@AlanSubie4Life thanks for the detailed explanation! I was quite pleased with my 230kwh/mi commute over the last 2k miles but now see I'll never get close. (Aside, I too owned several Subarus prior to the Tesla, the WRX was great).
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MASTER THREAD: 2021 Model 3 - Charge data, battery discussion etc
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AlanSubie4Life
Efficiency Obsessed Member
RWD. Totally different ballgame. The Range King. These AWDs are just piddling around in comparison to that beast.
travis3000
Member
Ahhh makes sense. I was going to say... that seems very high for a 2019 model. I guess the AWD kills the battery.RWD. Totally different ballgame. The Range King. These AWDs are just piddling around in comparison to that beast.
(about a minute in)
TimothyHW3
Active Member
No it doesn't. The difference is minimal. The front motor doesn't run 99% of the time anyways and the weight difference is 50kg or so. Around 5% to max 10% lower consumption depending on the speed. Have tested this with another RWD.
As another Ontarioan, I was originally concerned about the AWD's reduced range as well , especially in the Winter. But then was told that the front motor provides additional heat (as well as snow/ice traction) in the winter. Soooo ... decided it was worth it.
Might feel differently further South.
Might feel differently further South.
TimothyHW3
Active Member
Not sure what you mean by heat, probably the stators while supercharging heating up the battery. As for traction, I managed to climb a pretty steep hill, with 5cm of snow, with my all season tyres that are almost 2 years old. And it was a very big incline, I am surprised I even made it. I am def sure that I would never manage that with a RWD and even a FWD would've had issues. I think it was at least 20%-25%.
AlanSubie4Life
Efficiency Obsessed Member
This is the most definitive video that I have ever seen, confirming the suspected behavior of Tesla batteries that have a nominal full pack value that exceeds the "cap" value. Thanks for doing it, and keeping it so short (unlike this post)! It confirms what I (and others) have speculated about here for the last 18 months or so - that rated miles get "expanded" in energy content, if your vehicle nominal full pack exceeds Tesla's cap - I am defining the cap as: (max displayed rated miles for the vehicle) * (steady state charging constant). The steady state charging constant is the value you can calculate from the energy screen at any time (even in a vehicle that exceeds the cap) - which is the value that it settles to when the car degrades below the cap. (158.5Wh/km (255Wh/mi) or so for the Performance 2021, and the cap is about 80.6kWh (approx).)
It wasn't clear to me what the energy screen would show - but from your video it clearly gets in on the "capping" game as well - this ensures that except through careful observation of the trip meter relative to rated miles use, or use of SMT, the user cannot know by how much their vehicle exceeds the cap. It IS knowable without SMT - but you have to take a trip and log the trip meter data and rated miles extremely carefully. (Detailed at the end of this post.)
Thanks again for the video. (I'll definitely try to add this above the "cap" caveat to the "energy screen method for capacity" sticky. I suspected it probably worked this way but I had no definitive confirmation until this video.)
Yep, your "constant" will be higher and gradually decrease, until you hit the cap - then it WILL be a true constant. I've strongly suspected that is how it has worked, for a while - tons of posts speculating about it, but with no data - now you have provided it (THANKS!). A little history - 2018/2019 Model 3s had 77.8kWh packs or so when new, but their "cap" value on the energy screen was about 76kWh. So they in many ways had exactly the same behavior as the 2021 Performance - the rated miles were substantially more energetic when the car was new (by 2%!). This could be seen through careful observation of the trip meter on a very long trip and tracking rated miles use - then comparing the results, later in the car's life. So for 2018/2019, they did not degrade from 310 rated miles until the pack degraded below 76kWh. Before that, the rated miles were inflated. For 2020 they increased the range to 322 rated miles and set the energy screen cap to 77.8kWh or so. This meant that 2018/2019 typically didn't show degradation for a few months or a year, while the 2020 vehicles almost immediately started showing range loss (though it's possible the 2020 vehicles also came with a bit higher energy, typically - not sure). Anyway, I expect the same behavior for the 2021 Performance - most vehicles won't show range loss for a while. The clear advantage for Tesla is that they can sell cars with somewhat variable full packs - but they ALL show exactly the same max rated range of 508/509km when new, even if the packs vary by 1-1.5kWh. (FWIW, the EPA value of energy for the 2021 Performance was about 80.6kWh as I recall, so people who have "only" that are not getting "screwed".)
For 2021 Performance, it's basically the same thing as 2018/2019 - you have a cap of ~80.6kWh, but a pack that has nearly 82kWh NFP capacity. Some Performance owners will only have 81kWh or whatever when brand new, I am fairly sure.
I would say the energy screen method works just fine on 2021 vehicles, it is just that it is not intended to give the true full capacity when the vehicle exceeds the cap value - it's just a limitation of the method, because Tesla does not allow the energy screen to show values above the cap, and in fact continuously scales the values implied by the screen (by the ratio "Cap Val"/"Nominal Full Pack") - rather than capping them. As you say, this problem will resolve itself in about a year or so, probably...haha.
Picking a couple time points in your video, going through the math:
As we know, for vehicles below the cap value, the energy screen shows:
Nominal Full Pack * SoC% = EnerScreenProduct. EnerScreenProduct = (Recent Efficiency * Projected Range)
But for your vehicle, let's pick a couple points: 28 seconds and 2:14.
Point 1: 43.6kWh, 51.4%, 260rkm, 216Wh/km * 191km
Point 2: 80.4kWh, 98.7%, 500rkm, 216Wh/km *367km.
Using the equation above, we'd EXPECT the EnergyScreenProduct to increase by:
81.4kWh * (0.987-0.514) = 38.5kWh.
But instead it increased by only: 216Wh/km*(367km-191km) = 38.0kWh.
(Not coincidentally, 38/38.5 is about the same as 80.6/81.4 - the energy product is scaled by that ratio (probably ratio of cap value/nominal full pack - or perhaps ratio of: cap value/max nominal remaining). The cap value isn't accessible to SMT, or at least it is not displayed.).
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Anyway, let's say you don't have SMT, and you wanted to figure out your true pack capacity, and your car has max rated miles equal to the 509km (if it maxes at 504km or something there is no need to do this - your pack is below the cap)? You'd do the following:
1) Carefully put car into drive, immediately log starting rated kilometers and pull up the trip meter (since x:xx mode).
2) Drive a long distance, with NO STOPPING/PARKING, at least 200km of use (longer the better). And try NOT to regen to a stop (stop on an uphill section). It is so important to not stop or go into park. You just cannot do it.
3) Put car in park and IMMEDIATELY log the ending rated kilometers and the trip meter data. Immediately. Can't wait. But must first go into park to force the update to the trip meter.
4) Calculate DischargeConst = (TripMeter Wh/km * Distance)/(Start Rated km - End Rated km)
For you, this value will be about: 160Wh/rkm * 0.955*0.99 = 151.3Wh/rkm (For an owner with capacity loss it would be about 150Wh/km)
Anyway, whatever value you get, you then do:
5) MaxRatedKilometers* ( DischargeConst/(0.955*0.99) ) to give you your nominal full pack.
So for you: 151.3Wh/km /(0.955*0.99) * 509km = 81.4kWh.
(Within less than 1% - there is some error on that 0.99 value but it's always around 1% heat loss.)
Since these values and differences are so small (nearly less than 1%), it's important that there be no errors on any numbers gathered if you want the actual answer...
But anyway, the point is that you can figure out your nominal full pack even without SMT, if you really want to, even when it exceeds the cap. But you can't do it from the energy screen. The energy screen only works when below the cap.
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AlanSubie4Life
Efficiency Obsessed Member
I thought people were quoting it from some EU documentation, earlier in this thread. The DC version of it would be lower than the rated line in the car, and lower than the charging constant (which is not the same as the rated line as we know; it's 3Wh/km lower), necessarily, since the EPA range is lower than the WLTP range, and the consumption value would be the pack capacity divided by the range. I think it's also an AC number? So a couple steps removed...
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scottf200
Well-Known Member
Annotated graphic showing comparing my TMX to my sons TM3 in a 0-60-0 MPH test and also doing +5 cruise incrmenting (see his TM3 front motor in lower left).
TL;DR is my '18 TMX uses both on the way up and on the way down (regen). His uses his both to a degree under moderate accel but not the front for regen.
This is ScanMyTesla data from both our cars.
Its AC.
I think they charge it full and count the AC Energy.
WLTP for ’21 M3 Performance is 165Wh/km.
WLTP Consumtion during driving should be about 142-143 Wh/km or so depending on the actual battery capacity.
Here is good database for efficiency.
ev-database.org
EV Database
A complete overview of all electric vehicles in Europe. Search and compare by range, make, model and price.
ev-database.org
On BMW seems to be different drive modes. That's why there is wltp 160 - 240. Because there is own drive mode for this fastest 0-100km/h record. That's means that you need select correct drive mode to archive this speed.
2021 Model Y P, seems like ~80.6kw is the cap given from UI. Trip computer seems to calculate using only ~74-74.5 when navigating to a destination with trip planner.
AlanSubie4Life
Efficiency Obsessed Member
Yes, it would not want you to use the buffer, and there is maybe 1kWh heat loss, so that would automatically mean no more than about 75kWh. Not sure how exactly you calculated the 74.5kWh number from what the car says on the Energy->Trip page, but it seems about right.
TimothyHW3
Active Member
It has very random numbers, I wouldn't use that database for reference at all.
Random? When you open those specs WLTP and EPA should be correct. Only "random" numbers are those calculations what is range on different situations.
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