In the end I just got 2 X 5m 12V extensions with cigarette connectors and connected them together and ran the scope straight of the two big Kickass batteries back in the shed, a great all night session of viewing and imaging
The 12" Skywatcher from Astroshop is a great bit of kit. After a two star alignment the bloody thing put every object in a 10mm eyepiece!!
and in the steady early hours before dawn all 6 main stars in the Trapezium of the Orion Nebula were cleanly separated pinpoints..very happy
Mike