I have been using TeslaFI for a few years now. In May of this year my big battery died on my 2015 MS 85D 3 days after the warranty expired.
Tesla initially gave me a bill for $20K to replace the battery. Not cool just 3 days out of warranty.
I had noticed that my range had dropped over the winter months but didn't do anything about it as I assumed that Tesla had changed the range calculation as they have done many times before.
I pulled up my TeslaFI charging logs and it showed a history of degradation over a few months. I sent this info to Tesla and after about a month, corporate approved a replacement battery under warranty.
GO TESLAFI !!!
Customer support service by UserEcho