By chance, has anyone checked that driver with an oscilloscope? In modding these I’m bursting emitter bond wires like crazy - at currents as low as 3.6A. I’ve got two modded lights that have been running quite happily at 6A (MT-G2) and 5A (XM-L2) for several months now, and I’m trying to mod one to a less crazy extent for my dad (shooting for around 4.0-4.2A measured at the emitter). Last night the modded driver claimed an XP-G2 and an XM-L2 almost instantly. XM-L2 stayed alive long enough for me to read 3.58A on my DMM measured at the emitter. It’s resistor-modded with an extra R180 added, which should pull 4.4A, so I figure after losses it’ll be right where I want it. All the springs are totally unmodded, so I reckon that explains the 3.58A reading I got before the XM-L2 popped.
So I’m guessing there’s a voltage spike when the driver starts up… an XM-L2 should never die within 10 seconds at 3.6A. Either that, or the current is spiking up real high too fast for me to pick it up on a DMM? A previous Y3 I resistor-modded to target around 6A or so popped several XM-L2’s in the same fashion… I just assumed that the 6A target was too high for dedomed emitters. Same driver has been working perfectly with an MT-G2 for months now. Weirdly, I’ve had exactly zero emitters die at the hands of my first resistor-modded Y3, and it pulls around 5A at the emitter from the stock XM-L2 that came in it (now reflowed onto a maxtoch mcpcb and dedomed… all of the dead emitters were on copper mcpcb’s as well).
All of these have been with two 26650’s, BTW. So I’m thinking voltage spike at startup. Which sorta makes me wonder if this ever happens with unmodified drivers running XM-L2’s and multiple cells? I didn’t at all expect to pop emitters at <4A, especially when the stock resistor values call for 3A.
I dunno. The emitters I’ve blown with these drivers are all over in terms of where I got them, probably five different XM-L2s (T6 and U2), one XP-L (unknown bin, probably V5) and one XP-G2 (R5).
Tried the XP-L specifically because it appears to have a higher Vf than any of the others I’ve messed with. Baaaarely lights up with 2 AA’s around 3.05V.
Unless you can read what the output of the driver actually is I cant see a way to check if its leds or the driver. Try the leds in another light or return the Y3 driver to stock and try again. I'd suggest the leds should be ok up to 5 amps on copper.
Gotcha. Yeah… there won’t be any trying these LEDs in other lights. After inspecting them with a magnifying glass, the bond wires are all clearly broken. All of them turned on briefly in the modded Y3s, some for longer than others. But like I said… I’ve got two modded Y3’s that have been working perfectly for months. Though, the driver in the one with the MT-G2 claimed the lives of four XM-L2’s and one XP-L before I checked every solder joint for shorts, crossed my fingers and stuck the more expensive MT-G2 in there. These budget lights have a way of getting expensive sometimes.
I haven’t gotten around to messing with the Yezl Y3 driver. It seems pretty typical in construction IIRC, it’s a QX9920 based buck driver. QX9920 is entirely capable of blowing emitters though. RMM has discussed the problems with QX9920 based drivers some in ImA4Wheelr’s Driver Mod: HX-1175b & HX-1175B1 (Pic Heavy) thread.
It’s not a “voltage spike at startup” thing so much as it is constant voltage spiking. The output is probably not clean at all. Your DMM will not be able to indicate dirty power or it’s form to you. Observing the driver’s output on a scope is really the thing to do. As you bring the set current up the bad behavior should be visible on the oscilloscope before it gets to the level where it kills emitters.
The MT-G2 is much more resilient than the XM- or XP- series emitters. It is not a very good measuring stick when trying to determine whether you have a driver which kills emitters. (eg not killing an MT-G2 on 2s or 3s very likely proves nothing)
Could be a combo of the new emitters not able to take the high amps and an initial voltage spike. I've been staying away from the stock Y3 drivers with a fully modded Y3. I'm ok with a nice UI custom DD driver, single cell for XM-L2's, or zener mod 2 cell for MT-G2.