Thanks Alan. I'm assuming that by the 'buffer' you mean the undocumented and generally non-indexed capacity of all battery packs to discharge past an indicated zero? Curious what your understanding is of this buffer and how Tesla might view it also?
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Disappointing Range in P3D. Is this normal?
- Thread starter AtlasReardan
- Start date
Thanks Alan. I'm assuming that by the 'buffer' you mean the undocumented and generally non-indexed capacity of all battery packs to discharge past an indicated zero? Curious what your understanding is of this buffer and how Tesla might view it also?
AlanSubie4Life
Efficiency Obsessed Member
It's pretty well understood at this point. People with SMT and similar have confirmed it. The buffer is always about 4.5% of the maximum capacity of the battery. So if you have 78kWh at full, your buffer is 3.5kWh.
The 0%/0rmi level as displayed corresponds to remaining energy of 4.5%/3.5kWh in this case.
It's this 4.5% that creates the difference between the "charging constant" and the BMS/discharge constant. The full battery kWh is rated miles * charging constant (unless the max energy distributed as such would exceed the max allowed rated miles for the vehicle - but that's a special complicated case detailed elsewhere and unproven). But assuming you show less than max rated miles the formula holds. Yet, the 310rmi->0rmi is only 95.5% of that energy.
So assuming your battery has lost capacity down to 76kWh, splitting it across 310 rated miles, that's 245Wh/rmi. But 0.955*76kWh = 72.6kWh (which is what is available from 0% to 100%/ 0rmi to 310rmi). So splitting that up, that's 72.6kWh / 310rmi = 234Wh/rmi = (1-0.045)*245Wh/rmi.
So each rated mile as displayed contains 234Wh. While when charging, the car displays them as 245Wh (even though they don't really contain that much energy). You can tell they don't contain this much energy, because if you assume they do, and you measure carefully you get something like 93% efficient charging with 7.7kW charging. But we know from Tesla's EPA testing (presumably using the included UMC at 32A) that the actual charging efficiency is always about 88-89%. Not surprisingly, that's about a 4.5% difference...
But the true EPA miles DO contain 245Wh per mile. Because they are 76kWh split into 310 pieces. But the true EPA miles are not what are displayed next to the battery gauge.
This is also covered in that 2020 2019 2018 thread in the Battery & Charging area. The exact numbers are different for each vehicle type and even model year.
To be clear: you should never attempt to use the buffer, unless you're parked at a charger, sitting in drive (not Park), and you're using the heat to measure the size of the buffer. The car can shut down anytime.
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JCtx
Member
Interesting thread, but may I ask for myself and other potential M3 buyers what 'P3D+' and 'P3D-' mean? I only see 3 versions on Tesla's website: RWD, LR AWD, and Performance, so confused what the heck the D+ and D- mean. Glad to find out the LR's kWh rating is 76; no salesman could answer that 
. Thank you.
. Thank you.Interesting thread, but may I ask for myself and other potential M3 buyers what 'P3D+' and 'P3D-' mean? I only see 3 versions on Tesla's website: RWD, LR AWD, and Performance, so confused what the heck the D+ and D- mean. Glad to find out the LR's kWh rating is 76; no salesman could answer that
Dual motor performance plus or minus refers to whether or not you got the big brakes and 20 inch wheels. Originally, you could separate the performance motor option from those options. Not any longer. Cars with the performance motor package, but without the big brakes are often referred to as 'stealth' performance models.
Thank you. But why not call it 'P3+' and 'P3-' then? The 'D' in there makes no sense, but at least I know it means nothing
Actually, it does mean something it stands for dual motor as opposed to rear wheel drive.
MasterC17
Active Member
One more data point from this weekend.
Drove 169.75 miles, consumed 51.4Wh, average consumption 303Wh/Mi. Average speed was 75.6mph with ambient temperature of 44f. Had an 8mph headwind which was not helping me.
Drove 169.75 miles, consumed 51.4Wh, average consumption 303Wh/Mi. Average speed was 75.6mph with ambient temperature of 44f. Had an 8mph headwind which was not helping me.
Danny Brown
Member
303 Whr/mi seems pretty good for 44deg F & 84mph average “airspeed.” Do you happen to remember what your HVAC set to?
ElectricIAC
Good-Natured Rascal
Yeah that’s actually more or less excellent if riding on the stock stuff. Here’s my numbers from 80-85mph cruising with 10kt head/crosswinds and 30-40F ambient temperature. HVAC set to 68F.
MasterC17
Active Member
I've got 32000 miles on my P3D+ with the 20" rims and stock Michelin Pilot Sport tires (car is on second set of tires as best I can tell). The lifetime Wh/mi is 290 and I don't have a particularly light foot around town or drive below 65-70 on the interstate.
Interestingly, I reset one of the trip odometers when I bought the car so I could compare my values to the previous owner and it really hasn't changed much. They averaged 289 Wh/mi and I have averaged 291 Wh/mi. Considering I have only had the car in the winter I expect to get a bit better over the long haul.
I took the time to read through the EPA test procedures and I think it would be difficult to get the numbers they advertise because I never drive that slowly on the highway.
EPA Test Procedure
For reference, I had a 2015 Nissan Leaf for ~4 years and averaged 4.1 KWh/mi with that car which is roughly 245 Wh/mi. That said, I only had 85 miles of ideal range and a 55 mile commute so I took it slow and often left the heat off in the winter which I don't have to do in my TM3... so as long as I can keep the P3D+ around 275 Wh/mi doing the same type of driving I'll be content.
Interestingly, I reset one of the trip odometers when I bought the car so I could compare my values to the previous owner and it really hasn't changed much. They averaged 289 Wh/mi and I have averaged 291 Wh/mi. Considering I have only had the car in the winter I expect to get a bit better over the long haul.
I took the time to read through the EPA test procedures and I think it would be difficult to get the numbers they advertise because I never drive that slowly on the highway.
EPA Test Procedure
For reference, I had a 2015 Nissan Leaf for ~4 years and averaged 4.1 KWh/mi with that car which is roughly 245 Wh/mi. That said, I only had 85 miles of ideal range and a 55 mile commute so I took it slow and often left the heat off in the winter which I don't have to do in my TM3... so as long as I can keep the P3D+ around 275 Wh/mi doing the same type of driving I'll be content.
I know this is confusing because Tesla is constantly tweaking options/configurations but currently on Tesla.com...
You can configure a Performance Model 3 with and without the Performance Package (pedals, big red brakes, 20" wheels, spoiler) as a no cost option.
Before, you could get a discount on the Performance Model 3 without the Performance Package but now the cost of the same regardless of equipped or not.