacturer were claiming that their led was able to operate for a few thousand hours at a low temperature of 20 degree celsius ( I might be wrong ). But only 1 led lightset manufacturer was disagreeing that it was impossible to operate a bank of led light at that low temperature without active cooling and that even with active cooling, it does not ensure all the led bulb are evenly cooled to lay their led bulb lifespan of a few thousand hours. My leds are coming to a year of usage and it seems to look ever so slightly dimmed but to me they still looks usable. I do not have any equipment to support my claim but just take it with a pinch of your favourite brand salts.

ufoman420
03/18/2011, 05:42 PM
Mine run sort of hot when i touch the heat sink it is a little to warm to hold your hand too. I run my leds 13 hrs a day 8am to 9pm. It has been a year and a half and i have not noticed any difference in the output of light IE dimming or tank looking dull. I didn't use Cree's too expensive i used some china produced ones for 1.95 a piece and i would totally recommend them for use again. I did put 12 Cree's on there to see if I could visually see a difference and to my eye I do not see a difference. And price cost difference i could put 40 more led on my light for just the same price spent on Crees. To your point there have been tests done to conclude that the output is the same after 5,000 hours of use. But it is electronics and you will have the occasional bad one that goes out.

snorvich
03/18/2011, 05:55 PM
Mean Time to Failure is normally what is quoted and this, of course implies a standard deviation. What this means is that some percentage of the time you will find failures (below the mean) or successes (above the mean) at the three standard deviation level from the mean which is 99%. If they provided the standard deviation you could estimate your own curve of failure and success probability.

Pink_n_Purple
03/18/2011, 06:34 PM
i believe leds are rated for 50,000 hours of use, thats 10 years @ 12 on 12 off, ask anyone if there leds have lasted that long, either one burns out and comprimises the rest in the same seriese or the controller goes, for the price of them.... í'll stick to the old school mh,hps and ho flores

Shard
03/18/2011, 07:39 PM
So are you saying that the CFL life spans were "wild predictions" and NOT based on actual testing?

No, that is not what I am saying. All I am saying is that the curves generated by the statistics are a fairly good representation of the life span of the LEDs because the expected matches the observed so far, so the probability is it will continue to do so in the future. Operating conditions are an implied factor in this of course.


Also I disagree that in a reef environment that they will correspond with the datasheet, the datasheet specs were tested under optimal conditions, without daily on/offs and dimming.

Depends on the situation.... Some LED setups like the Aqua Illumination modules have logic control on their internal temperature. Others may use thermal cutoff switches that keep the temperature from going outside of their operating range. Many could mimic datasheet conditions fairly well.

Most CFL fixtures do not have the level of internal thermal regulation/control that some LED setups do, so they may spend a lot of time outside of their datasheet operating/testing ranges. Of course, some cheap LED fixtures, or simple DIY setups would do the same thing. I guess I am just saying that it is possible to have various LED setups, as well as CFL setups that last for widely differing amounts of time.

If you re-read my post, you will see that I did say that temperature control and proper power profile are a key part of having them last as long as the datasheet says. I guess I could be more explicit and say the closer you mimic optimum conditions, the better your results will be.

As for the on/off situation, some do account for daily on/offs as many of the lifespan quotes out there are based on X hours per day and so on. As for maintaining optimal conditions, logic control or thermal regulation devices can keep it pretty close as mentioned above.

As for the dimming, LEDs are dimmed by changing the current that goes through the circuit. So if the projection curve was generated at 700ma, and you run yours at 350ma, you may get more time out of them, as they will run cooler, have less stress on them, etc.

Anyway, it is nice to see you like LEDs as well. I think they will become more common place in reefing in the future. If I could afford to go all LED now I would :)

Cheers,
Landon

Shard
03/18/2011, 08:34 PM
Hi Pink_n_Purple, welcome to RC! I see you just joined.

Imo leds are still a new tech and havnt been around long enough in these situations (horticulture, aquariums) to even know how long they will last or perform.

Well if it helps, mine have lasted for a while, and there are others here with fixtures that have been going and growing for years. LED performance is documented over long courses of time here in some threads. Here is one that shows some actual SPS growth over time.

http://www.reefcentral.com/forums/showthread.php?t=1968168

Not the to mention the mixing of parts, and poor building practice of these unheard of manafactures, buying a power supply made by a different company than the light source itself! not to perform optimaly. All in all LED's r unpredictable, imo

I have used different LED types in various fixtures. They should be fine as long as you do not run them out of spec. A setup with components from different companies would not matter, as long as the specifications match. Matching specifications is more important than matching brand, as even with MH setups most people run bulbs made by a different manufacturer.

As for LED manufacturers, there are all types out there, just as is the case with other lighting manufacturers. There are several well known and respected LED fixture producers, as well as countless no-name chinese imports for sale. I am curious why you would say LEDs are not unpredictable? How do you come to that conclusion?

either one burns out and comprimises the rest in the same seriese or the controller goes, for the price of them.... í'll stick to the old school mh,hps and ho flores

If one burns out, replace it. One burning out would not compromise the rest of the series. It is like the old christmas lights, replace the one in the series that is out, and they all work again. It can be a relatively cheap fix at around $5-6 for a replacement LED.

Anyway, good luck in the future with reefing. I see from your signature you are new to the hobby. Might I suggest that you do a little more reading here on RC, as there is a wealth of information available. Don't be so quick to jump to conclusions about various technologies.

Landon

Reffer831
03/18/2011, 08:35 PM
No!!!! They are great in the beginning for the first year or two then they dim out just like any other light.

Anemonebuff
03/18/2011, 09:23 PM
CFLs and florescents in general are more difficult to keep at their optimal temp. Heat a CFL too much it will burn out and/or color shift quickly. Cool a CFL too much and it will not meet it's full potential. LEDs only enemy is heat. You can cool them to freezing temps and they will work just as good as a LED just at the max suggested temp. Just look at a CFL used outside in winter. Takes mine about an hour to heat up and give off the max light it can produce. It also takes the life out of the bulb more rapidly.

Shard
03/18/2011, 09:44 PM
That is a good point about the CFLs Anemonebuff. I was only thinking in terms of LEDs and regulating the max temp, I forgot about CFLs having a narrower range both above and below for optimal output/life.

Pink_n_Purple
03/18/2011, 09:55 PM
Yes i am very new to this hobby, and thanks Rc and members for the arcticles, and abundant info,awsome!

I was always under the assumsion that leds have a high life expectancy (longer than 2 years @12-12) thats just my oppinion, and multiple companies\manafactures claiming this.

Heat build up is there major down fall in life expectancy, which can result in current loss also. Most premade manafactures models dont coolo there systems well enough, they want yoyur leds to burn quicker, so you can buy another.

I'm sorry to say that most Diy are usually to cheap and or just take short cuts in try to creat there own heat sinks , that not cooled or at very best is a cheap attempt at doing so. It may be cheaper as a diy but replacement can be combersome due to poor planning and builds, also you have to make the decision of replacing them all or only a few a time and wich ones?(larger systems apply here) mutiple diodes increases chance for manafaturer mistakes also. shipping can be combersome and slow too if needed quicky.

IMO Led's should last you no shorter than 4 years at 12 on 12 off in other wise there just not worth the expense or trouble of replacing, and thats just my op.

Flippers4pups
03/18/2011, 09:56 PM
All i know is that my LED moons on my T5 HO fixture have burnt out twice in two years (Less than 8hrs a day on). The manufacturer replaced the first set under warranty, but the second is still out and I'm out of warranty. At this point I will replace them with an aftermarket pair and retrofit them into the fixture.

My point is that i was thinking of replacing the T5 HO fixture with an LED fixture, but after all of this, now i don't trust them. :worried:

Anemonebuff
03/18/2011, 10:20 PM
I'd venture to say that they used sub standard LEDs with sub standard cooling.

nanojg
03/19/2011, 04:29 AM
No!!!! They are great in the beginning for the first year or two then they dim out just like any other light.

No...

Midnightsun
03/19/2011, 05:04 AM
As mentioned, led life span really has to do with proper cooling and proper amperage feed (power). Heat is the led killer and again as mentioned, running led at reduced output (dimmed) will increase lifespan above manufacturers specs. In my case I have a powerhouse caddilac, the Vertex Illumina :love2: I run at max 50% during only a few hours a day and the balance is less as they are very slowly ramped up, held for a few hours and then very slowly ramped down. In this case if the manufactures claims 50,000 hrs I may last 20+ years.

My thinking for longevity is to get a larger system than required and simply drive the led with reduced power to increase life substantially, reduce heat substantially, (my fan senses heat and turns on if required, has never come on yet) and possibly never need to change a power supply as it also is working very lightly.

The most problematic part in led system is the power supply IMHO. In less than 3 months the power supply blew on my Maxspec. In about 7 months the power supply blew on my JBJ nano LED. Both of these systems run full bore and are not dimmable.

atreis
03/19/2011, 06:38 AM
I've been using CFLs in my house for 10 years now, and have found that on average they last about 5x the time that incandescents in the same fixtures lasted. There are exceptions - they last about the same in fully-enclosed un-vented fixtures as incandescents (the ballasts need to be able to cool), and every now and then I've gotten a bad batch (most of those seemed to be about three years ago). Likewise, I've had some last far longer than rated - I have a pair of CFLs rated for 8k hours that both have over 12k hours on them.

A year ago I installed my last CFL can light and started replacing them (as they go bad) with LED lights. I've only replaced two so far. Only time will tell. If they last as long as the makers claim (I'm using CREE bulbs rated for 50K hours, and these are replacing Ushio CCFL bulbs rated for 20K hours) I won't truly know for 20 years. For the non-can lights, I've not used all of my standard 60W replacement CFLs up yet, but also plan to stop buying those too and switch to LED.

I suspect you've not heard of many people doing this because: 1. It takes a long time assuming people do it as their current bulbs go bad, and 2. LED bulbs are expensive (the CREE can bulbs I'm buying cost $90 each). Even though they SHOULD pay for themselves in theory, the initial capital outlay is more than many people can stomach.


The tank: I use a 4-bulb T5 fixture, and a pair of Marineland Reef LED fixtures as supplemental lighting. I plan to replace the T5s with LED but not until next winter when my current T5 bulbs are due for replacement.

Anemonebuff
03/19/2011, 07:17 AM
[QUOTE=Midnightsun;18512925]As mentioned, led life span really has to do with proper cooling and proper amperage feed (power). Heat is the led killer My thinking for longevity is to get a larger system than required and simply drive the led with reduced power to increase life substantially, reduce heat substantially, (my fan senses heat and turns on if required, has never come on yet) and possibly never need to change a power supply as it also is working very lightly.

QUOTE]

I have also found that most of the major LED systems under drive their LEDs to increase the life of the diodes. Under driving reduces heat produced, making it easier to cool properly.

Midnightsun
03/19/2011, 08:02 AM
I've been using CFLs in my house for 10 years now, and have found that on average they last about 5x the time that incandescents in the same fixtures lasted. There are exceptions - they last about the same in fully-enclosed un-vented fixtures as incandescents (the ballasts need to be able to cool), and every now and then I've gotten a bad batch (most of those seemed to be about three years ago). Likewise, I've had some last far longer than rated - I have a pair of CFLs rated for 8k hours that both have over 12k hours on them.

A year ago I installed my last CFL can light and started replacing them (as they go bad) with LED lights. I've only replaced two so far. Only time will tell. If they last as long as the makers claim (I'm using CREE bulbs rated for 50K hours, and these are replacing Ushio CCFL bulbs rated for 20K hours) I won't truly know for 20 years. For the non-can lights, I've not used all of my standard 60W replacement CFLs up yet, but also plan to stop buying those too and switch to LED.

I suspect you've not heard of many people doing this because: 1. It takes a long time assuming people do it as their current bulbs go bad, and 2. LED bulbs are expensive (the CREE can bulbs I'm buying cost $90 each). Even though they SHOULD pay for themselves in theory, the initial capital outlay is more than many people can stomach.

Interesting as I have replaced all my halogen Par 30 lights in the soffit of my house with the led variety also but went the "beehive" led style route for cost reasons as they were only $14 each. They are also rated 50,000 hrs and draw only 4 watts/bulb. The lighting is superb and the total string draws only 128 watts compared to 1600 watts before. Yes I have 32 lights outside.:bigeyes: I have only been running them for a year but the warranty is 5 years. According to the supplier, 5 years constant on is 62,000 hrs. running normally about 5 hours/day I am supposed to be good for 1000 years. :lol: Regardless, energy consumption is way down there and if they last 10 years I will be more than happy.

Anemonebuff
03/19/2011, 09:21 AM
I wish this place sold Reef Bulbs. They give a 5 year warranty. I have some of the 36 watt PAR38s.\

http://www.ledliquidatorsinc.com/PAR_38_12_LED_Cree_light_bulb.php

Midnightsun
03/19/2011, 09:37 AM
I wish this place sold Reef Bulbs. They give a 5 year warranty. I have some of the 36 watt PAR38s.\

http://www.ledliquidatorsinc.com/PAR_38_12_LED_Cree_light_bulb.php

That is exactly where I purchased all my bulbs for my house. :dance:

nanojg
03/19/2011, 10:04 AM
So are the different versions the same LEDs just driven at different currents? (350, 700 and 1000 milliamps)

Pink_n_Purple
03/19/2011, 12:19 PM
As mentioned, led life span really has to do with proper cooling and proper amperage feed (power). Heat is the led killer and again as mentioned, running led at reduced output (dimmed) will increase lifespan above manufacturers specs. In my case I have a powerhouse caddilac, the Vertex Illumina :love2: I run at max 50% during only a few hours a day and the balance is less as they are very slowly ramped up, held for a few hours and then very slowly ramped down. In this case if the manufactures claims 50,000 hrs I may last 20+ years.

My thinking for longevity is to get a larger system than required and simply drive the led with reduced power to increase life substantially, reduce heat substantially, (my fan senses heat and turns on if required, has never come on yet) and possibly never need to change a power supply as it also is working very lightly.

The most problematic part in led system is the power supply IMHO. In less than 3 months the power supply blew on my Maxspec. In about 7 months the power supply blew on my JBJ nano LED. Both of these systems run full bore and are not dimmable.

I agree, Midnight have u tried to make any attemps at keeping your power source cool? Also by running your leds on half power is it safe to asumme than you are not getting full effieciancy from your leds(need more leds to get your lumen/par/ppf/ppfd up?) more leds more heat back to square 1. cost/ effieciancy is reduced buy having more leds to creat same light out put?

Ijust dont believe that the average personne really will ever notice leds full potiential.

Yes your leds should last longer than 10,000 hrs.

nanojg
03/19/2011, 01:04 PM
Actually the efficiency increases at lower current. The max lum/watt is at 350 milliamperes I believe, it decreases as you approach max current

Midnightsun
03/19/2011, 02:06 PM
I agree, Midnight have u tried to make any attemps at keeping your power source cool? Also by running your leds on half power is it safe to asumme than you are not getting full effieciancy from your leds(need more leds to get your lumen/par/ppf/ppfd up?) more leds more heat back to square 1. cost/ effieciancy is reduced buy having more leds to creat same light out put?

Ijust dont believe that the average personne really will ever notice leds full potiential.

Yes your leds should last longer than 10,000 hrs.

Like I said my led system is so powerful I can run it at half the required output and still be fine for any coral growth. That being said, running at half power reduces heat substantially which will add to longevity on all components. My previous attempts were maxspec and nano cube led which basically run full out all the time. Nothing wrong with this but design is critical and unfortunately most run on the edge which affects long term durability. To answer your question regarding efficiency, yes the output is reduced but I have twice the power required.

Compare it to running a car at very high speed all the time or running it at speed limit all the time. Which is going to last longer in the long run?

ksc
03/19/2011, 03:16 PM
"The Federal Trade Commission announced on Wednesday that it had sued Lights of America, a light bulb manufacturer based in California, for misrepresenting the light output and life expectancy of its LED bulbs. It is the first F.T.C. case challenging LED marketing claims".


http://green.blogs.nytimes.com/2010/09/08/federal-agency-sues-led-bulb-maker/

Pink_n_Purple
03/19/2011, 03:54 PM
So inefect, you believe running your leds sub par of there disinged intended use will give you better results than what the manafacturer quotes this already being at optimal conditions? all where really aming for is 24 to 30 degrees for optimal temp not very hard to do considering it can be done to a 1000w hps. producing bairly any warmth to the touch ( the glass tube, not the bulb, great effects with the life span of Hort blues/super blues and others)

I will assume that you dont cool your powersource or havnt tried to, i would expect the same result from your newest controller, short life spans. Heat and humidity is a killer in any lighting system and most electronics.

you only lose the efficiency in the conversion of watt to lumen/heat ratio(i use lumen losely) Heat be the end result, producing to much heat in comparison to how much light. you cant expect to get the same kelvin ( kelvin used losely) temp from your diode by dimming them.

Prebuilt systems are really expensive, and even the more expensive ones will not last more than 10,000 hrs. Unfortunate to say the least. When they can run much much longer, at a even lower expense.
I'm sorry for maybe ruining your thread, new to the forum thing too.

Shard
03/19/2011, 04:56 PM
Pink_n_Purple,

Again, welcome to the forum, but you are not understanding how LED systems work, or the physics of electricity involved.

So inefect, you believe running your leds sub par of there disinged intended use will give you better results than what the manafacturer quotes this already being at optimal conditions?

Running LEDs at a lower temperature and/or lower current is not a 'sub par' condition or somehow outside of 'optimal conditions'. You could argue that the lower temp/current is MORE optimal for them.


As mentioned above, most LEDs are the most efficient at 350ma, which gives the highest lumen/energy output. The efficiency decreases as you approach max current. If you would take 5 minutes to read the datasheet you would see that 350ma is the 'sweet spot' for many LEDs like the Cree ones used in most fixtures today, but they run well at higher currents as well. Also, keeping the LEDs cooler allows them to run more efficiently (just like many other electronics). LEDs have an upper temperature limit, not really a lower one. I could run my LEDs at 0 deg C and they would run fine. That is not outside of their 'optimal conditions'.


all where really aming for is 24 to 30 degrees for optimal temp

So many grammar and spelling errors, but anyway, no we are not. All we are aiming for is a temp BELOW the upper threshold, not really a tight range between 24 and 30. Again, you need to understand the difference here between an UPPER LIMIT for usage (LEDs), and a LIMITED RANGE (CFLs).


I will assume that you dont cool your powersource or havnt tried to, i would expect the same result from your newest controller, short life spans. Heat and humidity is a killer in any lighting system and most electronics.


Again, you are making general speculations about something without consulting the datasheet. You do not need to actively cool a LED driver (power source) as long as you are running it within spec. Are you assuming that almost every LED driver used is being run improperly? You are basically assuming that everyone from the designing engineer to the home user is an idiot.

You mention humidity above as well in reference to drivers, so again see a datasheet, but lets assume you are talking about humidity exposure for LEDs themselves in a hood. Let me quote directly from the Cree datasheet (will provide link below).

"Moisture Sensitivity
In testing, Cree has found XLamp XP-G LEDs to have unlimited floor life in conditions ≤30oC / 85% relative humidity (RH). Moisture testing included a 168 hour soak at 85oC / 85% RH followed by 3 reflow cycles, with visual and electrical inspections at each stage."

Sounds like they are pretty darn resistant to me.


you only lose the efficiency in the conversion of watt to lumen/heat ratio(i use lumen losely) Heat be the end result, producing to much heat in comparison to how much light. you cant expect to get the same kelvin ( kelvin used losely) temp from your diode by dimming them.


I don't really get what you are trying to say here, but I will give the link to the datasheet for Cree XP-G LEDs now.....

http://www.cree.com/products/pdf/xlampxp-g.pdf


Prebuilt systems are really expensive, and even the more expensive ones will not last more than 10,000 hrs. Unfortunate to say the least. When they can run much much longer, at a even lower expense.
I'm sorry for maybe ruining your thread, new to the forum thing too.

Many LED systems now cost the same if not less than some similar MH setups. Even if they cost more, many can make up for the difference in less than a year, but I really don't feel like trying to show you what has been calculated many times already on this board. They won't last more than 10,000 hours? Where is your proof other than just your speculative opinion? Read the datasheet, yes they will last longer, or do you not believe in science?

Landon

Pink_n_Purple
03/19/2011, 11:37 PM
[QUOTE=Shard;18515250] OMG i dont know how to multi quote!!!! this is confusing im sorry.

Again, welcome to the forum, but you are not understanding how LED systems work, or the physics of electricity involved.

Thank you, and no im not an electrical engineer nor do i own a spellchecker, or i cant find it.:spin1:

Running LEDs at a lower temperature and/or lower current is not a 'sub par' condition or somehow outside of 'optimal conditions'. You could argue that the lower temp/current is MORE optimal for them.

Keeping abient temp and heat sink temps in check are very important to longivity of your led and power supply. Dimming your lights can help manage this, but it may alter the light wavelength. I believe the cost per lumen increases when operating at lower voltages. Initial setup costs are larger. More diodes, more drivers+dimmers more space taken up more potientiall issues may arise. Replacement costs also rise as a result. I'm interested, Can lenses be reused? i've never heard of this, honest question.


As mentioned above, most LEDs are the most efficient at 350ma, which gives the highest lumen/energy output. The efficiency decreases as you approach max current.

your right, but operating at higher ma should not effect there lifespan, if cooled properly.


If you would take 5 minutes to read the datasheet you would see that 350ma is the 'sweet spot' for many LEDs like the Cree ones used in most fixtures today, but they run well at higher currents as well. Also, keeping the LEDs cooler allows them to run more efficiently

Giving them there natoriously long life span of 30,000 hrs with little shift in color, something companies such as Cree and others state.

(just like many other electronics). LEDs have an upper temperature limit, not really a lower one. I could run my LEDs at 0 deg C and they would run fine. That is not outside of their 'optimal conditions'.

Most systems run at there upper limit, including most diy, even dimmed.
yes but my point is that heat creats a loss in voltage and can increase load on your power supply, requiring power supplies to work harder, and getting a short 1-2 year life span.


So many grammar and spelling errors, but anyway, no we are not. All we are aiming for is a temp BELOW the upper threshold, not really a tight range between 24 and 30.

Ambient air temp in and around you leds and power source have a direct effect on there effectiveness to "cool themselves" . most systems are inclosed and some r even further inclosed within there tank setup. Why r you aiming for the upper threshold when a lower temp is possible and not that inconvieniant, expensive or hard to do and would result in a longer life span.

Again, you need to understand the difference here between an UPPER LIMIT for usage (LEDs), and a LIMITED RANGE (CFLs).

Yes and as stated most run at there upper limit. Thats why most consumers start to see color shift or dimming after anly 15,000 hrs-20,000hrs @ best.


Again, you are making general speculations about something without consulting the datasheet. You do not need to actively cool a LED driver (power source) as long as you are running it within spec. Are you assuming that almost every LED driver used is being run improperly? You are basically assuming that everyone from the designing engineer to the home user is an idiot.

i'm making speculations upon reall world use. I should start a thread---"has your led system ran 20,000hrs without any noticable loss of light or burnt power supplies?" or "has you led system dimmed noticbly in the last year or two of opperation".

You mention humidity above as well in reference to drivers, so again see a datasheet, but lets assume you are talking about humidity exposure for LEDs themselves in a hood. Let me quote directly from the Cree datasheet (will provide link below).

poor soldering connections, exposed wire, also dry and cracked wire insulation was my worry. espicially when running wire close to or inside heat sinks.

"Moisture Sensitivity
In testing, Cree has found XLamp XP-G LEDs to have unlimited floor life in conditions ≤30oC / 85% relative humidity (RH). Moisture testing included a 168 hour soak at 85oC / 85% RH followed by 3 reflow cycles, with visual and electrical inspections at each stage."

Sounds like they are pretty darn resistant to me.

except that at higher ambient temps air can hold a much greater water volume, and temps are usually higher than 30oC around the diodes and power supplies. When the lights, and power source go out there can be a build up of condinsation as the air cools, if your power supply isnt 100% air tight or have exposed wire and is sitting in these conditions than there is a chance for this type damage to occur, which could result in unexpected failure, or loss of life expectancy. ie a controller lasting alittle longer than a year.



I don't really get what you are trying to say here, but I will give the link to the datasheet for Cree XP-G LEDs now.....

i believe what i was try'n to explain was that there is a limit at wich point the diode produces more heat than light and is deemed inefficient.


http://www.cree.com/products/pdf/xlampxp-g.pdf



Many LED systems now cost the same if not less than some similar MH setups. Even if they cost more, many can make up for the difference in less than a year, but I really don't feel like trying to show you what has been calculated many times already on this board. They won't last more than 10,000 hours? Where is your proof other than just your speculative opinion? Read the datasheet, yes they will last longer, or do you not believe in science?

Savings in hydro use r different from place to place for instance i only pay 5 cent a kwh when lights are on pretty cheap when compared to others so the savings vary, then add in unexpected failures and that savings may not be as great for some. ie me, cheap hydro.

No there not idiots thats why we spend our money on these systems and seem to be content with short life spans of our led's and controlers. I never stated that they wont last longer, quite the opposite. it just seems that the majority of users, in the reall world situations, wont ever really experience the FULL POTENTIAL of there led systems. Mainly due to improper heat managment, resulting in shorter life spans.

this last paragraph is what i originally wanted to get across.
Cheers!

nanojg
03/19/2011, 11:53 PM
Uh... Is that post too long?

Shard
03/20/2011, 12:00 AM
OMG i dont know how to multi quote!!!! this is confusing im sorry.

You have to use a quote tag set for each section you want to quote. You cannot type anything yourself in between the quote tags.

For example the above looks like this to properly quote. {QUOTE=Pink_n_Purple;18516800}OMG i dont know how to multi quote!!!! this is confusing im sorry.{/quote}

You just have to replace the {s with [s.

Going to sleep as I have to dive early in the morning, will read over the whole thing later.

ccLansman
03/20/2011, 07:07 AM
LEDs last as long as the best test run someone ever did under the best circumstances on the best day, of the best month, of the best year, ....ect ...ect ect... you get the point. The life expectancy is normally based off this type of data to make a product sound better. I really have not seen actual data to support the claim but i am assuming that is where it came from as most findings come from the same type of thing. OR if they are good about it, it will be the average life expectancy, meaning they tested say 1000, and half lasted that long, some more, some less.

Anemonebuff
03/20/2011, 05:10 PM
LEDs last as long as the best test run someone ever did under the best circumstances on the best day, of the best month, of the best year, ....ect ...ect ect... you get the point. The life expectancy is normally based off this type of data to make a product sound better. I really have not seen actual data to support the claim but i am assuming that is where it came from as most findings come from the same type of thing. OR if they are good about it, it will be the average life expectancy, meaning they tested say 1000, and half lasted that long, some more, some less.

So if they say 50,000 hours and they normally get 25,000 in real usage, if that were the case and not a made up number, wouldn't LEDs still be worth it?

Reffer831
03/20/2011, 08:16 PM
No...

I was saying no to them lasting 10,000hrs

Elysia
04/11/2011, 11:51 AM
Sorry, I've been away a bit... The LED fixture I have has both white and blue LEDs in the same housing. You have the option of having them both on or just the blues, but there is only one power supply. The white LEDs continue to work while the blue LEDs do not. The unit is (and has been) plugged into a timer that is plugged into a GFCI.

I understand that LEDs fail when they overheat -- I had AIO nanos with canopys that included compact fluorescents and lunar LEDs and of course those LEDs were toast in no time. But there is nothing heating this LED fixture... and why wouldn't all the LEDs in the fixture failure, instead of just half of them?

Most importantly, do I have reason to contact Marineland about this? I am disappointed and I can not think of anything that I did to cause this failure, but I thought I should check with those of you who know more about these things first, before I question the manufacturer.

Ken Hahn
04/12/2011, 07:27 PM
There is some accurate and some pretty iffy LED info in this thread. Since I sometimes work with high powered LED technology in my industry (displays, not aquariums), I'd like to clarify a few points.

1. When the LED mfrs state a lifetime of 50,000 hours or so, that is a theoretical lifetime based on the known physics of LEDs. It is not a tested lifetime. Since it would take about 6 years to run that test, no one including the LED manufacturer has typically run one that long before initially releasing the part for sale. This estimated lifetime is generally considered to be pretty accurate under the ideal operating conditions that the lifetime is stated.

2. Achieving that rated lifetime in a light fixture requires that the lighting designers adhere to certain optimal junction temperatures of the LED die. These junction temperatures are not generally the same as the maximum junction temperature that is specified. A maximum junction temperature might be spec'd at 150C, but stated lifetime performance might be achieved at something under 100C. I saw one aquarium light mfr state that as long as the max 150C junction temperature wasn't exceeded the fixture would operate fine and that is simply not true. When you see a life rating on a light fixture, you can bet the manufacturer is just passing along the LED life rating from the LED mfr whether or not their fixture is operating those LEDs under the conditions needed to meet those lifetime specs.

3. High junction temperatures adversely affect LEDs short term for brightness and it tends to shift the color temperature of the light output. Lumen output of the LED are typically rated at some unrealistic junction temperature such as 25C, but will drop in brightness down to perhaps as much as 60% of that value as the junction temperature increases towards maximum.

4. High junction temperatures over time shorten the life of the LED, sometimes dramatically. Lowering the junction temperature, such as by running in dimming mode will lengthen the life of the LEDs - up to a point. For instance, I know one mfr that rates their super high power LEDs at 50,000 hours, but will increase their estimated life expectancy up to 80,000 hours as junction temperature is reduced but then they hit a theoretical limit as the LEDs tend to have other wear-out mechanism besides just the junction temperature. Obviously some mfrs of lighting might take the tact of hotrodding the LEDs to get the maximum brightness possible out of them as that is what the hobbyist wants to see, but that will directly lead to a shortened life.

5. Junction temperatures are a function of how much power is being put through the LED, generally in the form of current and how much heat is being extracted from the LED in the form of heatsinking. Low thermal resistance between the LED die and the heatsink is very important. Without cooling on the heatsink, you want it to get hot as a sign that it is pulling the heat away from the LED junctions, but when you apply the cooling to the heatsink, you want it to be adequate enough to significantly drop the temperature of the heatsink so that there is a good thermal gradient between the junction and the heatsink to help pull the heat away. A heat-soaked heatsink loses efficiency. If your heatsink is cooking, so are your LEDs probably.

6. I am sure that many lighting manufacturers pay little attention to the conditions that are necessary to achieve the maximum life and stability of the LEDs in their fixtures. To really characterize the junction temperature of an LED in a system is not a trivial exercise. It is very easy to build a fixture that turns a 50,000 hour LED into a 10,000 hour LED. It is also easy to design a fixture where failure of 1 LED increases the power through the other LEDs thus having an aging/failure ripple effect. You can also design the fixture so the bad (open) LED prevents the rest of the chain from operating.

7. As for LED ballasts and the like, all mfrs publish a maximum thermal spec. That thermal spec should not be construed that if it is set at 50C (for instance), that you are 100% fine running at 49C and going to instantly fail if you run at 51C. It is much more like a sliding scale with the closer you get to the upper range, the higher the failure rate will be. The upper temp spec is often gated by safety certification agencies like UL that care about burning stuff up and not about how long things last at different temperatures. Adding additional cooling to a particular unit that is running near the upper temp limit may not help, but you can pretty much be guaranteed that if a population of the devices are kept cooler rather than being run at their upper limit, the overall failure rate will be less over time. I like to think about it like the RPM redline in a car. While the car manufacturer says that you can run the motor up to 6000RPM safely, you know darn well that if you run around at 6000RPM all day, your car isn't going to last nearly as long as it would if you cruised around at 2000 RPM.

As one hard data point on LED life, we evaluated one well known high powered LED brand where we conducted measurements of stability over time measuring both brightness and color. In this case we were testing Red/Green/Blue LEDs and no white. At 10,000 hours we had measured less that a 1% drop in brightness and almost zero color shift using lab quality equipment. In fact the temperature fluctuations in the testing room had a bigger effect on brightness than time in this test. We were able to chart each time the air conditioning kicked on in the room. These devices were operating in a pulse mode of operation vs constant on, so this provides a more optimal junction temperature for best lifetime, but my point is that LEDs can be very stable over time given the right conditions.

I will also comment that white LEDs are typically phosphor converted blue LEDs. Phosphor has a similar thermally accelerated aging curve and some of the phosphors are bound with epoxy which can also yellow with age and temperature. I would expect that white LEDs would tend to be less well behaved over time in some regards for these reasons, though I don't have much long-term experience with them.

When you factor in not only all of the manufactures who in this industry vary from fairly large companies to garage shops, but also all of the DIY'ers that are randomly combining LEDs, heatsinks, fans and thermal paste into light fixtures, it is easy to image that the exact same LED might be lucky to last 5000 hours in one setup and be good for 25,000 hours in another. The desire to get the maximum brightness possible at the lowest cost possible in this hobby will probably always overrule achieving maximum lifetime because the first two affect the buying decision almost exclusively.

Yeesh, all of this writing just because I was doing a search on the Marineland LED fixture that I just saw down at the store to see if was any good. :(

snorvich
04/13/2011, 05:39 PM
Excellent posting by Ken Hahn!