FAIR UPDATE RE QS2L-X [Was: Disappointed in the new Foursevens Quark QS2L-X]
Hey all,
it's been a while since I've logged in, apologies for the delay, but better late than never!
I thought it would be fair to leave an update here for anyone reading this thread.
Note to anyone fast-scrolling through this thread: The software crashes of the QS2L-X can be reliably prevented. Read if you use RCR123's:
The RCR123's that I use (Fourseven's own ones!) are a bit longer than CR123's. That prevented the tailcap from being screwed down all the way, since it would press on the batteries too hard otherwise. So I just screwed on the tailcap until it made good contact with the battery, and used the light like that - but that didn't work reliably.
The problem appears to have been that doing it this way, there was not enough pressure on the tailcap's threads, leading to unreliable contact in the threads especially when the light gets bumped or sometimes even just moved a bit harder, and that upsets the brains of the light, leading to all sorts of erratic behaviour and what can only be described as software freezes with the light becoming unresponsive.
To reliably mitigate that once and for all, all I needed to do was to loosen the threaded retainer ring which holds down the pocket clip, by about a millimetre or so - just enough that when the tailcap gets screwed down, it now rests against that ring rather than putting undue pressure on the batteries. With that, I can tighten the tailcap properly, which leads to good reliable contact betwen the tailcap and the body of the light, under all circumstances, even when the light gets bumped hard. Problem solved.
I should note that fortunately the pocket clip still sits as tightly as it did before, despite its retainer ring having been loosened by a millimetre. No idea why, but obviously that's a good thing.
Once I figured this out, there have been no more crashes or malfunctions at all, not one single time, and the light has seen a lot of use in full time EDC duty for me ever since without a single glitch.
I am now really happy with it, and can't think of any other light that could do what this does for my particluar use case. I can definitely recomend this light.
Hope this may help someone make a buying decision or to get more out of their QS2L-X.
Have a great day!