I have unprotected Panasonic 3100mAh 18650s and would like to know generally what would be the recommended safe minimum and maximum charge on these.
I started searching around and find all kinds of info about this and that but no definite answer to my question.
I remember reading some time ago that those new cells can be run down lower (I just read some people run them down to 2.8v or 2.7v - is that still safe for this particular cells) and even charged higher then regular 18650s (up to 4.4v? Don’t really trust that though) but can’t confirm. The model is Panasonic NCR18650.
Assuming that you really mean the NCR18650A (which is the 3100mAh cell) and not NCR18650 (which is the older 2900mAh cell) then panasonic rates them for 4.2V MAX and 2.5V MIN.
The 4.2V is ABSOLUTE MAX - DO NOT exceed…
the 2.5V is the minimum to meet panasonic lifetime expectations. I would expect them to be safe a bit lower than that, but I wouldn’t go lower than that if I wanted my cell to last.