LED Help - Please don't hate me ;-)

My space is 2.5' x 2.5' x 4.5'. If my horrible math skills serve me as best they can, that's 6.25 sq. ft. of growing space.

I know that this is a small space and I could get away with one bar light but I was thinking I'd make two bar lights on 20" L x 4.9" W heat sinks, connected with aluminum angle, with 3 cob's each or just under 1 cob per sq. ft..

I will be drilling for the installation and using self tapping screws. I'd like the cob holders but I don't know if I need lenses with this type of setup. I see that @REALSTYLES uses lenses on some of his lights but my understanding is that there is some light loss (or some other light limiting variable) that comes with using lenses. Being that my space is small, I thought I'd forego reflectors and lenses. The interior of the box will be bright white.

I will use either 1 or 2 drivers depending on which is the most efficient. I don't care as long as they are running at the best possible efficiency and not "lagged" as @PurpleBuz has said.

For light spread I thought I'd leave a space between the heat sinks of about 8" or so where I'd install a "platform" of sorts, made from a thicker piece of white plastic with a rubberized bottom, like non slip mouse pad type material/neoprene, for the heat sinks and whatever else is needed for that space.

I've got a bunch of high end computer fans that I used creating my last box so I thought I'd use a couple of those, with a fan speed controller I have, for active cooling rather than passive. To @bassman999 's point, there will be heat and I can adjust the speed of the fans to somewhat control that if the ambient temps are cooler. (keep in mind my box is in my garage due to Mrs. Giantsfan's requirements and as such subject to exterior environmental fluctuations)

I'd like to keep the light close to the plants, 12" or closer, but want to prevent stressing or bleaching while still getting the best efficiency (I'm trying to stop thinking watts) and thus give myself the best opportunity for lighting success. (I understand that for the first couple of weeks, I grow clones, that they will probably need to be a little higher until the growth takes off and that's just fine.)

What I don't know: (still)
1) What is the best spacing between the cob's for this setup. I visually go for symmetry but I don't know if that's a detriment or not in this arena. Is this best determined by how far from the edge of the heat sink the outside cob's should be placed? Is that 2" or 3"?

2) Given the desired distance from the lights I'd like the plants, 12" or less, what cob/driver combo would best accomplish this, without having to dim them, and be the most efficient option? The drivers could be dimmable but I'm trying to create this with the least "moving parts" and wouldn't be adding dimmers if I don't have to.

3) Where is the best pricing for these cob's and drivers? I've heard cutter.com.au with a discount code of "cutandroll" and I've heard of a guy named Jerry. I've researched digikey and mouser but they don't seem like a benefit. Are there advertisers/sponsors here to support for what we need to create lights? Mean Well drivers are what I'm getting is the best option.

I'm not concerned about a couple of bucks here or there in terms of cost of this setup but want the best value for the efficiency of the light then, obviously, the highest possible production minus the growing skill. (which I can do)

This light needs to last me for quite a while. I don't intend on improving it anytime soon as long as I'm getting the production I'd like from it or I intend to expand. (at this moment, I don't see expanding in my future) Two plants, 6 zips minimum. I could easily do that with a 400w HID in that same space. I've done better than that.

Finally, I've been on a couple of other forum's. 420 mag and a bubbleponic forum that is now gone. I got booted from 420 for joining the other. This is a great forum with extremely helpful people, it's awesome. Thank you for all of the time you've all put in helping me to figure this out. My mind simply doesn't compute the figures like it does for most of you. Know that all the help is sincerely appreciated. Thank you.
 
Rahz said:
I think you make an unfair comparison and I've stated my reasons why. There's no point in arguing the point further.
Click to expand...


I also made the comparison of 26.3% increase wattage ability per cob at equal overall efficiency, but it didn't justify the 50% increase in price. There's really nothing to justify the price except high demand. If you can get them cheaper, yeah, less 3590s is better value than more 3070s, I'm just basing numbers on cutters USD prices.
 
giantsfan24 said:
My space is 2.5' x 2.5' x 4.5'. If my horrible math skills serve me as best they can, that's 6.25 sq. ft. of growing space.

I know that this is a small space and I could get away with one bar light but I was thinking I'd make two bar lights on 20" L x 4.9" W heat sinks, connected with aluminum angle, with 3 cob's each or just under 1 cob per sq. ft..
.
Click to expand...

my suggestion is to build Just One 2 foot heatsink bar and pack as many cobs on it as your driver will handle.
five 3070s at 1050 on an hlg 185 works well. One heatsink, one driver, one fan ... its a module!

That will ensure you have more than enough light, and if you want to add one more later thats cool but not necessary.
 
PurpleBuz said:
my suggestion is to build Just One 2 foot heatsink bar and pack as many cobs on it as your driver will handle.
five 3070s at 1050 on an hlg 185 works well. One heatsink, one driver, one fan ... its a module!

That will ensure you have more than enough light, and if you want to add one more later thats cool but not necessary.
Click to expand...

So in essence you're saying that I don't need to be concerned with light spread in that small of a space. Is that correct?
 
In an area 46" x 40" x 7' tall I run 4 to 6 5 gal buckets. I don't use lenses or reflectors. I have 8 cobs now soon to be 16. I had reflectors but prefer none and mylar walls. My space is totally walled up.
 
giantsfan24 said:
I want to drive those cobs at 75% don't I? I think?? Or said another way, use 3/4 of the driver space?

What's the difference between the 120 and the 185?
Click to expand...
Driver efficiency increases by using the majority of the forward voltage.
The main differences are the output potential, and cobs capacity then can operate
The hlg-120-1050 is rated 120 watts and likes 4 cxb cobs
the hlg-185-1050 driver is rated 185 watts and like 5 cxb cobs
 
bassman999 said:
Driver efficiency increases by using the majority of the forward voltage.
The main differences are the output potential, and cobs capacity then can operate
The hlg-120-1050 is rated 120 watts and likes 4 cxb cobs
the hlg-185-1050 driver is rated 185 watts and like 5 cxb cobs
Click to expand...

Ok so if I were planning on powering 3 cobs per driver than the 120 would be the best utilization of the driver?
 
giantsfan24 said:
Ok so if I were planning on powering 3 cobs per driver than the 120 would be the best utilization of the driver?
Click to expand...
Yes the hlg-120-1050 makes more sense than the hlg-185-1050 with regards to 3 cobs, and you have the ability to add a 4th cob if you so desire in the future. If you dont want to add a 4th cob ever, you could go with the hlg-185h-c1400 and have higher driver current if you want/need, full utilization of the driver, and dimming option to whatever current also
 
bassman999 said:
Yes the hlg-120-1050 makes more sense than the hlg-185-1050 with regards to 3 cobs, and you have the ability to add a 4th cob if you so desire in the future. If you dont want to add a 4th cob ever, you could go with the hlg-185h-c1400 and have higher driver current if you want/need, full utilization of the driver, and dimming option to whatever current also
Click to expand...

What's the benefit of higher driver current?
 
4 3070 BB 3500K = 620 PPFD
5 758 PPFD
@1050mA 54% efficient


used to think symmetric,but....... kind of push closer towards the edges while obeying symmetry and open the middle or spaces where two or more cobs intersect.....spread light evenly, sometimes with edges that doesn't always mean diodes match that pattern in their physical layout...sometimes symmetry has to be skewed to minimize too much overlap....
my recs :peace:
 
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