Newer batteries have a digital parameter for replacement: 70%.My 2015 90D AWD has 112K miles and a calculated battery capacity of about 64.5 KWh and a 100% range of 223 . It seems like it loses about 1 mile a month (not sudden loss) but that is a rough estimate. I asked Telsa about 6 months ago to look into the degradation, but they said nothing is wrong. I understand that one of the reasons Tesla will replace the battery would be due to faster than normal degredation based on the average, but I don't know if anyone would have a better understadning of this. Thanks for your expertise!
No such digital number for older ones. They only say something is wrong when your battery can't hold a charge anymore. That means a slippery slope: 65%, 50%, 30% capacities and Tesla could still say there's nothing wrong because it can still keep on charging.