This is how my batteries did one time resulting from a shorted cell in one of the batteries... This happened when I had my single mode converter/charger going and all of the charging DC voltages was 13.6VDC. This boiled out my battery fluids over time and it eventually shorted out one of its cells inside the battery... The first symptoms was like yours being intermittent...
Now I am running a multi-voltage smart mode converter/charger and also keep a somewhat close eye on my battery fluids...
Been going good since 2009 doing this...
Roy Ken