Batteries kept at 100% charge, or near so, by an accurate float charger do age, but very slowly. Batteries kept this way should last a very long time. Eight to ten years would not be at all unusual. When I lived on a boat at the dock, with occasional day sails, battery lifespan was never an issue. They only died when something when wrong. (Usually my fault!)
For a usage pattern that has a occasional maximum depth of discharge down to 85% followed by a quick recharge to 100% I can think of no reason for using anything other than simple flooded batteries. They will handle that service perfectly, and have a very long--and very economical--life.
The way batteries are used has everything to do with how long they last.
Fort Lauderdale, FL
---In amelyachtowners@..., <sailw32@...> wrote :
Danny , I have been able to keep my batteries in the 85 to 100% charge zone and when on the mooring 100% for long periods. Do batteries still degrade when generally kept in the 90 to 100% range. I too have wet cell , always have for the last 35 years , and see no reason I would switch out for a more expensive / complex system.