# Tesla Bjørn describes a sudden disappearance of 6% of battery capacity in his TM3



## Mike (Apr 4, 2016)

I watched this yesterday and figured I would draw my car down to 20% today before plugging in to bring it back up to 90% tonight:






When I was done with the car today, my SOC said a solid 20% (was showing yellow at 20%, then returned to green with 20% using my final brake regen event of the drive).

For giggles, I selected the range option and it showed 102 km, so a current rated range of 510 km.

Since Jack at EVTV says that the only way to really measure available battery capacity is to drain it and then measure what you put back into it, tonight I'm going from 20% to 90% and I'll see what my circuit monitoring meters say was pushed into the car.

If I still have 75 kWh of usable capacity, my gross amount of energy from the grid (that assumes my typical 3.5% onboard inverter loss) should be 54.3 kWh.

The net figure should be 52.5 kWh.

I'll report my findings tomorrow.


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## TeslaKiller (Oct 8, 2019)

I think you misunderstood what Jack meant. You have to measure the USED kWh while discharging and it has to be done on 1 go from 100-0%. If you measure what goes in afterwards, you have to measure it inside the car/battery, and not via outside measurements and it has to be done without any electronics running in the car, which is impossible.

So to truly measure your capacity, you have to drive for around 300miles at a consumption matching the EPA straight line in your energy graph called typical range and see what the used kWh says.

Also, Bjørn just posted a debunking video of his video yesterday where he explained that he got some of the numbers wrong.

You also never had 75kWh usable. The most you had, brand new, were around 74kWh, but those dropped down to 73kWh as soon as you crossed the first few thousand miles. I explain this in my video in the other sub, you can click on my name to find it.


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## Mike (Apr 4, 2016)

TeslaKiller said:


> I think you misunderstood what Jack meant. You have to measure the USED kWh while discharging and it has to be done on 1 go from 100-0%. If you measure what goes in afterwards, you have to measure it inside the car/battery, and not via outside measurements and it has to be done without any electronics running in the car, which is impossible.
> 
> So to truly measure your capacity, you have to drive for around 300miles at a consumption matching the EPA straight line in your energy graph called typical range and see what the used kWh says.
> 
> ...


I just watched your video, cheers.

I'll check his debunking video later.

The most usable I had when new last year was about 74.3 kWh as that was the only number that was always correctly satisfying my supercharger logged uploads (yes, primitive back of napkin number, but that is what it had worked out for me so I figured close enough).

I acknowledge your comments ref one single run from 100% to 0% and concur.

FWIW, I'll still report what my upload was to satisfy an apparent 70% EPA rated capacity refill.


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## JWardell (May 9, 2016)

Bjorn is basically saying v10 reduced range by 6% in this video, and we all know that is untrue. I'm not sure if he's just doing this for clickbait or confusing it with a recent Model S update to address battery fires in a small number of cars. It IS possible, however, that the temperatures dropped significantly there lately (it is Norway, after all), and the algorithm is compensating a bit for that. Last year range fell significantly with winter temperatures, I am waiting to see if the same happens this year or if Tesla changed the SOC algorithms.


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## JasonF (Oct 26, 2018)

JWardell said:


> Bjorn is basically saying v10 reduced range by 6% in this video, and we all know that is untrue. I'm not sure if he's just doing this for clickbait or confusing it with a recent Model S update to address battery fires in a small number of cars. It IS possible, however, that the temperatures dropped significantly there lately (it is Norway, after all), and the algorithm is compensating a bit for that. Last year range fell significantly with winter temperatures, I am waiting to see if the same happens this year or if Tesla changed the SOC algorithms.


I usually charge mine to 90%, and I noticed after the V10 update, that seems to be 283 miles instead of 285. Not a huge deal, because it simply looks like Tesla changed the guess-o-meter algorithm to be more conservative. There's very little chance 1% to 2% of the battery capacity can vanish with a single software update.


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## MelindaV (Apr 2, 2016)

JasonF said:


> I usually charge mine to 90%, and I noticed after the V10 update, that seems to be 283 miles instead of 285. Not a huge deal, because it simply looks like Tesla changed the guess-o-meter algorithm to be more conservative. There's very little chance 1% to 2% of the battery capacity can vanish with a single software update.


over the last year, I've had 2 separate instances where there was a 10+ mile drop following a new install. one recovered back within a few weeks - the other never has.


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## TeslaKiller (Oct 8, 2019)

JasonF said:


> I usually charge mine to 90%, and I noticed after the V10 update, that seems to be 283 miles instead of 285. Not a huge deal, because it simply looks like Tesla changed the guess-o-meter algorithm to be more conservative. There's very little chance 1% to 2% of the battery capacity can vanish with a single software update.


This is normal fluctation, 2 miles here or there is fairly normal. It could've been small degradation, it could've been colder weather, it could've been the charger, it could've just jumped from 283 to 285. That is a 0.8% difference, the margin error and rounding errors on your SoC % is higher (from 89.6 to 90.4 is the same number - 90%)

We have reports of people reading their BMS before and after the V10 update - zero changes in the way kWh are reported. Solid proof.
What Bjorn is saying is not that they changed the BMS calculation/algorithm, but that they tweaked the EPA rating - but this is easily debunkable - all you have to do is go to the energy graph and see V10 vs V9- it will be the same. He never showed it in his video, though.

Bjorn simply jumped the gun on this one and he knows it - in his newer video he kind of owned it, but he is also kind of not fully admitting it. But you can see it in the way he talked about it.

I think the clickbaiting prevailed on this one. And didn't really pay off, because even though it was quoted on a lot of websites, it actually got less views. I was a bit dissapointed by his video.



MelindaV said:


> over the last year, I've had 2 separate instances where there was a 10+ mile drop following a new install. one recovered back within a few weeks - the other never has.


Since I work with software, I can def tell you a thousand ocassions where I got reports of a "software update" breaking something, where actually "something else elsewhere happened" - either other software update, or another application was installed etc. etc. Thousand cases.

The said truth is - causation and correlation don't always work like that. Just because a software update happened, doesn't mean that it has anything to do with range.

In the video I linked to I talked about this - the rated range at the beginning is about 10 miles lower than the actual capacity of your battery when brand new.

So until you see 10 miles degradation in range, you already lost 20 miles or so from your original capacity, in kWh. But you simply don't see it, because it was never shown to you.
And some of these "degradations" happen over night. Noone knows how the BMS on Tesla works, but we have seen sudden drops (no software updates) in the chemistry basically over night. Usually when the car was fairly new - around the 10-15,000 miles point. This happens only at the top, highest range, so you shouldn't see such dramatic drop, unless the battery has a problem or the BMS isn't calibrated.

This is why, to make these claims, you actually need access to the BMS and monitor your values prior each update, to know wether something like this happened.

At least for the last 6 months, on an AWD and P, nothing of this kind has been reported. Doesn't mean it can't happen, like it did with Model S 85


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## Mike (Apr 4, 2016)

Mike said:


> FWIW, I'll still report what my upload was to satisfy an apparent 70% EPA rated capacity refill.


Here is my "steam driven, vacuum tube approach" to figuring what my usable battery capacity could/should/might/might not be as of today:

My refill, from 20% to 90%, required this much input from the grid:










I have figured "about" (yep, back of napkin numbers) 3.5% losses via the car's inverter, so about 51.23 kWh was actually injected into the battery to move it from 20% to 90%.

(100/70) x 51.23 = 73.185 kWh of current usable capacity.

Since the above technique (with all its errors) was used when the car was new, when comparing my 74.3 figure from June 2018 to this 73.185 figure, my back of napkin battery capacity loss is (73.185/74.3) about 1.5%.

So my "gross error check" shows about 1.5% loss since the car was new, based only on the above technique for measuring it since the car was new.


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## TeslaKiller (Oct 8, 2019)

Mike said:


> Here is my "steam driven, vacuum tube approach" to figuring what my usable battery capacity could/should/might/might not be as of today:
> 
> So my "gross error check" shows about 1.5% loss since the car was new, based only on the above technique for measuring it since the car was new.


Yes, not very scientific at all and surely a lot of errors, but probably in the ball park - how many miles do you have? If you are anywhere below 15,000m 20,000km it might work to about that.
Actually your 74.3 was probably very close to the real number when new. Probably a little higher even. New packs have statistically shown about 77-78 of which you substract 3.5kWh of buffer to get to the usable.


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## Needsdecaf (Dec 27, 2018)

Cross posted from Model 3 charging forum:

Here's my deg over 23k miles in under one year as estimated by Teslafi. Car is charged at least 5x per week, you can see I drive a lot. Limited Supercharging.










Note the big dip at the end of September. I'll blow it up so you can see what happened:









There is a slight uptick before the big dip. That uptick, to 305.7, is the first charge on 32.11. Before that, it was on 32.2.2.

The first and second dips are on 32.11. The trough at 298.2 is the first charge on 32.11.1. It's on 32.11.1 through that gradual climb and then the slight dip, from 300.7 to 299.7 is the first charge under 32.12.2. So I've done two charges on that.

Hard to draw any definitive conclusions on this. Could be simply the BMS recalibrating with new software? And although I lost range, it doesn't look as drastic as what Bjorn reported.

I will say that I noticed my consumption going up on my drive to work. HOwever it is getting colder.


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## Mike (Apr 4, 2016)

TeslaKiller said:


> Yes, not very scientific at all and surely a lot of errors, but probably in the ball park - how many miles do you have? If you are anywhere below 15,000m 20,000km it might work to about that.
> Actually your 74.3 was probably very close to the real number when new. Probably a little higher even. New packs have statistically shown about 77-78 of which you substract 3.5kWh of buffer to get to the usable.


I currently have a little over 38,000 kms.


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## Mike (Apr 4, 2016)

Needsdecaf said:


> I will say that I noticed my consumption going up on my drive to work. HOwever it is getting colder.


My routine summer time round trip to the YMCA is a 3% use event, while in the winter it is 5%.

So far this fall, I'm still showing either 3% or 4% use per round trip event.

For me, my next real test will be our regular drive to the in-laws (just east of Ottawa), sometime in November.

Historically, that 257 km trip requires 52% in the summer and 67% in the winter.

If I remember, I'll post my results of that trip's indicated energy use here.


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## Needsdecaf (Dec 27, 2018)

My drive to work typically takes 15%. Sometimes 16, but not as often. I always see if I can get it to 14. 

Lately has been 17. But it hasn't been that cold, honestly.


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## Mike (Apr 4, 2016)

Needsdecaf said:


> My drive to work typically takes 15%. Sometimes 16, but not as often. I always see if I can get it to 14.
> 
> Lately has been 17. But it hasn't been that cold, honestly.


I'll keep a higher amount of vigilance on this as winter progresses.

On my energy use graphic page today, I took the time and technique to see when my use and rated use lines merged and IIRC the figure was 144 wh/km.......again, IIRC this figure of 144 seems the same as earlier versions but in all honesty I really have not been following it closely.


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## NJturtlePower (Dec 19, 2017)

As I commented in response to this video, "I noticed this loss before the V10 update - I've charged to 85% for the past 15-months (3 LR RWD) and was always at 267mi then almost over night is now 256-260mi. "

After searching my TeslaFi charging logs my noticeable range decrease started AFTER my 8/21/19 update to SW version 2019.28.3.1 - Wonder if there is a pattern here among others...Anybody else able to confirm?


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## NJturtlePower (Dec 19, 2017)

Needsdecaf said:


> Cross posted from Model 3 charging forum:
> 
> Here's my deg over 23k miles in under one year as estimated by Teslafi. Car is charged at least 5x per week, you can see I drive a lot. Limited Supercharging.
> 
> ...


Here's mine, Day 1 to now...just under 13k miles, more than slight uptick curve followed by drastic drop with update 28.3


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## TeslaKiller (Oct 8, 2019)

Mike said:


> I'll keep a higher amount of vigilance on this as winter progresses.
> 
> On my energy use graphic page today, I took the time and technique to see when my use and rated use lines merged and IIRC the figure was 144 wh/km.......again, IIRC this figure of 144 seems the same as earlier versions but in all honesty I really have not been following it closely.


Wait, do you have a LR RWD and not AWD? This will explain the EPA consumption. Do you have a screenshot of the EPA rated - the typical straight line in the energy graph, when you match it perfectly with your consumption.
I think it should be more about 146-148 if I go by 77 kWh full and 525, but I am not quite sure how Tesla does it on RWD, they did change the constant to give more range.

Also, 73kWh at 38,000 will be extremely unlikely so it would be great if you can find a trip where you can drive to about 10% at EPA consumption and see what the used says.


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## Mike (Apr 4, 2016)

TeslaKiller said:


> Wait, do you have a LR RWD and not AWD? This will explain the EPA consumption. Do you have a screenshot of the EPA rated - the typical straight line in the energy graph, when you match it perfectly with your consumption.
> I think it should be more about 146-148 if I go by 77 kWh full and 525, but I am not quite sure how Tesla does it on RWD, they did change the constant to give more range.
> 
> Also, 73kWh at 38,000 will be extremely unlikely so it would be great if you can find a trip where you can drive to about 10% at EPA consumption and see what the used says.


Yes to LR RWD.

Here is a shot as the car sits tonight:










I'll try and get a shot the next time I achieve a merge.

That projected range of 378 km is with 73% SOC currently indicated.

My interpretation of this screen shot is .142 wh/km x 378 km range equals 53.676 kWh theoretically still available for me to tap into, thus (100/73) x 53.676 kWh equals a theoretical 73.528 kWh available for me to tap into at 100% indicated SOC......which is close to the 73.185 kWh figure I came up with based on my refill last night.


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## JWardell (May 9, 2016)

I will repeat what I've said elsewhere. Nothing has changed with the battery in v10. What has changed is the season. Temperatures are dropping and you are back to seeing more consumption and less range with colder overnight temps.


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## Needsdecaf (Dec 27, 2018)

JWardell said:


> I will repeat what I've said elsewhere. Nothing has changed with the battery in v10. What has changed is the season. Temperatures are dropping and you are back to seeing more consumption and less range with colder overnight temps.


If that's the case, I bought my car in December. Why didn't my range go up when it was in the 90's? Also, my drop of almost 10 miles occurred when it was still warm down here in Houston - still in the upper 80's.

What's the algorithm that the car uses to figure "max range" when you charge it to less than 100%? Is it based on your recent driving? Or is it based on the theoretical 240 Wh/mile EPA rating still?


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## NJturtlePower (Dec 19, 2017)

JWardell said:


> I will repeat what I've said elsewhere. Nothing has changed with the battery in v10. What has changed is the season. Temperatures are dropping and you are back to seeing more consumption and less range with colder overnight temps.


I agree.... it was BEFORE V10

See my post/chart #16 above...got my car last July and even through a brutally cold 2018 winter there was no such sudden range drop like there was this year after update 28.3.


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## MikefromBK (Feb 3, 2019)

JWardell said:


> I will repeat what I've said elsewhere. Nothing has changed with the battery in v10. What has changed is the season. Temperatures are dropping and you are back to seeing more consumption and less range with colder overnight temps.


Hey J,

I don't think that's it. I started seeing my drop mid-summer as many others have. dont remember with which update, but some version of V9. I don't think it's degradation necessarily, but rather a change in software calculation of miles.

Also, I believe the rated wH/mile changed for some as well. I can confirm that my line for rated wH/mile is at 250, whereas before it was 240. 250x73 usable kWH puts me at 292 miles which is pretty much what my rated range is at 100% now.

Mike


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## JasonF (Oct 26, 2018)

Whenever there's a sudden and drastic change, I always get the feeling it's because someone ruined things for everyone.

I get the feeling the guess-o-meter calculation was adjusted to increase the 0% emergency reserve, because too many people were running the battery down, getting stranded, and calling Roadside Assistance.


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## NJturtlePower (Dec 19, 2017)

JasonF said:


> Whenever there's a sudden and drastic change, I always get the feeling it's because someone ruined things for everyone.
> 
> I get the feeling the guess-o-meter calculation was adjusted to increase the 0% emergency reserve, because too many people were running the battery down, getting stranded, and calling Roadside Assistance.


Very well could be, problem is when you have technical owners who can see and identify the changes in the data without official word from Tesla it leads to all this drama and speculation.


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## MelindaV (Apr 2, 2016)

JasonF said:


> I get the feeling the guess-o-meter calculation was adjusted to increase the 0% emergency reserve, because too many people were running the battery down, getting stranded, and calling Roadside Assistance.


maybe people don't jump on here to tell stories of running out of energy, but in all the time the 3 has been out, I don't recall hearing a signal story of someone needing to be towed because they let the battery run to 'empty'.


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## JasonF (Oct 26, 2018)

MelindaV said:


> maybe people don't jump on here to tell stories of running out of energy, but in all the time the 3 has been out, I don't recall hearing a signal story of someone needing to be towed because they let the battery run to 'empty'.


Me either, but we don't have access to the statistics Tesla does. Plus, a lot of those people might have been embarrassed that they let it happen, and just quietly towed, charged, and moved on.


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## TeslaKiller (Oct 8, 2019)

Needsdecaf said:


> What's the algorithm that the car uses to figure "max range" when you charge it to less than 100%? Is it based on your recent driving? Or is it based on the theoretical 240 Wh/mile EPA rating still?


When you charge it is always based on EPA of 245Wh/m on AWD or P.

Algorithm 100% rated range:
Full capacity in kWh(a number the car calculates based on weather and chemistry)/typical consumption for this model.
(I have to specify what a typical consumption is because some people hang on to the word "EPA" rating as it is some religious cult... I refer to EPA rated consumption, but in reality this is just the typical value you see under straight line in your energy graph. It is somewhat based on EPA, but Tesla tweeks this value like they feel, like they did with RWD update. So a more accurate wording is "typical consumption")

But! you can't just calculate range or capacity based on 80-90% charge. First, there is BMS calibration that might be off, rounding errors of 1% and also the temperature as someone mentioned.

But if you want to understand all of that plus why you can't get the total 240miles, even if you drive at the 245Wh rated from 0-100%, watch my latest video.


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## JWardell (May 9, 2016)

Needsdecaf said:


> Cross posted from Model 3 charging forum:
> 
> Here's my deg over 23k miles in under one year as estimated by Teslafi. Car is charged at least 5x per week, you can see I drive a lot. Limited Supercharging.
> 
> ...





NJturtlePower said:


> I agree.... it was BEFORE V10
> 
> See my post/chart #16 above...got my car last July and even through a brutally cold 2018 winter there was no such sudden range drop like there was this year after update 28.3.


You are all ignoring the very important fact that a software update change to range estimates would be seen across the board by everyone. Dips you see on your own are a result of your own BMS's individual estimates, and it could be taking recent changes in driving style or temperatures into account.
The only time we have actually seen a software update change range was in March, when it was well publicized that Tesla was increasing range from 315 to 325 mi. And maybe last December when it seems they reduce the reduction due to cold temperatures. But there has been no changes with v10 or recent firmware. 
The only common issue is that it has been getting colder in the evenings and many of your batteries are getting colder. 
Also, you are zooming way in on what are fairly small changes. Getting worked up over less than ten miles of range. That is just normal fluctuation in the BMS estimate.

Here is mine, including a drastic 310 to 284-mile drop this time last year as temps dropped, and more significantly, dead flat with no changes in the last 10% of time with v10


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## TeslaKiller (Oct 8, 2019)

JWardell said:


> The only time we have actually seen a software update change range was in March, when it was well publicized that Tesla was increasing range from 315 to 325 mi.


Except that Tesla never really "added" any "range". They just tweaked the typical range constant a bit lower and thus "calculated" a typical range to 325mi and this is evident from the energy graph - typical value before and after the update...If you drive the same consumption before and after the update, you got the same exact range.


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## Needsdecaf (Dec 27, 2018)

JWardell said:


> You are all ignoring the very important fact that a software update change to range estimates would be seen across the board by everyone. Dips you see on your own are a result of your own BMS's individual estimates, and it could be taking recent changes in driving style or temperatures into account.
> The only time we have actually seen a software update change range was in March, when it was well publicized that Tesla was increasing range from 315 to 325 mi. And maybe last December when it seems they reduce the reduction due to cold temperatures. But there has been no changes with v10 or recent firmware.
> The only common issue is that it has been getting colder in the evenings and many of your batteries are getting colder.
> Also, you are zooming way in on what are fairly small changes. Getting worked up over less than ten miles of range. That is just normal fluctuation in the BMS estimate.
> ...


1. I'm not getting worked up. My high vs current is less than 10 mile drop in 23k miles. I wouldn't consider that bad.
2. I posted a nearly identical interval to yours, 23 k miles. I did zoom in on the one dip in that 23k to show more detail.
3. The reason I posted it was that my curve shows a gradual very slight decline for most of the car's life, which would be expected. Then there was a sharp drop. It's not a huge drop, but it's atypical with the previous 11 months. 
4. Not drawing conclusions, just wondering why. I literally said "hard to draw conclusions, could it be the BMS recslibrating?"


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## JWardell (May 9, 2016)

TeslaKiller said:


> Except that Tesla never really "added" any "range". They just tweaked the typical range constant a bit lower and thus "calculated" a typical range to 325mi and this is evident from the energy graph - typical value before and after the update...If you drive the same consumption before and after the update, you got the same exact range.


That is true. And why none of this really matters.



Needsdecaf said:


> 1. I'm not getting worked up. My high vs current is less than 10 mile drop in 23k miles. I wouldn't consider that bad.
> 2. I posted a nearly identical interval to yours, 23 k miles. I did zoom in on the one dip in that 23k to show more detail.
> 3. The reason I posted it was that my curve shows a gradual very slight decline for most of the car's life, which would be expected. Then there was a sharp drop. It's not a huge drop, but it's atypical with the previous 11 months.
> 4. Not drawing conclusions, just wondering why. I literally said "hard to draw conclusions, could it be the BMS recslibrating?"


Didn't mean to say you were getting worked up, just generalizing as some others are. Trying to offer some perspective.


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## John (Apr 16, 2016)

Let's all prove that batteries work, shall we?


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## John Rea (Jun 19, 2017)

A month ago a full charge for me was 310 miles. On Thursday night I charged to 100% to go on a trip on Friday. 100% is now 295 miles.
So, this matches up with what others are seeing. 
If Elon would upgrade my Dual Motor Long Range to Performance via OTA update we'll call it even. 
But seriously - a 5% decrease. For what reason? What justification?


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## Dr. J (Sep 1, 2017)

JWardell said:


> Dips you see on your own are a result of your own BMS's individual estimates, and it could be taking recent changes in driving style or temperatures into account.


Isn't the BMS just calculating range based on the voltage of the pack (along with the constant @TeslaKiller pointed out)? So, in that regard, it could be taking some things about your personal situation into account, but only as an after-the-fact artifact (see what I did there?) of your driving style. I'm agnostic about the effects of temperature on max range--not enough variation where I live to discern a pattern.


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## Mike (Apr 4, 2016)

TeslaKiller said:


> When you charge it is always based on EPA of 245Wh/m on AWD or P.
> 
> Algorithm 100% rated range:
> Full capacity in kWh(a number the car calculates based on weather and chemistry)/typical consumption for this model.
> ...


FYI /FWIW: I can confirm on my LR RWD that my "merge" of lines on the energy graph is 149 wh/km (unable to secure photo of same, but solid merge occurs at 149 wh/km).

I'm pretty sure this is unchanged since I took delivery in June 2018.


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## JWardell (May 9, 2016)

Dr. J said:


> Isn't the BMS just calculating range based on the voltage of the pack (along with the constant @TeslaKiller pointed out)? So, in that regard, it could be taking some things about your personal situation into account, but only as an after-the-fact artifact (see what I did there?) of your driving style. I'm agnostic about the effects of temperature on max range--not enough variation where I live to discern a pattern.


Unfortunately you can't really determine SOC from voltage of a lithium ion battery with an extremely varying load of an EV. The voltage flails wildly well over 100V while you drive. A BMS will instead count coulombs looking at all power in and out of a battery, and plenty of temperature corrections, as well as several curves from known performance from research, and it varies with each different soup of battery chemistry. It will then watch that over time, and perhaps when charging up over 90% when all systems are off it might finally compare to previous history of voltage at that state and tweak its calibration and determine a new estimated total capacity and range. It's also looking at things like every individual cell...if certain cells are underperforming as is expected over time, it probably adds that into the equation. A BMS is probably one of the most complicated parts of the system, with hundreds and hundreds of sensors and inputs, lots of algorithms and calculation, and leans on a lot of history/pre-determined data to compare to. That also means it is the hardest thing for anyone outside of Tesla to fully understand what it is really thinking.


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## PA_Ray (Nov 12, 2017)

My range estimate has dropped over 20 miles in the last 6 - 7 weeks. I figure the BMS is out of calibration but haven't been too worried since I don't use that much range a day. Is there any reason why I need to run the battery down below 20% and then to 100 to reset or is it safe to just go like this (probably a continued drift downward) until I get around to recalibrating it?


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## Phtp (Aug 25, 2018)

JWardell said:


> Bjorn is basically saying v10 reduced range by 6% in this video, and we all know that is untrue. I'm not sure if he's just doing this for clickbait or confusing it with a recent Model S update to address battery fires in a small number of cars. It IS possible, however, that the temperatures dropped significantly there lately (it is Norway, after all), and the algorithm is compensating a bit for that. Last year range fell significantly with winter temperatures, I am waiting to see if the same happens this year or if Tesla changed the SOC algorithms.


Agree. I don't believe it was related to v10 either. If that was the case I would've seen an immediate drop rather than it going up a bit.


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## TeslaKiller (Oct 8, 2019)

PA_Ray said:


> My range estimate has dropped over 20 miles in the last 6 - 7 weeks. I figure the BMS is out of calibration but haven't been too worried since I don't use that much range a day. Is there any reason why I need to run the battery down below 20% and then to 100 to reset or is it safe to just go like this (probably a continued drift downward) until I get around to recalibrating it?
> 
> View attachment 30284


What was your charge pattern? Plug it in each night, let it charge to 90%, mostly from 60-70?


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## JP White (Jul 4, 2016)

JWardell said:


> The only common issue is that it has been getting colder in the evenings and many of your batteries are getting colder.


If we were discussing a LEAF with a GOM I'd agree the BMS is making all manner of adjustments to DTE, temperature being a biggie. However I've always been lead to understand that Tesla vehicles use Ideal or Rated range and the car does not make a ton of arbitrary adjustments to the range. The energy graph does make such adjustments, but not the miles in the left portion of my display.

Last year I went through the winter with a very consistent 250 miles at 80% charge level. Now I'm at 238 and most of that reduction has been in the last 4-6 weeks.

Somethings up. I don't believe the battery has truly degraded to that extent. I'll be taking a trip in a few weeks which should shake out any drift in BMS calibration. My sense reading the posts here is that Tesla have changed the BMS and we are seeing fluctuations in rated range that we haven't before.


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## Feathermerchant (Sep 17, 2018)

It doesn't get cold enough to matter in Houston.


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## TeslaKiller (Oct 8, 2019)

JP White said:


> If we were discussing a LEAF with a GOM I'd agree the BMS is making all manner of adjustments to DTE, temperature being a biggie. However I've always been lead to understand that Tesla vehicles use Ideal or Rated range and the car does not make a ton of arbitrary adjustments to the range. The energy graph does make such adjustments, but not the miles in the left portion of my display.
> 
> Last year I went through the winter with a very consistent 250 miles at 80% charge level. Now I'm at 238 and most of that reduction has been in the last 4-6 weeks.
> 
> Somethings up. I don't believe the battery has truly degraded to that extent.


Could you please describe the charging pattern during those 4-6weeks? Were there a lot of 60/70%-90% charges? Like driving daily about 60 miles, go back home and plug in each day and charge to 90%?

You are right about the battery gauge - it is a static algorithm that doesn't take your consumption into account. Just the typical energy consumption. You are also right about the energy graph.
If you want to prove that, just try to match the straight line with the dottet line in the energy graph and see what happens to the energy prediction - it will match the battery indicator, because the battery indicator uses the dottet line to calculate range - always.

When you drive the long trip, try to match your avg. Consumption to the dotted and see how far can you go without charging (try going above 250miles) and write down the kWh used in trip meter since last charge(you should start right after unplugging and ideally from 100%)

This way you will know how much kWh the BMS thinks you have.


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