minimum number of cobs per driver?

hey my final setup would be 9 cobs @ 700ma over a 3x3 so I want to buy the hlg-240h-c700b and 9 cxb3590s on it but I am going to do three separate bars. my question is can i buy the 240h and only 3 cxb3590s and run it @ 700ma each? and then later buy the other 2 bars and upgrade? or will it blow up?

ty friends

it will run but wont be as efficient as if you max it out. but it should work fine

not a big deal like mid 80s vs low 90s in efficiency on the driver for 30% vs 70-100% loading. look at the chart on the datasheet on pg 7

http://www.mouser.com/ds/2/260/HLG-240H-C-spec-806189.pdf

@BOBBY_G so when you mean efficient, it would still be @ 64% efficiency as for calculating ppfd? is driver efficiency important?

minimum number of cobs per driver?

test report from HLG-240H-C700 (google hlg-240h-c700 test report)

CONSTANT CURRENT REGION: 68V ~ 357V/230VAC

cxb 3590 need at 700ma around 33volt(32.85volt), so 3 cxb 3590 per driver should be ok at 230VAC






But if i look at the normal pdf from hlg-240h-c700, it looks different

CONSTANT CURRENT REGION: 178V ~ 357V


178Volt / 32.85Volt(cxb 3590 @700ma) = 5,418569254185693, i would say that you need minimum 6 cxb 3590 pere driver


I have to say that my knowledge is not the best, maybe some other froum members can check that for you too.

banke1 said:

hey my final setup would be 9 cobs @ 700ma over a 3x3 so I want to buy the hlg-240h-c700b and 9 cxb3590s on it but I am going to do three separate bars. my question is can i buy the 240h and only 3 cxb3590s and run it @ 700ma each? and then later buy the other 2 bars and upgrade? or will it blow up?

ty friends

Click to expand...

BOBBY_G said:

it will run but wont be as efficient as if you max it out. but it should work fine

not a big deal like mid 80s vs low 90s in efficiency on the driver for 30% vs 70-100% loading. look at the chart on the datasheet on pg 7

http://www.mouser.com/ds/2/260/HLG-240H-C-spec-806189.pdf

Click to expand...

I am assuming you're using the 36v version and keeping them all on that driver.
The hlg240h-c700 will not run with only 3 CXB's. It has a minimum voltage of 178v for the 700ma version. That means you need to put at least 6 CXB's on there to just hit the minimum. Going to be lower than 35v's per cob.

The hlg240h-c700 can run 6-10 36v version cxb's. Not more, not less.

banke1 said:

@BOBBY_G so when you mean efficient, it would still be @ 64% efficiency as for calculating ppfd? is driver efficiency important?

Click to expand...

When people say a diver won't be as efficient it's like this...

You cobs will be 64% efficient at that current, and you are using a driver that is ~94% efficient
Assuming passive and no other electronics...
The electrical efficiency can be looked at as (64 x .94)= 60.16% efficient
then you can count optics after that to really be accurate...~5-10%
(60.16 x .95)= ~57.15% total system efficiency.

@Greengenes707

well I do my math off one cob per sq ft and running 9 of them over a 3x3 on a single hlg-240h-c700b I get about 702 PPFD correct? is that calculating in the loss for the driver efficiency and optics?

dont ask me how but the way I do the math is .7 x 35 x .64 x 44.78 = 702

I also do one plant per sq foot for 9 plants in the tray.

So if I run 2/3rds of the tray (technically a 2x3 tray at this point) and only put in 6 plants and have 6 36v 3590s over it on a single hlg-240h-c700b, my ppfd would be less than 702 because of less driver efficiency?

banke1 said:

@Greengenes707

well I do my math off one cob per sq ft and running 9 of them over a 3x3 on a single hlg-240h-c700b I get about 702 PPFD correct? is that calculating in the loss for the driver efficiency and optics?

dont ask me how but the way I do the math is .7 x 35 x .64 x 44.78 = 702

I also do one plant per sq foot for 9 plants in the tray.

So if I run 2/3rds of the tray (technically a 2x3 tray at this point) and only put in 6 plants and have 6 36v 3590s over it on a single hlg-240h-c700b, my ppfd would be less than 702 because of less driver efficiency?

Click to expand...

The driver won't affect your PPFD, but optics will.
Ya, your math is not how I do it, to each their own.

The variables...
-3x3= 9 sqft or 83m^2
-700ma through a 3590 will push ~33v =~23w and be in the 64% range.
-9x23w=207w
The math...
-207w x .64= 132.48radiant watts
-Using the conversion factor of 4.7photons per radiant watt...(4.7 x 13.48 ) = 622.66µmols PPF
-Convert PPF to PPFD(in m2)...622.66 PPF ÷ .83m^2= 750.19µmols PPFD.
- Then tax that based on the optics...750.19 x .95 = 712µmols after optics

@Greengenes707

ok so my math ends up pretty close somehow... ill just say i tax'ed it a little more .... so am I correct in assuming that the reason the 700ma is pulling only ~33v is because of driver efficiency? (.94 x 35 = 32.9?)

so if driver efficiency goes down to lets say 85% with 6 cobs on it then the math would be something like....

.85*35*.7 = 20.825w x 6 = 124.95w x .64 = 79.968rw x 4.7ppw = 375.8496µmols PPF ÷ .557418m^2 = 674PPFD taxed to 640ppfd.

is this correct?

this makes me want to run 9x 1050s instead of 9x 700s over my tray.... lol...

banke1 said:

@Greengenes707

ok so my math ends up pretty close somehow... ill just say i tax'ed it a little more .... so am I correct in assuming that the reason the 700ma is pulling only ~33v is because of driver efficiency? (.94 x 35 = 32.9?)

so if driver efficiency goes down to lets say 85% with 6 cobs on it then the math would be something like....

.85*35*.7 = 20.825w x 6 = 124.95w x .64 = 79.968rw x 4.7ppw = 375.8496µmols PPF ÷ .557418m^2 = 674PPFD taxed to 640ppfd.

is this correct?

this makes me want to run 9x 1050s instead of 9x 700s over my tray.... lol...

Click to expand...

The driver efficiency has nothing to do with light output of the cob. All that matter for that is the current and forward voltage that the cob is experiencing.

Voltage is tied to current. The more current you put the through a cob, the higher the forward voltage/resistance will be. The lower the current the lower the voltage.
It's on page 9 of the data sheet for the 3590

Ya, 1a would be great. Could always turn it down.

@Greengenes707

ok so new thought...

google sacred geometry.... you will find 6 circles around 1 circle, all with equal diameter touching each other.
something like this....
...OO
..OOO
...OO


this is 7 total cobs. over 9 sq ft. @ 1050 ma on a single HLG-240H-C1050B
pls excuse the extra decimals...

3x3= 9 sqft or 0.836127m^2
-1050ma through a 3590 will push ~35.61936w and be in the 60.35737%range
-7x35.61936w=249.33552w
The math...
-249.33552w x .6035737= 150.49radiant watts
-Using the conversion factor of 4.7photons per radiant watt...(4.7 x 150.49 ) = 707.314µmols PPF (respect the 707)
-Convert PPF to PPFD(in m2)...707.314 PPF ÷ .836127m^2= 845.9µmols PPFD.
- Then tax that based on the optics...845.9 x .95 = 804µmols after optics
then add ~48 ppfd for the Red Pontoon I have from Inda-gro.... 852 ppfd.

total ~290w.

2p's per tray is a common goal when using 4x4s, and if one plant per sq ft in a 4x4 that would be 56g per plant.
so in a 3x3 tray with 9 plants the goal would then be 504g.

504g from 290w would be 1.74gpw with a slightly higher avg ppfd than a gavita 1000w de (info from their website)

seems practical. and pretty cost efficient.

criticism please