This sounds like a typical Microsoft or Apple explanation of why the software does not perform as advertised...surely with Prius and Tesla having been in the market this long, the real answer should be out there - after five years, what real range will my battery deliver if I was getting 50 miles day one - the heck with kWH measurements, capacity and time to charge, charge range (20-80; 10-90; etc.) -it's like instantaneous MPG measurement in my old Prius - it was NEVER exactly what the hand calculated (gas in, mileage driven) result. Guess I'm just not a good little environmental/EV soldier - I just want to know if I'll be getting 80% or 50% of my EV range five years from now.
As he mentions, you never really know for certain what the min/max is as far as capacity. Oh, you know that, for instance that your battery "rated" at n kW, and you would certainly know when you hit zero (but how often does that happen in a Tesla unless you plan to call the flatbed). So even at best it's all a series of estimates. I am with you on not really caring about the day-to-day fluctuations in range. I, too, just want to know where I'll be on EV range 5 years from now when I see I have a "full" battery. I take all the numbers that flash on the dash as estimates. And it's weird, because a few times I've had 45 EV miles of range after a "full charge", and other times I've had less. I have also NEVER been able to move 17 kW into the battery - and that's from a supposed empty state (as in zero miles on the EV range). If the zero miles EV range is true, then 2kW must be held in reserve - but not accounted for in the EV range estimate. When I look at my history since I've had the car, I have one charge of 15.22kW, one charge of 15.01 kW, one of 14.85kW. In each of those cases, I had 0 miles of EV range showing. So I maybe I can use the average of those 3 "fill ups" as an index of sorts. There are just too many variables to try and make a meaningful statement about EV range degradation. Season/temps, load, mode, etc. All work together to eat away at range.
Unfortunately, that is correct. Furthermore, not everyone is going to experience the same degradation even over the same total distance driven. It depends on many factors, including driving style, how much heat and/or high humidity the battery is exposed to, the amount of DCFC sessions, and now much you "strain" the battery by charging it to near 100% or by nearly draining it. The best we can do is show a graph of how much capacity different cars have lost vs. total distance driven. And every car is going to be different, so the graph below for the Model S... only applies to the Model S. But why should we expect a simple answer? Can anyone predict how much MPG a gasmobile will lose vs. total distance driven, as the car ages? Of course not. It depends on many factors, just like range loss with a BEV.
