Lighting Cob build question

[Hpchacrx]

i have been reading your posts and seems you members really know your stuff about cobs. I have a shed I am using for a grow and I was wondering what you would use for a diy cob set up on 4x4 space that I can build multie units as I have the $ and time

Hpchacrx, 1 minute agoReport
Repl

 

[Hpchacrx]

All answers appreciated. Would like to fill the space light with less number cons driven harder but efficient. Look forward to your replies

 

[Hpchacrx]

Unless anyone has a better idea?

 

[iampepe]

A couple 200 watt drivers and 8-10 cobs

 

[Site]

Someone with some more experience will probably chime in on this but from my small involvement in making my own light and doing research, theres a few factors and things you should decide on...

I went with CREE COB's as I got 4 No. CXA3070's at a steal on ebay at £11 each and 4 No. CREE CXB3590 from china for £30 each. Cree LED's are the most expensive but boast to have the best efficiencies etc...you need to make a bit of a decision on cost vs efficiency of your light...BigSm0 on here really rates Citizen Cobs and if i was to make my light again i would probably go with them...they are super cheap but from the information and data BigSm0 has shown me recently they are almost hitting the same efficiencies as Cree...

Obviously they will run a few percent under the Cree efficiencies but for the price its worth living with...i think they might drop from 60-63% to around 57-58% or something...

Then you have driver selection, where you have 2 options really...you could go with cheap, individual drivers that can run the correct voltage and current you want, so for each COB you will have a driver. So for 8 COB's you will need 8 Drivers...the positive to this is on ebay you can get drivers for around £2 each....the downside is loads of wiring and drivers that will need to be mounted somewhere...

The other option is to use one or two larger drivers such as Meanwells HLG drivers which you can connect multiple cobs to...you will need to determine how many COB's you want to run and at what current to calculate the size of driver required...BigSm0 just put up a thread which explains driver sizing and wiring which is worth checking out, also growmau5 on youtube (think thats his username)...hes got some good videos explaining a lot....

You then have other factors such as spectrum of the COBs light output...most go with 3500K but I went for a mixture of 3500K and 4000K...the lower the spectrum number the output leans more towards the longer wavelength spectrum (reds, oranges etc) and the higher the number 5-6000K leans towards more blues/greens etc...

Other items to consider are heatsinks, holders, reflectors etc...heatsinks are fairly important and you need to decide whether to go passive or active...I went with active cooled heatsinks which were just CPU heatsinks and fans...they work well but became a pain in the arse to drill and attach to a frame...again if I was to do it again I would purchase a large flat heatsink (plenty on ebay etc) and mount all my COB's to that...reflectors, holders etc you will find out more about after watching some youtube videos etc

 

[Rapha El]

If you want to drive them harder but still be efficient you gotta go for the big ones aka the 200 watt cobs.
Here's the thing with those though: Standard 100w cobs cost you a tenner a piece, the cooling for one is going to run you another 15 bucks.
So if you run 1212s for example you have one single light for 25 bucks (not counting the driver, holder and wires)
The 200w cobs are for example BXRC-40E10K0-C-72 or CXM-32-40-70-54 the first one costing 23 the second one costing 33. That is without everything else.

Also if you got multiple instances hanging they produce hotspots at a lower hanging height than more items.

My suggestion is 8 cobs driven at 50 watts or 4 at 100, that'll illuminate a 4x4 space quite well. You could also double the number of cobs and half the current for each to raise the efficiency but that'd raise the buy-in price "a bit".
You could also run 10 total. That'd give you more cobs total and a better blend for my next thing to think about. I'd go half/half with 3500k and 4000k the latter one for veg only and once they hit stretch you switch on the remaining lights.

Let's hear what @BigSm0 thinks.

 

[BigSm0]

Thanks for the shout guys. I recommended 3 bars of 3 cobs. Hlg-120h-48a since they are inexpensive and won't overpower the cobs. More wattage meaner a more expensive driver and heatsinks. Yes 200w cobs are great but it's not the standard. For a standard light 50w is a great starting point in my opinion. Shit all of this and previous pages is just an opinion. 3 drivers, 9 citizen 1812's, 9bjb holders, 9 120mm pin fin heatsinks, thermal paste, 18g solid wire, M3x6 screws for the heatsinks, bunch of angle aluminum. And a day or two in time.

450watts in a 4x4 with good genetics and grow skills could net 1.5lbs.

I really think the difference between Cree and citizen is probably close the difference between Toyota and Honda. Both made in Japan, after a couple years they are most likely make in china now. Good mpg depending on model, reliable, not the fanciest but a good all around daily driver.

 

[Site]

I really think the difference between Cree and citizen is probably close the difference between Toyota and Honda. Both made in Japan, after a couple years they are most likely make in china now. Good mpg depending on model, reliable, not the fanciest but a good all around daily driver.

thats a good analogy...wish i had the funds to put a cree setup next to citizens and see what quantities of light we would get for power in etc...but thats what i was trying to get at...when i used the COB calculator cree was excelling citizen by nearly 10-15% which made me go with cree....looking at your data they are nearly matched so I would probably advise anyone to go with citizen just based off that....

 

[BigSm0]

It depends on the model. The more leds packed into the cobs the softer it needs to be driven and then more efficient. 1212 has 144 leds vs the 1818 has 324. Same as the 3070 vs 3590 Cree. Both use the same exact tech, they are just the same at different wattages to achieve the same efficiency.

 

[BigSm0]

what I do find funny is the cob guys, me included go nuts over a few %. Outweighing cost vs efficiency while 70% of the forum grows with mhydro or viperspectra and don't have a clue what efficiency even means. Not picking on anyone just an observation. They all work, some just cost more to buy while others cost more to run. We are the Prius owners who have 300hp turbo charged engines. Not the prettiest but super fast with great mpg. Others are driving scooters with flat tires.