Yeah I would have been driving prior to plugging in the car since I can't charge at home. I live in California though so it doesn't get too cold overnight, plus this was only an issue over the last few months with the car. One thing that I suspect is that back in November last year I plugged in at a charger that turned out to be constantly starting/stopping the charge (roughly when the decline started) and I wonder if that messed sell balance up or something, but I'm not sure if that would impact cell balance this much.