Hello,

I was to harvest some 18650 cells from a 5S 1P drill battery. After opening the battery, I checked each individual cell in the pack. The first 4 cells read between 3-3.7V while the last call reads 12.5V by itself. May be this is the reason for the battery to be bad. I have checked it repeatedly, I still get same 12.5V or so. The control board is still in place. I have not yet isolated or removed it out of the pack. I have never seen such a reading. Explanation?

 

That cell is open circuit or disconnected and what you rae reading is total voltage of the other cells.