Shorter days of Fall with solar panels isn't helping your cause. Maybe try the Meanwell first thing in the morning when the sun comes up at 15.3V for 30-45 minutes, every day and then let the solar do the rest of the work the rest of the day, on the sunny days?
I talked to my local golf course golf cart battery guy last week. Weather is cooling off, lots of tournament going on on the golf course, heavy, heavy golf cart usage as the weather gets nicer all day long, and batteries dropping dead like flies after a relatively light summer usage schedule. Cool weather in CA brings out the well to do, cart driving country club golfers out of the woodwork.
I think this seems to be a normal cycle in the golf cart battery world. Nice temps, lots of golf played, lots of batteries start to die after summer comes to an end here in So California. Seems to be possibly happening to your Screwy 31 too? Similarities are eery? Eerie? SP?