I don't have too good of luck here just trickle charging the batteries all the time... My trickle charge source is a small 10WATT solar panel laying in the windshield area of my truck or on top of my battery box...
I have to do a full routine of charging my batteries using my trailer smart mode PD9260C converter/charger if I want to have the full performance from the batteries...
I won't go more than a couple of weeks without doing this on my batteries...
Just me I reckon but my batteries are ready to go using this routine...
Roy Ken