OK, I just did some math (and it hurt). 14 cells will have a nominal voltage of 16.8v. I'm not sure of what the fully charged voltage will be. I know that all of my MM escs will handle 4S lipo, which comes off of the charger at 16.8v. Some of my MM escs will handle 5S, which comes off of the charger at 21v.

Perhaps you are right in trying out 12 cells first. 14 cells is probably an iffy proposition. I must apologize for my comment regarding the 14 cells. I have so much different equipment laying around that it's sometimes hard to keep track of what works with what all of the time.