Backstory- New to me 2017 Model S with 100kW battery. Picked up in June. Recently had a 240V installed and had the time to fully charge and attempt to balance the pack. I've done what I feel like is tons of research to not have to ask these questions, but... apparently not enough so here I am.... I drove the car down to 16% and parked in the garage. I wanted to go a little lower but it wasn't happening. Even stayed in the car a while with music and AC blasting but the percentage didn't change. Checked after supper and the car was now down to 11%??... Batteries cooled off? This drop for my car is not unusual. It doesn't always happen, but isn't uncommon for me. I checked the range left as I had never been this low, 34 miles. So I let the car sit for about 3 hours to hopefully sleep and get a good bottom starting point then plugged her in with 34 miles still showing. On the cell app I moved the charge limit to full and it estimated 309 miles. After about 20 hours at 20 amps the car said charging complete- range 278... The battery display on the phone didn't look full. I moved the charge limit slider back and forth but it never gave me the option to start charging again. I was messing with it for a minute or two, even closing the app and reopening but it wouldn't let me restart charging. Then I noticed my range, 282, then 283 and within less than a minute it was up to 285. The green showing the battery state of charge was climbing as well. I watched it climb for about five minutes and it settled at 302 and the battery display was showing full now. So it went from @92% to 100% without charging. I had always thought balancing would be a slow charge up to 100% but this has me scratching my head. Currently the car has sat overnight and has 84% with 13.x % used on our trip yesterday evening and I did leave the AC on for my wife while I ran in the store so the mystery 8% is still accounted for LOL! I'm sure the BMS has more tech than I can understand, but I'm just curious if anyone else has experienced this. Thanks for reading! tl;dr- car said full at 92% and stopped charging, then ghost charged to 100% within a few minutes.