L.E.D. vs HALIDE/T5/VHO

[Ron99]

Originally Posted by sphelps

As for fans, they are not needed, there are already plenty of LED lights for other applications which use high powered LEDs with properly designed heat sinks and no fans. It's a simple mater of cutting costs and the temperature gradient and heat transfer rate of LEDs is high and low enough respectively to eliminate the need for convective cooling. Computer components like CPUs run much hotter, their heat flux is way higher than an LED and require convective cooling. Computers are also built as cheap as possible, it's a huge commodity market.

So you want a fixture that looks stylish, has a long warranty but doesn't run any fans. I'm not sure all those are compatible criteria

[sphelps]

Originally Posted by Ron99

So you want a fixture that looks stylish, has a long warranty but doesn't run any fans. I'm not sure all those are compatible criteria

Well the warranty isn't that big of a thing if the quality is obviously there. But yeah for sure on stylish with no fans, otherwise I'll stick with what actually works, looks good, is reliable and quiet. I call them Halides and like it or not they are the best all around type of lighting for the average tank, just saying

[OceanicCorals-Eugene-]

Originally Posted by sphelps

As for fans, they are not needed, there are already plenty of LED lights for other applications which use high powered LEDs with properly designed heat sinks and no fans. It's a simple mater of cutting costs and the temperature gradient and heat transfer rate of LEDs is high and low enough respectively to eliminate the need for convective cooling. Computer components like CPUs run much hotter, their heat flux is way higher than an LED and require convective cooling. Computers are also built as cheap as possible, it's a huge commodity market.

Im not so sure about that, give me an example of high power LEDs thats out there that doesn't utilize some form of active cooling, the ones found in the new Audi cars utilize passing air from inside the engine bay is a quick one that comes to mind. Its not so much cutting cost, im sure that has something to do with it, But if the heatsinks were made adequate enough for the LEDs to start the addition of fans only adds to the overall benefit of the fixture by keeping the LEDs at a much cooler temperature than without. You keep pointing out that fans have reliability issues. If you rip open one of the fixtures made for our hobby you'll quickly see that the fans they use inside to reduce cost....only costs $1-2. A Prop fan that is made by a good company usually run in the range of $10-12 and are 10x more quite than the cheap ones and push more air as well.

Also i would differ to say that computers are build as cheap as possible, at my previous job i was custom building PCs to fit the need of individual people and if you dont get into the watercooling side of things, the heatsink design + fan is really focused upon in the design of a system. The cooling of a system sometimes allows you to push that much more "juice" out of the system without getting lag. Theres only so much a heatsink can do, in other words you'll never see a top of the line computer system run without some form of active cooling on its components.

[Ron99]

The other thing to consider is weight. Using fans lets you use smaller heatsinks. I have big heatsinks in my unit that probably would have done the job without fans and the bloody fixture weights at least 50 pounds. That is heavy. If I could have found thinner or lighter heatsinks in my price range I would have gone with them.

As you say, LEDs generate less heat than a CPU but you don't have 80 CPUs on one heatsink either. Either way, if you want to run the LEDs with higher current (more output) and keep the size and weight reasonable then fans are likely necessary. if you look at the units without fans they are either using 1 watt LEDs or driving 3 watt LEDs at closer to 1 watt to minimize heat.

[sphelps]

Originally Posted by OceanicCorals-Eugene-

Im not so sure about that, give me an example of high power LEDs thats out there that doesn't utilize some form of active cooling, the ones found in the new Audi cars utilize passing air from inside the engine bay is a quick one that comes to mind. Its not so much cutting cost, im sure that has something to do with it, But if the heatsinks were made adequate enough for the LEDs to start the addition of fans only adds to the overall benefit of the fixture by keeping the LEDs at a much cooler temperature than without. You keep pointing out that fans have reliability issues. If you rip open one of the fixtures made for our hobby you'll quickly see that the fans they use inside to reduce cost....only costs $1-2. A Prop fan that is made by a good company usually run in the range of $10-12 and are 10x more quite than the cheap ones and push more air as well.

Also i would differ to say that computers are build as cheap as possible, at my previous job i was custom building PCs to fit the need of individual people and if you dont get into the watercooling side of things, the heatsink design + fan is really focused upon in the design of a system. The cooling of a system sometimes allows you to push that much more "juice" out of the system without getting lag. Theres only so much a heatsink can do, in other words you'll never see a top of the line computer system run without some form of active cooling on its components.

Ok well these ones you sell come to mind


These 3W crees are enclosed in an aluminum housing which is supposed to keep them cool enough so they don't require fans. It's 3D inductive cooling as appose to just one sided but still a basic design. If fins were added to increase surface area and each unit was mounted to an additional heat sink I would bet the LEDs would run cooler than the fan cooled units currently available and those built by DIY'ers.


Also they make high powered LEDs for various residential applications including pretty much every light bulb standard available, none use fans.


Spotlights
http://www.udmdjstore.co.uk/category...ategoryID=2578
http://www.alibaba.com/product-gs/26...tdoor_LED.html

I could go on but I really do have better things to do these days.

As for computers my point was the CPUs run much hotter and it's commodity market and therefore not really compatible to the LEDs, that's all. I'm not here to debate anything on the subject of computer quality or price.

[StirCrazy]

Originally Posted by sphelps

Also they make high powered LEDs for various residential applications including pretty much every light bulb standard available, none use fans.


Spotlights
http://www.udmdjstore.co.uk/category...ategoryID=2578
http://www.alibaba.com/product-gs/26...tdoor_LED.html

I could go on but I really do have better things to do these days.

.

Ok, you better start doing something else as the two examples here don't show your point at all, the residential ones are 1 watt emitters not 3 watt so way way less heat, and after doing some digging on that block of leds you linked to they use a patent pending cooling system, which happens to be peltier active cooling, which in its self is a cool idea, but not practical for fish tank lights as it would lead to a ton of condensation inside your fixture.

Steve

[sphelps]

Originally Posted by StirCrazy

Ok, you better start doing something else as the two examples here don't show your point at all, the residential ones are 1 watt emitters not 3 watt so way way less heat, and after doing some digging on that block of leds you linked to they use a patent pending cooling system, which happens to be peltier active cooling, which in its self is a cool idea, but not practical for fish tank lights as it would lead to a ton of condensation inside your fixture.

Steve

Actually they have ones that use 3W LEDs as well
http://starwire-led.en.made-in-china...GU10-C3W-.html

Also you could use a peltier system and regulate the current with a simple thermo switch so the surface stays at a consistent temperature just like fans so condensation would be no different. As long as the surface temperature stays at or above ambient you won't get condensation.

The bottom line is many high powered systems already exist which don't use fans so it can be done and it can still be done better. I'm not sure why you all feel the need to debate that, if you like fans go nuts but I'd prefer a system without fans. It's a simple personal preference I guess, and I'm entitled to it.

[Ron99]

Also, have you handled one of those spotlights? They are much heavier than a standard spotlight bulb, So it goes back to weight and size. Scale that up to a full array and you end up with a large heavy heatsink if you want to go without fans.

Like it or not,if you want to run a larger array of 3W LEDs at or near full power without having a 50 pound light fixture you need fans.

[sphelps]

Originally Posted by Ron99

Also, have you handled one of those spotlights? They are much heavier than a standard spotlight bulb, So it goes back to weight and size. Scale that up to a full array and you end up with a large heavy heatsink if you want to go without fans.

Like it or not,if you want to run a larger array of 3W LEDs at or near full power without having a 50 pound light fixture you need fans.

I have some of the LED spotlights in use in my house, they are actually about the same weight as the halogens, much lighter than they look. A little bigger but certainly not heavier. The larger size is also due to need to include a driver not so much a result of the heat sink. The size difference is also only noticeable on the very small spotlights, pretty much every other type of house hold bulbs are of equal size.

Keep thinking that if you want but you don't have to add more weight to increase heat sink efficiency. Applying individual finned heat sinks to each LED will not add significant weight and reduce the the need for an additional large heat sink. You could very easily decrease the weight of the fixture with proper design. LEDs don't generate a lot of heat, they are at least 90% efficient meaning a 3W bulb can't produce more than 0.3W of heat which is very little. The reason you need fans is because you're simply bolting one side of the of it to a large aluminum plate which isn't a very efficient way to remove the heat.

[OceanicCorals-Eugene-]

Originally Posted by sphelps

Ok well these ones you sell come to mind

Like Ron has already pointed out, these lights alone, weight about 1- 1.5bs Also these lights run at a temperature of roughly 50C, the whole debate about whether or not we need fans for the fixtures was the debate on how efficiently the heatsinks alone can dissipate the heat to keep the temperature as low as possible. At 50C the LEDs will surely work close to there rated 50,000hrs life time. But the decrease in intensity will be larger over the course of the bulbs overall life.

Originally Posted by sphelps

Also you could use a peltier system and regulate the current with a simple thermo switch so the surface stays at a consistent temperature just like fans so condensation would be no different. As long as the surface temperature stays at or above ambient you won't get condensation.

The bottom line is many high powered systems already exist which don't use fans so it can be done and it can still be done better. I'm not sure why you all feel the need to debate that, if you like fans go nuts but I'd prefer a system without fans. It's a simple personal preference I guess, and I'm entitled to it.

A peltier system wont work without a fan im afraid, you need something to cool the hot side of the peltier or it ends up heating up both sides, so either way there needs to be active cooling in the use of peltiers.

again the debate on whether or not fans were needed started based on the idea of keeping the heatsinks as cool as possible. But a system without fans will work, just not as efficient as those that has active cooling, as you'll most likely see an increase in intensity drop through the life of the emitters.

Originally Posted by sphelps

I have some of the LED spotlights in use in my house, they are actually about the same weight as the halogens, much lighter than they look. A little bigger but certainly not heavier. The larger size is also due to need to include a driver not so much a result of the heat sink. The size difference is also only noticeable on the very small spotlights, pretty much every other type of house hold bulbs are of each size.

Keep thinking that if you want but you don't have to add more weight to increase heat sink efficiency. Applying individual finned heat sinks to each LED will not add significant weight and reduce the the need for an additional large heat sink. You could very easily decrease the weight of the fixture with proper design. LEDs don't generate a lot of heat, they are at least 90% efficient meaning a 3W bulb can't produce more than 0.3W of heat which is very little. The reason you need fans is because you're simply bolting one side of the of it to a large aluminum plate which isn't a very efficient way to remove the heat.

Applying individual finned heatsinks to each LED would create uneven cooling to each of the heatsinks. unless your talking about a fanless system, if thats the case then you'll need some fairly well designed light weight heatsinks. If we were to mill the front face of the aluminum heatsink with fins down to about 1cm would it increase the efficiency? It'll move the heat towards the fins faster, but without active cooling/air movement your not doing much with the extra speed in heat transfer from the LED to the heatsink.

Maybe we'll see a fixture out there in the future that will be fanless and be able to keep the temperature at 30-40C, when that day comes i'll purchase one to test and throw a fan on top to increase the lifespan of my LEDs(highly doubt it but i want to be optimistic)