DiY LED - Cree CXA3070

SupraSPL said:

To clarify the numbers in those charts, when Mr Flux calculated the CXA numbers he was not using the CXA3070 and he did not specify which bin so the lumen/W, efficiency, and flux would not be correct figures. Same goes for the Vero, the numbers would vary depending on which Vero you are runnning. To make it more complicated, the numbers would have to be adjusted depending on the current you are running. Also, there would need to be an adjustment for junction temp.

So the constants are LER and photons/PAR WATT, which should apply to all the CXAs of that particular color temp. That is very useful because it allows us to calculate the actual efficiency at a given current and Tj for any model of CXA of that color temp.

So in the example below with (4) CXA3070s on a heatsink running at 1A, if we have 58 PAR WATTS of CXA 3000K, we get 4.88 umol/s per PAR WATT for a total of 283 umol/s. So if you can fit 4 modules in a 3X3 you get 1131 umol/s/m2 (PPFD)

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Nice explanation! Agree with everything, just small nitpicking

3ftx3ft = 0.827225 square meters

therefore 4 x 283 umol/s at 3x3 = 1368 PPFD

Observe & Report said:

The thermal part is my weakness is 25C Tj realistic for our panels? I think they get the specs by giving the board a pulse when it's cold but our lights are on for 12+ hours. If your room is 25C and your heatsink is a few degrees above that, Tj has to be much higher.

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Sure, a realistic Tj is more like 50C; For the vero this would give a derating factor of about 0.96.

PSUAGRO. said:

Just send your DIY panels over to growers house!!!!....lol..... they did just recently buy a spectroradiometer from stellarnet($3500)

I still don't understand their "average" par/watt calculations, because the vero cob seems low

http://growershouse.com/images/ALTEST_infographic_1.pdf the philips 315w agro-elite cmh is getting over 22 par/watt ......that's crazy #'s

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Not a bad idea! For a 4X4 canopy Id send them 4 panels of 150W each and ask them to keep the distance 10". Would love to see how it stacks up. That CMH spectrum is very impressive and I am surprised how badly the HPS missed red and deep red.

anomuumi said:

Nice explanation! Agree with everything, just small nitpicking

3ftx3ft = 0.827225 square meters

therefore 4 x 283 umol/s at 3x3 = 1368 PPFD

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Good call that is a pretty big difference!

Yep 5% penalty for the Vero running with Tj 50C.

God I'd love to have that spectroradiometer..lol. Kinda interesting how most leds leave out all the yellow and mid wavelength that the cmh and hps show. You would think that would be wasted energy, but the cmh seems to do very well. I'd like to see the cobs in different temperatures under that meter, should be a little chart sent out or available with every led really.

Group buy on a lot of LED's to send to them for testing?

SupraSPL said:

Not a bad idea! For a 4X4 canopy Id send them 4 panels of 150W each and ask them to keep the distance 10". Would love to see how it stacks up. That CMH spectrum is very impressive and I am surprised how badly the HPS missed red and deep red.

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its because cmh use a ceramic arc and hps use an aliminum arc. The ceramic arc is able to distribute a more even spectrum than an aluminum arc. The ceramic arc is less susceptable to degrading, the cmh will last 2-3 times longer than hps with less spectral degrading

I used to have the philips allstart 330's. they were awesome. But i lost them.. I was thinking about running one again in vert, I'm stuck on led again

SupraSPL said:

Glad you decided to try diy! If you replace 2000HPS with 1000W of CXA3070 you might actually increase your yields and get better coverage in your canopy. Here is the formula I would recommend:

(8 ) Heatsink USA 10.08" X 6" = $350
(32) 3000K CXA3070 = $1375 (might save some $ by ordering from arrow instead of digikey)
(32) 1A drivers = $320
fans, wiring + misc $150

That would give you a 39% efficient lamp dissipating about 1200W for $2200

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Ok, after a lot of reading I'm thinking about doing like you suggested here only with individual heatsinks so I can spread them out for more uniform coverage. I'm thinking 11 in a 4/3/4 pattern (about 1 per square ft.) should work good for a 4x3 tray. Before I start ordering stuff though I have a couple questions and would appreciate any feedback (good and bad) on how I'm thinking of doing it.

1- http://www.amazon.com/dp/B001A5V1K2/ref=cm_sw_su_dp These are what Gaius used and what I'm planning on going with. Good option or is there something better? Also, what would I drive them with (I'm assuming the drivers you linked only power the cobs)

2- I'm ordering from arrow (the link you gave me), those are the one's I need (top bin) right?

3- All 3k's will work for me for a straight flowering lamp? Or should I order a few 3050 2700's to mix in there (like bbspills is using)?

Thanks for your help Supra (and anyone else who wouldn't mind chiming in). I seen a post somewhere where you gave a list of wiring and misc, I'll have to find it and get a misc parts list for you to verify I'm not missing anything too. I just haven't got that far yet. Thanks again for all your help!!

Yes those heatsinks will work great and it will save you $75 versus heatsink USA. The down side is more fans to wire and power (11 vs 4) and more rigging to hang or secure each one, which is why gaius strapped his together. You are correct, the fans will need their own 12V AC-DC converter. I have a bunch on order because I am trying to find some cheapos that have a decent efficiency (80% or better). You might be able to use something like this. It has adjustable voltage so you can reduce the fan speed a bit to reduce noise if needed.

Arrow is a good call, those are the mid bin but they are the best currently available.

All 3K should work fine. I am in the process of testing that, but since HPS works fine on its own, 3K should be good to go because it is actually a better spectrum than HPS (more red). The CXA3050 is slightly less efficient (7.5%) and the 2700K is less efficient again (we dont know how much because Cree does not give us the 2700K curve or the LER, but it is a significant penalty). The way I see it photons are more important than spectrum so I would advise against the 2700K, but if you are in the mood to experiment please do not let my advice stop you.

Cool, thanks Supra. I'll just stick with the 3k's then. And I'll wait till you test some AC DC converters out to see which one I'll go with. I can run several fans off of 1 converter though right? or do I need a separate one for each fan? You know much much more about this stuff than I do so I'm going to stick to your suggestions instead of trying to blaze new trails of my own. I do plan on making a mounting rig of some sort like Gaius did too, it would just be too much of a clusterf*ck in there if I didn't!

Haha yes I know what you mean. Even with the big heatsinks I got a challenge in the grow room trying to keep everything as neat as possible. In retrospect I might have considered using 4 conductor wire.

Yes you can use just 1 converter to power all the fans, just have to make sure the converter has enough amps to do the job but I don't want to oversize it too much either. That is another thing I will be able to test and report back on soon. I am using diy pigtails like these to get the fans all hooked up to the converter. The reason I am using multiple converters is because I need one for each room because they each have their own timers.

Each room has 500W LED now. Here is the 7 weeks room. Most of them faded early but they are all very frosty and sticky. The best yield looks like it will be the Darkstar and it is also very frosty and dank. Stacked Kush looks good too, still lots of white pistils so it seems to be the slowest.

SupraSPL said:

Each room has 500W LED now. Here is the 7 weeks room. Most of them faded early but they are all very frosty and sticky. The best yield looks like it will be the Darkstar and it is also very frosty and dank. Stacked Kush looks good too, still lots of white pistils so it seems to be the slowest.

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WoW!
Great !!!

S, Good work!
You were right, that module you saw (via pm) I made with (2) 3050's is amazing in <2 sf scrog.

Supra your stuff looks awesome. I finally bought some 3070s and a couple different drivers to experiment; the previous drivers I linked too weren't for me because their input was 200-240v. I was trying to hookup one of the leds but I'm not getting any light out I hooked up my multimeter and can read a voltage but not any amps; am I missing something?. Here is some pictures:

Looks like the output is only 24v, think you need close to 40 for the 3070.

beautiful colors supra..looks awesome in there.

Looks like you have a constant voltage power adapter. It is possible to power LEDs that way especially in the case of COBs, but the forward voltage at 1A is about 36V. I would recommend something like this cheapo or this meanwell

Thanks for the info guys. I wasn't sure what I needed so I bought 2 different drivers; would this one work better?

Also how do you calculate the forward voltage?

pct.cree.com

It is called a product characterization table and you can choose the LED you bought from out of the table. If you bought what supra has it would be the XLamp CXA3070 and the other dropdown should be Z2(Stands for which performance class it is in for calculating lumens). Also in the top right is a dropdown for the current range. You will probably want the "Coarse" option. Then scroll through the table and find something close to 1.250*1000=1250mA and Vf is the min voltage needed to power the light at that current. Good Luck