Originally Posted by Chunkypigs
So how did you rig those leds, is it all from scratch?
Yes LEDs are all built from scratch; it's really the only way to LEDify the room for a vert this large. The stack is actively cooled by a 6" fan blowing up through the middle and it exits right into the ceiling casette AC intake, so the heat has no opportunity to enter the room before being cooled. This is important since the one consistent issue I had with this room (until now) was heat buildup. Since it's such a small volume compared to the wattage, it heats up very very quickly. In the past I was using an RV AC unit set on top of the room; this was not ideal since it would cycle on and off. Since there is a minimum 5min off time before it cycles back on, that's five minutes with no AC with 3kw running full blast. The room would go from 78 to 95 in minutes before it kicked back on, which resulted in some strains foxtailing out and a general loss of quality and taste. I also end up replacing the RV ACs like once a year; inevitably they would freeze up or act weird and so after the third unit bit it, I finally wised up and installed a split. The inverter is key since the unit never cycles; so it maintains perfect, even temps with no heat spikes; and the quality benefits so far are obvious. The LEDs also distribute both light and heat more evenly, so I don't have any hot spots causing local heat issues.
Anyways I had a ton of the bridgelux Vero 13 3000k decor COBs that I rescued from a different project that was decommissioned, so I decided to give them new life in this new fixture. Each COB is thermally epoxied to a 40mmx40mm heat sink. I have the SE version of the COBs which have push-in spring connector terminals that make it pretty quick to string up a line of them without soldering. They clip onto a facing sheet of 1/8" acrylic with a plastic clip I designed specially for this purpose and fabricated with the assistance of my friend's laser cutter. Those sheets are then bolted onto a frame int he shape of a hexagon, along with a bottom flange to attach the 6" exhaust fan.
The units on the walls are a simple wooden "U" channel with the same plexiglas clip technique used on the top face. Each section has a 90mm PC fan blowing up through it.
Running 24 LEDs (all in parallel) off each power supply which are 400W rated 48V supplies. Then into a digital buck converter with constant current output, so pushing 320W (10A) at about 32V into each string of 24 LEDs, so each COB sees about 13W. Conventional wisdom is to NOT run the LEDs in parallel due to concerns about thermal runaway, but this hasn't been an issue in practice. All the heat sinks are within a couple degrees of each other after running them for a while. I believe the active cooling approach helps mitigate these concerns by keeping the junction temperature under control, making it impossible for a runaway event to occur.
Anyway, totally recommend COB leds over HID. It's an investment, but if yield increases by 25% and quality by 50%, it pays itself back quite quickly (not to mention cost of swapping bulbs every run otherwise). I mean, with my typical pull being 4-5 elbows under 3kw HID, an extra 25% is at least another elbow per run, which would pay for the lights and then some in just 2 runs.
Total material cost of the LEDs (all in including power supplies, fans, COBs, buck converters, wires, plexiglas, etc), is around $2500. And of course probably about 100 hours of labor