Shredderthirty
Well-Known Member
how close can you place the CXB3590s to each other?
Heatsinks for DIY LED lamps
- Thread starter SupraSPL
- Start date
robincnn
Well-Known Member
True, I have had odd readings as thermouple got near LES or just close enough that light messed up the reading.
For vero 29 I use ledil reflector holder and it shields Tc point from any light or radiation heat from LES.
With cree I am still testing Tc but the ideal connector blocks Tc point.
For vero 29 I use ledil reflector holder and it shields Tc point from any light or radiation heat from LES.
With cree I am still testing Tc but the ideal connector blocks Tc point.
ttystikk
Well-Known Member
This isn't an absolute number. It depends on whether you're passive or actively cooling, size and shape of your heat sink, how hard you're running your chips and intended environment.
ttystikk
Well-Known Member
If temperature droop isn't as much of a concern as current droop when calculating efficiency, what is a good number to stay below?
'Cold as possible' is completely useless to me, I'm looking for a temperature to never exceed, or a range to stay below for best longevity.
I'm betting I can maintain my chips at any temperature I like, so it begs the question; what would I like best- and why?
Shredderthirty
Well-Known Member
yeah i know it was a vague question but i typed out a lil paragraph up higher and it just got skipped over so i just threw that back out there, lemme copy and paste from above
so i'm just trying to imagine how much power i can ultimately run on this 10" by 36" heatsink. right now i have 200 W on it passively cooled with eight CXB3590s.
I want to put 200W more on it for sure and know it could take that, but the question is how close can you place the CXB3590s to each other? i guess it depends on how many watts are going to each cob.....really i was just bored and imagining trying to put 8 more CXB on this heat sink but that would require to get two rows 3 cxb wide on a 10" wide heatsink to properly space them all out....
I only really planned on putting 14 on this heatsink and running seven cxb/hlg-185-c700 but i've been thinking about cooling it with two large fans like the one @REALSTYLES uses and going with three drivers to power 16 cobs (two with 5cxb and one with 4cxb)
so i'm just trying to imagine how much power i can ultimately run on this 10" by 36" heatsink. right now i have 200 W on it passively cooled with eight CXB3590s.
I want to put 200W more on it for sure and know it could take that, but the question is how close can you place the CXB3590s to each other? i guess it depends on how many watts are going to each cob.....really i was just bored and imagining trying to put 8 more CXB on this heat sink but that would require to get two rows 3 cxb wide on a 10" wide heatsink to properly space them all out....
I only really planned on putting 14 on this heatsink and running seven cxb/hlg-185-c700 but i've been thinking about cooling it with two large fans like the one @REALSTYLES uses and going with three drivers to power 16 cobs (two with 5cxb and one with 4cxb)
ttystikk
Well-Known Member
I'm pretty sure that two of those big fans would be plenty, as long as they're getting reasonably cool air to work with. If they're stuck up in the top of a tent without ventilation for example, they'll get hot just because there's nowhere for the heat to go.
robincnn
Well-Known Member
Try as cold as possible.
Here is more for Vero cob. Cree should be similar. Will see if I can get LM 80 for cree
Try keep Tc below or at 55C are you are cool. Your cob will last long and minimal or no lumen loss at 10000hrs
Reach 85 C and be prepared to lose a little. 2% lumen loss at 10,000hrs
Reach 105 and 4% at 10000hrs.
I don't have any data beyond 10000hrs. But anything below 65C would not be my preference. Don't ask my why
Here is more for Vero cob. Cree should be similar. Will see if I can get LM 80 for cree
Try keep Tc below or at 55C are you are cool. Your cob will last long and minimal or no lumen loss at 10000hrs
Reach 85 C and be prepared to lose a little. 2% lumen loss at 10,000hrs
Reach 105 and 4% at 10000hrs.
I don't have any data beyond 10000hrs. But anything below 65C would not be my preference. Don't ask my why
ttystikk
Well-Known Member
'But anything below 65C would not be my preference. Don't ask my why' = ???
Did you mean 'beyond 65C'?
100F = 37.77C. My plan is to keep the temp right around here, +/- 5F. What am I giving up by not running at 70F? 50F? Forget how to do it for the moment, I'm just interested in what the upside might be.
bggrass
Well-Known Member
Hey guys, I'm looking at this sheet for a cxb3590 CD 36V @1.4A. How do I calculate how much heatsink I need from hsusa? I know I 40cm^2 per watt dissW@50 for active and 120cm^2 for passive.
I think I need 7.5" of the 5.88" profile, active cooling. Am I correct?
I think I need 7.5" of the 5.88" profile, active cooling. Am I correct?
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littlejacob
Well-Known Member
Bonjour
How are you my friend?
I am not sure you could go this low in temperature...
We should ask @SupraSPL the temperature of his cob on his biggest hs! And how low the temperature could be @1400mA!
Have a great day ★
littlejacob
Well-Known Member
Bonjour
Could you tell me why you want more cxb?
Why don't you run them @50w...1400mA?
What is the size of your box?
If you have a 4x4 and aim for a cob for each sq/ft why don't you put one over each sq/ft? To have the best coverage possible? It is my goal!
800w of dimmable cob!
Have a great day ★
ttystikk
Well-Known Member
I'm well my friend, hope you are the same!
I can go as low as I like. I think I've worked out a way to operate them and maintain a below freezing temperature if I thought there was a benefit to it!
For the record, I do not think any such thing, I'm thinking that the difference between 25 and 35C isn't worth the trouble. I'm concerned about condensation if I go too low.
However, before I allow this assumption to ruin my thinking, I want to hear from those who know.
EfficientWatt
Well-Known Member
Depends what the cost would be.
If you can run your cobs at -35°c (just a random negative numba) with no hassle whatsoever or extra cost, then trust me, you should.
Just looking at PCT ... with cxb3590 : a CB@-35°c is superior to a CD @+25°c !
If you can run your cobs at -35°c (just a random negative numba) with no hassle whatsoever or extra cost, then trust me, you should.
Just looking at PCT ... with cxb3590 : a CB@-35°c is superior to a CD @+25°c !
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ttystikk
Well-Known Member
I'm thinking that much below about 65F there's too much risk of condensation, so that's not really a viable option.
But, how much does the difference between 90F and 100 matter? How about 110?
EfficientWatt
Well-Known Member
You've never messed around with PCT ? : http://pct.cree.com/dt/index.html
1) Select Model.
2) Select Bin
3) Set "Current range" in top right to "coarse" (or "very coarse").
Mess with Tj, or whatever you wanna mess with
1) Select Model.
2) Select Bin
3) Set "Current range" in top right to "coarse" (or "very coarse").
Mess with Tj, or whatever you wanna mess with
sureshot138
Well-Known Member
I don't know how the math works but I went with the 10" profile 6" long. (thanks supra). I am in the process of building it.
bggrass
Well-Known Member
I'm asking for the math cause I thought I got that part, but someone questioned it, in another website. So I'm just trying to verify here. Thanks though.
4 cxb3590 36V CD @1.4A
4 x 48.85 = 195.4 heat watts
195.4 x 40 = 7816 heatsink area required
7816 / 260 = 30.06 inches of the hsusa 5.88" profile, active cooling
Am I missing anything?
lednewbie123
Member
I would like to have someone who knows the math verify before I end up wasting $500. Im horrible at math and my numbers dont match whats showed here. Tried figuring out the math that made 10284cm² -> 5.88" X 38" but I ended up with a very diff number. Long story short am I correct that the heatsinkusa 7.28inx7in is more surface area than the 5.866inx9.5in
qwerkus
Well-Known Member
Update 2 - new formula. As I need 2 more lamps, I brookered the following deal: I provide chips and drivers, and the chinese company builds the lamps, and ships them overseas. This means only 1 shipment, and reliable sources for the main parts (chip, driver). Price per lamp is $17lamp+$32chip+$6driver=$55 excluding shipment. This time it's cxb3070 guaranteed by jerry from KingBrite. Also, I brookered a deal to get a sample for citizen CLU046. For anyone interested, I will update this in the chips thread.
SupraSPL
Well-Known Member
Grabbed a bunch a thermometers and settled on this one
http://www.amazon.com/Digital-Candy-Deep-Fry-Thermometer/dp/B0075M5ESY/ref=sr_1_10?s=kitchen&srs=2530581011&ie=UTF8&qid=1446179683&sr=1-10&keywords=taylor thermometer
It gives readings that agree with the mercury, but much faster and easier (10-20 seconds) so I have a lot more confidence in the measurements/ I have abandoned the IR thermometer which has proven to be precise and repeatable, but very inaccurate for measuring aluminum.
These heatsink temps were taken directly behind the COB which was the hottest place on the heatsink that I could find, including the front next to the COB which was a few degrees cooler. Ambient in the tent was ~75F(24C) and there was decent airflow from the circulation fan hitting all heatsinks with a slight breeze.
Passive cooled in flower tent, all driver turned up to max
====================================
CXA3070 3000K AB bin @ 25.5W ea:
8.46"X12", 96F (35.5C) 188cm²/heat W
CXB3070 3000K AD bin @ 24.5W ea:
8.46"X12", 96F (35.5C) 222cm²/heat W
4.9"X14", 96F (35.5C) 153cm²/ heat W
CXB3590 3500K CD bin @ 24W ea:
8.46"X12", 93F (34C) 277cm²/heat W (good demonstration of the law of diminishing returns)
4.9"X14", 93F (34C) 190cm²/heat W (this heatsink was tilted unfavorably for cooling, did not matter)
4.9"X14", 93F (34C) 190cm²/heat W
10.08"X6" 90F (32C) 318cm²/heat W (overkill surface area, but a good data point)
CXB3590 3000K CB bin @ 26.5W ea
10.08"X6" 84F (29C) 247cm²/heat W (these were on the edges, must be getting the best airflow)
=============================================
Passive cooled in veg tent, driver set at maximum
single CXA3590 5K DB 24.5W:
5.88"X6" with slight airflow hitting heatsink 90F (32C), 179cm²/heat W
5.88"X6" with almost no airflow 108F (42C), 179cm²/heat W
According to the PCT, the difference in output between these 2 temps is about 2%.
=================================================
Active cooled veg fixture:
pair of CXA3590s 5K DB @ 85W ea:
3.5"X36" with 2.5W of 80mm fan, 108F (42C), 52.6 cm²/ heat W (measured 4% temp droop)
===================================================
Still digesting this data
http://www.amazon.com/Digital-Candy-Deep-Fry-Thermometer/dp/B0075M5ESY/ref=sr_1_10?s=kitchen&srs=2530581011&ie=UTF8&qid=1446179683&sr=1-10&keywords=taylor thermometer
It gives readings that agree with the mercury, but much faster and easier (10-20 seconds) so I have a lot more confidence in the measurements/ I have abandoned the IR thermometer which has proven to be precise and repeatable, but very inaccurate for measuring aluminum.
These heatsink temps were taken directly behind the COB which was the hottest place on the heatsink that I could find, including the front next to the COB which was a few degrees cooler. Ambient in the tent was ~75F(24C) and there was decent airflow from the circulation fan hitting all heatsinks with a slight breeze.
Passive cooled in flower tent, all driver turned up to max
====================================
CXA3070 3000K AB bin @ 25.5W ea:
8.46"X12", 96F (35.5C) 188cm²/heat W
CXB3070 3000K AD bin @ 24.5W ea:
8.46"X12", 96F (35.5C) 222cm²/heat W
4.9"X14", 96F (35.5C) 153cm²/ heat W
CXB3590 3500K CD bin @ 24W ea:
8.46"X12", 93F (34C) 277cm²/heat W (good demonstration of the law of diminishing returns)
4.9"X14", 93F (34C) 190cm²/heat W (this heatsink was tilted unfavorably for cooling, did not matter)
4.9"X14", 93F (34C) 190cm²/heat W
10.08"X6" 90F (32C) 318cm²/heat W (overkill surface area, but a good data point)
CXB3590 3000K CB bin @ 26.5W ea
10.08"X6" 84F (29C) 247cm²/heat W (these were on the edges, must be getting the best airflow)
=============================================
Passive cooled in veg tent, driver set at maximum
single CXA3590 5K DB 24.5W:
5.88"X6" with slight airflow hitting heatsink 90F (32C), 179cm²/heat W
5.88"X6" with almost no airflow 108F (42C), 179cm²/heat W
According to the PCT, the difference in output between these 2 temps is about 2%.
=================================================
Active cooled veg fixture:
pair of CXA3590s 5K DB @ 85W ea:
3.5"X36" with 2.5W of 80mm fan, 108F (42C), 52.6 cm²/ heat W (measured 4% temp droop)
===================================================
Still digesting this data
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