I've noticed a few times now on road trips that Supercharges take forever to finish. The battery will get to its maximum (a mile or two shy of its published maximum by the way) with the mention "calculating time remaining" and just seems to sit there. Except once shortly after I got the car in March, I've never had the patience to let it finish and just drive off. I understand a Supercharge slows down quite a bit towards the end but is this what you're experiencing too? My range charges at home do end up finishing though I don't monitor them as much (mostly overnight charges) and can't say if they get stuck on the 'calculating time remaining' mode.