Was the battery acid ever filled properly from new, it does come separately sometimes, it is only a few months old.
Yes. It should shut off when the battery reaches a fully charged state. If not the battery the acid will boil off.
That explains that then. Thanks for the info. I’m now assuming the trickle charger has ceased to work properly and thus caused the acid to boil off as it’s the only way to explain what’s happened here. New battery and new trickle charger required. Lesson learned. Thanks to all for the advice.