The 540C 9L handles 14.4 volts with no problem. Mine runs warm, but nowhere near too hot, on 14.8 volts. Most sensorless brushless systems are made to handle a lot of cells. In fact, it's routine to run extra cells when you have a sensorless system. Guys will stick a BK Warrior 9920 in a Stampede and run 10-12 cells. That controller (9920) will handle up to 20 cells!