evilc66 Posted January 18, 2008 Share Posted January 18, 2008 btw heating isnt bad until the after the first or second minute. Please explain this. What happens then? Link to comment
coolwaters Posted January 18, 2008 Author Share Posted January 18, 2008 lol i turned it off before that. i just finished it so i wasnt about to destroy it... i have to install legs so the LEDs will be upside down. and a small reflector around it. then i'll install the fans. Link to comment
coolwaters Posted January 18, 2008 Author Share Posted January 18, 2008 i just did a stress test with the fan. and i have to say....copper is the worst when it comes to releasing heat. i kinda dont know what to do but get a copper plate and use my aluminum heatsinks on top... just to let you know making heatsinks into low profiles isnt a good idea when your trying to cool off something this hot....my mistake. Link to comment
evilc66 Posted January 18, 2008 Share Posted January 18, 2008 Well, you learn from experience. I had a feeling you might have been pushing it a bit having so many LEDs in such a tight configuration on such a small heatsink. It could have worked if you had enough airflow over the unit, but the noise would be unacceptable. If you are going to use a copper plate and add aluminum heatsinks to the top, I highly suggest tightly bolting them together and not using thermal epoxy. Thermal epoxy is not a good choice for high thermal loads. The epoxy has a higher thermal resistance than the materials that you are mating together, and ideally it should be cured under relativley high pressure. It's not a substitute for surface contact. If you look at hybrid heatsinks, the copper insert is press fit into the aluminum. there is actually material removed from the surface of the copper slug when it is pressed in, and ensures that there is a tight, uniform fit to the parts. It make all the difference in the world between a good heatsink and a crap one. Link to comment
Gomer Posted January 18, 2008 Share Posted January 18, 2008 Well, you learn from experience. I had a feeling you might have been pushing it a bit having so many LEDs in such a tight configuration on such a small heatsink. It could have worked if you had enough airflow over the unit, but the noise would be unacceptable. http://webfiles.uci.edu/algomez/CreeProjec...2221%20copy.jpg I ran 12 crees at 700mA on that heatsink with only moderate air flow. It wasnt loud at all (fairly quiet) and the heatsink was quite reasonably cool. keep in mind that the copper heatsink in both our projects were ment for CPUs that likely push 60watts. 700mA @ 3.6Vf=2.52 watts. 16 LEDs would only be 40 watts Link to comment
coolwaters Posted January 18, 2008 Author Share Posted January 18, 2008 i got about the same heat sink. it looks like the U1 lowprofile copper. i'll try it again but this time for about 30min too see how hot i gets. ima try 3 fans... Link to comment
coolwaters Posted January 18, 2008 Author Share Posted January 18, 2008 i just raised the fan 1/4" above the heatsink cuz it was cause a lot of suction. which greatly reduced the air flow. the fa at 7.5v. its doing perfectly. i'jj drop the fan down to 6v cuz thats the quietest with the best air flow. iv noticed the cooper is a little warm but the aluminum on the sides is warmer. i'll probably have to add a small fan of thos. or find a better way. ok after about 20 mins on 6v its a little warm but i can work with that. i also left a sheet of white paper under the LEDs less then 1/8" way. theres some distortion on the paper. but it was expected. so that to me confirms LEDs emits very little of any IR or heat. Link to comment
snowlancer2720 Posted January 18, 2008 Share Posted January 18, 2008 i dont know if you have your heart set on the copper ones, but these are the ones that i used http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...item=5174245845 they seem to conduct heat pretty well, although i didnt really test them a whole lot because of my driver crapping out and everything. Link to comment
coolwaters Posted January 18, 2008 Author Share Posted January 18, 2008 it looks like it lacks a lot of fins. i got a heatsink with paper like fins and there was hundreds of them. it never got hot... Link to comment
snowlancer2720 Posted January 19, 2008 Share Posted January 19, 2008 did you ever find legs for it? im using the "docking mounts" that you can get for those current usa lights, and just cutting off the little tabs Link to comment
coolwaters Posted January 19, 2008 Author Share Posted January 19, 2008 im using my 1/4" tall copper heatsinks from my last project Link to comment
coolwaters Posted January 20, 2008 Author Share Posted January 20, 2008 im having trouble mounting the LEDs... i'll probably end up buying a light fixture from home depot or walmart... also check out my new tank project http://www.nano-reef.com/forums/index.php?showtopic=143558 Link to comment
Alittlefishy Posted January 20, 2008 Share Posted January 20, 2008 Hi guys. I'm new here, but have been reading about your ventures into LED lighting. I just finished my setup, but it does not use the style of LED you all have. Mine are 5 chip in water-clear bulb rated at 240000mcd at 40 deg pattern, or 90.941 lumens each. With the thought that a standard 100W light bulb gives off around 1700 lumens, I am using 100 white at the above specs and 50 blue at 130000 at 40 deg. That should be around 11550 lumens! Math-wise, that is almost like 7-100W light bulbs. FYI this is for my AP24. My main reason for this is: 1. Something different 2. Reduce heat issues and water evap. 3. Just to see if it will really work. I chose the bulb type because they only run 100mA at 3.4-3.8 VDC. I am running them at 3VDC and 82mA. This keeps everything from getting hot enough to need a heat sink. Obviously the soldering was a little more intensive they using the stars that you have, but not too bad. Here are 2 pics. The first one is the stock PC lights, and the second is the LED's. Tell me what you think. BTW, total cost was 75 for the led's and 6 dollars for the resistors. Enjoy. Link to comment
Hans Dorn Posted January 20, 2008 Share Posted January 20, 2008 Hi Alittlefishy, your lumen numbers are a bit off, I'm afraid. The 5-chip whites are probably about as efficient as the current high power LEDs - ca. 80lm/W, give or take 5lm. At 80mA, they'll put out ca. 20lm - still not too bad for the price you pay for them The blue LEDs you have are 5-chip too, I guess. I'm looking for these myself, where did you find them. Are you cooling your LEDs, how warm do they get? And last but not least, post some more pics of your mod Regards Hans P.S: Looking very nice BTW! Link to comment
Alittlefishy Posted January 21, 2008 Share Posted January 21, 2008 The lms may have been off, I'm just now delving into that realm. But I can say with out a doubt that this setup beats the stock PC by far. It's nothing like the pair of 400w MH on my old 140, but imo it looks like it would be a little stronger than a 70wMH. Maybe equal to a 150W, but I think that is pushing it. Here are the blues I used: 5-Chip Blue LED's and here are the whites: 5-Chip White LED's Also, here is the link to my album. Photobucket Album They get a little warm, but I'm using the pair of 60mm fans that came with the AP. I made a cover out of plexi and sealed it so that the fans blow out and air is pulled in the stock top vents onto the back of the circuit boards. It does not get nearly as hot as the PC lights. I also wanted to run a canister type filter, so I have removed the black partition, and modified the hood to clear a Magnum 250 HOT. It provides 250gph and can filter particles or just hold carbon. For the price, it really seems to do the job. I also have a ViaAqua 80gph just for extra flow and to mix up s/w. I just filled it up tonight, and hope to have some rock next weekend. Now that it is all said and done, I really regret buying the AP, because the point was to just leave it alone and let it run. Next time I'll just buy the tank and go to town on that instead of hacking up a perfectly good all in one. Now I am going to use some leftover plexi to create a holder for some macroalgae, but I think my mods are finished for now. BTW, I now have a brand new set of PC lights with the reflector that have been used about 20 min if anyone is interested. Link to comment
coolwaters Posted January 21, 2008 Author Share Posted January 21, 2008 ok first of all about 50 cents for something thats rated at 100lumens at .35 watts is BS... if somehow its 100lumes at .35ws then that will pass the theoretical lumens per watt limit... something at 100mA will burn out fast. even with fans cuz theres not heatsink...whats the point in fans when plastic is blocking the flow? tell use how bright it is in about 3 months of use. i'll w8 until theres more results btw hope your regulating them... Link to comment
strangelove Posted January 21, 2008 Share Posted January 21, 2008 Well, you learn from experience. I had a feeling you might have been pushing it a bit having so many LEDs in such a tight configuration on such a small heatsink. It could have worked if you had enough airflow over the unit, but the noise would be unacceptable. If you are going to use a copper plate and add aluminum heatsinks to the top, I highly suggest tightly bolting them together and not using thermal epoxy. Thermal epoxy is not a good choice for high thermal loads. The epoxy has a higher thermal resistance than the materials that you are mating together, and ideally it should be cured under relativley high pressure. It's not a substitute for surface contact. If you look at hybrid heatsinks, the copper insert is press fit into the aluminum. there is actually material removed from the surface of the copper slug when it is pressed in, and ensures that there is a tight, uniform fit to the parts. It make all the difference in the world between a good heatsink and a crap one. Agree, I think a huge heatsink is key to keeping your LEDs running cool. Guess I'll be joining you guys after all. Got my hands on a bunch of Luxeon LED emitters. Now what? Link to comment
coolwaters Posted January 21, 2008 Author Share Posted January 21, 2008 now u try to make them last 5 years. by using regulators and heat sinks. Link to comment
evilc66 Posted January 21, 2008 Share Posted January 21, 2008 Well, you are going to have to hit 5500lm to be brighter than a 70W MH, and you are probably just over 2200lm with the setup that you have currently. Granted, it's still going to be bright. I agree a little with Coolwaters on the heat. See if you can get an infrared thermometer and check the die temperatures after they have been running for half an hour. The data sheet should have the temperature rating on it for normal operation. Drawing air over the LEDs may work if the temps aren't too high, but if they do, you are going to need better ways to pull the heat away from the LEDs. If you are regulating the current with resistors (which no-one here recommends), are you using a good power supply? If you are using a wall wart style power supply I suggest replacing it as soon as possible. Switching power supplies are cheap and will not lead to the premature failure of your array. And on another note, can we keep the topic to what the original theme was supposed to be and not hijack the thread with everyone elses projects. This has happened to my thread and others recently and it gets a little irritating. If you have a good project, start a thread and come on here and say something like "Hey guys, nice stuff. I have something I've been working on too. Check out my thread if you are interested." We are glad you have found our experiments intersting and inspirational, but dont hijack our threads. Link to comment
Hans Dorn Posted January 21, 2008 Share Posted January 21, 2008 And on another note, can we keep the topic to what the original theme was supposed to be and not hijack the thread with everyone elses projects. This has happened to my thread and others recently and it gets a little irritating. If you have a good project, start a thread and come on here and say something like "Hey guys, nice stuff. I have something I've been working on too. Check out my thread if you are interested." We are glad you have found our experiments intersting and inspirational, but dont hijack our threads. Whoops. Sorry, I didn't mean to derail this thread (or yours either). I was playing around with the idea of LED lighting for some time already, but wasn't sure if it would work out. It was basically your and Coolwaters' threads that got me going - so thanks for the heads up Maybe we should start some kind of generic LED thread to share ideas, without limiting it to a single project. Regards Hans Link to comment
evilc66 Posted January 21, 2008 Share Posted January 21, 2008 That doesn't sound like a bad idea. I didn't mean to pick on anyone in particular, and I don't know if Coolwaters even cares about it, but it gets a little irritating after the third project that gets tacked on to you thread hiding your work. Honestly, I'm truely excited to see so many people interested in LED lighting. It seems that the interest comes and goes in other forums, mainly due to failure. We have seen some succesful project here, and I think it has really sparked some great conversation and ideas. Lets keep it going.... ....just in other threads Link to comment
coolwaters Posted January 21, 2008 Author Share Posted January 21, 2008 lol i dont really care i havent been doing much with my LEDs. busy with new tank. i'm still figuring out how to mount the LEDs to a hood. and then on to the tank. im throwing out the idea of low profile. just going to get a 3.5"X3.5" 1/8" copper plate (can someone help me with that?) and use my CPU heatsink. its going to be like 3" tall but w/e BTW 70w is around 5500lumens would be around 4000kevlins. i dont know people with that kind of bulb in there SW tanks... at 14k lumen should be around 3000... Link to comment
strangelove Posted January 21, 2008 Share Posted January 21, 2008 OK so this is what I got and I am assuming that they are emitters. So would you suggest getting stars to mount these LEDs or should I go about it a different way? Link to comment
coolwaters Posted January 21, 2008 Author Share Posted January 21, 2008 hey!!! u got the 1w common LEDs too? i havent touched them yet.. tell me if their bight. i was planning to use them as refuge lights. Link to comment
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