Heatsinks for DIY LED lamps

G

gresskar

New Member
Airwalker16 said:
You kbow, that's a cool idea
You could use multiple small short length's for each cob and just mount this style to whatever your hear desires! :)
But FYI: I'm not too sure that say, an Ideal Chip Lok style COB holder will even fit on that would it? Or do you plan on using kapton tape?
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according to the ideal brochure, the two holder screw holes have the same spacing (unsure about hole-diameter) as on the heatsink. The cob holder is larger than the inner circle of the heatsink, but I figured it's not a problem since screw holes are aligned, and the actual LED cob will be covered by the inner circle.

came across the seller's website when searching for a european alternative to heatsinksusa, kinda looks like they've designed the heatsink for LED cobs with the 3070's size
 
J

john0000

Well-Known Member
well got my stuff from kb today..and trying to drill and tap and broke two taps so far ..piece of shit irwin taps ..so heated right now ...the taps are so small for 4-40 screws its a joke
 
alesh

alesh

Well-Known Member
frica said:
Easily.
It would be able to handle it at 1.5A easily too.
1.8A too.

You generally want to keep the temperature of the COB under 85 degrees, it can handle more heat when driven below 2.8A but going hotter means sacrificing efficiency.
The heatsink temp increases by 0.738 °C every watt, so let's say you want to keep the temp within 50 degrees of ambient it can dissipate around 67 watts of heat.
A CXA3070 doesn't even pull 20 watts at 500mA, so it will barely heat up with that heatsink.
Also not everything in the LED becomes heat directly, it's probably 55% efficient at 500mA so the heatsink only has to dissipate less than half of what the LED pulls.

At 60mm it will be able to handle up to 2.1A easily.

Remember to use a good heat pad/heat paste
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Only under testing conditions which usually include high temperature difference between the HS and ambient. In our case, the temperature difference is smaller and Rth is therefore higher.
 
frica

frica

Well-Known Member
alesh said:
Only under testing conditions which usually include high temperature difference between the HS and ambient. In our case, the temperature difference is smaller and Rth is therefore higher.
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The ones on bal-group based on a temperature rise 60 degrees celcius above ambient which is imo reasonable enough that it's imo accurate enough for LEDs.
You could also pretend that a LED is only half as efficient as it really is and then base the heat sink choice on a hypothetical lowered efficiency.
 
Mary's Confidant

Mary's Confidant

Well-Known Member
Can someone walk me through the calculation to determine surface area of heatsink needed to passively cool a cob?

I'm going to run 3070 BBs at 1050 or 1400. I'm looking at the 7.2" profile and I'm wondering what size piece would adequately cool a single cob running at those currents. Anyone care to walk me through this or point me to the equation? I'm on page three of this thread and I'll work my way up but I was hoping someone could streamline this for me.
 
Greengenes707

Greengenes707

Well-Known Member
Mary's Confidant said:
Can someone walk me through the calculation to determine surface area of heatsink needed to passively cool a cob?

I'm going to run 3070 BBs at 1050 or 1400. I'm looking at the 7.2" profile and I'm wondering what size piece would adequately cool a single cob running at those currents. Anyone care to walk me through this or point me to the equation? I'm on page three of this thread and I'll work my way up but I was hoping someone could streamline this for me.
Click to expand...
 
S

ScubbaStevve

New Member
SupraSPL said:
Finally got around to organizing this and I figured it might come in handy for those who are designing DIY lamps. These charts show the surface area and surface area/cost for each of the Heatsink USA profiles.
View attachment 3300177

So in summary, the cheapest surface area is the 2.08" profile. It gives a lot of spread, maybe too much spread for our purposes. The 4.85" is also cheap and might be good for a vegging heatsink. Thin base plate though, not ideal for COBs.

The 4.6" serrated is a good value and it has a .23" baseplate thickness/riser height so it might be good for COB and gives a good spread between COBs. It has decent height to the fins, so uses active cooling efficiently (120mm fan should cover all fins). The 4.9" has a thick.3" base plate and still gives a good spread, should be very good for high powered COBs. Same with the 5.88" and it fits 140mm fans.
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Can you put those up in a Google Sheet and share them? Saves me time of retyping. I'm putting together a full calculator - based on the CXB 3590 3500K CB 36V (w/ different mA and efficiency) - where the input parameters are PPFD, and Coverage area, it will spit out a table the number of drivers required, then allows input for number of grow hours and cost of electricity (per kWh) and shows what the pay back time period in years to choose the more efficient driver to achieve the same PPFD.
This is all part of my process on research, design, and intelligent decision making for building a good light setup. It'll be my first DIY lighting, actually knew to gardening too. Just finished my first aeoponics cloner DIY.

Thanks, ScubbaStevve
P.S. do you know the mouser pricing on HLG - 240H-c drivers? I put in $80 for now. ...I'll post / share a the Gsheet soon.
 
Fastslappy

Fastslappy

Well-Known Member
SupraSPL said:
Cheapest place I know of for ordering small amounts of drivers is Onlinecomponents.com
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+1 Supra
same day shipping & flat rate , they did me right each time I ordered , i got them the next day
granted they are across the Bay from me , but $8 flat rate next day
they do charge sales tax but will take a wholesale #
well packed as well that's a big issue with me Packing !
their site says to call 4 price match on qnty IIRC
the drivers ship outta Oakland & they have various warehouses in AZ & CA did some snooping
pretty legit place ,gonna turn into my go to 1st for shopping on hardware components
i've ordered drivers @ 5pm pst & still got them next day , the do all shipping on swing shift
all the UPS waybills are done by midnite & i get tracking that shows UPS has p/u shipment @ 12;30am
 
bassman999

bassman999

Well-Known Member
Fastslappy said:
+1 Supra
same day shipping & flat rate , they did me right each time I ordered , i got them the next day
granted they are across the Bay from me , but $8 flat rate next day
they do charge sales tax but will take a wholesale #
well packed as well that's a big issue with me Packing !
their site says to call 4 price match on qnty IIRC
the drivers ship outta Oakland & they have various warehouses in AZ & CA did some snooping
pretty legit place ,gonna turn into my go to 1st for shopping on hardware components
i've ordered drivers @ 5pm pst & still got them next day , the do all shipping on swing shift
all the UPS waybills are done by midnite & i get tracking that shows UPS has p/u shipment @ 12;30am
Click to expand...
Just dont expect them to return the sales tax on returns, because they wont
 
Danielson999

Danielson999

Well-Known Member
@SupraSPL
I have 18" lengths of Heatsinkusa's 4.85" profile. What do you think is the optimal current to run Vero 29's on them if I use some active cooling? Do you think 1050ma (38.2w) and 2 cobs on one sink would be appropriate? As you know, 1400ma isn't a great choice and 700ma pushes my budget alittle too far so I'm thinking of an HLG-120H-C1050 could run 4 of them on 2 of those sinks.
 
frica

frica

Well-Known Member
At what point does aluminum get too hot to touch?

Currently waiting for some AC fans so my vero setup is currently cooling passively.
The aluminum is too hot to touch, it should be able to handle the heat passively.
Is it because aluminum can already cause burn wounds at 60 degrees celcius?

Edit:turned on normal fan on bottom of the growbox and the metal is safe to touch now
 
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dionysus4

dionysus4

Well-Known Member
frica said:
At what point does aluminum get too hot to touch?

Currently waiting for some AC fans so my vero setup is currently cooling passively.
The aluminum is too hot to touch, it should be able to handle the heat passively.
Is it because aluminum can already cause burn wounds at 60 degrees celcius?

Edit:turned on normal fan on bottom of the growbox and the metal is safe to touch now
Click to expand...
i also would like to know about this(how how should sinks be?)
 
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