I am new to BLF in regarding to posting, the forum has provided me for years already in sound advice about the different flashlights I own. but now I am tempted to switch to 26650 for powersupply and a multi XM-L emitter (preferably U2 bin) flashlight. At first, after reading about multi XM-L emitter flashlights here on BLF, I was drawn awards the Trustfire TR-J12. As I was browsing the various sites of flashlight sellers my eyes were drawn on the relatively new multi XM-L U2 bin lights. I wonder if anyone could gine some advice of any of these Uniquefire lights I came across are any good, or that I should rather go for the Trustfire TR-J12. The lights I am interested in are these ones:
It should do around 1.69A to each LED. With 7 LEDs that will generate a lot of heat in smaller hosts like the TR-J12/J18. I think the designers knew this, and thats why the J18 does not emit more lumens than the J12. This 100X however looks like it has a MUCH bigger heatsink, so it all depends on the thermal performance of the host. It definitely looks big/massive enough to handle the extra current.
Pok in another thread pointed out my calculations were off, because I was assuming Vbatt = 4.2V x 3 = 12.6. Which is incorrect.
4A x 12.6V = 50.4 W pulled from cells
50.4W x .80efficiency(typ) = 40.32W into LED array
40.32W / 7LED = 5.76W/LED
5.76W / 3.4Vf = 1.69A per XML (assuming 3.4Vf)
In reality Vbatt sags under load to about 3.5V to give…
4A x 10.5V = 42W pulled from cells
42W x .80efficiency(typ) = 33.6W into LED array
33.6W / 7LED = 4.8W/LED
4.8W / 3.4Vf = 1.41A per XML (assuming 3.4Vf)
So on paper it should still emit more lumens than the TR-J12. Since the J12 and J18 are both ~30 watt designs I would expect the X100 to be brighter than the J18 too. Note also this is just a ball park estimation. It does not account for cumulative resistance of the springs, switch, and host body. It does not factor in for variations in XML Vf or cell performance. Driver efficiency of .80 is not a “given” either.
Thank you very much, kramer5150, for your eleborate answer.
I hope someone can tell me more about the UniqueFire models I posted. For now my choice would be the x100, but I will wait with buying until I get some info on the UniqueFire flashlights.
Sure… someone double check me on XML Vf too… Another forum member pointed out that Vf is lower than my 3.4V estimation in the very last calculation. If that is true then I am under-estimating the current to each LED.
Looks like a very nice/impressive light, but no 26650 and, more important, if I bought that one I’m sure my wife would have me legally declared insane and have me put away, spending that much on one flashlight.
holy crap that is interesting. its like an automotive led inside a reflectored head. cant wait to see someone pick one up and put up comparison beamshots