DiY LED - Cree CXA3070

stardustsailor

stardustsailor

Well-Known Member
happy75 said:
I don't get it.



Thanks for the calculations, its clear to me now. 40 leds equals 4 600w HPS. But for the electrical bill...300 watts savings is not much and the fans need to be driven also. So maybe 200 watt savings, that is not much. But the profit must come from a larger grow.
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1) Do not worry .It's more like a weird-stupid-occult-mystic-supernatural-foolish law ,of my electronics "Codex" ...
Anyway ....
My dad ,since I was a child,has been always telling me this one ..
"Never go over 70% " ..
Regarding mainly ,the HI-FI's amplifier sound volume ..:P

(later ,I've discovered ,that this "rule" applies in many aspects of life ..
Never go over the 70% of your daily drinking,eating,fucking,working,sleeping,swimming,reading ,etc capabilities ... )

I apply the 0.707 (√2 / 2 ) / RMS rule to plenty of aspects ..

Including the max driving figure of the CXAs !!!! ( Weird !!!!Crippy!!!! )

CXA can be driven up to 2.8 A ...
Well ,ok ...My standard's max is 0.707 * 2.8=2 A and not the rated 2.8 of the manufacturer ...


2 ) Well ...You might not have such a difference in direct W comparison ,but the actual kWh consumption will be less with
CXA's (dimmed during Veg,Less exaust fan power/energy spent at summer ,even less at winter time .. )

And ...The real differences will be in quantity and quality of harvested herb ...
You'll see with your own eyes ..

Don't worry ,about that ,either ...(:

Cheers.
:peace:
 
SupraSPL

SupraSPL

Well-Known Member
SDS, does that calculation take into account the reflector and glass losses of the HPS? I have been of the mind that 40 CXA3070 ABs @ 1.4A (2080W) = 4000W HPS in terms of yield. My 137lm/W figure was based on a Tj of 50C, which may be a little optimistic for 1.4A but I am not certain. Would that Tj be possible with an ambient temp of 23C? Those 92mm CPU coolers are amazing, heatsink is only a few degrees above ambient.
 
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churchhaze

Well-Known Member
If I had 40 CXA3070 ABs, I'd run them at ~500-800mA.

Like happy mentioned, the larger your scale, the more efficiency matters.

SupraSPL said:
SDS, does that calculation take into account the reflector and glass losses of the HPS? I have been of the mind that 40 CXA3070 ABs @ 1.4A (2080W) = 4000W HPS in terms of yield. My 137lm/W figure was based on a Tj of 50C, which may be a little optimistic for 1.4A but I am not certain. Would that Tj be possible with an ambient temp of 23C? Those 92mm CPU coolers are amazing, heatsink is only a few degrees above ambient.
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A

anomuumi

Member
Reflector losses, penalty from non-uniform irradiance, penalty from a small point source light source leading to less diffusion(?) etc. It's not only the raw theoretical numbers that dictate the difference between HPS and LED imo :) ..in a very optimised setup where photons are taken up optimally by the plant, 1gram/1PPF is possible, that means 1g/w with fluorescent tubes!
 
SupraSPL

SupraSPL

Well-Known Member
I just set up small test. A CXA3070 Z2 (ceramic plate is actually cracked all the way across and it still works) running at 1.4A on an 80mm CPU cooler (Arctic) The fan is running at 12V. Ambient temp is 73F (23C). It has been running for about 30 minutes. Heatsink fins 28-29C. Tc is 33C. When I switch the power off and immediately measure the COB surface it is 51C.

Not sure how this data will really relate to Tj but i suspect that a Tj of 50C may possible in the next test, an AB on a 92mm CPU cooler.
 
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SupraSPL

SupraSPL

Well-Known Member
churchhaze said:
Those are from heatsinkusa.com right?Which profile/cross section sink is that? I was looking at the 4.850" wide one (cheap) and was thinking to put 4 on each, running at 1A. That would allow 120mm fan(s) too.
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Those are the 5.88" X 24" long. It gives 6240cm² each so that is about 30cm²/dissipation W. So in your case you would need 4560cm² which is about 23" of the 4.85" profile.

One thing to consider though, the 4.85" profile has a base plate that is only half as thick as the 5.88" profile, so that is why I decided against those for COB purposes. The thick base plate helps spread the heat along the length of the heatsink to all the fins faster which is important since the COBs are spaced relatively far apart and each is like a hot spot. So the thick plate decreases the temperature gradient which is exactly what we are after. The 4.85" might be a good option for vegging though because smaller LEDs are normally used and the heat doesnt need to be moved as far.
 
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SupraSPL

SupraSPL

Well-Known Member
CannaBare said:
Can I ask how you make your heatsinks so level? I started with that and had the trouble of misaimed lights
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In the case of the 5.886" profile, it is only important to get it flatter in the opposite direction of the fins, so you can focus your effort by running the sand paper in that direction. Do you have pics of the uneven lights? If they are on a very flat surface but pointing slightly different directions that might actually be a good thing for the canopy.
 
Rrog

Rrog

Well-Known Member
I'm about to start on some major panel construction for my new grow rooms. I last made a 10 x 24" panel. Works great. I had thought at the time that smaller panels in an array would be better. These strips are great.

I like the small panel / strip idea because you can place a panel where you want rather than horizontal or vert. The remaining issue is how to mount these... Some sort of clamp on arm on a pole(s), maybe.

I'm looking at all LED for veg and flower, so I also have to re-investigate what the current LED selection is these days... I've been out of this for over a year now.
 
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CannaBare

Well-Known Member
SupraSPL said:
In the case of the 5.886" profile, it is only important to get it flatter in the opposite direction of the fins, so you can focus your effort by running the sand paper in that direction. Do you have pics of the uneven lights? If they are on a very flat surface but pointing slightly different directions that might actually be a good thing for the canopy.
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I'll try to get pictures for you soon. My second design was on a 14'' x 1.813" profile with a 10,000 RPM fan blowing through the fins. The only reason I changed back was because of the unevenness, and my first design was great. It was the holes, I could never get them perfect on all sides and I wanted it perfect. But it was noticeable.

My design now is the 1.813" x 1.813" profile with the same fan. I have 2 lights and fans per "module" and the Tj is around 52*C. My modules are two drivers and a fan driver sitting atop a peice of cut wood. The wood has two hooks that hold the two lights(adjustable) over the plants. Between 2 modules I have 1 repile light(expensive, I need four).

It worked out because I had 20 LEDs to work with. so now I have great sidelighting because those modules were also adjustable.

Canna
 
Rrog

Rrog

Well-Known Member
Thanks. I'm looking for some articulated arm array that would allow me to move and lock a panel(s) around a plant as it grows
 
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