DiY LED - Cree CXA3070

hayrolld said:

That driver is not a good choice for what you want to do. Watts=amps X volts. To figure volts needed in a driver, find the cob's voltage forward and multiply by how many cobs you want to use. For cxa3070, Vf is 38.5volts for one, or 77volts for two. The driver you linked maxs out at 36volts, so not a good choice. If you want 25-45% of 3000ma, get a Meanwell hlg-120h-c1400 that is dimmable. It will cover the power range you want, and you can run up to three cxa3070s with it. Price should be close to what you were looking at. Please find and read the sticky thread on DIY LEDs - How to Power Them, this is all explained there and a better place for questions like this. It will help you figure out how to power and wire everything for your build.

Mod- not sure if its possible, but could my response and the previous post be moved to the DIY how to power thread please?

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@hayrolld the meanwell HLG-120H-C1400 will not run three CXA3070'S at 1.4A from my understanding but will in fact run 3 CXB'S cause of the lower Vf of the CXB'S. Driver has CC region of 54v-108v as per @SupraSPL spreadsheet CXA3070 @ 1.4A has a vf50 of 37.3V which would put you over the 108v of the driver.

Supra do you have thermal modeling? From my reading the further out you get the less cooling being done. So I figure my long skinny profile is less effective than short wider more square piece.

You are correct a long skinny heatsink with the heat load at the ends will have a higher thermal gradient than a short wider heatsink. Another way to look at it, the heatsink is not being used as efficiently as it could be. But with that said, because white COBs are essentially blue dies, the difference in COB output due to a slightly higher Tj might be less than 1%. The benefits of the long skinny heatsink are improved uniformity/spread and more convenient to use versus separate CPU coolers. Also, it makes very efficient use of fan power and provide a strong functional structure to mount components.

I have not done any thermal modeling with software although I can see the value in that, I prefer to experiment with heatsink profiles in situ. One example where this comes int play, a pair of CXA3590s mounted on a 3.5"X36" profile with 80mm fan in the center. The CXAs are dissipating 80W ea, 39W of which is heat. They are mounted 6" from the edges so the heat load is very uneven. There is a noticeable thermal gradient you can feel by hand the ends of the heasink are warmer, although only 95F (35C). Temp droop measured 3.6%. So I could either increase fan speed, move the COBs closer to the center, or use a wider heatsink profile. But all I stand to gain is about 1% temp droop and probably less than that. I believe that the uniformity in spread is actually more beneficial in this case.

Worth mentioning, the 3.5" profile has a thick base (.3" or 7.62mm). Long skinny heatsink with a thinner base likely not to perform as well with uneven heat loads.

These 4 lamps are designed to cover 5 sq meters as evenly as possible (vegging at 270 PPFD)

SupraSPL said:

, it makes very efficient use of fan power

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I'm finding the air flow down a long skinny heatsink to be a huge advantage. I have been playing with the thin base 4.85" profile and 5 vero18s. a couple of 120mm fans on a 40" long heatsink, instead of 1 fan per cob does the job efficiently and also provides redundancy.

I'll be trying something similar soon with some cxb3070s on a 4' long setup.

SupraSPL said:

These 4 lamps are designed to cover 5 sq meters as evenly as possible (vegging at 270 PPFD)

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What size and angle lens are those. I was thinking of trying the 100mm lens from KB
Your APV-12-12 test data matches closely with apc-12-350

Greengenes707 said:

Nice. Even at full current load it's almost the same figures...just tested apv12-12 vs 16-12 and got near identical characteristics wile running (6) .18a@12v fans.
Lower apparent power from the 16 actually.

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Thanks for the info. I guess fixed losses of bigger power supplies are higher. I wonder if APV-8-12 will be even more efficient than 12-12.

I use the 50mm wide 90 degree lenses. No special reason for using those lenses other than suitable width and low cost. The width of the beam pattern depends on the distance from the LES to the lens. If you increase the distance, the beam gets tighter but more light escapes out the side.

Thanks supra, I have the 2+" profile I think but only on the small veros I have. The arctic coolers on the 3070.

One of the two drivers I got from you crapped out. I plugged the second driver into the cob and it worked. So quick questions.

How many watts on the 3070 should that arctic cooler be able to handle? I forget which, was the recommended one at the time. I'll buy two drivers and crank them up to full wattage if I can.

What coverage should I get at said wattage for one cob? For two cobs? I'm not looking to produce but I want to pop some seeds and let the pollinate before they lose any more viability. I'm not sure these strains are still around as they were a gift from a personal breeder.

Thanks

Sry to hear that, will address it. The Arctic can handle at least 100W of dissipation reasonably well. With the pair of COBs at 50W ea, you could cover a 1.5X2' with good flowering intensity.

SupraSPL said:

Sry to hear that, will address it. The Arctic can handle at least 100W of dissipation reasonably well. With the pair of COBs at 50W ea, you could cover a 1.5X2' with good flowering intensity.

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What distance and with or without lenses or reflectors are you thinking in that scenario Supra?

At that power I do believe lenses would be beneficial. The distance to canopy would depend on which lenses used and how they were mounted. I will try to approximate it but in practice I constantly adjust the distance to canopy as needed. In other words I eyeball it rather than measure it because my canopy is very...dynamic. That is a nice advantage of lenses they give a sharp cutoff so you can adjust it by eye.

Thanks. I'm less worried about efficiency at this point.

I think I'm trying to cover 2x4 with only 4ft total height.

I'm looking to do a lot of small plants just to seed out. I have multiple strains to run through to keep the seeds viable.

I assume ozone will kill pollen between runs, I'm just wondering how much it would need and how it'd effect the panda film.

I'm not wanting you to replace it but I may buy another one off of you or go up to 100 watts. I don't have any lenses either.

SupraSPL said:

At that power I do believe lenses would be beneficial. The distance to canopy would depend on which lenses used and how they were mounted. I will try to approximate it but in practice I constantly adjust the distance to canopy as needed. In other words I eyeball it rather than measure it because my canopy is very...dynamic. That is a nice advantage of lenses they give a sharp cutoff so you can adjust it by eye.

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I have had pretty good luck using trig to predict the footprint from a lens. It's only approximate though, since the foot print will vary depending on the size of the LES and it's distance from the lens.

I have a friend wanting my two 3070's to grow two small to medium bushes since I'm not using them at the moment. I asked for a footprint but he just kept saying two plants. Sigh.

I may sell them to him for the price of the newer cobs and upgrade my personal set if there's that much difference. But I'm not sure the two at 50w will be enough or if they should be stepped up to 100w each

Voidling said:

I have a friend[...]
I may sell them to him for the price of the newer cobs[...]

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Doesnt sound very friendly to me. Or am I missing something here?

Voidling said:

I have a friend wanting my two 3070's to grow two small to medium bushes since I'm not using them at the moment. I asked for a footprint but he just kept saying two plants. Sigh.

I may sell them to him for the price of the newer cobs and upgrade my personal set if there's that much difference. But I'm not sure the two at 50w will be enough or if they should be stepped up to 100w each

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Earning something for your labor is OK, I am flowering two pplants under two cxa3070, it will work but it is a small grow

I just got my worst yield in my life. Now I am not sure if it is because I am still learning (aka I suck) or if their is something wrong with my light. It was my first run on LED lights.

I have 4 cxb3070 3000k cobs being run by a maxwell 1400. It pulls about 220 watts when all going. Could I have screwed up somewhere with my lights ...... or does that sound normal and it is my grow skill?

Here we have a mainlined plant .. 8 weeks veg ... a whopping 10 grams (after 8 weeks of flower) I had my light mainly 16 inches from the top.

tick tack toe said:

I just got my worst yield in my life. Now I am not sure if it is because I am still learning (aka I suck) or if their is something wrong with my light. It was my first run on LED lights.

I have 4 cxb3070 3000k cobs being run by a maxwell 1400. It pulls about 220 watts when all going. Could I have screwed up somewhere with my lights ...... or does that sound normal and it is my grow skill?

Here we have a mainlined plant .. 8 weeks veg ... a whopping 10 grams (after 8 weeks of flower) I had my light mainly 16 inches from the top.
View attachment 3497799 View attachment 3497801 View attachment 3497802 View attachment 3497803

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Did you give them any cal/mag what was your ph? To much nitrogen makes the harvest poor also.

@tick tack toe If you confirmed the 220w @ the wall with a Kill-a-watt, and there is not a short with the driver's dimming wires, I would assume the light is working correctly.

Based on your pictures, I can confidently say that salt build up from the nutrient solution led to a nutrient lock out scenario at some point in the plant's life. You mentioned that you are still learning, so if I may suggest the next time around, try coco as your medium. A regimen of nutes, nutes, fresh water, repeat works well for me to avoid salt build up.


Or alternatively, if you want to stick with your current method, top feed 3-5 gallons of fresh water once per week to flush all the salt build up out of the media and keep it from collecting at the top of the hydroton(as pictured above)

that poor plant it looks so sad and sickly,, i wouldnt blame the lights, growing is a huge learning curve, one I amn still learning myself

tick tack toe said:

I just got my worst yield in my life. Now I am not sure if it is because I am still learning (aka I suck) or if their is something wrong with my light. It was my first run on LED lights.

I have 4 cxb3070 3000k cobs being run by a maxwell 1400. It pulls about 220 watts when all going. Could I have screwed up somewhere with my lights ...... or does that sound normal and it is my grow skill?

Here we have a mainlined plant .. 8 weeks veg ... a whopping 10 grams (after 8 weeks of flower) I had my light mainly 16 inches from the top.
View attachment 3497799 View attachment 3497801 View attachment 3497802 View attachment 3497803

Click to expand...

I am using coco but I think I over watered during veg so it didn't create a good root ball .... therefore I think I might have over watered coco. I do have very crappy water that has an ec of 0.7 (of that 87mg/l is calcium and 13mg/l is magnesium). Ever since coming here I have had issue just into flowering ..... veg, no worries.
here is my next throw of the dice. 16 days old - blue dream and trainwreck



How know or see if there is a short in the dimming wires?