[F3AFlyer7]

Marcelo,

It depends on how their controller is rated. A lot of times, unless you are using a high voltage type controller, the more cells you use, the less peak voltage the controller can handle. I'm not too knowledgeable about Cyclon esc's, but I would check to make sure you aren't over drawing the controller. You didn't happen to put a wattmeter on your set-up before it blew did you?

Take, for instance, the Castle Creations 80 amp controller (Not the High Voltage version). The more cells you use, the less peak amperage you have. If you are using 6 cells, the peak draw for that controller is 40 amps. This is why the High Voltage line of controllers are so nice, because you don't have any peak current loss all the way to 12 cells.