A quick update. This is very sensitive to battery quality. I have an 18650 from Voldemort - and when it runs down the device starts to display a behaviour pattern - not so with my AW IMRs - it behaves impeccably until it runs out of juice. Interestingly with the battery from he who shall not be named, the device's erraticness is that it switches voltage down - this is not to the default 4 that it starts at, but to a level, I suspect, where it can function...so, I wonder if it has the same chip as the ZMax - just wired differently - because it seems to be running over current protection and.or wattage management