Like I said Leo, it was an observation and may be a freak issue, but it definitely made a huge difference to go from a seperate battery to a BEC.

Out of interest did you measure the voltage because a high current draw (assuming a fixed resistance) may cause a dip in voltage. (Ohms law, if you increase the current with a fixed resistance then a drop in voltage will occur if the voltage regulation isnt up to it)

Again out of interest, what was the voltage of the battery pack?

As this is an easy one to test, I may stick in a 6v voltage regulator and see if it makes any difference to the whole set up with the Roboteq. If it does, its worthy of further investigation, if not then its not worth persuing.

Andy