In order to remember the lessons we have learned in recent years I would like to write a ‘best practice’ article on preparing a boat to overwinter (unattended) in very cold climates. It would be great to use this thread to collate the experiences of others.
Simon

Hi Simon,
That is a very impressive stat: 6 yo AGM battery bank left for winter on its own and reads 12.7 after 9 months: even for lightly used batteries. Part of me wants to argue with you that it is not possible while the other half intends to go out and buy AGMs for Alchemy. It would have been interesting to know what the “in line” battery v was after a winter of parasitic draw as well as the bilge pump.
Is Ivan watching over Shimshal in Lewisporte? If so, I bet he could get an extension cord to the boat for a charge. In any case, it sounds like it is un-necessary with the AGMs lasting so long and it sounds like you may have disconnected them.
I doubt you will have an unpleasant shock and need new batteries. My gels always gave me a year or two warning.
My best, Dick