Don't chastise plz.. legit question on led drivers

I am Groot

I am Groot

Member
Ok first off I know there is a search button and I have been scouring for answers on a limited internet connection, so I decided to ask my brothers in arms to rescue me. Be gentle lol.. I'm sure the answer is here in like page 122 in some thread.
Well I'm having a bit of confusion on drivers and how they work, giving an example of
6 -100w cobs at 3000ma 30-34volts
What driver would I need?
I'm not understanding drivers, I'm fimaliR w 12electronics but led drivers are different from speakers and amplifiers..
I think I understand how the led works as far As running in series or parell, but how do u select a driver after what I was watching growmau5 on u toob he explained a driver as a bank, giving his example of a hlg 185 has 144v to distribute. But after lookin at the mean wwell spread sheet it doesn't show a 144v at all so I know I'm missing something. Some one help me just so I can get this down. Even a compatible driver I would be able to research and see the comman denominator.
 
I am Groot

I am Groot

Member
Thanks for the reply, I Looked over quite a few pages on the thread, and now faced w new Questions. I was reading a different post by SupraSPL where he gave a few scenarios of cobs w drivers and that helped a lot but also brought out questions. Now I know im missing something on the math and I was going to post this on another thread, but im refraining from a thread jack. so maybe someone can help me out. I just was a understanding on the math, and some noob questions. I know a few equations but I would just like a confirmation on my end.

1) Calculate watts of a Cob ( max FVxMax (ma) = max watts?
2) How Do u calculate Heat watts?(max watts x Non Efficiency%??)
3)How to calculate PAR
4)How To Calculate PPFD
5) what is the optimum light output PPFD
6) how to calculate efficiency

That's what I got for now and im sure I still have more, but I have been reading and just getting more questions and questioning my math and sanity lol.. thanks to all
 
BOBBY_G

BOBBY_G

Well-Known Member
1)watts are based entirely on the current you are running through it. cob voltage will rise slightly with current so its not simple 36V x current, its 34.81 or whatever corresponds to the current. you will find this data in the drivers datasheet (as a curve you must interpret) or by using cree's product characterization tool at http://pct.cree.com/dt/index.html

2)what you call "max" watts is what most people call "dissipation" watts and it is the total of PAR energy+heat energy from the fixture.or more simply how much power is drawn from the wall. so yes a fixture with 1000W power draw that is 55% efficient has 550 PAR W and 450 heat W

3)see #2 for PAR W. divide by your coverage area to get to (average) PAR W/SF

4) ppfd = 45 x PAR W/SF

5)you can grow good plants with high GPW efficiency with as little as 500. if youre trying to maximize yield per square foot you can go as high as 1200-1500. 700-900 is popular

6)efficiency for a fixture = PAR W/ dissipation watts
efficiency for a driver, etc = usable energy out/energy in
 
I am Groot

I am Groot

Member
Thank You Bobby G, Its making sense but im using an example by supra and im missing on the Par calculation
@45.7% 83.63/183 understood
(2) CXB3590 3500K CD 36V @ 2.5A (91.65W ea) $95 Off of spreadsheet ( question, what if no spreadsheet avail)
(2) HLN-80H-36A $90
183 dissipation W -> 99.37W heat 183-83.63 Understood
(2) Arctic 64 Plus CPU coolers $26
(2) lenses $8
83.63 PAR W covering 5 ft² = 749 PPFD Here im having trouble I cant calculate PAR still and I need that to get PPFD and all other equations lol I got the framing but missing foundation.
$219 = 2.62/PAR W
Im sure the answer is right in front of me and im just missing it. any more help I would appreciate it, I know its probly painful for yall to see me try to understand this,
 
BOBBY_G

BOBBY_G

Well-Known Member
"what if no spreadsheet avail" > Cree PCT tool i linked which has exact data for lumens, watts, and voltage for amperages from 1.4A up to 3.6A

83.63 PAR W / 5 SF = 16.726 PAR W/SF

16.726 * 45 = 753 PPFD

("45" is an approximation you can see its very close)
 
giantsfan24

giantsfan24

Well-Known Member
BOBBY_G said:
"what if no spreadsheet avail" > Cree PCT tool i linked which has exact data for lumens, watts, and voltage for amperages from 1.4A up to 3.6A

83.63 PAR W / 5 SF = 16.726 PAR W/SF

16.726 * 45 = 753 PPFD

("45" is an approximation you can see its very close)
Click to expand...
I'm sorry @BOBBY_G .... what does the "45" represent?
 
BOBBY_G

BOBBY_G

Well-Known Member
its an empirical constant back calculated from supras numbers

i think you need to know LER of a given light source to accurately calculate ppfd so its just an approximation for our cobs
 
I am Groot

I am Groot

Member
Awesome I knew I was doing something wrong. Thank u.

On the No data sheet I was meaning like non cree leds. I have a hand full of china ones that don't have great data sheets but are pretty general

Example
100 W warm White
input voltage 30-34 Vdc
power: 100W
Input Current 3000ma
luminous Flux 9000-10,000
that pretty much all that is said on the spec sheet

I wanted to mess w them cause I have a old mars knock off ... than I wanted to retrofit w cob's
but the drivers it has
(2) Output 80-130v
Constant Current 550ma
input 100/240Vac 50/60 htz
all trying to light a 2x2 room (18"x18" actual)
 
Last edited:
I am Groot

I am Groot

Member
Ok would this be it, given the products mentioned above.

83.3% Eff
6-34v [email protected] (18.7 W ea)
2-80-130V drivers @.550ma
112.2 Dissipation 19 Heat Watts
93.2 Par 2ft² = PPFD 2097
Yey or neh and be brutal. lol..

side question how do u post (ft²) the little 2 I had to copy n paste lol.
 
I am Groot

I am Groot

Member
18.3% efficient ? I grabbed the wrong side im guessing.. I thought it was the larger because they weren't being pushed hardly..
6- 34V China @ .550ma (18.7w ea)
2-80-130v Drivers @ .550ma
112.2w Dissipation 91.7 Heat Watts
10.25 Par 2ft² = 461 PPFD?

hope this is it, and thanks again for the patience
 
BOBBY_G

BOBBY_G

Well-Known Member
you really know nothing about the 'current droop' of these chips (aka how the perform over a range of currents with respect to voltage and luminous output)

the fact that they are 10000 lumen at 100W would make me not want to waste my time messing with them. thats like t5 fluorescent efficiency. buy yourself some vero 18s or $14 cree 2530s that you can get a spec on and design a proper system
 
Travola Pistola

Travola Pistola

Member
BOBBY_G said:
1)watts are based entirely on the current you are running through it. cob voltage will rise slightly with current so its not simple 36V x current, its 34.81 or whatever corresponds to the current. you will find this data in the drivers datasheet (as a curve you must interpret) or by using cree's product characterization tool at http://pct.cree.com/dt/index.html

2)what you call "max" watts is what most people call "dissipation" watts and it is the total of PAR energy+heat energy from the fixture.or more simply how much power is drawn from the wall. so yes a fixture with 1000W power draw that is 55% efficient has 550 PAR W and 450 heat W

3)see #2 for PAR W. divide by your coverage area to get to (average) PAR W/SF

4) ppfd = 45 x PAR W/SF

5)you can grow good plants with high GPW efficiency with as little as 500. if youre trying to maximize yield per square foot you can go as high as 1200-1500. 700-900 is popular

6)efficiency for a fixture = PAR W/ dissipation watts
efficiency for a driver, etc = usable energy out/energy in
Click to expand...
I was looking on the cree product characterization tool... But i ran into a problem with it.
I want to do a 500-600w build using EITHER 4, or 16 cxb3590s....
The problems im running into are
1) i cant find a quality constant current driver to run 4 cxb3590s at max current.... Theres no constant current drivers that run even close to 3600mA for the 36v 3590s, AND i can run the 72v 3590s on the hlg240h-c1750 for max lumens, BUT i dont want to have to run a driver for each cob. $$$$
AND 2) the cree product tool sheet doesnt show any data on the cxb3590s under 1.4A which = 390w for 8 3590s... so i cant find what current to run 16 3590s at to get them down between 500-600w
.....do yiu have a formula to calculate watts from current?
 
BOBBY_G

BOBBY_G

Well-Known Member
go read up on the matching cobs and drivers thread. every answer you seek is there, i promise

ill follow up later but dont have time right now
 
I am Groot

I am Groot

Member
BOBBY_G said:
you really know nothing about the 'current droop' of these chips (aka how the perform over a range of currents with respect to voltage and luminous output)

the fact that they are 10000 lumen at 100W would make me not want to waste my time messing with them. thats like t5 fluorescent efficiency. buy yourself some vero 18s or $14 cree 2530s that you can get a spec on and design a proper system
Click to expand...
Agreed, I never considered that the lumen output was low, I just saw 100 watts lol took that hook LINE n sinker .well It costed me a few bucks but gotta charge that to the game. I will deff consider something way better I was just doing a proof of concept kinda run to see if I could figure it out b4 investing in good stuff. Just wanted a upgrade from my cheap led fixture that produced ugh very little. Currently doing cfl grow but would deff run a diy cob fixture in the future
 
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