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I was typing my reply, but Dana beat me to the punchUseful life of LED luminous flux is often cited as when it reaches 70%, which is more common than sudden, complete failure. Reduction of luminous flux can be caused by heat, drive current, and humidity, causing yellowing of the optics (which lessens transmission of blue light.) Other chromaticity shifts reported include shift to blue (due to phosphor changes), yellow shifts (lens oxidation, phosphor efficiency), green shift (phosphor oxidation, reduction in red emissions) and red shift (shifts in green and red emissions). High temps can cause phosphors to settle, curl, delaminate which causes reduction in photon emissions. If heat and humidity are well-controlled, it is not unreasonable to expect a LED luminaire to provide years of service. If PAR is the only concern, use of a quality quantum meter (Apogee) will tell the tale (and possibly report PAR loss due to extreme spectral shifts.) Spectral shifts are best reported by a spectrometer, although a Seneye device could possibly 'see' them. As usual, no pat answer as to useful LED life. It depends.
Great minds think alike.I was typing my reply, but Dana beat me to the punch
Well my lights at 70% were way to intense for my 210, and if you are not running at 100% intensity which most of us are not, you will get much longer then 5 years. Im over 5 years on mine, and have no major loss of light. Matter of fact I had to turn them way down as I was running to much intensity for this whole time. Im sure they degrade as described above, but that would really only matter if your tank required 100%
Correct.Depends on who you talk to..
50,000 hours of actual use.I know. I'm one of the weirdos who hasn't upgraded his LEDs to the newest ones out... I've got a Radion Gen1 that I upgraded to the Gen3 pucks a few years ago, and I'm wondering how long I should expect it to last before I need to be thinking about replacements? Also, should I expect gradual PAR decrease, or would the diodes just burn out when they're done?
Btw, I do still love my radions. I just am wondering at what point I need to expect to retire them and how I'll know what that looks like.
@Dana Riddle @Tim at EcoTech #lightinggurus
I would think therefore that the percentage they're run at would make little difference to lifespan
a diode a 100% will run much hotter even with a fan and good heatsink then one running 15 0r 30%.
Difference in a car engine is they run a steady temperature and water cooled with a thermostat regulating cooling. But temps still rise dramatically in all performance applications. 100F day I can hold 195F on a LS7, but on a track 230 240 is common. As far as our lights are concerned, they are simply air cooled, and by that I mean the heatsink is cooled down. The diode temps vary greatly depending on intensity, no matter how well they are thermostatically controlled. Our fans simply remove excess heat from the heatsink, as needed. They in no way regulate diode temps accurately, they just removes peak heat conditions. My fans dont even come on as low as run my current set up. Fact is with air cooled electronics less wattage equals less heat. Even if we water cooled the heatsink, the actual diode itself will run much hotter at full throttle then less. This is also seen directly by looking at CPU temps in water cooled graphic cards and CPUs. Which have 20 X better interface with much better thermal compounds these diodes do not have. We actually hand lap the CPU cores to #3000 grit then polish before applying thermal compound. So dont take this as arguing against you, you are semi correct, im just pointing out small details that matter. The heat transfer is not instant from diode to heatsink, and the thermostat may not even be in play at lower temps. All I posit is not running a led at full intensity will naturally run cooler and will increase its lifespan.a thermostatically controlled system
Difference in a car engine is they run a steady temperature and water cooled with a thermostat regulating cooling. But temps still rise dramatically in all performance applications. 100F day I can hold 195F on a LS7, but on a track 230 240 is common. As far as our lights are concerned, they are simply air cooled, and by that I mean the heatsink is cooled down. The diode temps vary greatly depending on intensity, no matter how well they are thermostatically controlled. Our fans simply remove excess heat from the heatsink, as needed. They in no way regulate diode temps accurately, they just removes peak heat conditions. My fans dont even come on as low as run my current set up. Fact is with air cooled electronics less wattage equals less heat. Even if we water cooled the heatsink, the actual diode itself will run much hotter at full throttle then less. This is also seen directly by looking at CPU temps in water cooled graphic cards and CPUs. Which have 20 X better interface with much better thermal compounds these diodes do not have. We actually hand lap the CPU cores to #3000 grit then polish before applying thermal compound. So dont take this as arguing against you, you are semi correct, im just pointing out small details that matter. The heat transfer is not instant from diode to heatsink, and the thermostat may not even be in play at lower temps. All I posit is not running a led at full intensity will naturally run cooler and will increase its lifespan.
If your car engine is increasing above its recommended working range when on track then what you are saying is that it does not have enough cooling capacity for that workload and it needs e.g. a larger radiator.
Trying not to argue with you but thermal management has been a hobby as much as my 26 years of reef aquariums.(and i don't know for sure, which is why i want to see the data),
If you're driving a LED with less current, you can expect a longer life (if other factors such as heat and humidity are controlled.)
My 628HP NA lS7 which I hand built myself, based on the data I provided you with, is actually running in its working temperature range, its just a known fact when you run harder, you run hotter. And I already run the largest radiator made for that specific application.
Trying not to argue with you but thermal management has been a hobby as much as my 26 years of reef aquariums.
And I do know, Here is one example found for you "" Between the LED's thermal impedance and the MCPB, I would guess you will probably be in the 5 C/W range from past experience. ""
What you will find is heat in diode is directly tied to wattage going in regardless of thermal management. Due to the factual thermal impedance
None of this is worth arguing, and these details not furthering the topic. Fact is if you run a led at 100% it wont last as long as running one at 50% it is also why manufacturers are claiming 50 to 100,000 hour longevity .
Dont trust me trust Dana
I'm tagging along here. I have a paper by the Next Generation Lighting Industry Alliance (Cree, Philips, GE, etc.) that has pertinent data but as @outhouse has said, we're beating a dead horse.My 628HP NA lS7 which I hand built myself, based on the data I provided you with, is actually running in its working temperature range, its just a known fact when you run harder, you run hotter. And I already run the largest radiator made for that specific application.
Trying not to argue with you but thermal management has been a hobby as much as my 26 years of reef aquariums.
And I do know, Here is one example found for you "" Between the LED's thermal impedance and the MCPB, I would guess you will probably be in the 5 C/W range from past experience. ""
What you will find is heat in diode is directly tied to wattage going in regardless of thermal management. Due to the factual thermal impedance
None of this is worth arguing, and these details not furthering the topic. Fact is if you run a led at 100% it wont last as long as running one at 50% it is also why manufacturers are claiming 50 to 100,000 hour longevity .
Dont trust me trust Dana
I'm tagging along here. I have a paper by the Next Generation Lighting Industry Alliance (Cree, Philips, GE, etc.) that has pertinent data but as @outhouse has said, we're beating a dead horse.