Want to build 9 cob led for 4x4 sqft area

P

PotHead3

Well-Known Member
Everyone says Cob leds kill hps and what not. What im trying to figure out is How many watts should i run a 9 cxb3590 3500k cob led setup to equal the the same yield and quality of a 1000 watt hps light in a 4x4 area?

My future goal is to build 4 sets of 9 cxb3590 to fill a 8x8 area.
Im basically trying to get a baseline knowledge so i can gauge how much im actually saving.

what many people say is they get much higher grams per watt. but yield is mostly due to sqft area when using 1000 watt hps.
example is in a 4x4 area i yield 2lbs with 1000 watts for strain A which is aproximately .9 grams per watt
so if i change over to use cxb 3590 cobs and want the same 2lbs in the 4x4 area how many watts should i run my cobs at?

if lets say i run 500watts as someone on this forum says they do that will equal about 1.8 grams per watt.
what most people lack in information is do they get that 1.8 grams per watt in the same space?

Thanks

currently im actually deciding if i want to go the cob route or the 1000w gavita as they can cover a 4x6 area meaning increase yield. but then i will be building a 8x12 room instead of a 8x8 so theoretically i should get about 3lbs with gavita since coverage area is bigger.

i am doing a sealed room and using co2 fyi
 
C

churchhaze

Well-Known Member
A 1000W HPS lamp has ~38% radiant efficiency and ~34% PAR efficiency, so you'd be replacing ~340W of PAR.

As an approximate, if you had something with 50% PAR efficiency, you would need 340W/0.50 = 680W of dissipation.

If you had something with 40% PAR efficiency, you'd need 340W/0.40 = 850W of dissipation.
 
Rahz

Rahz

Well-Known Member
3 HLG-240H-C2100 drivers, 3 cxb3590 each, 675 watts total output. If you want to expand add 3 more cobs, still under 1000w.
 
wietefras

wietefras

Well-Known Member
It's not just the PAR watts that you are replacing. An HPS bulb has a lot of reflector losses. Around 15% of the light already gets converted to heat on the reflector and then a further 10% is lost on the walls. For COBs you only lose around 5% on the walls and 6% on the reflectors (if you add those).

If you want to see the PPFD that a Gavita 1000W gives on the plants then you better use a set of measurements that was taken in an actual grow tent rather than a set of measurements taken in an open room. HPS needs either overlapping light from multiple fixtures or properly reflecting walls.

Gavita designed a tent to best fit their light and they come out at an average PPFD of 800umol/s/m2 over 2m2 (so around 1600umol/s PPF)
Gavita 1000W in Mammoth G1 PPFD matrix.jpg

You can either go for 1600umol/s for 1000W HPS and add 5% to cover for the wall losses and add 6% if you must have reflectors on your COBs. Or use an average PPFD of 800umol/s/m2 as the light intensity and multiply that with the surface area (and again correct for losses).

Then divide the amount of light that you need by the amount of umol/s a COB emits. Which is about 150umol/s for a CXB3590 CD at 1750mA or 170umol/s when it's driven at 2100mA.

If you want 1.8g/W you will need to run at a low wattage to get high efficiency. That means you will need to buy a lot more COBs than the 9 you are thinking about. You'd need 13 of them at 1050mA or even more at 700mA.

For something more reasonable like 1.4g/W to 1.5g/W you could use 9 CXB3590 CD bin 36V at 1750mA. That would be 62W a piece for a total of around 550W, 1350umol/s (total light) and 900umol/s/m2 over a 4x4 area. Or accept a slightly lower g/W yet get more harvest from those 9 COBs and use the 2100mA drivers that Rahz mentioned.
 
BM9AGS

BM9AGS

Well-Known Member
wietefras said:
It's not just the PAR watts that you are replacing. An HPS bulb has a lot of reflector losses. Around 15% of the light already gets converted to heat on the reflector and then a further 10% is lost on the walls. For COBs you only lose around 5% on the walls and 6% on the reflectors (if you add those).

If you want to see the PPFD that a Gavita 1000W gives on the plants then you better use a set of measurements that was taken in an actual grow tent rather than a set of measurements taken in an open room. HPS needs either overlapping light from multiple fixtures or properly reflecting walls.

Gavita designed a tent to best fit their light and they come out at an average PPFD of 800umol/s/m2 over 2m2 (so around 1600umol/s PPF)
View attachment 3733055

You can either go for 1600umol/s for 1000W HPS and add 5% to cover for the wall losses and add 6% if you must have reflectors on your COBs. Or use an average PPFD of 800umol/s/m2 as the light intensity and multiply that with the surface area (and again correct for losses).

Then divide the amount of light that you need by the amount of umol/s a COB emits. Which is about 150umol/s for a CXB3590 CD at 1750mA or 170umol/s when it's driven at 2100mA.

If you want 1.8g/W you will need to run at a low wattage to get high efficiency. That means you will need to buy a lot more COBs than the 9 you are thinking about. You'd need 13 of them at 1050mA or even more at 700mA.

For something more reasonable like 1.4g/W to 1.5g/W you could use 9 CXB3590 CD bin 36V at 1750mA. That would be 62W a piece for a total of around 550W, 1350umol/s (total light) and 900umol/s/m2 over a 4x4 area. Or accept a slightly lower g/W yet get more harvest from those 9 COBs and use the 2100mA drivers that Rahz mentioned.
Click to expand...
Thanks for that! Do you know if that tent and reflector are in production? Much better data for me. Cxb still beats it. Interesting to see the tents performance...6'... That's legit.
 
wietefras

wietefras

Well-Known Member
Yeah nice huh? Gavita basically did a flat plane integration of their light in a grow tent. Which is exactly what we need.

Not my find though. I copied it from someone elses post over here (forgot who, sorry)

They do sell those tents and reflectors. Look for G1 Mammoth. Or G2 if you want to use two lights.

Of course COBs beat them by a large margin. HPS after losses is only 1.6umol/s/W. While the COBs will come out at 2.3umol/s/W at moderately priced loads or well over 2.5umol/s/W if you go low wattage.
 
BM9AGS

BM9AGS

Well-Known Member
wietefras said:
Yeah nice huh? Gavita basically did a flat plane integration of their light in a grow tent. Which is exactly what we need.

Not my find though. I copied it from someone elses post over here (forgot who, sorry)

They do sell those tents and reflectors. Look for G1 Mammoth. Or G2 if you want to use two lights.

Of course COBs beat them by a large margin. HPS after losses is only 1.6umol/s/W. While the COBs will come out at 2.3umol/s/W at moderately priced loads or well over 2.5umol/s/W if you go low wattage.
Click to expand...
Couldn't find hrt reflector used in example. Also, my data was taken from open wall measurements.
 
wietefras

wietefras

Well-Known Member
Yeah those open wall measurements are killing for HPS fixtures. Leds usually have much smaller beam angles and therefore are less penalized in measurements without reflective walls.

A 1000W HPS bulb is usually placed around 36 to 40" above the plants (or at least I did). Without walls and at that height, only about 40% of the HPS light actually falls on the 4x4ft square.
 
weed-whacker

weed-whacker

Well-Known Member
Rahz said:
3 HLG-240H-C2100 drivers, 3 cxb3590 each, 675 watts total output. If you want to expand add 3 more cobs, still under 1000w.
Click to expand...
if u must use 9 cxb cobs then this is what you should do, 816ppfd average

if you go with the 1750mA you would be @ 730ppfd, well below what a gravity DE

if u haven't already bought the cobs it seems there are a few which would serve ur purpose better. the CXB is really for high efficiency and low heat builds.
 
Victor6634

Victor6634

Well-Known Member
I saw the gavita and the special tent on growershouse the tent is made by mamouth.
Details
Designed by Mammoth and Gavita, especially for use with the new Gavita M Small Room Replacement Reflectors. The result of combining Mammoth Grow Tents and Gavita M Reflectors: ULTIMATE 1 and 2 light grow room with Maximized light uniformity made just for Gavitas Double Ended Light technology.

  • Deep Penetration of Light - Mammoth Elite reflective walls and tent shape maximize light in all directions
  • FootPrint - tent matches the Gavita Light footprint
  • More Ports! - Port on front allows access to Gavita Master Controller
  • Never Overheat - at almost 8 feet tall this tent keeps its cool
  • 100% Waterproof Flooring - built in water tray
  • Heavy duty frame with 22 mm steel poles
  • Rugged, light proof canvas exterior and reflective mylar interior


Benefits of Mammoth Tents
Mammoth Tents has the widest range of grow tent sizes on the market, with 75 different sizes. TheMammoth Tent Elite Modular System can also link multiple tents together in both length and width. Mammoth Tents are the only tents with an Class A rating for official flammability properties tests.

Specifications
Dimensions: 43 in x 70.86 in x 94.48 in (110cm x 180cm x 240cm) 3.6 ft x 5.9 ft x 7.88 ft
Surface: 4,26m2
Material thickness and coating: 600D
Mylar reflectance: 95%
Light density: Level 2
Number of front doors: 2
Number of Rear Doors: 0
Number of doors sideways: 0
Cable openings: 6 x 7.6cm
Floor Tray: integrated, two-ply, waterproof
Side windows: 3
Air intake: 2 x 275mm
Air outlet: 2 x 275mm
Frame Poles: 22mm diameter, 0,7mm thickness / steel
Corners: PA66
Accessories: 5 x carabiner 6 x S-Hook 2 x Straps
 
You must log in or register to reply here.
Top