My employer has recently provided me with an LED Lenser X21, due to my job involving out-of-hours visits to remote substation sites.
Now I have to say, although I'm fully aware of it's flaws, to me this is a fantastic piece of kit, I've certainly never encountered a torch/flashlight quite like it! In terms of sheer output it makes my Passat's headlights seem puny in comparison and the focusing function is excellent - lost of nice floody light for use as a worklight, or a viciously intense beam for spotting (and probably blinding!) intruders.
BUT: as most of CPF seems to be aware this light is far from perfect. To start with, and in my eyes the most serious flaw, it will only run on alkaline cells - at least, if we want the LEDs to have any sort of useful lifetime. This results from the use of a rather cheap-and-nasty direct drive system which relies upon the batteries' internal resistance to limit the current to a safe level (NIMH cells having much lower internal resistance which, in theory, could cook the LEDs).
Another consequence of the direct-drive setup is that the light has only two modes - "high" and "low", where "low" is still rather intense. Also, the mode selection is achieved via some sort of two-position push button switch which either completes the circuit directly or via a resistor - the flaw being that the light defaults to "high" before allowing "low" to be selected.
Soooo... I'm now pondering if this can be improved, and if any CPF'ers have attempted such a feat of engineering. I've quickly measured the current drawn from the batteries on each setting (5.6A high, 0.8A low, although I really ought to make a bit more effort and check the actual current and voltage seen at the business end) and am now thinking along the lines of retrofitting a regulated driver board that can effectively turn the light into a regulated, multi-mode affair - four or five modes would be nice, especially if a lower "low" can be achieved, and without having to suffer the flashing/blinking/strobing/SOS modes that blight some of my smaller lights. And, of course, being regulated this would permit the use of a nice set of rechargeable NIMH cells rather than alkalines.
Thoughts, input, advice all welcomed! Anybody who's attempted to do something similar, or can recommend a driver board that would suit my purposes, or guide me on what to look for in a driver board, etc etc (although "chuck it out and buy Light X" isn't a goer; the only reason I have a £240 light in the first place is that work provided it and none of our official suppliers offer anything even remotely comparable to the X21!)