nfhiggs
Well-Known Member
How many watts of LEDs do you need to cool?
Is this a Vero 29 killer?
- Thread starter JorgeGonzales
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nfhiggs
Well-Known Member
Not sure what you are on about here....
DrMisunderstood
Member
Finally, someone gets me.
The watts belongs hidden in the technical specifications. Watts should NOT be used to define the fuckin' unit!
How about some professionalism for once. I like heliospectra. They are professionals. Me not so much. I had the Heliospectra units doing a light show in sync with music.
Normal? Can't even imagine how awful that must be.
If you're trying to be normal, you will never know how amazing you can be.
Overcome the notion that you have to be normal. It robs you of the chance to be extraordinary.
DrMisunderstood
Member
Bait or troll never entered my mind.
I think UV is very specie dependent. I asked one of the professors about it. He answered while subconsciously shaking his head no, he said some stuff way the fuck over my head, but used the word shock and something about signalling . Unless you know what you are doing with UV, do not use it. You are doing fine with out it. If you have an isolated plant you want to experiment with then go for it. I believe they cited studies of UVB but I think their UV emitter is UVA. I do not want to go back and fact check that one.
Every string I do has its own Buck CC driver with analog and PWM dimming. I use 48V constant voltage supplies. I generally do not do parallel strings, and if I would I would use a $0.50 load balancer like the Texas Instruments LM3466. If the string were driven with less than 350mA and would never need dimming, I use a CCR like the On-Semi NSI50150 which is a basically a dynamic resistor with current adjustment.
High density is not a good thing. You want things spread out good for thermal and uniformity. The BLM SPYDR is considered a good design.
Heilospectra is high density, but they have great uniformity with their optics. When the University gets a new fixture the first thing they ask for is the PPFD mapping.
The reason you see high density is because PCBs are priced per sq. inch. That's an obstacle. How do you get around it? Slice up the board into tiny strips and spread them out. Like BLM but with a vengeance. The strip is wide enough (0.40") just for the LED (0.120), a little space between the LED and heatsink (0.080) and a 4/40 screw (0.20) to mount it to the heatsink.
Older 0.7" wide revision, Luxeon Rebel and XLamp, XLamp not used here.
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DrMisunderstood
Member
No, I think they are stupid for selling a product that can kill their customer. 100VDC or more I will not touch. I'm too careless. You've got to know your limitations.
It's no better than the Quantum Board. If you can be patient, I'll hook you up with some PCBs. If necessary, I'll show you how to solder the SMD parts. It's easy.
frica
Well-Known Member
Chilled does provide the umol/j on the reports page, their lights are sphere tested.
Anyway, most consumers will first look at wattage. Most consumers don't know what to do with umol/j and total ppf except that higher is better.
frica
Well-Known Member
I think you're way too paranoid about the voltage.
Maybe you're too careless with it, by far most people haven't been.
DrMisunderstood
Member
Yeah, they'd be okay if I didn't know how to make a PCB.
DrMisunderstood
Member
I'm not being paranoid. I won't touch it because I am that careless. But as far as selling a product, it is insane to take on that liability. And I suspect it is technically a schlock job which will bite them in the ass.
DrMisunderstood
Member
Parallel strings driven with a shared CC driver will experience thermal runaway. When one string operates at a slightly different temperature than the other, the voltages will change, the current will change the temperature will change and over time one sting will be drawing most of the current. CoBs are matched pretty well in voltage and temperature, so it would take a long time, like days for it to happen if they were left on 24/7. If I were to fire up one string wait a minute then add the second string they would start out with a significant thermal imbalance, within 12 hours one would be burning up, the other flickering out. If I switched which one I fired up first then the other would flicker out. The more LEDs in the string, the higher the voltage mismatch, and the greater the difference in temperature the more likely it will happen.
CobKits
Well-Known Member
"will"?
how about "may in some cases"
many many many examples of parallel builds in this forum. not a single case of thermal runaway that im aware of. pretty easy to mitigate with proper driver matching and proper heatsink sizing
DrMisunderstood
Member
Maybe I am just unlucky. It happened to me 100% of the time. Two strings on separate boards no heatsinks, forward voltage 42.2V and 42.4V, 16 LEDs each, white Luxeon Rebel ES, do not remember the current, it had to be under 300mA shared, less than 150mA each.
It does not happen immediately for me it was overnight. I'd get up the next day and one board would be flickering very dimly the other very bright. Someone not running 24/7 may never notice.
When selling a product you do not want any field failures, they are a nightmare. These guys are looking for headaches. It only costs $0.50 a string to balance.
BTW: I was on your website, you should sell Thermal Cut Offs. It's an inexpensive $0.60 (small qty) thermal fuse. Twice I have had CoBs overheat but was saved when the solder melted and the wire fell off. I am rather careless.
I will try again measuring the current with a data logging meter.
You are correct the situation can be mitigated. It does require a mismatch in the dynamic resistance which is exacerbated with temperature.
If you match the forward voltages and keep the temperatures the same, it is less likely to happen.
This is the thermal measurements with a similar board no heatsink.
All measurements were made at least a half hour after the current adjustment except for the first.
DrMisunderstood
Member
How many products do you buy where you look at the wattage first? I could care less what the wattage is. The PPFD per watt, yes. These LED grow light hucksters sell their stuff like snake oil, they drive me nuts. I want a product description and tech specs. But this is over the top Real 1200 watt power draw – none of the silly marketing nonsense with “LED watts vs Electrical watts”. Using the phrase "Real 1200 watt power draw" is silly marketing nonsense itself. The pot calling the kettle black.
And those number look good. After knowing that, why would I care about the wattage?
Sphere testing LED fixtures bugs me. It's like LED lighting guys are stuck with a light bulb mentality. A sphere is for measuring isotropic flux, like from light bulbs. They also measure Intensity but I want irradiance not steradian intensity. A flat surface, (i.e. irradiance) pattern in terms of PPFD is what I'd like to see. Sphere measurements have nothing to do with what reaches the plant. It skews the µMoles/J by inflating the number of photons because it includes the photons that would not reach the plant.
DrMisunderstood
Member
I was kinda kidding about the ice maker, I did consider it though. The plan is to keep adding fixtures until the water starts getting warm so I know the thermal capacity. A friend of mines son is moving to Oregon next week to run a $Million indoor cannabis grow facility. So if things work out hopefully a lot of kW. Unfortunately I am not ready for them yet.
I have not had good luck using thermal dynamic formulas so would rather do an experiment than the math.
There are three kinds of people. Those that understand math and those that don't.
DrMisunderstood
Member
Write that down on a sheet of 8.5 x 11 linen bond paper, fold, insert in #10 envelope, and send it to someone that gives a shit what you think.
I was sent that link and asked my opinion.
Go buy yourself your own personality, the Rainman wants his social skills back.
Why don't you apply another coat of lube to your butt plug and drink a big glass of shut the fuck up.
CobKits
Well-Known Member
because thats how 9 out of 10 growers size a room
DrMisunderstood
Member
Good to know there is at least 1 out of 10 with some brains.
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