Thanks for the replies.
I am operating single battery Barkingmad.
Latetonite, the discharge light comes on if there is a discharge. If you have fault with the battery charger it can come on even if the No2 transfer bus is supplying AC to it. The reason I am considering divert or return in this situation is that I wonder if eventually I'll lose the standby system ( or part of it).
Cheers