(Updated July 16) Review/Test: Illumination Supply Direct-Bonded 16mm Copper Star with Cree XM-L2 U2 1C

My thoughts exactly about production variations between emitters. You’ll notice a sudden plunge in luminosity should your emitter start to fail after a reflow and turn-on readings should all be close.

The survey is how I got my AL sinkpads. Just a hunch, but I bet they will perform far better than most people would expect.

The Vf and lumens are consistently lower than Match's tests on a SinkPAD - I think he used a U2 1C as well. Now this difference isn't a bad thing at all - just interesting to note. More important is it's in the neighborhood and your lumens curve looks really, really good and match's up with Match's, accept for that hitch at 5.2-5.4A. So could be just the measurements/calibration, emitter differences, or the copper star is that much different from a SinkPAD - no telling yet, still early... Very interesting to watch this data fill out...

FP, I just filled out the survey at SinkPAD, one more product to compare to (eventually).

Tom E, that blip at 5.4A is when the light meter went from the 20,000 lux scale to the 200,000 lux scale. I believe the 2,000 and 20,000 lux scales read slightly low on my meter. Nothing drastic, but noticeable.
I’m avoiding interpreting any data at this point. Once I have more data from more tests and can compare to other direct-bonded stars.

One important note is that in statistics, a sample size of one is mostly useless. There could be some undetected defect in that sample, or it could be a stand-out performer. Either way, the test results from one sample are likely not going to represent the average performance of a mass-produced product. Product characterization requires several samples from several production batches to average out those anomalies.
But alas, we live in the budget world. I would not expect a supplier to sent multiple samples from two production runs, nor would I have the time to test that many. We work with what we have and as long as we are aware that the data is limited, all will be OK.
One thing I would not like to see is someone read through the review, see the positive test results, order a bunch and have them comparatively under-perform and then blame the review for misleading them. This potential issue exists with any product review of one sample. Most reviews out there are just that.
[\rant]

I will make one observation though; these stars perform much better than a standard aluminum star. That I am confident in saying.

I was curious too about the Vf data. Seems good cells (i.e. Sanyo 2600mAh) in single cell lights could sustain regulation at drive currents up to about 2.8A.

-Garry

relic - +1, agree on all points... Scale change explains the 5.4A hitch.

One other note Tom; on Match’s data, it is not clear where Vf was measured at. I measured directly across the star wire pads to eliminate wire drop.
I will be testing the drop across the star traces as well. It is possible that the IS-DCB star traces are thicker than the ones on a SinkPAD (I have not compared them yet). That could also be a contributing difference in Vf.
Actually, I just did a quick comparison of the four XM-L DCB stars I have:

  • SinkPad 20mm star (what Match used) has a ~1mm trace ~5mm long from wire pad to emitter pad, both pos and neg.
  • SinkPAD 16mm star has a ~2mm trace ~2mm long from wire pad to emitter pad, both pos and neg.
  • Noctigon 20mm star has a ~4mm trace ~4mm long from wire pad to emitter pad, both pos and neg.
  • IS-DCB 16mm star has a ~3.75mm ‘trace’ ~2mm long from wire pad to emitter pad, both pos and neg.

Curiosity got the best of me, so I went ahead and tried a quick current test. 6A driven directly from the wire pad to the emitter pad. Multiply by two to get the total voltage drop on the star traces.

  • SinkPAD 20mm star: 43mV (7.1 mOhm)
  • SinkPAD 16mm star: 21mV (3.5 mOhm)
  • Noctigon 20mm star: 22mV (3.7 mOhm)
  • IS-DCB 16mm star: 14mV (2.3 mOhm)

Nothing conclusive, as I need to do this a little less ad-hoc. It does indicate how Match might have gotten a higher Vf reading.

Edit: It has been pointed out that comparing trace resistance of 16mm boards to 20mm boards is not entirely fair. I tend to agree with that, and was not suggesting anyone do that with this data. I recommend limiting comparisons to within the sizes of the stars.

Interesting. So the preliminary results suggest that the traces on the Illumination Supply stars have the least resistance.

You know, this could change some think'n around here, that the bigger the star, the better. The 16 SinkPAD is half the 20, and the IS one even better, hhhmmm.

The difference between the best and the worst board is 0.7V, at lower currents that will be lower. That is important stuff for the fine-tuners, that means I am ok .

Even though it may not be of much relevance to my mods, I love data, the more the better, keep it coming !

Cool thread. Thanks for the testing, Keep up the good work. You are saving many of us money with this data.

Where do you see the 0.7V?

I would like to see a comparison before and after dedoming

watching closely.

The 16mm boards have the lowest resistances because, well the traces are shorter.

Insanely good data, good job relic!

That makes sense.

Relic … could you test the resistance on a 16mm Noctigon?

Funny you should say that. I have been asked by Hank from Intl-Outdoor to do just that. Since I do not have any 16mm XM Noctigons, he is sending me samples.

Hikelite, you are correct, 16mm boards do have shorter traces. However, good trace design can greatly reduce the resistance. Take the two 16mm samples I provided above. The Sinkpad has a thinner trace than IS-DCB and it shows in the test results. The same can be said about the 20mm boards.
As I noted with an edit in the original comment, it is not entirely fair to compare a 20mm board to a 16mm board.

I have completed the testing, and added several graphs and comparison information. I am awaiting feedback from Calvin on the potential reflow issue (i.e. could it be a single unit or a larger issue). I will update the OP when we know more.

WOW insane information, thanks for the effort relic!

Thanks again relic38. I doubt any off us are doing any better on the reflows so consider your data ok. It would be interesting to see these tests conducted on a flashlight with no external cooling and comparing the different stars on different pills in the same light. We need a mule light. It appears that when you get to around 2.8 amps plus that the copper star would be worthwhile. You could possibly get away running an led on a copper star at 2.5 amps with the same output as an aluminium star and led at 3 amps.

Thanks MRsDNF, I think you are right about the aluminium star when driving the emitter to spec. The gains are significant, but not huge. When you want to drive well over spec, the direct bonded stars do their job.