how many led/watt for my grow room

G

greenfrank

Member
Hi, I have a DIY grow room 3,94 x 5,25 h.6,56.

I have read several posts here but I haven't really understoood how many watt I need to my grow space and how calculate that. I know that I need 850-1100 ppfd for.

At the moment I use a 600w Hps with good results (0,7 gr/w) in cocco but I want improve them.

My idea is to buy 2 MW HLG-240H-C1400 and 10 cxb3590 cd bin 36v.

Some questions:
1. How to calculate ppf and ppfd
2. How to calculate the efficency
3. Why on http://pct.cree.com/dt/index.html there is no data for cxb3590 cd bin 36v under 1400ma ?

upload_2016-10-11_21-40-50.png


Thanks in advance
 
coreywebster

coreywebster

Well-Known Member
Hello greenfrank.

I cant tell you how the efficiency calculations are done on paper I'm afraid, I would love to know though. But I can guide you to the DIY cob calc thread which will do the math for you.
https://www.rollitup.org/t/diy-cob-led-calculator.890214/page-11#post-13022704
Download the top link in bggrass sig from any of his posts.

the info it gives will look something like this.

CXB3590CD36V3500K 10 COBS @1.4A ON 1.813 PROFILE HEATSINK
20 SQ.FT. CANOPY 92.5% EFFICIENT DRIVER @11 CENTS PER KWH
Total power watts at the wall: 527.57
Cobs power watts: 488
Total voltage forward: 349
Total lumens: 89080
Total PAR watts assuming 10% loss: 247
Total PPF: 1148.55
PPFD based on canopy area: 618.14
PAR watts per sq.ft.: 12.35
Cob efficiency: 56.34%
Power watts per sq.ft.: 24.4
Voltage forward per cob: 34.89
Lumens per watt: 182.54
Heatsink riser thickness / number of fins / fin's length: 0.3in/6/0.95in
Heatsink area per inch: 100.94 cm^2
Total heat watts: 213
umol/s/W / CRI: 4.65 / Estimated
Heatsink length passive cooling @120cm^2/heatwatt: 253 inches
Heatsink length active cooling @40cm^2/heatwatt: 84 inches
COB cost dollar per PAR watt: $1.93
Electric cost @12/12 in 30 days: $21.39
Electric cost @18/6 in 30 days: $31.84
Cost per cob: $47.62
Heatsink cost per inch cut: $0.66
Total cobs cost: $476
Total heatsink passive cooling cost: $167
Total heatsink active cooling cost: $55

Your not hitting your ideal suggested target ppfd but you are beating a 600w hps. Which in a 1.2m square tent is about 690, your area is not a 1.2m square but if it were your ppfd with the set up you suggested would be 772, beating a 600w hps no matter what your square footage
 
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G

greenfrank

Member
Thank you @coreywebster for the fast answer, that's a great tool !!!

I recalculate it in meter (I'm in europe) and the ppfd are too low:

CXB3590CD36V3500K 10 COBS @1.4A ON 1.813 PROFILE HEATSINK ************ 2 mw 240 @1400ma
1.92 SQ.M. CANOPY 94% EFFICIENT DRIVER @19 CENTS PER KWH
Total power watts at the wall: 519.15
Cobs power watts: 488
Total voltage forward: 349
Total lumens: 89080
Total PAR watts assuming 10% loss: 247
Total PPF: 1148.55
PPFD based on canopy area: 598.2
PAR watts per sq.m.: 128.65
Cob efficiency: 56.34%

Now my choise are:
- add one more driver and 5 cobs (PPFD 900.94) with same efficiency
- use 2 mw 320h @1750 with 10 cob (PPFD 714.45) that are less efficient

If I understood correctly using as driver the mw320@1400 with 6 cobs is not good because the cobs use only 209v of the max 229v and this is not good in terms of efficiency right?
 
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MeGaKiLlErMaN

MeGaKiLlErMaN

Well-Known Member
greenfrank said:
Thank you @coreywebster for the fast answer, that's a great tool !!!

I recalculate it in meter (I'm in europe) and the ppfd are too low:

CXB3590CD36V3500K 10 COBS @1.4A ON 1.813 PROFILE HEATSINK ************ 2 mw 240 @1400ma
1.92 SQ.M. CANOPY 94% EFFICIENT DRIVER @19 CENTS PER KWH
Total power watts at the wall: 519.15
Cobs power watts: 488
Total voltage forward: 349
Total lumens: 89080
Total PAR watts assuming 10% loss: 247
Total PPF: 1148.55
PPFD based on canopy area: 598.2
PAR watts per sq.m.: 128.65
Cob efficiency: 56.34%

Now my choise are:
- add one more driver and 5 cobs (PPFD 900.94) with same efficiency
- use 2 mw 320h @1750 with 10 cob (PPFD 714.45) that are less efficient

If I understood correctly using as driver the mw320@1400 with 6 cobs is not good because the cobs use only 209v of the max 229v and this is not good in terms of efficiency right?
Click to expand...

I would suggest 5000ks and red supplementation. @The Dawg made me a believer in the formula. Plus the massive amount of efficiency you get from less coating. Check that on the calculator to see if you like the results.
 
HydoDan

HydoDan

Well-Known Member
greenfrank said:
Thank you @coreywebster for the fast answer, that's a great tool !!!

I recalculate it in meter (I'm in europe) and the ppfd are too low:

CXB3590CD36V3500K 10 COBS @1.4A ON 1.813 PROFILE HEATSINK ************ 2 mw 240 @1400ma
1.92 SQ.M. CANOPY 94% EFFICIENT DRIVER @19 CENTS PER KWH
Total power watts at the wall: 519.15
Cobs power watts: 488
Total voltage forward: 349
Total lumens: 89080
Total PAR watts assuming 10% loss: 247
Total PPF: 1148.55
PPFD based on canopy area: 598.2
PAR watts per sq.m.: 128.65
Cob efficiency: 56.34%

Now my choise are:
- add one more driver and 5 cobs (PPFD 900.94) with same efficiency
- use 2 mw 320h @1750 with 10 cob (PPFD 714.45) that are less efficient

If I understood correctly using as driver the mw320@1400 with 6 cobs is not good because the cobs use only 209v of the max 229v and this is not good in terms of efficiency right?
Click to expand...
I am running 6 cobs with a 320@1400 works just fine... 56.4% efficiency..
 
The Dawg

The Dawg

Well-Known Member
MeGaKiLlErMaN said:
I would suggest 5000ks and red supplementation. @The Dawg made me a believer in the formula. Plus the massive amount of efficiency you get from less coating. Check that on the calculator to see if you like the results.
Click to expand...
Brother I'm An Old School Mh Grower From The 70's So Naturally I Like The Higher Kelvin Rated Cobs. You Can Use Them For Veg And Flower Easier Than The Lower Rated Kelvin :hump:

Oh Btw My Favorite Platform Is The 36v Vero29 Matched With The 320-2100 :clap:
 
SaltyNuts

SaltyNuts

Well-Known Member
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