I'm new to 18650s. Purchased two NIB Zebralight H60w headlamps, spend a long time researching which cells were correct, finally went with Zebralight's own recommendation, the UNprotected Panasonic NCR18650s. (The H60 is sensitive to overly-large cells, and most of a protected cell's functions are covered by this particular battery and the light's electronics...more on that later if you're interested. For now, remember it's the manufacturer's recommended cell.)
Researched chargers. Purchased a new Pila IBC charger. Here's what happened.
All voltages measured with no load. I took notes during charging so assume times are accurate w/in 10 minutes. The time line:
Cells arrive in the mail, 3.66V each.
Start charging 6 pm in new Pila IBC charger.
By 6:30 pm I note I can rest my fingers on the cells (with moderate pressure) for 5-6 seconds before needing to remove my hand.
By 8:00 pm 5-6 seconds is still possible but not pleasant. Unplug the charger. Take voltage at 4.04V each.
Research CPF for info. Get advice in the parent forum, to post in the Hot Cells subforum.
8:30 pm, cells are room temperature, voltage now 4.03V each.
Where do I go from here? Did I do something wrong?