COB efficiency Spreadsheets

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todd86

Active Member
ok so ive just ordered all the parts to make this:

8 x CREE CXB3590 3500K, CD 72V
2 x Meanwell HLG-185-C700B
8 x Heat Sinks(these can be used with out a fan)
8x Ideal COB holders
2 x 100k Pedometers (dimmers)
10m of Wire (to hook everything up)
1 x ABS Box(to house the dimmers)
plus grommets etc to finish the job properly.

8 x MF20 x 151.1 from conrad

http://www.conradheatsinks.com/products/flat100_350.html

oh and https://kingbriteled.en.alibaba.com/product/60259719620-801574224/CREE_CXB3590_3500K_CD_CXB3590_0000_000R0HCD35G.html

8 x reflectors too

will this setup cover a 4x4 1.2 meter x 1.2 meter tent.

please tell me it will, fingers crossed.
 
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BOBBY_G

BOBBY_G

Well-Known Member
that will be about 13 PAR W/SF, or about 550-600 ppfd.

should be fine but prob a little on the light side

why 72V cobs?
 
ttystikk

ttystikk

Well-Known Member
todd86 said:
ok so ive just ordered all the parts to make this:

8 x CREE CXB3590 3500K, CD 72V
2 x Meanwell HLG-185-C700B
8 x Heat Sinks(these can be used with out a fan)
8x Ideal COB holders
2 x 100k Pedometers (dimmers)
10m of Wire (to hook everything up)
1 x ABS Box(to house the dimmers)
plus grommets etc to finish the job properly.

8 x MF20 x 151.1 from conrad

http://www.conradheatsinks.com/products/flat100_350.html

oh and https://kingbriteled.en.alibaba.com/product/60259719620-801574224/CREE_CXB3590_3500K_CD_CXB3590_0000_000R0HCD35G.html

8 x reflectors too

will this setup cover a 4x4 1.2 meter x 1.2 meter tent.

please tell me it will, fingers crossed.
Click to expand...
That setup will do well in a 4x4. Some might tell you that you still need more light, I'd say run a few crops first and then let them tell you if you need more light.
 
T

todd86

Active Member
BOBBY_G said:
that will be about 13 PAR W/SF, or about 550-600 ppfd.

should be fine but prob a little on the light side

why 72V cobs?
Click to expand...
The driver version is dimmable dims 100-50%, so the 700mA driver goes from 350-700mA.
This means if you have a 36V cob setup, they will work on 12,5-25W each.
If you have 72V cobs, they will work on 25-50W each with this driver.

less than 25W for cob is not enough for good penetretion(intensity) thus 72v better choice
 
BOBBY_G

BOBBY_G

Well-Known Member
B drivers dim to 10%. 70-700 mA in your case

the C-1400B driver would go 140-140mA, which with 36V cobs is exactly the same wattage range (20-200W total) as the C-700B w/72V cobs.

just to make sure you understand that a C700B with 72V cobs will operate exactly the same as a C1400B w/36V cobs, there is no advantage to either setup

the only advantage im aware of with a 72V cob is being able to push cobs harder with a constant current driver, for example with your 185 series the current tops out at 1400. which puts you shit out of luck if you want to run cobs above ~50W each. so you get a 72V cob and run it at 1400 mA and now youre at ~100W per cob.

this is becoming less of an issue now that there are HLG-320HC series which runs up to 3500 mA and pretty much maxes out a cxb3590
 
T

todd86

Active Member
BOBBY_G said:
its actually ideal as they are a lot more efficient below 25W, but cost goes way up as now you need a shitload more of them
Click to expand...
Interesting stuff, real reason i brought the 72v package with everything in it was I purchased from someone who no longer had a suitable place to grow, 72v was effectively their choice not mine.
 
ttystikk

ttystikk

Well-Known Member
BOBBY_G said:
its all good, as i said it will work the same with a 700mA driver. running 3590s at 36V/1400 ma (i.e. 72V/700 mA) is a popular setup and im sure it will work well for you!
Click to expand...
My chips are 72V and I'm running them on a Meanwell 185H - C700B driver.

By your calculations above, I'm hitting my plants with nearly 1000PPfD. When I started the build, I was under the impression it was good for 824 PPfD.
 
BOBBY_G

BOBBY_G

Well-Known Member
depends on space size

par W = totalW x efficiency

ppf =~ parW*45

ppfd = ppf/SF of area

i think... something like that off the top of my head. thats extrapolated from supras calcs but i think it might vary for different K temps
 
ttystikk

ttystikk

Well-Known Member
BOBBY_G said:
depends on space size

par W = totalW x efficiency

ppf =~ parW*45

ppfd = ppf/SF of area

i think... something like that off the top of my head. thats extrapolated from supras calcs but i think it might vary for different K temps
Click to expand...
That's giving me around 1000 PPfD. Anyway, it's bright.
 
wietefras

wietefras

Well-Known Member
Multiplying PAR W by 45 can't be right. I think SupraSPL uses a constant between 4.47 (5000K) and 4.66 (3000K) depending on colortemperature.

I keep seeing these calculations with PAR W and such for getting the umol/s values. Instead of going through all these calculations for efficiency and PAR W which are all depending on constants and then multiplying by some other constant, why not divide by a single constant?

If we take all the individual steps we get:
Efficiency=(lumen/W) / 325
par W = Total W * Efficiency
umol/s = PAR W * 4.66

To calculate umol/s in one formula we get:
umol/s = (Total W * (lumen/W / 325)) * 4.66

Which simplifies to:
umol/s = lumen / (325/4.66) = lumen / 70

or for 5000K to:
umol/s = lumen / (325/4.47) = lumen / 73


I took a list of umol figures that SupraSPL posted:
Cree CXA3070 3K AB @ 52W = 2.11 umol/s/ dissipation W
Cree CXA3070 3K AB @ 25W = 2.46 umol/s/ dissipation W
Cree CXB2530 3K U2 @ 18W = 2.4 umol/s/ dissipation W
Cree CXB3070 3K AD @ 50W = 2.34 umol/s/ dissipation W
Cree CXB3070 3K AD @ 24W = 2.7 umol/s/ dissipation W
Cree CXB3590 3K CB @ 49W = 2.52 umol/s/ dissipation W
Cree CXB3590 3K CB @ 23W = 2.86 umol/s/ dissipation W
Cree CXA3590 5K DB @ 24W = 2.96 umol/s/ dissipation W

Looked up the lumen for those and arrived at a conversion factor of around 65. so i use:
umol/s = lumen / 65

The luminous flux values that Cree reports have a 7% tolerance, so it's not like it's all very exact anyway.
 
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