While that may be true (using only “protected” batteries), I have tested a few other Wuben flashlights, namely Wuben TO46R, L50 and LT35 and both flashlights also come including with a Wuben protected 18650 — however, the L50 and LT35 do not overcharge batteries — I tried charging unprotected 18650s in these 3 other Wuben 18650-flashlights and they checking the battery voltage after charging, they are around 4.20v or a bit less — unlike the C3 which continues charging when the user does not unplug the flashlight from the USB power. Also, 4.57v (could have been higher, since I unplugged after about 2 or 3 hours after the C3’s charge indicator light turns green) is definitely too high for 18650 batteries.
I suspect some people will charge overnight and may not be able to monitor the charging state, and overcharging would not be good then (if they use an unprotected 18650 on the C3)
I ordered it and so far, haven't tried charging another battery without protection. I did observe that the green LED comes on at 4V and when the battery was at 4.18V, the charging current was at 0.002A.
I didn't let mine charge that long but I can confirm the problem too. The voltage on the DMM is taken directly from the battery after charging with this light.
I have a C3 bought about 6 weeks back. Guessing it’s got this over-charge “feature”
I do like the light though (despite the 2600mAh “protected” battery- wass’up with that?). Still a nice throw for it’s small form factor. I’ll just charge via the Zanflare Vs. the internal USB port anyway. Also prolly’ use a Q30 or something a bit more modern battery wise.
I would be too. I posted a picture above so the outer and inner spot IS round and it's just that outer TIR artifact, aka. spill, I think, what some commenters find detracting.