Thanks for the responses guys, much appreciated. The batterys i'm using are turnigy nano a spec 4200 shorty 65-130c.
The servo is my new piece of kit, I've checked with a volt meter the amp draw of an old slow servo - 100mA . New digital servo , 1.75 amps draw!! So they are def power hungry, and this is operating it on a bench with wheels off the ground. Maybe my esc 3amp bec can't handle it with the punch turned up to max on high grip carpet / tight start / stop track. Think lowering punch setting and more sensible boost start rpm are the way to go. Will also try lowering the low voltage cut off from 3.2v to 3v or off to see if it helps , I never take much charge out of a pack during a 5 min heat. Thanks again
