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## Is the EPA rating way low or is the Model 3 battery really 90KWh?

## Is the EPA rating way low or is the Model 3 battery really 90KWh?

Submitted by bjrosen on August 14, 2019

The EPA rating of the M3 AWD is 116 which is 290W/mile, that translates into a 90KWh battery for 310 miles of range. Everything I've read says that the M3 battery is only 75KWh. To get 310 miles out of a 75KWh battery the you would need to get 241W/Mile which is an MPGe of 139 (33700/241), that's not unrealistic I'm doing better than that I'm getting 224W/Mile which is an MPGe of 150. So which is it, is the EPA rating way low or is the battery really 90KWh not 70KWh?

jebinc| August 14, 2019I'm getting 250w/miles on my 310 mil rated LR AWD...

bjrosen| August 14, 2019@jebinc your number is consistent with the EPA rating and a 75KWh battery, which means that the 310 mile number, while possible in the summer and driven by an old dude like me, is deceptive.

gmr6415| August 14, 2019241 Wh/mi x 310 miles is 74,710Wh of usable capacity. There is also some sort of top end and bottom end buffer. It has been stated that realistically the total or gross Wh capacity of the battery is closer to 84kWh.

With my LR RWD I average a little over 200Wh/mi around town and 220Wh/mi on the highway averaging 75 mph while driving in warm climates.

bjrosen| August 14, 2019@gmr6415

The EPA rating is 290W/mile, the 241W/Mile is my calculation for the efficiency needed to go 310 miles on 75KWh, that's an MPGe of 139 not 116. Did Tesla understate the EPA number or overstate the range number?

rxlawdude| August 14, 2019I seem to recall that 227Wh/mile was the benchmark for RWD LR M3s.

rdavis| August 14, 2019@bjrosen, you're not calculating correctly.

My guess is that it's calculated off the total batter capacity and not usable.

"The EPA calculates that 33.7 kilowatt-hours of electricity is the equivalent to one gallon of gas."

The LR NON-AWD Model 3 gets rated 26 kwh / 100 miles = 130 MPGe. Would work out to an 84.5 kWh battery

The LR AWD Model 3 gets rated 29 kwh / 100 miles = 116 MPGe. Would work out to an 89.9 kWh battery

My guess is they are looking at total battery size, not usable size. So the actually battery may be between 85 to 90 kWh, but I think most people have come to the realization of 75 kWh or usable.

Just like the MPG on a ICE car, it's just a number to compare other to. I don't think it really is meant to be taken as a "real world" expectation. There are way too many variables in the real world for both and ICE and EV to have a standard that is really to be "believed".

rdavis| August 14, 2019^^^^^

Opps sorry about that first line... I was thinking the NON-AWD, you were talking AWD. The rest of that post above should be good...ignore my first line about your calculations.

andy.connor.e| August 14, 2019Its possible that Tesla is marketing their battery capacity at usable capacity. Unlike other companies that market it deceivingly where you're not getting what you think you're getting.

ie. Selling 32BG iPod, where they're really selling you 32 billion bytes, which 1024 bytes = kilobyte and so-on. So after all of that, you're down almost 10% capacity, and then the operating system takes up another 2GB. So before you know it, you only get about 27GB of that 32 you bought. The numbers scale worse the lower you go.

Its possible that Tesla has an honest marketing technique.

bjrosen| August 14, 2019I've just done the same calculation for the Volt which I've been driving for three years, it looks like the EPA MPGe number is significantly derated from the range number. I'm new to the Model 3 so I don't have year round numbers but I've had the Volt for three years and I've gone through three winters with it so I have a good idea of what the average range of it is and the 53 mile rating is pretty much dead nuts on for a year round average, in the summer I get 72 miles on back roads, 60 on highways and in the winter it's in the 40s. The available KWs are also easier to know on the Volt because it's an EREV you always empty the battery and fill it to the max, the battery in the Volt is 18.4KWh but GM has hard guardbands built in so there is 14.1KWH available. 14.1KWh/53 is 266W/mile which is an MPGe of 126. The Volt's EPA is 103 which is 81% of the actual MPGe. The Model 3's EPA is 116 but from the range numbers it should be 139 which is 83% of range based MPGE, pretty similar.

Magic 8 Ball| August 14, 2019Doesn't the EPA rating base calcs on energy used to charge the car and factor in that from wall socket to battery is not 100% efficient?

andy.connor.e| August 14, 2019Doesnt the car have an energy meter on it? So you can see how much kWh you put into the battery?

Magic 8 Ball| August 14, 2019Energy from wall > energy delivered to battery.

MDMatt| August 14, 2019I am pretty sure that Magic8Ball is correct. When the EPA is doing their calculations, they are using amount of energy that comes out of the wall socket. Since 100% of that energy does not make it into the battery, you end up using more "wall energy" per mile compared to the "battery energy" per mile. So, it might take 90kWh to fully charge the 75kWh battery pack. There is energy loss in the charging process. I thought that I had read someplace that it is about 85% efficient in charging.

As with most things, there is a lot of people saying things out there, but not a lot of very good direct information from Tesla, so this could be wrong, but to the best of my knowledge this is correct.

roger.klurfeld| August 14, 2019This is a very old discussion. Originally Tesla said the nominal size of the long range battery is 75 kWh.

However, the EPA rated the size as 80.5 kWh. Tesla then filed a response to the EPA that the battery pack has a usable capacity of 78.27 kWh. So all the people who do precise calculations using the 75 kWh nominal amount wind up with the wrong numbers.

The EPA doesn't do testing to determine mileage ratings. The EPA describes the standards for city and highway testing and the manufacturers do the testing. I assume that is true for EVs.

beaver| August 14, 2019A few comments:

- L2 (240 V) charging is 90%+ efficient va 80% for L1 (120 V. Personally I get 95% efficiency out of my dedicated meter and large gauge wiring for 100 A.

- TeslaFi says my LR RWD Target efficiency is 218 Wh/mile

- I have measured charging capacity of 73 kWh and discharge (drive) capacity of 68 kWh using long charges and long drives to measure.

- I heard the physical capacity of the LR model 3 battery is 80 kWh, with 5-10% unavailable to protect the battery likely split across the bottom and top of the battery capacity so we don’t charge too high or run down too low

mrburke| August 14, 2019I was told there would be no math on this test. Much less fractions, percentages and decimals.

Tronguy| August 14, 2019@mrburke: Speaking as a EE, math is everywhere. Sneaking up on you. Hitting you over the head with its club of partial differential equations and complex number fields. Your brain knows this and does the math that keeps you from tripping over one's feet, able to catch a ball (parabolic arcs, anyone?), and to breathe.

People don't bitch about calculating MPG.

(Disappearing back into the pit from which he pops out from time to time to scare liberal arts majors. Just kidding.)

jebinc| August 14, 2019@bjrosen - yeah, I'm an older dude as well...

cmh95628| August 15, 2019@Tronguy You crack me up! Thanks for the laugh.