SinkPads copper 20mm and XM-L2 U2 initial results

emitter current, good point, perhaps someone should test emitter current and voltage drops, a table of this would make a great sticky thread

flashlightlens.com - it's a little big, think it's thicker. You got usually 1mm to play with in width. Pretty sure I can't fully screw down the bezel as far as it used to, but its over the o-ring.

Bort - as far as the HD2010 doing better in lumens then the 7G9, amps helps but it's not the only thing that matters. We are talking minor differences here, and that HD2010 reflector does well for putting a lot of light out - good in throw, while the 7G9 targets throw more - tighter hot spot. So is my lightbox perfect? No, no chance, but could the HD2010 be a little better at putting out lumens in it's setup than the 7G9, certainly could be. There's also signifcant differences in batteries, LED emitter from one to another, etc. For example a binned 1C can be all over the place, more cool or more neutral sample to sample.

One difference is certainly the battery configuration - HD2010 running a 26650 (good one - KK) while the 7G9 uses 3 18650's in parallel - tested with Panasonic 2900's unprotected. Batteries make a big difference in measurements I've taken. You put 10 mins of runtime on a battery, brightness suffers quite a bit, even with regulated drivers.

great results, particularly the reduced output drop with the sinkpads. Possible lower Vf might help too, but everything else (host etc) should be equal. Although output after 5min or longer would be interesting, you’ll then be looking at the thermal properties of the host/ dropin etc, not the LED star.

Well, I used a paste that was marked to do aluminum, but it would do other metals as well - bit expensive because of it supposedly for soldering aluminum but I didn't have much luck with it, so, used the same stuff for the LED mounts - worked well.

Got it here: http://www.amazon.com/dp/B0058ED0LE/ref=pe_175190_21431760_3p_M3T1_ST1_dp_1

Where did u get the sinkpads?

nitro organized a group buy thing - nitro posted above. Not sure, but he may have more left. I wish I ordered more now , but 16 mm's would be great, but the 16's are not stock items at SinkPAD, the 20's were. Possible plan is to put another group buy together for 16's (or 14's), but include payment for the tooling costs to SinkPAD, so it will cost more but the more we buy, the less % is the tooling cost.

Thermal compound/paste is only good for bridging vewwy vewwy tiny gaps, such as microscopic irregularities in surface finish, down to the scale where you can't see any roughness with the naked eye. If you have a divot or pocket or wide gap, skip the paste, it won't do anything but make a huge mess later on when you take it apart again. Heat just doesn't transfer thru a big glob of paste.

I know a lot of you guys just like tweaking things for the sake of tweaking, but the fancy expensive exotic compounds aren't doing anything but lightening your wallets... just pick up a giant tube of white silicone-based paste from the electronics store. It'll last you thirty-seven forevers, and performance, when used correctly, will be within the margin of error for whatever equipment you're measuring with. Changes in ambient temp during the test will show more variation than between the most expensive and cheapest stuff.

Similarly, for filling gaps or pockets so you can correctly use thermal paste, or for permanently mounting stuff, plain ol' JB Weld is just as good as Arctic Alumina or any of the other fancy ones. And like the white thermal paste, you can get it in giant tubes that last forever ('Industro-Weld' - exact same JB Weld, just in bigger tubes). Skip the JB Quik - it's not as strong or as good at heat transfer. If you're curious, squirt out some of the black JB, and poke at it with a magnet... (hint: it's got lots and lots of metal in it, but it's not electrically conductive).

Interesting, comfychair. I’ve used superglue to bond stars to a heatsink before. apply a small amount, press with a lot of weight for about 10 seconds, and it’s on. I was surprised to see the star only be 4-5 degrees hotter than the heatsink. Worked quite well, and it’s temporary since the glue will not bond good to smooth aluminum. I would not use it in a real application unless in a pinch, Shock or lateral pressure seems to jar them loose sometimes.
I either use Fujik (probably a fancy name for overpriced silicone sealer) or thermal paste when I have something to hold the star down.

Has nothing to do with driver efficiency, I promise. They’re both linear drivers (AMC7135 Based) which means that tail current = emitter current.

PPtk

i see, do you know anything about voltage drops, as i am looking to order a driver very soon and would like the one with the least drop

If you’re wanting to stay with a Linear driver, then any AMC7135 based driver will have VERY similar voltage drop. If you are looking for switching buck, then they’re all going to be vastly different in how much overhead they need in order to maintain regulation. You’d have to ask the vendors.

PPtk

Thanx comfychair - I hear what you are say'n, but I'm trying to stay away from the epoxys, just using grease as much as possible. I got a few small tubes of the Arctic MX-2 for like $1 each, and am only using tiny dabs now. As long as I can get the two critical surfaces (bottom of star and top of pill where it mounts) as even as possible and very smooth with 2000-2500 grit paper, nothing much more is needed, from what I understand. I thought thermal grease is still better than air (according to heat xfer specs) so still think filling larger gaps is better than nothing. Just following others advice, measurments, tests, published data mostly - don't have instruments or the setup to measure these issues. I read all sorts of issues/opinions/facts on this subject here and on CPF, and believe me, it's a tough call. When someone tested toothpaste to be as effective as the top shelf stuff, I was stunned to say the least - but that's true only in thin applications, thicker applications the higher grade thermal greases/epoxies proved to be better from what I recall. However you view it, I'd rather take my chances with better stuff that seems to have been shown to be more effective in some circumstances. For example, you can test toothpaste when fresh, but what about after 3 hours of high temp use? Even for a $7 tube that lasts through 70 mods, that's only 10 cents per mod - I can live with that. Oh, even if I use epoxy now, I'll use it partially so the parts are easier to get apart later, the rest is grease. I'm trying to stay as thin as possible - general consensus I've been hearing.

Bort - it’s important to remember a couple things about the binning. Cree states +–7% error in flux measurements used to bin them. That’s basically ± 1 bin in error if you are just looking at the average difference between the bins. Statistically the bins are just chunk of what is likely a normal distribution (I once saw a graph released showing old Luxeon bins that was normal). That means the top bin is always in the tail of that distribution. The bin below may or may not include the peak of the distribution. Bottom line is it’s likely that the expected difference between the top bin and the bin just below is less than the average difference of 7%. The measurement error is then bigger than the expected difference.

Bottom Line - Everything else equal, the top bin is likely, but not necessarily, brighter than the one just below it.

The XinTD is next! Going to 3.8A with XM-L2 U2 on a SinkPAD. Started it, removed the U3 (ouch) - hoping to complete this evening. The SinkPAD doesn't quite fit, again, so will sand it down a bit, not as much as for the HD2010. I already got 2 copper discs in the pill, so it should help.

Wow! I am watching this one closely Tom. C8 size lights are my favorites ( except for my A60 ) and this one is going to be a monster.

mostly good advice - but a pocket of air isn’t helping either, so why not fill the gap with something, if you’re not paying too much for it ;)…

also, jb weld isn’t a good conductor - but it isn’t a very good insulator…afterall, it has all that metal in it. be careful how you use it, w/ respect to electricity, ie don’t pot drivers with it. I love JB weld - I’ve used at least at least 100 oz of the stuff - I buy the 2x5oz jb weld off ebay.

I'm hoping on over 1200 because the XinTD is in the 900's now at 3.5A and a U3.

JB isn't conductive, I've used it on very sensitive low voltage stuff like bare motherboard & video card traces, and high voltage/current stuff as well. I guess if the voltage is high enough just about anything will turn into a conductor, but not an issue with things that won't kill you dead. I've even used it for potting, of a sort, for USB thumbdrives that had cheap flimsy housings... stripped them down naked, gooped on the JB, then sanded down after cured. They worked fine.

It's a good thermal conductor, and good electrical insulator. Now if those were reversed, then it'd be about the worst thing possible to use.

i think capacitance is more of an issue than conductivity. because you succeeded at encapsulating electronics with epoxy/powdered steel doesn’t mean it is a good idea - do you think I’m speculating? or do you think I found out the hard way lol :wink:

back to the OP

Tom, the numbers look great, but what are your eyes telling you?