High power cob leds: do you hang them higher?

A

Audihenry

New Member
Hey guys,

I undestand cob leds tend to be run at about half power for efficiency and heat management, but there are ones that even at half power they're putting out 80 to 160 watts. How are these usable? Wouldn't they be too bright or hot for plants?

So do you guys mount the higher or what?

Thanks in advance
 
CobKits

CobKits

Well-Known Member
i have a 400W clu058-3618 in veg tent, it doesnt run any closer than 24"

yes they are brighter and must be higher
 
CobKits

CobKits

Well-Known Member
sure if you want to spend more money out of the gate. theres all different kinds of cob arrangements
 
CobKits

CobKits

Well-Known Member
cat of curiosity said:
is there a thread with a breakdown of these arrangements and parts?
Click to expand...
hundreds of them, tbh

most people are using cobs at 35-75W (relative to their 100-200W rating) at about 30-40W/SF. so (9) 70 W cobs in a 4x4 or 16 40W cobs in a 4x4.

the softer you run them, the more efficient they are but the cost of the rig goes up. 25-35W a cob is the bottom where it starts to get really expensive to add incremental amount of efficiency
 
cat of curiosity

cat of curiosity

Well-Known Member
CobKits said:
hundreds of them, tbh

most people are using cobs at 35-75W (relative to their 100-200W rating) at about 30-40W/SF. so (9) 70 W cobs in a 4x4 or 16 40W cobs in a 4x4.

the softer you run them, the more efficient they are but the cost of the rig goes up. 25-35W a cob is the bottom where it starts to get really expensive to add incremental amount of efficiency
Click to expand...
can you link me to a cob curriculum for old ac guys (or dummies)? interested in a permanent setup for a 20x20...
 
sunny747

sunny747

Well-Known Member
WOW! 20 x 20.. Cobkits is your best source for something like this. You would need approximately 100 cobs and a framework by my calculations. That would be tough to make up in electricity savings I am guessing.

check out Growmau5 on youtube. He runs cobs in a pretty large space.

I run 2 cobs at 90 watts a piece. So far so good.
 
CobKits

CobKits

Well-Known Member
easiest way to visualize it is to break the 20x20 down into 16 5x5s

each of these would have 16 cobs at 50W each
32W/SF which seems on the low side but at 50W/COB youre very efficient and would be north of 850 PPFD with excellent uniformity

and it would be trivial to add more driver capacity (maybe another $50 per 1000W of lights) to get them up over 1000 PPFD on the same heatsinks.

with the first setup youd probably save 35-40% of the electrical energy over your HPS. about 30% less heat to remove which reduces the AC energy load as well. also plants under LEDs generally like it 5 degrees hotter air temp to get the same leaf temps youre used to with HPS
 
A

Audihenry

New Member
How high do you mount those?

sunny747 said:
WOW! 20 x 20.. Cobkits is your best source for something like this. You would need approximately 100 cobs and a framework by my calculations. That would be tough to make up in electricity savings I am guessing.

check out Growmau5 on youtube. He runs cobs in a pretty large space.

I run 2 cobs at 90 watts a piece. So far so good.
Click to expand...
 
CobKits

CobKits

Well-Known Member
in a room like that id go 18-24" depending on uniformity of canopy. generally you just want it uniform and your distance to plants is same as spacing between cobs.. your "penetration" comes from every area of the canopy getting hit from a dozen angles.

plants could grow up within 10" of any of those cobs and not burn at all
 
sunny747

sunny747

Well-Known Member
Audihenry said:
How high do you mount those?
Click to expand...
About 16 inches. I could probably get closer with no issues, but I keep them a little high to get a good spread. With the dimmer attached I pull 185 watts from the wall. If I take the dimmer off it's around 205 watts, but that's a bit more light than they like.

I'll share a pic, but no laughing :)
20170627_193943.jpg
 
cat of curiosity

cat of curiosity

Well-Known Member
Rahz said:
20x20 inch? Is it for veg only or flower?
Click to expand...
20x20 feet, probably going to start with half that, and replace other half once the first is dialed in. i have never used led, and am going to have to remove rails, ducting and hoods to build the cob light rails.
sunny747 said:
WOW! 20 x 20.. Cobkits is your best source for something like this. You would need approximately 100 cobs and a framework by my calculations. That would be tough to make up in electricity savings I am guessing.

check out Growmau5 on youtube. He runs cobs in a pretty large space.

I run 2 cobs at 90 watts a piece. So far so good.
Click to expand...
thanks, i'll check his vids ;)

CobKits said:
easiest way to visualize it is to break the 20x20 down into 16 5x5s

each of these would have 16 cobs at 50W each
32W/SF which seems on the low side but at 50W/COB youre very efficient and would be north of 850 PPFD with excellent uniformity

and it would be trivial to add more driver capacity (maybe another $50 per 1000W of lights) to get them up over 1000 PPFD on the same heatsinks.

with the first setup youd probably save 35-40% of the electrical energy over your HPS. about 30% less heat to remove which reduces the AC energy load as well. also plants under LEDs generally like it 5 degrees hotter air temp to get the same leaf temps youre used to with HPS
Click to expand...
that does paint a clearer picture, thank you :)
 
Rahz

Rahz

Well-Known Member
cat of curiosity said:
20x20 feet, probably going to start with half that, and replace other half once the first is dialed in. i have never used led, and am going to have to remove rails, ducting and hoods to build the cob light rails.
Click to expand...
Wow, big job. If you're concerned about work space consider keeping the cobs close around the outside and raising them up towards the center of the room. @Greengenes707 has done some large rooms so maybe he can give you some advice.
 
CobKits

CobKits

Well-Known Member
also i imagine you'll have aisles in there, in which case you'll want reflectors at least on the cobs near the aisles. some peopel use rolling trays and pack em in there so may not be applicable
 
cat of curiosity

cat of curiosity

Well-Known Member
CobKits said:
also i imagine you'll have aisles in there, in which case you'll want reflectors at least on the cobs near the aisles. some peopel use rolling trays and pack em in there so may not be applicable
Click to expand...
aisles are at five foot intervals, but they fill in by week four flower lol. i am still interested in reflectors to direct the majority straight down. think scrog with a napoleon complex... ;)
 
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