Hi, yes, we're not desperate (yet) as I said it does come back on and works for the rest of the day.
we have 660Ah AGM batteries so they take 90A for about an hour before decreasing ...
yes, if we were stuck we could use the starter battery alternator!
i think a brush thru to remove built up dust, dog fluff on its heat sink might be the first port of call, if I can get inside it
and then maybe a service From cox auto - new brushes kit be in order