Maintaining AGM batteries during storage

[max from alaska]

I have a 2014 R27. During the winter I have plugged the shore power into my home outlet, and turned the battery charger on. The intent is to keep a continuous charge on the battery bank during the winter. However, I read on line that a continuous trickle charge on an AGM may damage it, because there isn’t any “circulation” in the battery. Question: Is storing the boat over the winter with shore power “on” and the battery charger “on” a good thing or a bad thing and why?

Last winter I actually removed the batteries from the boat, placed them into my garage, fully charged them with a battery charger, then let them sit all winter, topping them off with a battery charger every 2 months. Is this a better way to preserve battery life of the AGMs?

Thanks,

 

[marksandyham]

I pull the 24/7 fuses, turn off the battery switches and all of the 120v breakers except the battery charger and then power up the boat once a month for 8+ hours.

 

[ssperera]

Yes, I am looking for the same answer- I have a 2013 28 Cutwater in my heated garage and I have it connected to shore power and battery charger ON but is this the correct thing to do or do I unplug from shorepower and just let the boat be- i have nothing in the fridge as well. Just wanted to do the right thing since all of my AGM batteries are new from last year. I am hoping a tech person will reply from Cutwater. This is my first time asking a question- not sure how to use these forums.
Thank you
Senal Perera/Snohomish WA

 

[ixlr8]

On my '18 27OB- I pulled all the 24/7 fuses and shut off everything I could when I put the boat away for winter storage. I checked the battery voltages after 1 month, they were down some but not enough to be concerned about. I checked them again after 2 months and they were getting low enough (11.8v) that it was concerning to me and after that I plugged my boat into "shore power" in my storage building every month. AGM's do not like to be held at full charge for extended periods. These batteries are way too expensive to mistreat them.

 

[NewMoon]

I've kept our boat battery banks (all AGM) continuously connected to smart charging over the winter for more than 20 years with no problems. Heart Freedom inverter/chargers on both boats are not by any means the very most modern, but they are smart multi-stage chargers which take good care of the batteries over the winter.

A smart charger set to the right voltages for your AGM's should do the job.