thanx for the link.Use a trickle charger. That way your batteries stay charged and you do not have to disconnect them. Check here http://batterytender.com/selection_guide.php?osCsid=85d68586ebf1cabe18a326c6ad7732f2
That will work just fine as far as keeping them from draining. If you wanted to make sure they kept maintained too, you would want a charging system likethe Kinetik Intelligent Power Supply -> LINKthanx. I had a read of the article and things are more clearer now.
Rather than the isolator method, I will just disconnect both negatives