Watercooled Smart IC COB LED Build

[NoFucks2Give]

any thoughts on the likely efficacy of an aluminum RHS

What's an RHS?

 

[NoFucks2Give]

d bar together in a press to increase the contact area and make it more uniform,

This was someone's idea on how to increase the contact area. Would do a good job of that but...


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It comes at a price.

 

[CobKits]

Great thread. Everyone has valid points of view and there is heaps to learn.

this. lots of out-of-the-box thinking here and its refreshing.

 

[nfhiggs]

The hottest would be the Deep Blue and White in strings of 16. The typical Vf of a 16 LED white string is about 45V with 1 amp current so 45 watts electrical. More than half of that is converted radiated light and less than half is heat.

When generating heat for experiments I use a Mean Well HDD-1500 (1.5 Amp) to drive the CoBs. Vf is 30-38V or between 45 and 60 Watts where more than half is heat.

The reason I use individual LEDs is for thermal management. When the heat is spread out it is easier to manage. I test with CoBs because they are very difficult to manage. When the heat is so concentrated there is too much thermal flux in a too small an area to significantly reduce the temperature. But CoBs are not all that sensitive to heat. You lose about 10% in a typical application where the Tj is 100° C. Whereas a red LED will lose 40% at that temperature. But then red LEDs Vf is less than white.

Results for no thermal management. View attachment 3972404

Results for water cooled red with minimal 40 gal/hr water flow and an air gap between pipe and copper bar.View attachment 3972406

The bar was soldered on the ends and in the middle. Did not use many screws. The solder added fair amount thermal resistance. there was not thermal flow through the air gap.

View attachment 3972410

Have you tried various flow rates? Whats the temp delta of the water in/out?

 

[Mullumbimby]

What's an RHS?

RHS is circular, square, and rectangular hollow sections.
I think the R can mean mean Rigid, although I meant Rectangular Hollow Section. I'm talking about aluminium extrusions.

 

[NoFucks2Give]

Have you tried various flow rates? Whats the temp delta of the water in/out?

These blue temps are from the same time as the red in the previous post. Sept. 2016
In both there is a column with the delta Δ symbol, that's the difference column

Being blue the forward voltage is higher than red. The red were about 35V @ 700mA and these blue are 45V @ 1.0 amp.
With ice water 0° C the delta averaged 22.6° C At ambient 23° C no cooling the average delta was 13.6° C

At 0° C water temp the thermal pad temperature was only, on average, 22.6°C. Lower than the datasheet 25° C.
With no cooling the average pad temp was 41.7° C at ambient 23° C.

There was not any significant change in water temp in and out.

With the LEDs off the pad temp was 11° C
Took 4 minutes to get up to 22° C and stayed there.
I did not always measure the same LED. The 24° C reading was probably an LED that had a gap to the copper.




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FLOW RATE

This was my first setup.
The flow rate did not seem to matter. I now use two 60 gal/hr DC brushless pumps. Two for when one fails.
The pump: https://www.amazon.com/gp/product/B00JWJIC0K/
I picked these because they can up pump to over a 6" height (Static lift).
It is best to have as little as possible difference in height between the water reservoir and the heatsink. The height difference slows the flow.







Water really absorbs a lot of light. It is very likely that the light helped raise the water temp in this setup.

 

[nfhiggs]

These blue temps are from the same time as the red in the previous post. Sept. 2016
In both there is a column with the delta Δ symbol, that's the difference column

Being blue the forward voltage is higher than red. The red were about 35V @ 700mA and these blue are 45V @ 1.0 amp.
With ice water 0° C the delta averaged 22.6° C At ambient 23° C no cooling the average delta was 13.6° C

At 0° C water temp the thermal pad temperature was only, on average, 22.6°C. Lower than the datasheet 25° C.
With no cooling the average pad temp was 41.7° C at ambient 23° C.

There was not any significant change in water temp in and out.

With the LEDs off the pad temp was 11° C
Took 4 minutes to get up to 22° C and stayed there.
I did not always measure the same LED. The 24° C reading was probably an LED that had a gap to the copper.



FLOW RATE

This was my first setup.
The flow rate did not seem to matter. I now use two 60 gal/hr DC brushless pumps. Two for when one fails.
The pump: https://www.amazon.com/gp/product/B00JWJIC0K/
I picked these because they can up pump to over a 6" height (Static lift).
It is best to have as little as possible difference in height between the water reservoir and the heatsink. The height difference slows the flow

Water really absorbs a lot of light. It is very likely that the light helped raise the water temp in this setup.

I'm thinking along the lines of how an engine uses a thermostat to restrict the water flow so it has more time to absorb heat as it flows through the block - looking at your numbers with the ice water - there is a 22.6C temp difference between the water and the thermal pad, and no difference between the inflow and outflow, correct?. That says to me that the water is moving too fast. I would split the temp difference and install a thermostatic valve that opens at 10-12C.

 

[ssj4jonathan]

Finally got my hands of a power meter. Here are the results:

Full Spectrum COB

VAC 110 90 75

Amps .545 .18 .015

Watts 53.5 13 .5

Power Factor .9 .81 1


Cool White COB

VAC 110 90 75

Amps .52 .16 .015

Watts 51.5 12 .015

Power Factor .9 .83 .5


12 COB Rig (Metered off VARIAC)

VAC 110 90 75

Amps 5.76 1.77 .17

Watts 568.5 133.5 8.5

Power Factor .9 .84 .69


12 COB Rig (Metered off wall)

VAC 112

Amps 6.17

Watts 621

Power Factor .91


VARIAC + 100W COB (@87V, Metered off wall)

VAC 119

Amps 1.15

Watts 109

Power Factor .84


Watercooling Setup (1 Fan, 2 pumps)

VAC 120

Amps .215

Watts 15.5

Power Factor .6


Tent Exhaust (2 Fans, 1 timer)

VAC 120

Amps .205

Watts 15

Power Factor .64


Entire Setup (100W of COBs, Watercooled ,and Exhaust)

VAC 119

Amps 1.5

Watts 146

Power Factor .82

I highlighted the results for the 12 COB rig metered at the wall. Its pulling 621 watts! I can only assume that somewhere around 590 watts is going directly into the LEDs and 31+ watts are being burned up by the linear integrator chips. There's no way to be sure, as the single COB measurements at 110VAC (the rated voltage for these cobs) gave me 53.5 and 51.5 for the FS and CW COBs. Guessing 50 watts go into the LEDs and the remainder is used up by the linear drive chips? At 110VAC the linear chips are putting out 80mA per chip, and theres 5 per COB, which comes out to .4A. The tricky part is knowing how much of the 110V is being used on average, since the power is cutting on and off 60hz.

Youtube user DiodeGoneWild said that the LEDs are being powered for 4.7ms, and cutting off for 4ms, and the chips take .75ms to charge up and turn on the LEDs.

What this all means, I have no idea. I'm not an electrical engineer and I won't be scrapping off any silicone from a COB to get some more measurements off the IC chips. Maybe NoFucks2Give will be kind enough to get his hands dirty and give us a full electrical analysis on these chips.

All and all, I can live with the efficiency of these COBs and don't mind burning up 10W to turn the power down 500watts. I'm planning on building an identical rig except the cool white lights will be switched out with warm white. Come flower time the Variac will be put to rest and 600 watts of the 2nd rig (soon to be made) will be put into service.

Can't wait to see the buds this light makes coupled with a water farm. Give it a month and check out my (signature) Current Grow Op to see the progress!

 

[ttystikk]

You did not specify the type of switching power supply. Your exact words were " which every switching power supply uses."




It took seconds to solder and the cost is almost nothing as previously stated.



No, a MAP torch is a $10 can of MAP gas with a torch head screwed on it. Looks exactly like a propane torch but with hotter burning gas.



I have a couple of those, and four Heliospectra RX30s, a couple of BLM Spydr, a KIND and on and on.

I am buying the milling machine to drill and tap holes. It's a glorified drill press. I wanted the table with a 23" x axis travel so I can move the table rather than the piece I am drilling. The milling machine cost much less than one Heliospectra RX30 which run about $3,000 each. I need the mill becasue I make a lot of LED fixtures.

You see I have been an accomplished electrical engineer for over 40 years. I am now a consultant to the University of Florida's Horticulture Department that does the LED grow research. I design LED fixtures for them. I was hired by Dr Thomas Colquhoun who is arguably the guy that knows more about LEDs and growing plants than anyone else on this planet.

Oh, if you want send me one. I have a radiospectrometer with dual NIST traceable calibration from 200nm-800nm with the NIST LED calibration protocols. I attached a sales PDF that describes the capabilities. I highlighted the calibration I bought.

This is my test setup for measuring lux, radiant watts, and µMoles. I also measure the wattage at the wall, the current flowing through the LED(s), the forward voltage, the temperature, and other stuff.

View attachment 3971886


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See the thing circled below. That is how you measure the LED current. It's a current shunt in series with the LED's power supply. It's a precision resistance with a very small value. You measure the voltage across the shunt to calculate the current. Then the forward voltage is measured between the shunt and the other power lead to the LED. an easy way to measure both current and forward voltage with out the hassle of changing the setup from measuring current to measuring voltage and back and fourth.

View attachment 3971915

I did build the Cree/Meanwell Cadillac water cooled light;

4 x CXB3590 3500K CD bin 72V per Meanwell hlg185h c700b. These were mounted on 2x4" square section aluminum bar, welded end caps. I used 80 degree lenses.

The plan was to run chilled water through them, which was so effective the grow room would not warm up sufficiently lol



I'd very much like to hear your thoughts on the design.

 

[CobKits]

horizontal grow?!?! blasphemy!!!!!

 

[Mullumbimby]

I did build the Cree/Meanwell Cadillac water cooled light;

4 x CXB3590 3500K CD bin 72V per Meanwell hlg185h c700b. These were mounted on 2x4" square section aluminum bar, welded end caps. I used 80 degree lenses.
The plan was to run chilled water through them, which was so effective the grow room would not warm up sufficiently lol
I'd very much like to hear your thoughts on the design.

I know you're not asking me but I think it's a Beautiful Thing.
How did you 'chill' the water, and how do you think the efficiency of the chips would go, if using a radiator (in or out of the room, depending on the weather). Do you think you'd be able to hold the Tj at a couple of degrees above ambient?

 

[ttystikk]

I know you're not asking me but I think it's a Beautiful Thing.
How did you 'chill' the water, and how do you think the efficiency of the chips would go, if using a radiator (in or out of the room, depending on the weather). Do you think you'd be able to hold the Tj at a couple of degrees above ambient?

I used a 5 Ton chiller. Nothing if not overkill, as it turned out...

I was able to keep Tj well below ambient, to the point where the aluminum blocks were dripping wet with condensation. The original idea was to remove all excess heat from the growing space and at that task the approach was an unqualified success; 225W per module x 24 modules = 5400W in a 6' wide by 12' long by 8' tall space and it would never get warmer than 72F. And that was with additional heat from outside the space...

To answer your question more directly, 'it depends' on;
1. Wattage and therefore heat load going into the system
2. Extraction capacity of the radiator and fan
3. What the ambient temperature is where the radiator is placed.
4. Size of pump and therefore velocity of water passing the heat through the system.

 

[ttystikk]

horizontal grow?!?! blasphemy!!!!!

That was a shot of early veg. They went vertical shortly after.

 

[MMJ Dreaming 99]

These blue temps are from the same time as the red in the previous post. Sept. 2016
In both there is a column with the delta Δ symbol, that's the difference column

Being blue the forward voltage is higher than red. The red were about 35V @ 700mA and these blue are 45V @ 1.0 amp.
With ice water 0° C the delta averaged 22.6° C At ambient 23° C no cooling the average delta was 13.6° C

At 0° C water temp the thermal pad temperature was only, on average, 22.6°C. Lower than the datasheet 25° C.
With no cooling the average pad temp was 41.7° C at ambient 23° C.

There was not any significant change in water temp in and out.

With the LEDs off the pad temp was 11° C
Took 4 minutes to get up to 22° C and stayed there.
I did not always measure the same LED. The 24° C reading was probably an LED that had a gap to the copper.


View attachment 3972646

___________________________________________________________________________________

FLOW RATE

This was my first setup.
The flow rate did not seem to matter. I now use two 60 gal/hr DC brushless pumps. Two for when one fails.
The pump: https://www.amazon.com/gp/product/B00JWJIC0K/
I picked these because they can up pump to over a 6" height (Static lift).
It is best to have as little as possible difference in height between the water reservoir and the heatsink. The height difference slows the flow.

View attachment 3972649




Water really absorbs a lot of light. It is very likely that the light helped raise the water temp in this setup.


View attachment 3972648
View attachment 3972647

Here is a question that is not being a smart ass just curious. Why bother w water cooled COBs when you can use QB boards that run so cool?

My impression is if you want to still run big numbers it is still SE and really DE HPS.
COBs are pretty comparable with QBs. I have yet to see a 3 lb per light grow using COBs or QBs. I have seen first hand 2.9 lb with middling SE HPS.

Not trying to stir up trouble just looking for opinions and input.

 

[ttystikk]

Here is a question that is not being a smart ass just curious. Why bother w water cooled COBs when you can use QB boards that run so cool?

My impression is if you want to still run big numbers it is still SE and really DE HPS.
COBs are pretty comparable with QBs. I have yet to see a 3 lb per light grow using COBs or QBs. I have seen first hand 2.9 lb with middling SE HPS.

Not trying to stir up trouble just looking for opinions and input.

In my case, I wanted better control over the heat generated.

 

[CobKits]

Here is a question that is not being a smart ass just curious. Why bother w water cooled COBs when you can use QB boards that run so cool?

because watt for watt they put out simlar amounts of heat to your space, its jsut spread out over a larger surface area. COBs and QBs are only 30-40% more efficient than HIDs (and heat removal from LEDs is not always as obvious as heat removal from HIDs in air-cooled fixtures), so heat still is a factor that must be controlled.

For example if you use CO2 it is in your best interest to remove heat directly without pulling air from the grow space, both water cooling and air cooled hoods (sealed, with fresh air intake) accomplish this.

also a side benefit of water cooling is the heat is more easily recovered and repurposed

My impression is if you want to still run big numbers it is still SE and really DE HPS.

theres not much basis to that assertion

I have yet to see a 3 lb per light grow using COBs or QBs. I have seen first hand 2.9 lb with middling SE HPS.

overall yield "per light" is somewhat irrelevant. keep in mind that historically the major incentive for using larger lights is that the efficency is higher. before 600W bulbs were common you were taking a big hit to use 400W bulbs instead of 1000W.

In any case, if youre looking for impressive numbers "per light", how many LED rigs have you seen that draw 1100W from the wall? your 2.9lb = 1.2GPW. Thats on the low end of what people get with good LED grows

growmau5's latest well-documented grow was 1.7 GPW, 2.7lb from 711W

one other major benefit to water cooling with LEDs is direct removal of heat makes a big difference in chip efficiency. you can gain 3-5% or more by dropping chip temp substantailly with water cooling. you do the math on 3-5% more par on your canopy 5-6 cycles a year

 

[ttystikk]

because watt for watt they put out simlar amounts of heat to your space, its jsut spread out over a larger surface area. COBs and QBs are only 30-40% more efficient than HIDs (and heat removal from LEDs is not always as obvious as heat removal from HIDs in air-cooled fixtures), so heat still is a factor that must be controlled.

For example if you use CO2 it is in your best interest to remove heat directly without pulling air from the grow space, both water cooling and air cooled hoods (sealed, with fresh air intake) accomplish this.

also a side benefit of water cooling is the heat is more easily recovered and repurposed


theres not much basis to that assertion



overall yield "per light" is somewhat irrelevant. keep in mind that historically the major incentive for using larger lights is that the efficency is higher. before 600W bulbs were common you were taking a big hit to use 400W bulbs instead of 1000W.

In any case, if youre looking for impressive numbers "per light", how many LED rigs have you seen that draw 1100W from the wall? your 2.9lb = 1.2GPW. Thats on the low end of what people get with good LED grows

growmau5's latest well-documented grow was 1.7 GPW, 2.7lb from 711W

one other major benefit to water cooling with LEDs is direct removal of heat makes a big difference in chip efficiency. you can gain 3-5% or more by dropping chip temp substantailly with water cooling. you do the math on 3-5% more par on your canopy 5-6 cycles a year

I concur.

My own results with water cooled LED support your assertions above.

 

[NoFucks2Give]

Why bother w water cooled COBs when you can use QB boards that run so cool?

I do not use CoBs. I use strips of red, white, and blue discrete LEDs with dimmers on each string of 16 or 21 LEDs.
LEDs, especially red, are very temperature sensitive. The cooler they run the more photon flux produced per watt of electricity.
The heatsink is also the frame of the fixture. The copper pipe's cost is less than an aluminum heatsink.

 

[NoFucks2Give]

linear integrator chips

Linear integrator is not a thing. Regulator is a thing.

thermoregulating the current.

Thermoregulating is not a thing.

chips have to reach somewhere around 130C

That is too hot for any chip. Chips work better, longer, and more efficiently when cool. A 1° C rise in temperature reduces the life span 5%. So a 10° C rise will reduce the life of a semiconductor 50%. 130° C is not good.

 

[NoFucks2Give]

RHS is circular, square, and rectangular hollow sections.

The post below is a cool mac by @mahiluana in this thread. There are two aluminum square tubes. There is a square cut out under each CoB exposing the thermal pad to the water in the square pipe.

coolmac-system.