some crude measurements of the MT-G2 on a Noctigon board

I have been waiting for a while for people to come up with high current testing of the MT-G2 on copper, and now decided to do some testing on my own, I tested up to 7300 mA before the power supply gave up (not the led). When looking at the numbers below keep in mind that nothing is calibrated, and I do not have the skills and certainly not the accuracy of match or texaspyro, let go something fancy as a integrating sphere. But I will show you the set-up so you can judge the experiment for yourself, at least I am confident that the lumen measurements are within say 5%, for the current and voltage numbers I trusted the readings of my Kert stabilized power supply (which is of reasonable quality) but perhaps not rightly so (please feel free to disagree with the method), it does give an idea of the performance anyway.

So before giving the numbers, this is how it was done:

The led was reflowed on a Noctigon copper board and screwed tight onto a well flattened block of aluminium with a thin layer of arctic silver in between. The block was clamped onto a larger bar of aluminium. Nowhere during the experiment any significant heating up of the led board was felt, so the heat was transferred away very well, in fact at 4A (=26W) the lumen reading at started at 2156 lumen and stabilised after 2 seconds at 2140 lumen and that did not change anymore.

The led was directly connected to the power supply with short thick wires. In this experiment I regarded the power supply voltage reading therefore a measure of the Vf (and again, please correct me if this assumption is way wrong). The power supply also provided me with a current reading, no idea of the accuracy of that, but i used it anyway . Unfortunately the power supply is rated for currents up to 5 amps, but I was glad it went up to 7300 mA all the same before some temperature/current/or whatever protection shut it off. So no higher current readings sadly .

I placed a 49mm reflector+(non-coated)lens coming from my Trusty Budget Test Throwertm on top of the led board to simulate an actual budgetlight-real-world-situation , it fitted very nicely. So the lumen readings that are given in this post are not led lumens but lumens that could actually be expected out the front of your budget modded light.

The light was directed towards the ceiling to be able to do ceiling bounce lux measurements. This was done the standard djozz way, 77cm from the ceiling, light measured with a Tondaj lx-1010b el cheapo luxmeter, calibrated with a few known flashlight outputs. In favor of the method, the djozz way has given me enough measurements that were close enough to ANSI-values or other people's measurements to trust it within a few percent.

Somewhere halfway during the test run:

The beam pattern on the ceiling, actually not bad at all with this reflector:

A peek at the led at less than 1 mA :

So here are the numbers, again mind that the lumens are simulated OTF-lumens, not bare led lumens:

The fact that the Vf at 7 amps goes up to 7V might indicate that there may still be a voltage loss between power supply and led so the real Vf might be lower, someone better equipped (and less lazy) than me please correct these numbers. EDIT (may, 29th): some other measurements with this same set-up 'may suggest' that the Voltage measurements from this power supply are about 0.15V higher than the real Vf of the led. This would also be more consistent with MT-G2 data from Cree (although you don't really know, Cree's data were at 85 degC, no idea what the led-temperature is in my set-up)

I could not get the graph out of excel (I have to educate myself sometime) so here are the numbers in my original oldfashioned graph:

So what are my own conclusions from this rough and dirty test? Well, to get the most out of it, do not be satisfied with 5 amps for this led on copper, it did not care less for 7.3 A and that does not seem to be the end of it (so who is going to test at 10 amps? :evil: )

Nice work, the 1ma shot is pretty cool. I wonder if stadiums will start using these, you could probably expect a few thousand more lumens too.

Very cool test, thanks for shedding some light on the MT-G2 and taking a risk with high current testing. Glad the LED survived!

Oh, what’s the orange piece of plastic hanging out from the star? Just wondering. :slight_smile:

Thanks again!

Silly me, I was beginning to think that 9A driver I have on the way might be too much! :evil:

Kapton tape, to insulate the leads from the reflector.

Gotcha, thanks. I thought it was the same stuff the covered the base of my Noctigon PCB.

Thanks for taking the time to make this test and publish your findings.

It would appear to be Kapton tape (or similar) used to avoid shorts from the reflector.

(Edit) Djozz was faster than I at replying. :)

Thanks for the confirmation Chicago X! :slight_smile:

Interesting test. I would love to see testing on every led in a "real world" situation, say a 3/4" dia x 1/8" thick, round of Aluminum with the led/star on top, instead of huge chunks of aluminum. With the huge heat sink, many things are possible, but with just a small heat sink (like in a flashlight), many things are not possible.

I am not knocking your test. It's good to know what the led can do in "the lab" and I am grateful for your hard work.

Thank you for posting your results here.

Very good info. Thank you very much for the hard work and reporting. This emitter keeps getting more interesting.

Wow. Thanks djozz.

Very nice test, good numbers and well done. Thanks, gives me some ideas…comfychair can be my tester :wink: Would love to see 3000 lumens out of my S2200, would be totally awesome!

Thanks for all the appreciation for the test, it was fun doing it, I had to close the curtains to prevent strange looks from the neighbours :-)

This is great info djozz!

Thanks for doing it, and sharing.

7amps and 7 volts… 49W!! And output is still not leveling out!! Sick! 8)
I know you have good heatsinking here, but with that heat sinking, it sure looks like the sky-is the limit! At least until… poff… 0:)

I also take note the djozz-lumens is lower than Match lumens (No surprise, due to reflector, lens and such) But since you had the emitter on copper, the lumen curve does not flatten out as much as the ones Mach posted (his emitter was on aluminium). This just shows that the copper (Noctigon) mcpcb seems to do its job… :slight_smile: Which is good to know…

Direct drive off two 26650s? Wonder what the current would level off at after the voltage sag...

The Vfs I measured with my QL-355 on an Aluminum MCPCB (2mm thick) place over an aluminum finned heatsink (70mm diameter, 20mm thick) , 26C ambient temperature. No active cooling.

Nice pics!

Only if this leds where CW….or NW, i hate warm white.

It's not WW.