Yes I know this subject has been beaten to death, but I have finally been digging into some data and figured out why you can't get the range the car tells you even if you use exactly what is considered 'rated range' consumption.
My car is 85 and the energy graph shows very clearly that 300 Wh/mile is the rated range. It literally says 'Rated' on the right side of the line and '300' on the left side. My car will not get it's rated range when I drive exactly at 300 Wh/mile. Jason looked into the software and found that under the hood the car actually used 295 Wh/mile to calculate rated range. I trust him so I will use that number. Now my theory is (and what I found supports it) that to calculate rated range Tesla is using the entire battery capacity, all the way down to true zero. Technically it's not a lie, but it is most likely that the car will shut down before it reaches true zero to protect the battery. But for the EPA numbers they can use the entire capacity as a basis. I did the math and it actually works out that way. When using the entire battery capacity reported by the BMS and dividing it by the 295 Wh/mile rate range energy usage, I get exactly what the car reports to me as rated range. (it's off by 0.1 kWh probably due to rounding errors in all these calculations)
Here is the BMS reported full pack capacity.
My car reports 242 miles of rated range when fully charged. When divided by 295 Wh/m it comes out to 71.4 kWh.
So yes, Tesla is kind of lying to us about the range as you can't discharge the battery all the way. Here is more evidence. This is a graph from the CAN bus charging the car from 2.5% to 92%. I captured two values. "State of Charge" (what is shown to the user in the car) and "State of Charge Min". I assume this value represents the true full to empty range as a percentage. At the start the battery was at 2.5% (shown on the main screen) while the SoCMin was 10.3%. As the battery fills up the values get closer. I assume at 100% they will match.
So the car tells you you have X amount of range but as you drive, the percentage that is shown to you on the screen counts down at a faster rate than what is used to calculate the range! Technically the range is in the battery but the BMS (= battery management system) will protect the battery from being discharged all the way to zero and shuts down the car before it reaches that. In my car the difference is aprox 18 miles. So if the car shows me 242 miles of range it should rather show 224.
I hope this helps explain why the car doesn't get the true range even if you drive at the rated consumption. BTW this has nothing to do with degradation. The BMS keeps track of degradation is adjusts all values down. Based on what I found there doesn't seem to be any trick to hide degradation. I would certainly notice as my car has 172k miles and a good amount of degradation already.
Just for reference, here is Jason's post about the true consumption numbers used by the car
Calculate usable battery capacity based on rated miles values
My car is 85 and the energy graph shows very clearly that 300 Wh/mile is the rated range. It literally says 'Rated' on the right side of the line and '300' on the left side. My car will not get it's rated range when I drive exactly at 300 Wh/mile. Jason looked into the software and found that under the hood the car actually used 295 Wh/mile to calculate rated range. I trust him so I will use that number. Now my theory is (and what I found supports it) that to calculate rated range Tesla is using the entire battery capacity, all the way down to true zero. Technically it's not a lie, but it is most likely that the car will shut down before it reaches true zero to protect the battery. But for the EPA numbers they can use the entire capacity as a basis. I did the math and it actually works out that way. When using the entire battery capacity reported by the BMS and dividing it by the 295 Wh/mile rate range energy usage, I get exactly what the car reports to me as rated range. (it's off by 0.1 kWh probably due to rounding errors in all these calculations)
Here is the BMS reported full pack capacity.
My car reports 242 miles of rated range when fully charged. When divided by 295 Wh/m it comes out to 71.4 kWh.
So yes, Tesla is kind of lying to us about the range as you can't discharge the battery all the way. Here is more evidence. This is a graph from the CAN bus charging the car from 2.5% to 92%. I captured two values. "State of Charge" (what is shown to the user in the car) and "State of Charge Min". I assume this value represents the true full to empty range as a percentage. At the start the battery was at 2.5% (shown on the main screen) while the SoCMin was 10.3%. As the battery fills up the values get closer. I assume at 100% they will match.
So the car tells you you have X amount of range but as you drive, the percentage that is shown to you on the screen counts down at a faster rate than what is used to calculate the range! Technically the range is in the battery but the BMS (= battery management system) will protect the battery from being discharged all the way to zero and shuts down the car before it reaches that. In my car the difference is aprox 18 miles. So if the car shows me 242 miles of range it should rather show 224.
I hope this helps explain why the car doesn't get the true range even if you drive at the rated consumption. BTW this has nothing to do with degradation. The BMS keeps track of degradation is adjusts all values down. Based on what I found there doesn't seem to be any trick to hide degradation. I would certainly notice as my car has 172k miles and a good amount of degradation already.
Just for reference, here is Jason's post about the true consumption numbers used by the car
Calculate usable battery capacity based on rated miles values