Originally Posted by Casper

So it runs fine with nimh but not with the lipo? That is very odd. You say you checked the voltage of the lipo and it is above 7V? I am not all that familure with the sidewinder so not sure if there may be some other setting in there that my be messing with stuff.

Sensored motors have a separate sensor wire that plugs into the back of the motor. I am assmuing your setup is sensorless though.