Advice on a cob build

KushyMcKush

KushyMcKush

Well-Known Member
hey guys, so im getting ready to build a cob system here in the next few weeks, and need a little advice. Ive been obsessing over data sheets, reading countless posts and looking at numbers for various currents, and talking to several people. It seems like everyone tends to favor one or another depending on what they sell/use, so i thought Id throw throw it out to the public.

Im going to be in a 4x5 space, running this set up alongside a 315w cmh (3100k phillips agro elite). Ill either hand two bars on either side with the cmh in the center, or side by side... but probably centered makes more sense to even things out.

Now, Ive been looking at mostly citizen (1212 & 1818), vero29, and obviously cree. Ive settled on vero or citizen for the cost:performance factors. Im going to use either 2 hlg-185-xxxx, or 2 x hlg-240-xxxx depennding on chips for a total of 400-450w. My budget is going to be calped at $600, but obviously cheaper is better without sacrificing quality.
I wont list sinks, just chip/drivers, but for the 1750ma drivers Ill probably be using sst-x square splayed pin passives which are ~$24ea. Also considering extruded active if thats a better option for my situation. Im open to all suggestions!

Ok, so, my build ideas without going into too much detail. I figure all of these will fall within my budget. Efficiency is second priority, but should still be a factor. Just want to fill this room with as much light as possible for my money really.

1) 2 bars with 4 citi 1212 each (8 total)
Hlg-240-1750 drivers
2) 2 bars of 4 each citi 1818 each (8 total)
Hlg-240-1050. Will have room left over on driver which is not optimal but will work.
3) 2 bars each of 3 citi 1818 each (6 total)
Hlg-240-1400. Fewer chips, driven harder
4) 2 bars each of 4 vero29 36v (8 total)
Hlg-240-1750 (more expensive than the other 2 builds.

These are basic ideas and from what Ive been seeing they will all put out roughly similar numbers I think. What do you guys think? Any ideas or suggestions would be greatly appreciated so i can stop obsessing over numbers and get this thing built!!
 
KushyMcKush

KushyMcKush

Well-Known Member
Are the vero29 worth twice as much as the citi 1212? I can get the 1212 for around $14 each, and the vero29 are $30 each with holder/reflectors.

Also, I saw someone mention that they wanted to run 4 citi 1818's on a 240-1050 driver and use a 5th chip, a citi 1212 to fill out the rest of the driver. So that might be an option too. Just so many options!!
 
visajoe1

visajoe1

Well-Known Member
I'm now running 5 citi 1212's at 1.2a over 5.2 sq/ft, 43% efficiency, 230w at wall. four 3000k, and one 4000k. 930 ppfd
 
verticalgrow

verticalgrow

Well-Known Member
KushyMcKush said:
Are the vero29 worth twice as much as the citi 1212? I can get the 1212 for around $14 each, and the vero29 are $30 each with holder/reflectors.

Also, I saw someone mention that they wanted to run 4 citi 1818's on a 240-1050 driver and use a 5th chip, a citi 1212 to fill out the rest of the driver. So that might be an option too. Just so many options!!
Click to expand...
1818's seem better in utube vid @ 40 - 44min
 
visajoe1

visajoe1

Well-Known Member
KushyMcKush said:
hey guys, so im getting ready to build a cob system here in the next few weeks, and need a little advice. Ive been obsessing over data sheets, reading countless posts and looking at numbers for various currents, and talking to several people. It seems like everyone tends to favor one or another depending on what they sell/use, so i thought Id throw throw it out to the public.

Im going to be in a 4x5 space, running this set up alongside a 315w cmh (3100k phillips agro elite). Ill either hand two bars on either side with the cmh in the center, or side by side... but probably centered makes more sense to even things out.

Now, Ive been looking at mostly citizen (1212 & 1818), vero29, and obviously cree. Ive settled on vero or citizen for the cost:performance factors. Im going to use either 2 hlg-185-xxxx, or 2 x hlg-240-xxxx depennding on chips for a total of 400-450w. My budget is going to be calped at $600, but obviously cheaper is better without sacrificing quality.
I wont list sinks, just chip/drivers, but for the 1750ma drivers Ill probably be using sst-x square splayed pin passives which are ~$24ea. Also considering extruded active if thats a better option for my situation. Im open to all suggestions!

Ok, so, my build ideas without going into too much detail. I figure all of these will fall within my budget. Efficiency is second priority, but should still be a factor. Just want to fill this room with as much light as possible for my money really.

1) 2 bars with 4 citi 1212 each (8 total)
Hlg-240-1750 drivers
2) 2 bars of 4 each citi 1818 each (8 total)
Hlg-240-1050. Will have room left over on driver which is not optimal but will work.
3) 2 bars each of 3 citi 1818 each (6 total)
Hlg-240-1400. Fewer chips, driven harder
4) 2 bars each of 4 vero29 36v (8 total)
Hlg-240-1750 (more expensive than the other 2 builds.

These are basic ideas and from what Ive been seeing they will all put out roughly similar numbers I think. What do you guys think? Any ideas or suggestions would be greatly appreciated so i can stop obsessing over numbers and get this thing built!!
Click to expand...
option 1 gives you the most ppfd out of the citi brands (755 ppfd based on 14 sq ft since it will be supplemental)

I would recommend placing these bars on the sides
 
KushyMcKush

KushyMcKush

Well-Known Member
@visajoe1 @verticalgrow thabks for the advice. Im kind of leaning toward the 1212's, but the 1818's do sound nice as well. I feel ill get more coverage with the 1212's, but then again the space is so small and it will be reflective, so Im not so sure that really matters in my case. Those 1818's are beats though. Im just stuck with using my phone currently so I cant open the sims to compare what these would look like at various currents. Makes things tough. Ill take a look at that video later.
Im not so much looking at the leds as supplemental lighting as just a mixed lighting. Im eventually going to go all leds and use the 315 in my veg room. Just dont have enough $$ to do that right now.
 
KushyMcKush

KushyMcKush

Well-Known Member
visajoe1 said:
I'm now running 5 citi 1212's at 1.2a over 5.2 sq/ft, 43% efficiency, 230w at wall. four 3000k, and one 4000k. 930 ppfd
Click to expand...
So why 1.2a? Is that just for efficiency? Anyone know what would be considered th "optimal" current is for these model chips? Is 1750 too much for that 1212? Am I gonna have issues cooling that? I haven't really seen anyone running those over 1400ma.
I guess my only issue with the 1818 is the driver compatibility. Id like to be able to easily swap out chips easily if something new and better comes out, and it seems like 36v is kind of the "stagndard" were moving to. No?
 
visajoe1

visajoe1

Well-Known Member
KushyMcKush said:
So why 1.2a? Is that just for efficiency? Anyone know what would be considered th "optimal" current is for these model chips? Is 1750 too much for that 1212? Am I gonna have issues cooling that? I haven't really seen anyone running those over 1400ma.
Click to expand...
When you can, get the citi calculator. The link is in @bggrass sig, So you can see what you get with different configurations. For your 5x4, 12 1212's or 10 1818's is what you'll need. Target ppfd is 700-900. But for now, you can run 8, or 6, cobs with your 315 and kill it

https://www.rollitup.org/t/diy-cob-led-calculator.890214/page-9


I'm running 1.2 because three of my drivers are preset at that amperage, so I just dialed my other one in to match. Its a bonus that its pretty efficient and cool, only putting out 23 heat watts per cob. I didnt plan to run this many cobs, hence the separate drivers, but it just worked out this way :bigjoint:
 
KushyMcKush

KushyMcKush

Well-Known Member
visajoe1 said:
When you can, get the citi calculator. The link is in @bggrass sig, So you can see what you get with different configurations. For your 5x4, 12 1212's or 10 1818's is what you'll need. Target ppfd is 700-900. But for now, you can run 8, or 6, cobs with your 315 and kill it

https://www.rollitup.org/t/diy-cob-led-calculator.890214/page-9


I'm running 1.2 because three of my drivers are preset at that amperage, so I just dialed my other one in to match. Its a bonus that its pretty efficient and cool, only putting out 23 heat watts per cob. I didnt plan to run this many cobs, hence the separate drivers, but it just worked out this way :bigjoint:
Click to expand...
Thats kinda what I was thinking for total. Ill most likely complete this run with the cmh/led and plan to replace the 315 for the next cycle.
Oh ok that makes sense. Id love to run the citi & vero calculators but they wont open on my phone, so Im kind of stuck with trying to find ones that people posted here and using those. I honestly think Ill be good with either configuration, but Im a stickler for finding the best of the best lol. It can be exhausting, but I want to know that my $$ is going as far as it possibly can.
 
KushyMcKush

KushyMcKush

Well-Known Member
Gonna bump this up woth another question here. How do people feel about wiring in parallel? I saw a cool build on reddit ising 3 citi 1818's on a hlg-185-48A running them at ~75w each... which is what? About 1600ma? That seems like it would pump out some major light. I just saw growmau5 mention thermal runaway in one of his videos so it made me a bit nervous. I keep seeing people doing it though, and a few people Ive spoken to say that they've never seen it and have not evem been able to indice it on purpose. What do you guys think?
 
ledgardener

ledgardener

Well-Known Member
KushyMcKush said:
Yea Ive read that. I was more looking for opinions from those here who have done it or just know more about this stuff than I do. Thanks though.
Click to expand...
I've been doing some testing on parallel/constant voltage setups lately to see if I could get COBs to go thermal. I found that they were very stable until I threw a ton of current at them (like 3 Amps), at which point they did go into thermal runaway on me.

Interestingly enough, when I increased cooling on my heat sink by pointing a by fan at it, I was able to prevent thermal runaway, even at 3 Amps into a CXB3590.

I have been running 2 Veros in parallel on a constant voltage driver at their typical current for a couple weeks now though and they are 100% stable.
 
KushyMcKush

KushyMcKush

Well-Known Member
ledgardener said:
I've been doing some testing on parallel/constant voltage setups lately to see if I could get COBs to go thermal. I found that they were very stable until I threw a ton of current at them (like 3 Amps), at which point they did go into thermal runaway on me.

Interestingly enough, when I increased cooling on my heat sink by pointing a by fan at it, I was able to prevent thermal runaway, even at 3 Amps into a CXB3590.

I have been running 2 Veros in parallel on a constant voltage driver at their typical current for a couple weeks now though and they are 100% stable.
Click to expand...
Thats some very cool info! Thank you. So maybe it might be a good idea to go active cooling just in case? Or will it be fine on those sst-x Ive been eyeballing? Im really considering this. With that driver they would be just around 1600ma correct? Thats a lot of light.
 
ledgardener

ledgardener

Well-Known Member
Those passive sinks will probably be fine and you can always add air to them later if you have to. Just monitor the current on each COB for the first while and make sure it's stable.

The current through each 1818 will depend on the voltage you set on the driver. To get 1600mA through an 1818, you'd need to give it ~52.5V. The driver you mentioned in the Reddit thread is rated for a max of 187W (it'll probably do a little more power but not much) so I'm thinking those 3 COBs will get closer to 65W. I could be wrong though, some of those drivers do a surprising amount of power compared to what they're rated for.
 
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KushyMcKush

KushyMcKush

Well-Known Member
ledgardener said:
Those passive sinks will probably be fine and you can always add air to them later if you have to. Just monitor the current on each COB for the first while and make sure it's stable.

The current through each 1818 will depend on the voltage you set on the driver. To get 1600mA through an 1818, you'd need to give it ~52.5V. The driver you mentioned in the Reddit thread is rated for a max of 187W (it'll probably do a little more power but not much) so I'm thinking those 3 COBs will get closer to 65W. I could be wrong though, some of those drivers do a surprising amount of power compared to what they're rated for.
Click to expand...
Hmm this is sounding more enticing by the minute. Its a good way to get a lot of light for pretty cheap. He says they will pull 75.3W each. Heres the link if you want to take a look:
https://www.google.com/amp/s/amp.reddit.com/r/microgrowery/comments/51umvr/i_made_a_quality_cob_build_list_for_a_3x3_tent/

I could very well be wrong. A week ago I didn't even know what a milliamp was, so Im still trying to figure all of this out. I just read the specs on that driver and its 3.9a, so would that actually be 1.3mA per chip? Thats still a damn good current for that cob. If Im doing that right? Apperantly that driver actually supplies 226w?
 
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