Back to Glenss question, the 6v drop is probably caused by the brushless motor - which draws a huge amount of current at zero revs. I had a similar problem with Velocirippa as the drive motors were switched by dc contactors, the current draw was sufficient to prevent any other circuits from working. In many fights the steering would stop working but functioned perfectly on the bench - the problem was solved by fitting another battery pack to run the ancilliary systems and have the main battery pack working only the motors.

Trev