We have a 2017 550, with the original Marinco charger built in. Put in a new Enersys
DataSafe 70ah AGM battery in it two years ago. Always plugged in while not in use.
Now, this year, if I unplug the charger, voltage is at 13 v, but if it sits for 12 hours, voltage drops to 12.4 (80%).
It...