I modded another nitefighter C8 style light today and decided to see what the SST-40 would do if I put it on the aluminum mcpcb that comes with them. I did put down good thermal grease to give it it’s best chance of surviving the low resistance FET driver, heavier wires and spring mod. Surprisingly it did not kill the emitter even with a LGDBHE4 which is a pretty good high amp battery.
I did this because I was curious how many amps they can handle without being put on direct copper mcpcbs. Ton’s of lights like the SRK’s and other multi-emitters are a lot easier and cheaper to mod if you re-flow onto the original mcpcbs. From this I would say that there is little to worry about even when using high amp batteries.
Does anyone know how many amps these SST-40’s can handle without putting them on copper mcpcbs? I wouldn’t think they could handle this much and now I’m curious what the max is.
^ DTP boards perform pretty close to each other (a few years ago relic38 and I tested a number of types that all came pretty close to each other), but I have the impression that in non-DTP boards there is a huge variation in performance. The best I have seen is a cheap (copper core) 20mm XM-L board that easily allowed to run an XM-L2 led at 5A while performing only 5% less than a Sinkpad. But on the safe side I think 4A is no problem for almost any ledboard, also with a SST-40.
Today I modded a LuckySun D80 with a BLF-A6 driver and a Black Flat on led4power’s new, promising, Oslon board.
Unfortunately the modding attempt took all day and turned into an investigation of this new type of board, and this is what I found:
to compare this new mod to, I have a driver-less (so led directly connected to battery, with only the switch in the circuitry) ‘Mitko-thrower’ with a Black Flat on a XP-DTP board, current is 4.5A and output is 700 lumen after 30 seconds, which is pretty consistent with my Black Flat emitter test.
But this D80 mod, very neatly performed, did just under 500 lumen (at 4.2A, close enough), so there is 200 lumen missing somehow. The light was clearly more purple on the highest setting compared to the lower levels, a bit more purple than the (higher output) Mitko thrower.
I thought maybe the driver is off, so I put a new BLF-A6 driver into the D80. Result: still a bit under 500 lumen.
I reflowed a new (my last ) Black Flat on the board to see if it was the led that was wrong, result: still under 500 lumen.
I suspected that my D80 has a really bad reflector, so I took a brand new Convoy C8 host with beautiful smooth reflector and transplanted driver and board+led into it. Result: 4.2A and just under 500 lumen.
then I tried driver-less, connecting led-minus thoroughly to ground. Result: under 500 lumen.
then as a last way out, I reflowed the led on a 20mm Noctigon and soldered it into the C8 (with the BLF-A6-driver, but with the DTP-board the driver is bypassed and led is directly connected to battery). Result: clear and present 620 lumen (and a small black speck on the led from all the transplants).
In all steps above I made sure that the led was perfectly centered and in focus, they were finished mods.
Conclusion: I can still think of other explanations, but for me the most plausible one at this moment is that this new type of board (at least the one that I did the test on), when heat-shedding really counts with a severely overdriven led that has the small Oslon footprint, performs not as good as a DTP board. I hope that I will be proven wrong by others as I really want that easy to use well-performing Black Flat board.
Yeah, but reflowing another LED yielded the same result while switching MCPCBs brought an improvement. This is a strong indication that MCPCB was the reason for low performance.
That’s indeed a disheartening result.
Yeah you definitely want DTP if you want to get the most out of this LED.
Thermal paste is a must.
If you want to do 5-6A then you need a proper heatsink, not a flashlight host, to dissipate the heat.
I suspect heat spreading on oslon black flat is pretty bad, bottom pads are very small so power density (W/mm2) is very high at board-pad junction, over 15Watts per 1mm2 of LED die.
This board was designed for IR oslons (black flat was still not very known at the time of design) , and it should perform much better than existing insulated boards like non-dtp copper pcb for XP, and Bergquist 804087 .
I will have two oslons flat for testing soon,after test I’ll do “autopsy”, I’m very interested in how cross section of oslon flat looks inside (thermal path specifically). Plastic case of oslons always was downside for me, I assume there is no ceramic like alumina inside, just copper pad, the question is how thick.
I did some calculation, mosx have thermal resistance equivalent to <250um of solder layer, and if I remember correctly someone did the test noctigon vs. sinkpad 2 (gap on top) ,and there were no visible difference in performance for xm-l2 and similar leds, but they have ceramic substrate and pads have decent size.
Yes, the observation is the same: with the XM-L footprint, the thickness of a solder layer under the led is not critical as long as you get rid of the thick dielectric layer. But apparently at the same powerlevel but a 5 times smaller footprint, the details of what happens under the led are more critical, makes sense
I ordered some MosX oslon boards for testing too , and i already have some Oslon black flat leds (LUW HWQP) here …
Right now i tested one at a Thorfire C8S on a DTP board (without a driver) , with AR glass and i get otf 720 lumens & (only) 170kcd @ 5 amps , using sony VTC5 .
Stuck one of the Luminus SST-40 emitters on a 20mm SinkPAD and put it in a baked Eagle Eye X6 with a Bistro driver. On a 38A 2100mAh Efest it makes 2601 lumens out the front. I don’t really care for the blue tint side of things so I cut a piece of 223 Lee Filter and put it on top of the AR coated UCLp lens. Now I have a 5500K tint but with a 14% loss to around 2200 lumens. Looks good though, nice spot with an aura and then a useable spill.
Nice, they state these are 97% throughput but even after adding the lee filter it’s still at 86% so it’s worth it. You won’t get 2200 lumens out of a similar tint XM-L2.
That’s what finally dawned on me, reducing a 1A to a 3C is going to cost lumens output in a similar fashion anyway, and the SST-40 has a higher launch to begin with so it’s still a win.
This is what they call one eighth O.T.C. (Orange Temperature Color) and has an 85.2% transmittance with 7% absorption rate. You can see on the bottom right corner where I wrote down the lumens before and after, seems it was pretty spot on.
I simply looked at a color wheel and chose the opposite of the daylight white blue-white color I was seeing in the output, which is a light orange. Then went through the Lee filters to find the correct shade of orange and it works great. So far, anyway. I’ve melted more than a few of these pieces of film and this one doesn’t seem to have a fire retardant counterpart.
Very cool, let us know if it melts, but if it doesn’t it’s a good solution for sure. I’ve used a similar film when making lanterns from scratch before. I’ve also used one with diffusion to take the doughnut hole out of the XHP series.
) Black Flat on the board to see if it was the led that was wrong, result: still under 500 lumen.
) which is 700 lumen but does not have and AR lens.
