Can you please recommend an appropriate driver for a Convoy S2/S2+ triple with LH351B 2.200K or 3.000K? I don't know if these LEDs are capable to be operated with DD or a simple FET driver? When using Nevens LD-A4 driver and choosing the "constant current" option on highest level something odd happened as the flashlight starts to blink, probably due to overheating. Apparently, this has something to do with too much power dissipation. As only few drivers fit into the S2/S2+ host and as it needs to be single-sided it is quite hard to find something.
Well, I do have a Convoy S2+ XP-E2 red triple with the LD-A4 (constant current @ 4.5A) and this one works fine so far. But I understand this is a different LED and therefore not comparable to the LH351B. Thanks for the hint about the LD-B4 Lexel!
H1-A boost driver with emitters in series. Stock sense resistor is 25mΩ with 75mV sense voltage for 3A output current. Swapping the stock R025 with both R050 plus R100 stacked would net 2.25A output, for example, and an R050 alone is 1.5A which for ≈10V of output that is ≈15W at the emitters.
Current newer versions of the H1-A can drive 3S emitters straight out of the box.
Cheers ^:)
P.S.: my current EDC is a heavily modified SK98 with dome shaved XHP50A G4 3500K CRI90+ driven with an H1-A with R100 + R200 sense resistors on top of the stock R025 (4.125A). It's bright. ;-)
Could you please explain what do you mean?
Power dissipation of a linear driver = (battery_voltage - current*circuit_resistance - Vf) * current.
Assuming battery voltage of 4.2V and circuit resistance of 0 we get ~(4.2-3.25)*4.5 or about 4.2W.
At 6A that’s ~(4.2-3.3)*6 = 5.4W or 30% more.
Actually both numbers are lower than that, battery sags (more so at 6A) and there is some resistance (which drops the voltage more at 6A).
I read that LD-A4 was designed for up to 6W of dissipation, so it should be enough…
Thank you @Barkuti. The H1-A however is a 20mm driver that won't fit into the S2. It might fit into the S2+ with lots of modification onto the tube but the S2 is out of the question. Moreover, it's uncertain if 9.77V would suffice to run this triple as the Vf of the LH351B goes beyond 3.5V. You also end up with only 2.41A per LED which seems to be below the possible peak value. First tests with a BLF A6 driver and a Samsung 35E at 10A revealed that the triple LH351B 2.200K can run up to 1,500 lumens, i.e. about 3.3A per LED (possibly a bit lower due to losses with the tail cap). With a Samsung 30Q at 11.5A (without tail cap) it became less bright with only 1,350 lumens.
"Bare" LD-A4 can handle about 2Watts of heat @60C, with thermal kit ~7W@60C, at room temperature (when flashlight is cold) those numbers are ~2x higher.
I’ve just finished building last night a Copper Convoy S2+ with triple Samsung LH351B and FET+1 driver from MTN. Using a 30Q cell in it and on turbo the body of the light heats up rapidly, but it’s running fine.
