TimothyHW3
Active Member
Can you link me to it? I would better have a km screenshot as there are rounding errors.
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Anyone LR AWDs Showing 322 Miles Fully Charged?
- Thread starter diezel_dave
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Thanks for the information. It looks like from the numbers here, your constant was 249 before, and now is 242. But it is hard to get exact values without the rated miles decimal precision that you need from a 3rd party API app.
This also shows that they didn't change the full pack kWh value when they did the update, only a constant change; pretty straightforward.
One thing you might want to check is the SMT SOC value vs. the car reported value. I believe the SMT value is based on nominal remaining, and it should be based on ideal remaining. On model 3 cars, most people report that expected remaining is the same as ideal remaining, but that isn't true for my model S.
TimothyHW3
Active Member
That's good. I see that the recent SMT readout in this thread shows an SOC expected under the battery tab, but not SOC ideal.
AlanSubie4Life
Efficiency Obsessed Member
Thanks, so ~318, not 322 (the maximum), as I expected (you'd have to charge to 100% to be sure of course - I'd expect no more than 320 rated miles at 100% for you). To be clear, there are people with your vehicle who see 322 rated miles at 100%.
Thanks. As suspected (wasn't sure, as seen in italics above), the SMT available energy did NOT change with the software update(good information; thanks). And you are maxing out right around where I predicted. So all is well (other than your energy being a smidge low - you're about 1kWh lower than one would hope for brand new vehicle - but it's possible that energy estimate could adjust with a little more driving - so few miles on the car it definitely could be slightly off - though generally I would expect it to trend downwards over time).
I agree with other comments here that you should use the car's %, and double check that it matches SMT's reporting. Sounds like the discrepancies have been resolved, but all the calculations above assume that you're using the car's displayed % (which you aren't).
AlanSubie4Life
Efficiency Obsessed Member
2020, 2019, 2018 Model 3 Battery Capacities & Charging Constants
Note that the rated line is always about 5Wh/mi higher than the Charge Constant given in this table.
TimothyHW3
Active Member
Which row value in that table corresponds to the straight line under energy?
TimothyHW3
Active Member
It takes the ideal remaining value from the BMS for calculation instead of nominal remaining. The previous SOC value took the nominal remaining. Basically in some cases, especially in colder conditions, as explained by @ran349, the nominal remaining and ideal remaining will be two different values. The SOC on screen then will use the ideal remaining and therefor the SOC in ScanMyTesla was not accurate.
If you plug the car while cold to a charger that shows the %, meaning it reads it from the BMS, you will see a higher SOC than what you see in the car - this is the SOC value which comes from nominal - the actual remaining if your battery was warm. This will be the case if you see the blue block and the snowflake.
So basically nominal ideal is what you see when in % inside the car if the battery is cold.
Nominal remaining is the one including the colder block - the one reported by the car as actual remaining to the charger.
Both values, SOC and SOC ideal are calculated by the app, not delivered by the BMS.
AlanSubie4Life
Efficiency Obsessed Member
Take the second green column and add 5Wh/mi. Like I said, the charge constant.
Just a little addendum: The SR row is incorrect. I have updated it in my spreadsheet, but have not updated that thread.
vsansal
Member
Here are the pictures as promised. Attaching 50KM energy graph for both 19 and 18 inch wheels. And 100% charge from the app.
TimothyHW3
Active Member
Thanks. I was hoping we can actually see the value, maybe you can try and get it to 150+ avg somethings?
AlanSubie4Life
Efficiency Obsessed Member
Here's one from the 19." But this was taken PRIOR to the 2020.4.1 update, which was an intermediate stage. (Line is at 264Wh/mi for the update just prior to 2020.4.1.)
Obviously everything just scales from there according to the EPA ranges, and changes based on wheel selection (for 2020 models). (299/304/322)
Model 3 Range Constant Check
And the 2020.4.1 update lowered the 19" constant to ~255Wh/mi, and the rated line to ~260Wh/mi
TimothyHW3
Active Member
It would be great if we can get it in km as there are too many rounding errors with miles.
By the way - you keep sticking to your "constant" naming
I think we had this conversation already - the only constant is the rated line - anything else is just an extrapolation from the whole 0-96%, -4% buffer thing.
Constant is really not the proper word for what you are calculating. A constant is pi, it is always the same and is static...
By the way - you keep sticking to your "constant" naming
I think we had this conversation already - the only constant is the rated line - anything else is just an extrapolation from the whole 0-96%, -4% buffer thing.Constant is really not the proper word for what you are calculating. A constant is pi, it is always the same and is static...
AlanSubie4Life
Efficiency Obsessed Member
The charging constant really is a constant in this case. For 2020 AWD, the calculated capacity of the battery is the min( charging constant * rated miles at 100%, 77.6kWh). (This formula does NOT apply at any other %.) That will align exactly with SMT data unless you have a brand new vehicle and your available energy exceeds 77.6kWh.
It's a constant, but sure, it is occasionally changed by software. It's also what is used by Tesla to calculate and display the "kWh" added to the car on the charging screen (even though that does not represent the true kWh added - since that kWh is derived from the constant and the miles added, and does not measure the actual energy added to the vehicle).
Etc. etc. It's a constant. It doesn't account for heat losses or the buffer. There are different constant for different vehicle variants, and for different software builds (occasionally, but rare).
The constant is always lower than the rated line by 5Wh/mi (3Wh/km).
The discharge "constant" is not a constant (the one you would calculate on a drive by looking at rated miles used and kWh consumed). That's approximate due to heat losses, battery warming, meter losses, etc.
The BMS constant IS a constant. It is used to calculate the displayed rated miles based on the SMT kWh (CAN bus). You multiply that CAN CAC/ kWh by 0.955 and then divide by the BMS constant to get the displayed rated miles. That's just the simple relationship.
It's not complicated. If you don't want to call it a constant that's fine, but it's really just semantics and is of no consequence.
The rounding error due to it not being in km is certainly there, but small. Call it 158Wh/km or 159Wh/km. And the line is at 161 or 162 Wh/km. For the 19" 2020 AWD/3P+.
TimothyHW3
Active Member
Nothing else did I say - the thing you call "charging constant" is the energy graph value...And the thing about it being lower or higher than the line - it is hard to know because we don't know what capacity Tesla is working with initially. But if you do the math from the rated range in KM for example it is pretty spot on - so no, it is not 5Wh higher or lower. It is exactly what it says on the straight line. In KM at least...
AlanSubie4Life
Efficiency Obsessed Member
You'd have to show me the evidence of that. In my car, when charging it, I KNOW that the constant is 245Wh/mi. If I add 200 rated miles to the car, the screen will say it has added 49kWh (not 50kWh). (You can also use apps that access the API and get this same value without having to worry about the lack of precision (rounds to nearest kWh) on the charging screen.) It's also the number that comes out of the energy screen when you do the calculation (Projected Range * Recent Efficiency) / Rated miles remaining.
And I know the line is at 250Wh/mi.
Obviously this is very easy to verify yourself, too, if you don't believe me. I imagine it is exactly the same on your car.
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TimothyHW3
Active Member
I have explained to you multiple times that the added kWh displayed on the display are not accurate. It is a calcuation with the straight line constant and the rated range. On top of that there are again rounding errors. No idea why Tesla does that.
The straight line on Model 3 AWD is 153Wh/km. If I pull the lever to 100% inside the app it shows 487km. 153 * 487 is exactly 74.5kWh what the battery is now reporting due to the colder weather.
Hence the "charge constant" is 153
And please work with KM!
Why don't you get an OBD II Adapter and see for yourself if you are so interested in these values?
The straight line on Model 3 AWD is 153Wh/km. If I pull the lever to 100% inside the app it shows 487km. 153 * 487 is exactly 74.5kWh what the battery is now reporting due to the colder weather.
Hence the "charge constant" is 153
And please work with KM!
Why don't you get an OBD II Adapter and see for yourself if you are so interested in these values?
AlanSubie4Life
Efficiency Obsessed Member
No, you didn't explain that to me. I already knew that. I already said so up above.
See:
When set to miles, the rated line is at ~156Wh/km (250Wh/mi) in my car. I dug up a picture for you from my car from another post. I'll attach it shortly. Enjoy.
You can also see that 155Wh/km*358km/365rkm = 152Wh/rkm. (Not 156Wh/km...just as I have been saying...)
Sure. That's exactly what I said. 153Wh/km = 246Wh/mi Close enough (it seems to be slightly less than 153Wh/km...)
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The line on the energy graph doesn't really matter, because the SMT readout along with the displayed rated miles/km will allow you to calculate the constant value closely, but not exactly, because of the rounding of the car displayed rated miles/km value. But the SOC%(calculated correctly) and Nomfullpack kWh values are precise.
Would you be willing to display your recent SMT readouts and associated rated miles/km to show what it calculates for your car?
And do you think your constant has ever changed for your car since it was new?
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