When i was at Whilton Marina on shoreline, the battery charger replenished the batteries to 100% with a voltage of 14.2v. We cruised to Blisworth, 10 mile cruise, now batteries are showing 88% and 13.7v while on shoreline... guessing the charger isn’t getting enough AC voltage to produce the 14.2v to recharge the batteries..? I had a similar issue with a touring caravan years ago on a large site that provided hook up...
I have a single sola panel fitted to the roof and a cheap looking “solar panel controller” by photonic universe, which has pretty flashing LED’s on it, however know way of showing if it is actually doing anything.... looks a bit of a Heath Robinson installation to me... the vessel had four other panels prior to sale, which must have had a “better” management unit fitted. I’ve welded up the 20+ holes left from the previous owner who thought self tappers, rubber washers and RTV makes a waterproof solution...