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MASTER THREAD: 2021 Model 3 - Charge data, battery discussion etc

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Is that news to you? Tesla doesn't calculate the "added" kWh in the battery - they simply get the remaining range in miles/km from the start and the remaining range in miles/km at the end, diff is the "added miles/km" and then they multiply this number with the constant to extrapolate km/miles to kWh and show you "added kWh".
Excuse me if I misunderstood your message above.
Are you saying that Tesla is taking the range number left at the end of the trip (lets say 10 miles) and uses the range number at the start of the trip/leg (lets say 150 miles), does a simple math 150-10 = 140 miles and compares this number with the 100% SOC number (lets say 273 miles for 60.2 kWh) and does another simple computation giving you the kWh your car get's ? This is pretty much stupid, if they do that.
It would mean that we don't pay kWh but "Tesla kWh".

My opinion is that the number we see as kWh added are the real ones, that get into the car, including the loses due to external and internal different factors that have an impact on it (temperature, etc.). The range number is not an indication of the real range of the car anyway, so why bother doing the whole thing above ? It would be idiotic, IMO.
 
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In general it’s hard to know or estimate the heat loss, in most cases the guestimate will be wrong so I would say that we should use the energy we did get out and instead refer to the circumstances, like “at 80 mph highway” or so.
It is not that hard, I have already checked the heat loss on numerous routes

A good rule of thumb for heat loss in Model 3/Y

- Summer, above 20C, very slow driving - about 0.5kWh
- Summer, highway speeds (80mph) - about 1kWh
- Summer, german highway speeds (100mph) about 1.5kWh to 2kWh depending on the wind. From there on it goes to above 5kWh heat loss with higher speeds

- Winter: just add about 1kWh to each.
 
Are you saying that Tesla is taking the range number left at the end of the trip (lets say 10 miles) and uses the range number at the start of the trip/leg (lets say 150 miles), does a simple math 150-10 = 140 miles

They take the range number at the beginning of the charging and the range number at the end of the charging.
and compares this number with the 100% SOC number (lets say 273 miles for 60.2 kWh)
no.

They do an algorithm calculation based on their predefined formula.
For your example in km as it is what I use: If they added 140 miles is 225km.

You added 225km then you multiply it by the EPA constant for that model and firmware, let's say Model 3 2022 and above have a constant of 137Wh/km =2.25*13.7 is 30kWh added.

They display 225km added or if you change to kW charging - 30kWh added. Actual added into the battery should be about 28-28.5kWh (roughly half of the released buffer as 225km is roughly 50% added)

Same goes backwards from rated range at 100%.
If your 100% is showing 575km, then you take 5.75*13.7 is 78.7kWh which is the initial LG battery capacity.

Then with degradation (time passes or if the BMS is not calibrated) - 100% is let's say 560km, now you have 76.7kWh total capacity and so on.
 
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It is not that hard, I have already checked the heat loss on numerous routes

A good rule of thumb for heat loss in Model 3/Y

- Summer, above 20C, very slow driving - about 0.5kWh
- Summer, highway speeds (80mph) - about 1kWh
- Summer, german highway speeds (100mph) about 1.5kWh to 2kWh depending on the wind. From there on it goes to above 5kWh heat loss with higher speeds

- Winter: just add about 1kWh to each.
How would you check that?

Its hard, as heat loss varies with a lot of things, for example battery age and how much calendar aging it have.

For EPA-wise driving or slightly faster ypu should not add any energy at all.
For fast highwaydriving maybe little, but in general the heat loss is not part of the energy delivery.

If you test a 5000 mah cell that delivers for example 5000 mah in the test and 18.5Wh (5Ah x 3.7V) that cell also will get heated but that is not a part of the delivered energy but a part of the energy loss from the charging until the energy is delivered.

The heat loss is also a part of the degradation. Higher internal resistance means higher heat losses and that is part of the explanation why we get less energy from hour batteries.
 
How would you check that?

Quite simple - I check what scan my tesla is reporting for available capacity at the begining and how much kWh the car used for the drive vs how much it should've used if it were to use the full available capacity. There is always a difference between the two.


Its hard, as heat loss varies with a lot of things, for example battery age and how much calendar aging it have.
How would heat loss vary with calendar aging...There is a mathematical law for the heat loss according to discharge rate. Peukert's law applies to lithium batteries as well, they are less affected by it, but still affected.


For EPA-wise driving or slightly faster ypu should not add any energy at all.
For any driving there is a heat loss. EPA driving is very reservative, but even then there is heat loss on the highway run.
The EPA also doesn't always get the same energy out of the battery and it certainly doesn't get 100% out of the BMS calibrated capacity at start...
The heat loss is also a part of the degradation.

No:) You are confused about the terms it seems. The heat loss is also not only confied to the batteries - there is heat loss in the cables to the drive units so there will always be some losses. You will never be able to get the full kWh from the battery. Maybe if you drive at constant 30km/h throughout the journey then you can minimize the losses to absolute minimum.
 
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How would heat loss vary with calendar aging...There is a mathematical law for the heat loss according to discharge rate.
The calculated result of this law is highly dependent on the internal resistance of a cell. You can calculate the heat loss from knowing the IR and the power/current.

15EF713E-EE1F-4B6B-8F9F-F0410DB34C47.jpeg



For any driving there is a heat loss. EPA driving is very reservative, but even then there is heat loss on the highway run.
The EPA also doesn't always get the same energy out of the battery and it certainly doesn't get 100% out of the BMS calibrated capacity at start...
The rating of a battery for example Watt-hours, does not include the heat loss at that specific load. The rating is the electrical energy delivered at that specific load.
No:) You are confused about the terms it seems. The heat loss is also not only confied to the batteries - there is heat loss in the cables to the drive units so there will always be some losses.
The heat losses to all parts of the car, motors/heating-cooling system etc. is most certain measured. The measurement for voltage+ amphs is to a very high degree of probability situated within the battery pack and all energy leaving the pack is measured - to believe otherwise is to think too low of the enginers at Tesla.

Of course there is heat losses. Anywhere there is energy used, there is losses. But for all losses outside the battery they are measured as electric energy, as they where electric energy leaving the pack.

You will never be able to get the full kWh from the battery. Maybe if you drive at constant 30km/h throughout the journey then you can minimize the losses to absolute minimum.
For a certain cell specified at a certain energy level I will get that energy level out of the cell as long as I follow the conditions stated.
The 18.5Wh 2170 cells I have delivered 18.5 Wh or slightly more at 0.2C (1A) when new( cycled a few times to ensurecthe had woken up) which is close to the power in C I used for my 513 km drive (cruise ctrl set for 92km/h one way and 93km/h the other way.

This lead us to the Full Pack When New number. It most certainly is not a part of that that is heat losses counted in. Its the specified electric energy that Tesla means it could deliver. This is probably at a poser rating close to the one needed to pergormthe EPA test.

My 513 km drive was with an average of 12 kW or so, which was at a lower power and consumption than the EPA rating. For that drive I would say that there should not be any heat loss ”added”.

If you use more power, the heat loss increases, (mainly same ahmps delivered but at a lower voltage, due to the IR, reducing the energy delivered). So in this case the heat loss is higher, as the power/current is higher then the current stated in the spec.
 
This lead us to the Full Pack When New number. It most certainly is not a part of that that is heat losses counted in. Its the specified electric energy that Tesla means it could deliver. This is probably at a poser rating close to the one needed to pergormthe EPA test.
The "full pack when new" number is not what we are talking about. I was reffering to the difference between the kWh used reported by Tesla on display and the actual kWh used according to the BMS. The delta between nominal full at the begining and nominal full at the end (actually "ideal remaining", not "nominal", as Tesla is calculating with what SMT calls "ideal remaining")

As far as I know the "full pack when new" is a static value the SMT developer puts himself depending on the battery type. This is why this value was wrong on the capped model 3s with old panasonic batteries (which is what I found out, by testing the max V at full charge)

I have no idea what you are talking about to be honest...
 
was reffering to the difference between the kWh used reported by Tesla on display and the actual kWh used according to the BMS.
@AAKEE, yeah this has been fought about (for some reason) before here. Anyway @TimothyHW3 is just (I think) referring to the difference in the delta on the SMT for a given run, vs. that on the trip display (being careful about the start and end points to make sure that park losses are not confused as part of the loss).

These numbers typically do not match, around 0.5-1% lower on trip meter, though that is very approximate and difficult to predict.

I cannot remember but I think the new trip meter may have lost a significant figure for some purposes so it is even harder to make the comparison now (maybe).
 
@AAKEE, yeah this has been fought about (for some reason) before here. Anyway @TimothyHW3 is just (I think) referring to the difference in the delta on the SMT for a given run, vs. that on the trip display (being careful about the start and end points to make sure that park losses are not confused as part of the loss).
Yes, I understand this. It is so obvious that I didnt think I would need to comment about that. ;)

The drive I was refering to, my 100-0% drive started at 78.8 kWh nominal remaining
Stopped at work after the first part of driving. Nominal remaining then 41.9kWh
Delta= 36.0 kWh.

The consumption display showed 36 kWh used, and was 235km x 153 Wh/km= 35.955 kWh.
If I do not rememberbit wrong we have discussed this before, that for low power (the rated power or current that set the nomimal full pack) we should be able use all energy as it is rated. Higher power than the rating means loosing energy to heat loss from the rated power.

This is SMT just before rolling, just when stopping and also the trips display.

C9F7E73D-240D-48D2-9F4C-8F25A3608461.jpeg543ECFB0-78BF-4701-8FB1-14A2C59DB619.jpeg1155467E-1791-4940-B0F6-7D27C8E40143.png

For this drive it would seem odd to add energy to the calculation, I’d say? :)

[Edit]
The return trip used 39.5 of Nominal remaining and 39.3 on the energy calculation.
 
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AAKEE, the graph in #2966...
View attachment 939273

Are the temperatures ambient or internal battery temperatures ?
In general they refer to the tempersture chamber that the cell was placed in during the test. They are adjusting the chamber themp so ehen the battery heats the chamber it is cooled to the set temp.
I do not remember the details for this specific test. This report.
 
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In general they refer to the tempersture chamber that the cell was placed in during the test. They are adjusting the chamber themp so ehen the battery heats the chamber it is cooled to the set temp.
I do not remember the details for this specific test. This report.
Thanks for that.... I can’t say that I read all 94 pages yet..but I did skim it.
This graph from the report is quite similar to the ones that you have posted in the past..
7C0BB391-8BA5-4F1B-BFE7-07AEDD672111.jpeg

Whereas the one you posted in #2966 showed that temperature wasn’t really a factor for the first half million kilometers...which I found more reassuring because it can get quite hot in the South of France where I live 😎
 
Thanks for that.... I can’t say that I read all 94 pages yet..but I did skim it.
This graph from the report is quite similar to the ones that you have posted in the past..
View attachment 939319
Whereas the one you posted in #2966 showed that temperature wasn’t really a factor for the first half million kilometers...which I found more reassuring because it can get quite hot in the South of France where I live 😎
Remember that calendar aging will take the absolute largest bite from your battery.
It won't be the cycles.

Model S cells cycled 500 cycles, about 200K km.
40C is about the same as 25C.
Warm cells is happy for cycling.
They lost about 13% for 200K km. They where cycled 100-0% (2.55V, 2.5V is 0% so 100-1% then….thats 3.5% below 0% displayed).
So about 0.65% per 10Kkm or maybe 1.3% per year. But if you do smaller cycles, the cyclic aging is much less. Lets say 0.5% per year or less.
56502730-B97B-46C2-B254-9F71BF4DAE3A.jpeg



3DFB94CC-EDD5-48F6-A5E1-830139352D71.jpeg

At 25C you loose 5% the first 10 months —> 5.5% the first year.
After eight years you still loose about 1% per tear to calendar aging,
So, calendar aging took a 15% bite after 8 years.
Cyclic aging might be 4-8% during the same time.

I have my formulas, tell me:
-the cars age(manufacturing month/year or delivery mont/year)
-Charging SOC
-End of day SOC (begore charging)
-Time of day when charging start.
-climate, warm, hot or cold
- if the car is outside or garaged at home
-odometer reading
-average consumption since new.

…and I will calculate a probable degradation.
 
Doesn’t it say 77.9?

Anyway I have seen it match on occasion but for my car at least it is usually low on the trip. But I don’t have SMT so I have resolution problems of course unless I am very very careful. Which I never care about anymore of course.

@AAKEE’s car is different year so maybe it behaves a little differently. Or perhaps it is just normal variability.
 
Doesn’t it say 77.9?
Yes, it was a typo from me. Was too tired I guess.

77.9 - 41.9 = 36.0 kwh.
@AAKEE’s car is different year so maybe it behaves a little differently. Or perhaps it is just normal variability.
Its a different year but probably not different in that way (?), at low power /low speed I have seen it match more than once.
At higher speeds /higher power there is a difference in my car as well.
 
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