Hi
Just a very late update.
Since my last post i have had the batteries on charge 24/7. Due to other commitments have not been able to take boat out till last week.
The Smart gauge read 100% when we started,Only cruised about an hour a day(Spent the week between Whilton and Blissworth).
We used the 12v Fridge, and at night 240v TV for about 6 hours ,this sent the smartgauge down to about 93%. my wife used her 240v hair dryer on a couple of occasions!
The Smart gauge never went below 80% all week, I checked the water level when we got back to mooring , they did not need topping up(Thats the first time they have been checked since i installed the Sterling Pro).
It seems that the problem was with the way i had wired the battery bank after all!
Thanks for your help