Just checked and we're now running at 14.8v and drawing 3A. It's definitely fizzing and bubbling. It is also overflowing slightly so the volume of acid is somehow going up!
it'll be full of bubbles... tap on the side a bit with a screwdriver/stick to free the bubbles off, they'll come up and pop, level should drop :-)
I 'saved' a dead 254v forklift pack by leaving it on charge at 10amps for a month