Almost 15% range loss Model 3 Awd

[TimothyHW3]

You have to keep explaining it because your explanations don't make sense no matter how many times one reads them.

You are making pretty bold assumptions for someone who lacks access NOR understanding of the data. Yes, I very well know what EPA rated is(245 on a Tesla Model 3 AWD), what heat loss is, how Tesla calculates these things(actually pretty straight forward) etc.
The fact that you don't understand my explanation doesn't mean they "don't make sense". The problem is not with the broadcast, but with your "receiver" I will leave it at that... Don't bother replying by the way...

And by the way - if anyone does want to make sense of it, even though I did explain that a few times, disregard what he said about the buffer. The buffer DOES gradually "disappear" from the 100% state(included) to the 0% state(not included) The process is the same for all Tesla's yes even X and Bjørn Nyland had a Video with a CAN Bus software reader developer where he explained exactly this phenomenon. The video is from 2017 and anyone interested can find it.
The gist of it - Tesla calculates the rated miles 310 including the buffer, but the available capacity you have from 0-100% doesn't include the buffer so technically 100% of 310 is actually 95% of 310 miles
You have to drive way below the EPA of 245Wh/m rated to reach 310.

 

[ajdelange]

I just meant the constant is different. Obviously the concept applies to all Teslas.

Roger that.

These numbers do not include the reserve.

The reserve isn't visible to you in a Tesla any more than it is in an ICE vehicle.

It’s very clear. No need for CAN bus access, though obviously that allows more visibility into the size of the reserve.

It really is but some people just can't see it.

I have not seen any evidence of any dependence of the discharge constant on discharge rate.

More common sense.

 

[AlanSubie4Life]

you are quoting at 75.2(might very well be that to be honest) includes the buffer and the usable you quote is far from the real value since the most buffer on Model 3 is 3.5kWh. So your calculation is off by 2kWh.

I agree that the trip meter is not the real value, but it is not because of the buffer.

If this were the case, energy would be disappearing. It can’t be the buffer accumulation you suggest. Otherwise it would not take more energy to restore the energy (because adding energy to a buffer suggests it is not actually used).

What I am saying is that to charge all the way back up to 306 miles in situation above, it would take more energy than the trip meter showed used. (Specifically it would take 56.4kWh on the charging screen, never mind rounding errors...)

Was the 43.4kWh you posted the used quoted by the car as used under Trip or something else? A calculation, the charge going inside the car?

This was from the charging screen at the end of the Supercharging session. It took me to 253rmi.

Summary:

It consistently appears that you are putting more energy into the car (by ratio 245/230) than you take out. Very obvious from charging and trip meter data. If I can ever post pictures, it will be clear, anyway.

Of course we are not actually doing this - we can just say the trip meter reads low by ratio 230/245. Then it all makes sense.

For the second segment of my drive, here is the data showing this. I can’t post pictures, but let’s just take my word for it:

Start at Yermo SC: 253rmi @ 7:53AM

Finish at Las Vegas LINQ SC @9:49AM
139.5mi @ 341Wh/mi
Remaining charge: 45rmi
Of course:
139.5mi* 342Wh/mi ~= (253rmi-45rmi)*230Wh/rmi
(It’s actually 228.6Wh/rmi - perhaps due to rounding error on start point or whatever - within 1% is good enough.)

So used: 47.6kWh

At Vegas SC:

Added 194rmi according to the screen taking me to 238rmi (not 239 due to rounding error presumably). This took 48kWh according to the screen. (Was closer to 245Wh/rmi * 238rmi = 47.6kWh (coincidentally).)

So I used about ~48kWh, added ~48kWh, and have 15 fewer rated miles than I started with!

This always happens - it is not an outlier or weird or anything else.

It’s not a big deal - just means the trip meter reads low. Can’t be explained by the buffer.

 

[TimothyHW3]

It’s not a big deal - just means the trip meter reads low. Can’t be explained by the buffer.

No, it CAN and is explained by the buffer... I am attempting a last try in explaining it with real data and if not I give up...

Total nominal capacity of my car is 75.6kWh.
My buffer is 3.4kWh
Usable capacity is 72.2kWh

Rated KMs at 100% around 495 shown on screen (75.6 divided by a rated EPA constant 153Wh/km)


I will give you some readings from CAN.

At 91% SoC UI
Nominal remaining is 69.1kWh

At 30.9% SOC UI (on screen)
Nominal remaining is 25.7kWh.

Do you see the pattern? 25.7 is not 30.9% of 75.6kWh nor is 69.1kWh 91% of it. So why is the SoC all of a sudden reporting false information?

Do you know what the SOC percentage actually represents? It represents the amount of usable capacity still available, not full( including buffer) like it was at 100%.

69.1-3.4=65.7 which is 91% of 72.2
25.7-3.4=22.3 which is 31.9% of 72.2

And thus the buffer being available at 100% now disappears under the 0% mark and the SoC actually represents the available and not nominal, like it does at 100%. Hence your rounding errors and missinterpretation of the kWh available.

 

[ajdelange]

I am attempting a last try in explaining it with real data and if not I give up...

That would probably be the best as clearly you are getting frustrated and nobody is going to accept you explanation for reasons given in earlier posts. Beyond which most people don't have CAN bus readers and if they did wouldn't want to fiddle with them. What drivers want, when they are on the road is a clear picture of their fuel status and what they want to know at home is how their battery is aging. The BMS through the UI and the API give plenty of information to allow the owner to satisfy himself with respect to both these requirements.

Total nominal capacity of my car is 75.6kWh.
My buffer is 3.4kWh
Usable capacity is 72.2kWh

The usable capacity of your car is 75.6 kWh. Reserve is not part of usable capacity.

Rated KMs at 100% around 495 shown on screen (75.6 divided by a rated EPA constant 153Wh/km)


I will give you some readings from CAN.

At 91% SoC UI
Nominal remaining is 69.1kWh

At 30.9% SOC UI (on screen)
Nominal remaining is 25.7kWh.

Do you see the pattern? 25.7 is not 30.9% of 75.6kWh nor is 69.1kWh 91% of it.

No. 69.1kWh is 91.4% of 75.6 is 91.4% and 25.7 kWh is 34.0% of 75.6 kWh. One is within 0.4% (and this is spot on if you round to 1%). The other isn't. And this brings me to a question: How does one get his screen to display tenths of a percent SoC? I have an X so maybe it's different in a 3 but in the X I don't find SoC reported in other than whole percents. This doesn't surprise me as tenths of a percent represent what we call "empty precision" because I don't believe the BMS can estimate SoC to better than about 1%.

So why is the SoC all of a sudden reporting false information?

Well clearly it isn't in the first case. The second I can't comment on because I don't know where you got to 30.9% UI SoC number.

Do you know what the SOC percentage actually represents?

Yes. It represents the estimated charge above the empty state divided by the amount of charge it takes to charge from empty to full.

It represents the amount of usable capacity still available, not full( including buffer) like it was at 100%.

It represents the amount of usable charge not including the reserve which is located below the empty state and stays there. It never includes the reserve. It defintiely would not serve the driver to do so and it flies in the very face of what a reserve is. It's what you have left if you run the gas gauge down to Wm

69.1-3.4=65.7 which is 91% of 72.2

25.7-3.4=22.3 which is 31.9% of 72.2[/QUOTE] Actually it is 30.8 % but we get the idea. It appears that you noted and apparent discrepancy and concocted this shifting buffer scheme to explain it. You either groped around to find the 3.4 number or you solved 25.7 - x - .319*76.6 + 0.319*x for x. But let's give you the benefit of the doubt. Do you have any evidence for this theory other than that it fits your numbers (approximately)/

Hence your rounding errors and missinterpretation of the kWh available.

I'm starting to form some picture of how you have gone down this path. At this point I think it may be largely due to understanding of numerical precision and error propagation techniques. I would like to help you see the light but my main concern is that readers may think that the UI is lying to them as you suggest. It isn't. The numbers it displays are indeed subject to some error, of course. With SoC being difficult to observe I wouldn't take any SoC reading as being better than at least ±1% and maybe a bit more. But whilst driving you don't know your realized Wh/mi to much better than that so that a SoC at destination number is going to be at least that noisy and then some (± sqrt(2)%). We learn to make allowances for this as w drive the car and with common sense most of us do fine.

 

[TimothyHW3]

No, the USABLE capacity is nominal full minus buffer =72.2kWh. The second part of your sentence was correct, the first was not.

The buffer is available when you go down below 0%/0km

When you go below 0% then the car starts eating up the buffer of about 15 miles rated.

Hence the available energy you have is full pack minus buffer - this is your 0-100%.

There are people who have tested this and the data provided by the CAN, used by the BMS of the car, doesn't lie. You can also do it yourself by driving 0-100% at rated consumption of 245 (like @Alan said you will not be able to reach 310 rated because you only have 96% real) and then continue below 0%.

Anything else you said below that sentence was incorrect...I told you where I get my data from - the CAN bus, the same where the car gets it from... Find the Bjørn Nyland video and watch it, you will learn a great deal about Tesla's batteries.

 

[ajdelange]

What I'd really like to know is where you are reading fractional percent SoC from the Tesla UI.

 

[TimothyHW3]

Well, if you actually did read my comments... It is in the very last sentence -CAN bus via OBD II

The fractional percent is the result of available (nominal- buffer) and used kWh. The values are available in float numbers from CAN.

Here is the video since you seem too lazy to read my comments or Google it...It is from his X, the values are obviously different, but the basic principles, including the suggestions he makes, are the same for the 3.

At 3:20 he explains the usable(nominal subtracting buffer)

 

[ajdelange]

At 30.9% SOC UI (on screen)

 

[skatefriday]

It would help us see if he's just burning a ton of power and thus the range is actually accurate based on his usage. If he's getting 250 Wh, then its a problem. If this guy is using 400 Wh then maybe not. Some people are running AC on high, driving at 95 mph on the interstate and wondering why EPA range isn't happening.

People use the term range when they should use capacity. Range is a function of driving habits. Capacity is the amount of energy the battery is capable of storing. In this case he's reporting reduced capacity. A legitimate worry.

 

[AlanSubie4Life]

No, it CAN and is explained by the buffer... I am attempting a last try in explaining it with real data and if not I give up...

Total nominal capacity of my car is 75.6kWh.
My buffer is 3.4kWh
Usable capacity is 72.2kWh

Rated KMs at 100% around 495 shown on screen (75.6 divided by a rated EPA constant 153Wh/km)

A couple questions:
Is the 75.6kWh number read from the CAN?

While monitoring the CAN, can you compare these two numbers?:
1) The number of kWh the charging screen says was added when you add, say, 100km. (I don't care how much you add exactly, as long as it is a large value.
2) For the same charging event, what is the change in the value of the CAN reading of "Nominal remaining?"

 

[TimothyHW3]

I will make a video with some screenshots, hopefully it will be more understandable. I am doing a longer drive in a month and hopefully I will be able to drive at rated speed and show you the discrepancy between the kWh with buffer and the SOC in %. I have some screenshots while stationary, they show a good picture, but want to add some more tests to really make it understandable to everyone

Not sure what the problem is with the numbers I present - you basically confirmed what I am saying with your test. The rated miles can only be achieved by driving under the rated consumption, due to the fact that you only have 96% rated miles from 0-100%

Also, the screen added kWh doesn't show you decimal points so you could be missing 1kWh in your calculation and at about let's say 30kWh that is around 3% off. Below, even more.

 

[AlanSubie4Life]

Also, the screen added kWh doesn't show you decimal points so you could be missing 1kWh in your calculation and at about let's say 30kWh that is around 3% off.

Yeah, Stats shows the decimal though. So no big deal there - 245Wh/rmi

Not sure what the problem is with the numbers I present

Just wondering whether the quantities being reported have the same units/ can be compared, that is all.

due to the fact that you only have 96% rated miles from 0-100%

Certainly I agree with this.

The rated miles can only be achieved by driving under the rated consumption,

Don’t agree with this. By definition you can get the rated miles by driving at the rated consumption rate (just don’t use the trip meter to monitor your consumption!). However, you would need to exhaust the entire reserve, just as they do in the EPA test.

 

[TimothyHW3]

Well, you actually proofed that, so why would you disagree?

Of course I am talking about usable and not full capacity - if you use the whole battery, including the buffer ,of course you will get the rated miles at rated consumption, simple math, but this means to go from 0-104% or 4% below 0km... first, nobody does that and second it is not good for the battery.

 

[AlanSubie4Life]

Not sure what the problem is with the numbers I present - you basically confirmed what I am saying with your test. The rated miles can only be achieved by driving under the rated consumption, due to the fact that you only have 96% rated miles from 0-100%

I guess my issue is that we know from the EPA document that a car with a new battery (~4000 driven miles) contains 79kWh or so of available energy (this is in the EPA document for the AWD - it was 79.2kWh). (What this is indicated as on the CAN, I do not know.) But your 75kWh number seems low - that would suggest a battery that had degraded by 16 rated miles or so. There can't be any funny business with this number - the EPA would get very upset if consumers were not provided with the measured available energy. So I wonder about how the CAN bus number is scaled.

The car doesn't have to report that EPA number, really - it's kind of arbitrary what it reports - as long as the actual available energy for a new car is ~79kWh. The CAN bus number could be scaled. We need to determine whether it is.

So I am trying to align your CAN bus data with some other quantity - say, what is reported on the charging screen. Then we would know how that CAN bus data reported capacity is scaled relative to "real" kWh (or at least relative to what is reported on the charging screen - we of course don't know whether those are exactly real kWh either - but there is reason to think they would be since Tesla charges for them at Superchargers and there are presumably laws about how accurately they are counted).

I suspect the capacity of my car is about 307rmi*245Wh/rmi + 3.4kWh (reserve) = 78.6kWh. If we posit the existence of the reserve (which I do believe exists of course but will hopefully never confirm), that's what the charging screen data suggests. And furthermore, supporting my claim, that number aligns roughly with the EPA submission.

So, similarly for your car, I'd like to compare that CAN bus data for reported capacity vs. the capacity you can infer from a charging event (plus some assumption about the size of the reserve - I'm really not concerned about the exact size of the reserve - maybe it is 3.4kWh, maybe it is 2.4kWh - for this purpose we just need to know it exists and the approximate size). Importantly, I want to compare the CHANGE in reported capacity on the CAN, and compare it to the charging screen data "added kWh" for that same specific charging event. That would allow us to see how those quantities compare. I suspect there will be a ~5% (4.7%) scale factor between the two. But we will see.

 

[diamond.g]

I guess my issue is that we know from the EPA document that a car with a new battery (~4000 driven miles) contains 79kWh or so of available energy (this is in the EPA document for the AWD - it was 79.2kWh). (What this is indicated as on the CAN, I do not know.) But your 75kWh number seems low - that would suggest a battery that had degraded by 16 rated miles or so. There can't be any funny business with this number - the EPA would get very upset if consumers were not provided with the measured available energy. So I wonder about how the CAN bus number is scaled.

The car doesn't have to report that EPA number, really - it's kind of arbitrary what it reports - as long as the actual available energy for a new car is ~79kWh. The CAN bus number could be scaled. We need to determine whether it is.

So I am trying to align your CAN bus data with some other quantity - say, what is reported on the charging screen. Then we would know how that CAN bus data reported capacity is scaled relative to "real" kWh (or at least relative to what is reported on the charging screen - we of course don't know whether those are exactly real kWh either - but there is reason to think they would be since Tesla charges for them at Superchargers and there are presumably laws about how accurately they are counted).

I suspect the capacity of my car is about 307rmi*245Wh/rmi + 3.4kWh (reserve) = 78.6kWh. If we posit the existence of the reserve (which I do believe exists of course but will hopefully never confirm), that's what the charging screen data suggests. And furthermore, supporting my claim, that number aligns roughly with the EPA submission.

So, similarly for your car, I'd like to compare that CAN bus data for reported capacity vs. the capacity you can infer from a charging event (plus some assumption about the size of the reserve - I'm really not concerned about the exact size of the reserve - maybe it is 3.4kWh, maybe it is 2.4kWh - for this purpose we just need to know it exists and the approximate size). Importantly, I want to compare the CHANGE in reported capacity on the CAN, and compare it to the charging screen data "added kWh" for that same specific charging event. That would allow us to see how those quantities compare. I suspect there will be a ~5% (4.7%) scale factor between the two. But we will see.

Does the 79 listed come from what it took to recharge the battery? Cause in reddit someone posted the battery sticker and it says 75 kWh.

 

[AlanSubie4Life]

Does the 79 listed come from what it took to recharge the battery? Cause in reddit someone posted the battery sticker and it says 75 kWh.

This info is all in the EPA document. The recharge event energy for the AWD is 89.6kWh.

This link isn't for the AWD (I'm too lazy to look it up but the document is at the same site and I have it on my computer):

https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=46584&flag=1

For the AWD, it is 79.2kWh for discharge (so that's the available energy for a car with 4000 miles! Document with the odometer readings: https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=46968&flag=1) and 89.6kWh for recharge (obviously that includes charging losses so this really tells us nothing about capacity).

 

[diamond.g]

Interesting. I just pulled some can data...
So 292 shows me that my screen lies to me (car says I have 54% but can bus says I have (SOCui) 58%.
352 shows that I have a 73.8 kWh battery with a 3.3 kWh buffer (which I presume means my battery is 77.1 kWh).

 

[AlanSubie4Life]

Interesting. I just pulled some can data...
So 292 shows me that my screen lies to me (car says I have 54% but can bus says I have (SOCui) 58%.
352 shows that I have a 73.8 kWh battery with a 3.3 kWh buffer (which I presume means my battery is 77.1 kWh).

Interesting (and consistent with the claims above). The "lying" UI is not a surprise of course. The question is how all of these numbers are scaled (the offset is less interesting). I would be curious for you to get this reading, immediately add 30-40kWh according to the charging screen, and then immediately redo the reading, to see how much the numbers change.

I assume your battery still shows 310 miles for a 100% charge?

There's no reason the charging screen, the CAN bus, and the trip meter UI could not have completely different scales (definitions/values of kWh). It's all completely arbitrary (except arguably for the charging screen where there may be rules about accuracy since the energy is charged for), as long as there are actually ~79kWh (true kWh) available for a new-ish car. But we can find out the relative relationships, even if we can't ever actually really know the absolute quantity of the energy (at least not without the calibrated measurement equipment used at the laboratory where the EPA testing was done).

 

[diamond.g]

Interesting (and consistent with the claims above). The "lying" UI is not a surprise of course. The question is how all of these numbers are scaled (the offset is less interesting). I would be curious for you to get this reading, immediately add 30-40kWh according to the charging screen, and then immediately redo the reading, to see how much the numbers change.

I assume your battery still shows 310 miles for a 100% charge?

My battery showed something closer to 300 the last time I did a 100% charge. Stats claims it would show 299 (said 303 yesterday, lol). The remaining to 90% (where it shows I need 25 kWh) is pretty much right (90% of 73.8 is 66.4, car says it thinks I have 41 kWh remaining).
I usually charge every night, if I remember I will try to check the can data in the morning.