Heatsinks for DIY LED lamps

Randomblame

Randomblame

Well-Known Member
That's 65w per COB and should work. You can measure the heatsink temps after a few hours to see where they stabilize. Maybe runnuing the fans at only 9 or 6 volts is already enough, these cheap fans are a bit noisy at 12v.

But such a small heatsink is not fail safe. If the fan fails, they will quickly overheat. You should switch to a HLG-240H-36A, and wire the COB's in parallel and add a thermal switch to each heatsink (simple bimetal switch, "NO" means "normal open", 90°C off). If one fan fails and the radiator temperature exceeds 90°C, it will be switched off and the others will continue to run. With a series connection that is not feasible!

You can still use a series circuit, but if one fan fails and the corresponding COB fails too the whole light will be switched off and you need to locate the faulty one, which is far easier with a parallel setup.

Why not use passive 120 or 130mm Ø pin fin heatsinks? Yes, they cost a lot more, but they cool passively. No additional power consumption, no wiring and they are fail-safe! With such a heatsink/fan combo I guarantee you the first failure within the first year. Parallel wiring is also much safer for you, as it uses only 36v, which is also in the worst case not fatal.
 
jahrigami

jahrigami

Member
Randomblame said:
That's 65w per COB and should work. You can measure the heatsink temps after a few hours to see where they stabilize. Maybe runnuing the fans at only 9 or 6 volts is already enough, these cheap fans are a bit noisy at 12v.

But such a small heatsink is not fail safe. If the fan fails, they will quickly overheat. You should switch to a HLG-240H-36A, and wire the COB's in parallel and add a thermal switch to each heatsink (simple bimetal switch, "NO" means "normal open", 90°C off). If one fan fails and the radiator temperature exceeds 90°C, it will be switched off and the others will continue to run. With a series connection that is not feasible!

You can still use a series circuit, but if one fan fails and the corresponding COB fails too the whole light will be switched off and you need to locate the faulty one, which is far easier with a parallel setup.

Why not use passive 120 or 130mm Ø pin fin heatsinks? Yes, they cost a lot more, but they cool passively. No additional power consumption, no wiring and they are fail-safe! With such a heatsink/fan combo I guarantee you the first failure within the first year. Parallel wiring is also much safer for you, as it uses only 36v, which is also in the worst case not fatal.
Click to expand...
Thank you for replying to my question. But i already have everything ready except for these rare wago conductor connector and waterproof powersupply since im in the philippines and i dont have any access to passive heatsinks other than online market and im running out of budget 9361236C-F701-4AE1-B270-028FCC4CE1AA.jpeg
 
Airwalker16

Airwalker16

Well-Known Member
Pedro Mello

Pedro Mello

Well-Known Member
Hi guys!
I'm planning to use one I70 cooler (Coolermaster) per vero29 working at aprox 75w (i'm using 50 heat watts for design).
Coolermaster's site says that this cooler has 95W TDP. So I concluded it'd fit. Is this the right way of think?
Besides that, how do I know if this cooler matches with veros' dimensions? Does the square base area of passive heatsink have necessarily be higher than the cob area?
Thanks since now!
 
JavaCo

JavaCo

Well-Known Member
Pedro Mello said:
Hi guys!
I'm planning to use one I70 cooler (Coolermaster) per vero29 working at aprox 75w (i'm using 50 heat watts for design).
Coolermaster's site says that this cooler has 95W TDP. So I concluded it'd fit. Is this the right way of think?
Besides that, how do I know if this cooler matches with veros' dimensions? Does the square base area of passive heatsink have necessarily be higher than the cob area?
Thanks since now!
Click to expand...
Would be more like 37 watts of heat for a gen 7 vero 29 but i really doubt you will be able to mount a vero29 on a I70 cooler unless you use a thermal adhesive which I don't recommend. So much better off drilling and taping holes so you can remove the chip and replace the thermal paste every 5 to 10 years or so depending on the quality of thermal paste used. I would find a heatsink big enough to let you drill and tap holes so the vero 29 is removable.
 
Pedro Mello

Pedro Mello

Well-Known Member
JavaCo said:
Would be more like 37 watts of heat for a gen 7 vero 29 but i really doubt you will be able to mount a vero29 on a I70 cooler unless you use a thermal adhesive which I don't recommend. So much better off drilling and taping holes so you can remove the chip and replace the thermal paste every 5 to 10 years or so depending on the quality of thermal paste used. I would find a heatsink big enough to let you drill and tap holes so the vero 29 is removable.
Click to expand...
Thank you, man! It's a very useful info.

Just to get sure: the method is an simply comparison between cooler's TDP and cobs heat watts, considering the contact area. Was I right thinking this?

And btw, do you have any cooler suggestion for me?
 
JavaCo

JavaCo

Well-Known Member
Pedro Mello said:
Thank you, man! It's a very useful info.

Just to get sure: the method is an simply comparison between cooler's TDP and cobs heat watts, considering the contact area. Was I right thinking this?

And btw, do you have any cooler suggestion for me?
Click to expand...
A cpu would be putting out 95 watts of heat unlike a COB like a vero29 gen 7 would be putting out over 50% light and 50% heat ( if it was 50% efficient @ 95 watts) . So if you ran it at 95 watts it would need 47.5 watts of heatsink cooling. So that heatsink could handle more wattage Just not a good way to secure the cobs. Personally i would go with something like these 134mm heat sinks that are passive so no fans to worry about https://led.cdiweb.com/Products/Detail/MODULEDMEGA134100BHBG-MechaTronix/574067/
 
Pedro Mello

Pedro Mello

Well-Known Member
JavaCo said:
A cpu would be putting out 95 watts of heat unlike a COB like a vero29 gen 7 would be putting out over 50% light and 50% heat ( if it was 50% efficient @ 95 watts) . So if you ran it at 95 watts it would need 47.5 watts of heatsink cooling. So that heatsink could handle more wattage Just not a good way to secure the cobs. Personally i would go with something like these 134mm heat sinks that are passive so no fans to worry about https://led.cdiweb.com/Products/Detail/MODULEDMEGA134100BHBG-MechaTronix/574067/
Click to expand...
Nice! I've spent a quite time searching about passive HS. My problem is that I live in Brazil and the market of passive HS here is shameful. My only manner to get those would be importing from US or another country, which would be very expensive. =(

I've just looked some guys talking about Alpine 11 cooler. I think it's probably cause its base is apparently big (squared with no gaps). Do you think it's a smart choice for my case?

Thank you again, you are being very helpful.
 
JavaCo

JavaCo

Well-Known Member
Pedro Mello said:
Nice! I've spent a quite time searching about passive HS. My problem is that I live in Brazil and the market of passive HS here is shameful. My only manner to get those would be importing from US or another country, which would be very expensive. =(

I've just looked some guys talking about Alpine 11 cooler. I think it's probably cause its base is apparently big (squared with no gaps). Do you think it's a smart choice for my case?

Thank you again, you are being very helpful.
Click to expand...
Yeah lots of people using the Alpines never heard any complaints and they are fairly cheap. You can drill and tap them too so that a big plus. I would imagine you will have to replace the fans at least once during the lifetime of the vero 29 a flowering only light can last 20 years or longer.
 
madininagyal

madininagyal

Well-Known Member
Pedro Mello said:
Nice! I've spent a quite time searching about passive HS. My problem is that I live in Brazil and the market of passive HS here is shameful. My only manner to get those would be importing from US or another country, which would be very expensive. =(

I've just looked some guys talking about Alpine 11 cooler. I think it's probably cause its base is apparently big (squared with no gaps). Do you think it's a smart choice for my case?

Thank you again, you are being very helpful.
Click to expand...
They are not passive but they work really well with my cxb 3590 @36v they even could handle 72v
 
Pedro Mello

Pedro Mello

Well-Known Member
madininagyal said:
They are not passive but they work really well with my cxb 3590 @36v they even could handle 72v
Click to expand...
Thanks!

Does the cobs have to fit exactly on the little different-gray square of the Alpine?
Is alright that the cobs are a little bigger than these square or the dissipation would be prejudiced?
 
madininagyal

madininagyal

Well-Known Member
Pedro Mello said:
Thanks!

Does the cobs have to fit exactly on the little different-gray square of the Alpine?
Is alright that the cobs are a little bigger than these square or the dissipation would be prejudiced?
Click to expand...
1541649181696335827799.jpg

I wipe the grey square when i clean it with iso and i put a thermal pad under the cob
 
You must log in or register to reply here.
Top