I was thinking of saving a few $ and buying unprotected 18650s since the new ones can go down to 2.5V. does anyone know if the ultra fire UF-2100 5 mode will cut off at a certain voltage or will it suck a battery dry?
I tried looking but couldn’t find an answer.
Thanks.
My dinodirect version just drops down one mode when the battery starts getting low. Usually after it drops a mode it can be switched back to high as long as the battery isn’t severely depleted. I think it will drop back a mode when the battery gets down to about 3.5volts, so there is plenty of time to recharge a unprotected cell.
I wouldn't worry too much, it simply uses a linear driver. By the time it reaches down to 2.6V or so, the voltage barely match the minimum Vf for the XM-L. Meaning even if the driver is still not shut down then, you get really really low light with really tiny current.
It's quite hard not to notice.