For the sake of easy reference, I made made this thread for the driver found in various lights.
Single XM-L J18 lookalike thrower has it.
As with all budget lights, variations could happen in terms of small differences on the driver, and which driver comes with the lights.
Stock output on high seems to be 1,8-2A to the emitter. I had one that did 2A and one that did 1,8A+ (a bit higher output with lower input voltage)
It can be used with 1 or 2 cells. Input amps is basically the same as output amps (with two batteries double the tailcap amps). Its a 5 mode with next mode memory.
Driver diameter is about 21,85mm,
Driver height: 6,75mm
Driver circuit should look like this:
Blue circle shows one of the sense resistors. Based on my very limited testing. The driver does not handle to be pushed to the "extreme" ( 4A+) smelled burnt very quickly. It might be able to do 3A nicely. Adding one R330 will probably give you around 3A. As always, do this at your own risk.
(I saw 2,27+A with R500 added, or 3,8A with R120, but my driver seemed to be 1,83A with normal input voltage from two cells. I would not recommend R120 or such low values)
Red circle shows a resistor valued "0". Remove it if you want the make the driver become a 3 mode with high, "mediumlow", stobe.
(with my slightly modified driver, added R500, I saw 2,27 on high and 0,5x on "mediumlow")
In the green circle is a capacitor Add a low resistance resistor on top of it to remove next mode memory. Then it starts on high every time. (I used a 22K resistor from this package, labeled 273.)
Personally I have no intentions of using this driver in any high/extreme output thrower, but it might be nice for lights where you want 2A output or a bit more. Removing next mode memory makes it much more likeable IMO. :)