Final connections - earth lead to auxiliary battery is far too long - ideally it should be 165mm measured tip to tip with M8 ring connectors:
View attachment 7823781
And temperature sensor taped to the the auxiliary battery near to the positive terminal. (I might investigate the thermal paste mentioned in another post):
View attachment 7823782
I'm going to leave the smart alternator cable unattached for the time being, taking the lead from what Ineos have done with the Smartpass, at least until they come back with answers to the outstanding questions on this topic. I am minded to attach them if I get no sense.