Cobs smoke

Budies 101

Budies 101

Well-Known Member
Hello, I have built 2 led lights in the past and now am building out a bunch more for my grow.

I built a veg light with CXB3070's bd 5000k bin and the driver is Meanwell hlg-240H-C1750A and with 4 cobs I see a draw from the wall of 150watts or more and the cobs start to smoke. I have 2 fans on this light as well.

It takes about 20 seconds for them to start smoking. Has anyone had this issue?

I'm at a loss because I thought these 4 cobs should be able to handle 240watts fairly easily, yet at 200+ watts they instantly start to smoke. I was under the impression I'd be running the driver at near or max with no issues but it seems like I have to dim the driver almost all the way to not get burning.

I used a thermal paste between the cob and the metal backing as well.

I'm at a loss =(
 

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iHearAll

iHearAll

Well-Known Member
David Abrahamson said:
Hello, I have built 2 led lights in the past and now am building out a bunch more for my grow.

I built a veg light with CXB3070's AB bin and the driver is Meanwell hlg-240H-C1750A and with 4 cobs I see a draw from the wall of 150watts or more and the cobs start to smoke. I have 2 fans on this light as well.

It takes about 20 seconds for them to start smoking. Has anyone had this issue?

I'm at a loss because I thought these 4 cobs should be able to handle 240watts fairly easily, yet at 200+ watts they instantly start to smoke. I was under the impression I'd be running the driver at near or max with no issues but it seems like I have to dim the driver almost all the way to not get burning.

I used a thermal paste between the cob and the metal backing as well.

I'm at a loss =(
Click to expand...
you're probably over volting them. ignore power for a moment. what is the voltage theyre rated for? what is the voltage of the supply? 200w could mean 1v 200a (not going to happen but you seee what i mean).
 
iHearAll

iHearAll

Well-Known Member
although i have used a variable power supply to test chinese basic chips and they were not what was sold. they were mixed up somehow and were 20v chips being sold as 32v chips. those smoked up. but were only 2.50$
 
Budies 101

Budies 101

Well-Known Member
iHearAll said:
you're probably over volting them. ignore power for a moment. what is the voltage theyre rated for? what is the voltage of the supply? 200w could mean 1v 200a (not going to happen but you seee what i mean).
Click to expand...

I thought 36v a cob.
 
HydroRed

HydroRed

Well-Known Member
David Abrahamson said:
Hello, I have built 2 led lights in the past and now am building out a bunch more for my grow.

I built a veg light with CXB3070's bd 5000k bin and the driver is Meanwell hlg-240H-C1750A and with 4 cobs I see a draw from the wall of 150watts or more and the cobs start to smoke. I have 2 fans on this light as well.

It takes about 20 seconds for them to start smoking. Has anyone had this issue?

I'm at a loss because I thought these 4 cobs should be able to handle 240watts fairly easily, yet at 200+ watts they instantly start to smoke. I was under the impression I'd be running the driver at near or max with no issues but it seems like I have to dim the driver almost all the way to not get burning.

I used a thermal paste between the cob and the metal backing as well.

I'm at a loss =(
Click to expand...

How thick did you apply the thermal paste? It should be applied so thin it will almost be translucent. Lots of ppl think more is better and that couldn't be further from the truth when it comes to thermal paste. I dont know your technical experience level so this is just an observation.
 
Budies 101

Budies 101

Well-Known Member
HydroRed said:
How thick did you apply the thermal paste? It should be applied so thin it will almost be translucent. Lots of ppl think more is better and that couldn't be further from the truth when it comes to thermal paste. I dont know your technical experience level so this is just an observation.
Click to expand...
At first I did a small amount and I don't think it covered the whole led. Next I did a carp ton so it was pressing out the edges.
 
Budies 101

Budies 101

Well-Known Member
HydroRed said:
This may be your issue. The heat cant transfer properly if the paste is on too thick.
Click to expand...

Ok, I went back and wiped all the paste off the first try and added a lot more to see if it would help. I will try less but maybe a better spread.

Even at 150 watts the cobs feel really hot, like almost untouchable. I don;t touch the cob surface, but even the holders next to the cobs are burning hot.
 
iHearAll

iHearAll

Well-Known Member
that's nuts. its not reading the current correctly then. it should work on feedback from the output." if the output is 1750mA then maintain this voltage."
 
Budies 101

Budies 101

Well-Known Member
iHearAll said:
that's nuts. its not reading the current correctly then. it should work on feedback from the output." if the output is 1750mA then maintain this voltage."
Click to expand...

OK, I had a weird issue with the draw reading on my first 2 lights.

When I would see a draw on 5 cobs it would be at like 62 watts... And the driver was maxed at 320watts. I figured it was somehow giving me a reading on a single cob.

Maybe its the watt/amp reader I have that sucks.
 
iHearAll

iHearAll

Well-Known Member
David Abrahamson said:
OK, I had a weird issue with the draw reading on my first 2 lights.

When I would see a draw on 5 cobs it would be at like 62 watts... And the driver was maxed at 320watts. I figured it was somehow giving me a reading on a single cob.

Maybe its the watt/amp reader I have that sucks.
Click to expand...
im thinking that since the driver is a constant current driver, it is trying to regulate something that is out of its range of reading. it says on the datasheet that it reads a range of 72-143vdc and you're one volt higher than you should be for a constant current driver. you need a constant voltage driver.

a constant voltage driver would work on a range of amps at a particular voltage.
a constant current would work on a range of voltage at a particular current.

make sense?

the drivers datasheet also say that at 146v it is an open circuit. i think this means that it is guaranteed to be unregulated currents up there. which may be past the 2800ma max of those chips.

http://www.trcelectronics.com/Meanwell/led-power-supply-erp.shtml
ERP-350-36 36VDC 9.7A 349.2W
 
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