Well amazing what you can do with a pair of pliers, a screwdriver, and a socket set; oh and a small non-english speaking electrician with a multi meter. After much crawling around the engine room last night, and tracing battery wires (there are loads of them) I discovered that the problem was the Battery isolator, and the fact that when I had replaced in Hong Kong (8 YEARS AGO!) it had been wired up the wrong way. Re-wired it, and used the spare terminal and we now have temporary fix, and very well charged batteries. So looks like we might be on the move tomorrow, or Sunday or Monday or....................