Heatsinks for DIY LED lamps

[SupraSPL]

Good info SDS! I guess that raises the question, which version are we currently getting from Digikey..

 

[SupraSPL]

Thanks for doing this testing supra, really important stuff to know. I'm sure you're already planning on it, but do you anticipate seeing how the Vero and CXA stack up at lower currents?

Definitely curious to see how 1.4A comparison turns out.

 

[FrozenChozen]

doing some testing myself... Went today and picked up half a dozen of each of these intel heat sinks for a whoping $5.... These Feit cobs I've been playing with are running fairly low but still killing it, I just can't hang with how dim they are out of the box as a screw in, and how hot they get.... I'm loving the "inexpensive but effective" route and quickly I'm building up to my own panel with these and some "interchangeable" 3 watt chip red/blue/white arrays.... Right now, testing though. I'm going for CHEAP at the moment as a trial run, so far only have about $60 into this panel and I am expecting more promising results!

 

[SupraSPL]

Nice, those will be running super cool even at 5V.

 

[SupraSPL]

Here are the results, Vero 29 3K @ 1.43A on Rosewill vs CXA3070 3K @ 1.43A on Rosewill.

Again I tried to estimate the actual efficiency numbers. Both Vf and temp droop are taken into account. The CXA creates 6.8% more light/W. Fan speed is good at 5V 6V or 7.5V. 5V is quietest and the most efficient, but not by much. 7.5V would lead to a slightly lower Tj and less lumen depreciation.

It is noteworthy that even though the Vero has a superior thermal package, the CXA showed less temp droop, probably due to the excess of cooling power removing the Vero's advantage and the CXAs higher conversion efficiency creating less heat.

It is also noteworthy that even without the fan running and the heatsink too hot to touch, overall efficiency was about the same as active cooled. The downside of running so hot though, lumen depreciation. So that makes me wonder, would passive cooling be more efficient than active at lower currents?

Notice the Vero's larger Vf shift with temp. Not sure that means anything, but shows the different behaviors of each design.

 

[Dloomis514]

more 5v success

can i slow down my current fan drivers? What would i goggle to figure that out?

the fans only have 2 wires

 

[Greengenes707]

@SupraSPL, or anyone testing cooling parameters...Im just curious...and if you have the time/powersupply...how does 12v perform. From what we have seen so far... it's obviously an excess of cooling...but just curios how the full rated fan power would perform. 12v meanwell apv's are hard to pass up for how many fans they can run...but 12v is the lowest voltage.

 

[PurpleBuz]

@SupraSPL, or anyone testing cooling parameters...Im just curious...and if you have the time/powersupply...how does 12v perform. From what we have seen so far... it's obviously an excess of cooling...but just curios how the full rated fan power would perform. 12v meanwell apv's are hard to pass up for how many fans they can run...but 12v is the lowest voltage.

actually there is an apv-12-5 which is a 5 volt
and an apv-12-15 which is 15 volt

aternately could you put a couple in series ?

 

[Greengenes707]

actually there is an apv-12-5 which is a 5 volt
and an apv-12-15 which is 15 volt

aternately could you put a couple in series ?

You are correct...I have the 12v. But when seeing these test I went to look for lower V version and was looking at the model # which reference the watts.
Thanks.
Series could work too, never thought about it.

 

[SupraSPL]

Thank you PB for the part number I wish I had grabbed an APV-12-5 with my last order. And very good point about 12V GG, would be good to know whether it would be worth it to swap out adapters for those who are allready using 12V. Also, I realized I wanted to see how the Alpine 11 with CXA AB compares at 1.4A, and the Alpine 11 fan is lower RPM than the Rosewill, so I will do the test with 12V 9V 7.5V 6V and 5V.

 

[Abiqua]

I have been looking for old Cpu coolers thinking they could be had cheap. But looks like they don't get salvaged. Seems like an opportunity there

Nice, those will be running super cool even at 5V.

Looking at datasheets, like the V10 for instance, it seems running them " super cool" is just a voltage drain and hence in-efficient. Truth? Running @ 22C, the V10 almost pulls 4-5v's higher than @25C Tj-C. Which i thought was weird.....

 

[SupraSPL]

Where in the datasheet do you see that discrepancy? The Vf at Tj/Tc 22C should be almost exactly the same as at Tj/Tc 25C.

Here are some measurements from the 2700K 80 CRI Vero 10 I have on hand:
155mA - Heatsink stabilized @ 33C - Tj~39C - Vf 24.5
155mA - Heatsink cold start 24C - Tj 24C - Vf 24.67

 

[Abiqua]

Picked up 1 one of each, mess around with small cobs. V10's etc. Needed cheap heatsinks and I scored these 3 for $8.50. Trying to mess around with positioning of small Vero's in Veg....... All 5v fan's too, another perk...

The dell ran a P4 S478, which ran north of 75 watts....


the sony, has me a tad worried, because it ran a Pentium M1.6, which may be only as much as 15w under 90% power....


The duals ran a Conroe aka Core2 Duo in a Gateway., should be stout.....for 7.5 watts, lol

 

[Abiqua]

Where in the datasheet do you see that discrepancy? The Vf at Tj/Tc 22C should be almost exactly the same as at Tj/Tc 25C.

Here are some measurements from the 2700K 80 CRI Vero 10 I have on hand:
155mA - Heatsink stabilized @ 33C - Tj~39C - Vf 24.5
155mA - Heatsink cold start 24C - Tj 24C - Vf 24.67

I interpreted it incorrectly, for some reason, I thought it was a fairly consistent linear curve. which at first it seems, but then I realized that what it is showing, that even running @ Max Current @ -40C only increases about 5v's when at 85C and only 3Vs! at 25c.....whoops.....these seem to be very stable, on the datasheets and from your testing that is now showing it too.....

 

[SupraSPL]

Gotcha, in the case of Vf shift due to change in Tj, there is a corresponding change in output as well, so it does not affect efficiency directly. The actual temp droop is separate from that.

 

[SupraSPL]

The 5V setup on the Alpine11 was drawing less fan power than I thought. The 5, 6 and 7.5V were the best options for the A11. The 12V option resulted in about 3% less light/W but only a slight decrease in Tj. The 3.5V option did not result in any increase in efficiency, good to know. I figure the best option is the highest fan speed that does not result in any loss of efficiency, because it does result in a slightly lower Tj, reducing lumen depreciation over time.

 

[AquariusPanta]

So in short, the best of both worlds can be met when it comes to CPU coolers. Instead of one extreme, either passive (no power to fan) or full active (12V to fan), one can take the route of lesser-active (5-7.5V) to reach suitable efficiencies and temperatures.

Well that will be one thing I change in the coming projects - PSU's bearing lower potential. Thank you Supra for the countless efforts that you've put into this research of yours!

 

[SupraSPL]

Thanks AP. It is all great news for DIYers. We can use less heatsink than previously needed and we are getting more efficiency than previously thought. Saving a few watts on fan power supplies never hurts and makes the grow quieter.

On the other hand here are some examples where the heatsink fans can help circulation for the grow. I have to run 65W ceiling fans in each flower room so if there was a way I could use 140mm fans to eliminate the ceiling fan, I would definitely consider that. I chose the ceiling fan because it is almost silent, especially compared to my 42W oscillating fan, now retired.

In the vegging area I dont need as much circulation so even at 5V I can get a decent breeze in the canopy from a high RPM 140mm fan.

 

[SupraSPL]

700mA, 800mA and 1050mA tests on the Alpine 11 + CXA3070 AB coming up. One thing worth mentioning, at lower currents the heatsinks run so close to ambient temp that 5V is all you need. Increasing fan speed does not increase light output at all. But when I tried running it passive, it gets smokin hot even at 700mA.

 

[bicit]

700mA, 800mA and 1050mA tests on the Alpine 11 + CXA3070 AB coming up. One thing worth mentioning, at lower currents they run so close to ambient temp that 5V is all you need. Increasing fan speed does not increase light output at all. But when I tried running it passive, it gets smokin hot even at 700mA.

They have massive amounts of surface area, but the fin spacing is so close that they act like a solid block without the fan. Compared to the heatsink usa fin spacing anyhow.