I do like the neutral color temperature of the XM-L2 T6, but the operation is kinda sketchy. Once on, it often takes 2 “half presses” to advance to the next mode. And the memory of the last mode is often not retained when shut off…it often advances to the next mode between uses, which is a problem when you expect “high” at turn-on, and you get “moonlight” instead.
It uses a Nanjg 105c-based driver (though with custom firmware), that operation is NORMAL! That's just how the memory works on those, it's a hardware limitation. The driver only knows how long it's been ON - if it's been on for less than around 2 seconds and you cycle the power, it changes to the next mode. If it's been on more than around 2 seconds and you cycle power it does not change mode. The driver has no way of measuring how long it has been off, only how long it's been on.
If you turn the light on, leave it on for less than 2 seconds and then turn it off, when you pick it up 2 hours later it doesn't know it's been 2 hours, it only knows it was last switched on for less than 2 seconds, and it should switch to the next mode.
I have found that the 2 "half-press" thing is usually the result of the switch, not the driver. At least it was in the lights I had issues with changing modes on.
Nope, completely normal with this driver. If it's been on long enough for the memory to set (~2 seconds), it requires a double-half-press to change modes. To the driver, the first half-press appears exactly like turning the light off for an hour, then turning it back on. Less than 2 seconds between clicks and it will change modes, longer than 2 seconds between clicks and it will not change mode no matter how many times you do it.
Try it - turn it on, count to 'one...' and give it a half-press, count 'one... again, another half-press, it'll change modes every time. Turn it on and count 'one, two, three, four..." and do a half-press, then count again and half-press, it won't change modes.
Comfy is right. The available drivers are usually “mode memorized after two seconds beam on”. If you want to have one half press to change mode, you need feature of ” mode change after one second beam off”. This is usually available in brand lights only, like fenix ld20 I have.