How to determine if my Model 3 LR battery degradation is as should be expected or is at an accelerated rate?

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WhiteDust

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<citation needed/>
EPA testing is done at room temperature. So even if climate control is on, it won't be doing much during testing.

https://www.myev.com/research/buyers-sellers-advice/how-the-epa-rates-electric-vehicles

Sorry, I wasn't referring to EPA testing, but rather the (vehicle's calculation) rating displayed in vehicle while driving. Current Trip/Lifetime.

I'm looking for the citation.

Edit: It wasn't Elon and range wasn't mentioned, but rather the target consumption for the HW 3 chip. I guess I'm just remembering it wrong and equating it to the range estimates. www.youtu.be/Ucp0TTmvqOE @1:42:00. This is an example of the brain putting a bunch of things together over long periods of time and not exactly remembering them correctly.
 
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NYer

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@NYer, yes this is a topic discussed a lot. First and foremost be aware that battery degradation and the rated range shown for your car may be 2 totally different things. The battery degradation is a real, physical process. The rated range displayed in the car is from an algorithm that none of us fully understand.

Here are some links. First is a long description in a long thread. I quote it because it and follow up posts contain info quoted from Tesla.


Second link is because when JWardell speaks, people are wise to listen. He has spent more time than most of us diving into details of our how our cars work.


And the third link is because it’s the most recent thread hat I immediately thought of about battery range predictions.

This is extremely helpful. Thank you for providing this information.

I'm a bit disappointed that I need to deep drain and recharge my battery in the hope that the BMS recalibrates itself as it strains the battery in the process. Good info nonetheless.
 

JasonF

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I'm a bit disappointed that I need to deep drain and recharge my battery in the hope that the BMS recalibrates itself as it strains the battery in the process. Good info nonetheless.

I was told that wasn't necessary, and just charging slightly above 90% a couple of times would do it.
 

MelindaV

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@MelindaV, @JWardell , what's the latest info on how to correctly recalibrate the BMS?
I'm having trouble locating some of the latest posts on the topic - it's been discussed a lot.
sorry - not sure how I missed this, it just came up in my alerts today! (weird)...
for me, after spending a year trying all sorts of different combinations (charging daily to 90% - only charge when the battery gets down to sub 20%, then charge to more than 90% - only charging on reduced power instead of the full WC 50A capacity - etc, etc.. ). for me, what seems to have made a difference was stop driving to the office daily, and let the car sit for days at a time without being driven (not a very fun way to change something). or it was just a coincidence
Screen Shot 2020-07-27 at 6.41.19 PM.png


for timeline reference, that flat section was March 12-19 when I was at a rental house and plugged into a 110v outlet, followed by the drive home and a few months of maybe taking the car out once a week for a short drive.
 

Thorongil

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I've got to wonder what impact phantom drain/AC/Sentry has on the algorithm as well. I was worried about range loss, given that I've got pretty high efficiency overall when I noticed that total range seemed to creep down as phantom drain crept up. Does the total range take into account loss of actual range due to phantom drain? If so, this would make a lot of sense...
 

Ed Woodrick

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sorry - not sure how I missed this, it just came up in my alerts today! (weird)...
for me, after spending a year trying all sorts of different combinations (charging daily to 90% - only charge when the battery gets down to sub 20%, then charge to more than 90% - only charging on reduced power instead of the full WC 50A capacity - etc, etc.. ). for me, what seems to have made a difference was stop driving to the office daily, and let the car sit for days at a time without being driven (not a very fun way to change something). or it was just a coincidence
View attachment 34988

for timeline reference, that flat section was March 12-19 when I was at a rental house and plugged into a 110v outlet, followed by the drive home and a few months of maybe taking the car out once a week for a short drive.

I don't see you mention anything about charging to 100% (at least 95) and letting it sit for a few days.
40,000+ miles and still 311 for me.
 

eyedrop0

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Best method for revealing capacity loss Ive found is:

Drain car as low as possible, then charge to 100% full at the slowest rate possible (110v) Let it settle/balance for a day then try charging again. Once your sure its at 100%. This makes sure your balanced before starting the test.

Next, run it down again to as low as possible then charge to 100% using a third party charge counter (such as a DC fast charging station or app connected wall charger.) It will show you how many kWH you put into the battery. Compare this to reference new pack usable kWH, account for the few miles left in the battery, and there is your answer.

And BTW, tracking the range number/GOM could be useless as the car updates driving history, changes firmwares, etc... Better to think in terms of sheer battery capacity loss.
 

Bigriver

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I don't see you mention anything about charging to 100% (at least 95) and letting it sit for a few days.
then charge to 100% full at the slowest rate possible (110v) Let it settle/balance for a day
Where is this suggestion to let it sit at 100% for day(s) coming from? I don’t recall hearing anyone ever suggest that. Although I consider myself pretty willing to exercise my battery, I can’t imagine being willing to let it sit at that high SOC for any length of time.

Next, run it down again to as low as possible then charge to 100% using a third party charge counter (such as a DC fast charging station or app connected wall charger.) It will show you how many kWH you put into the battery. Compare this to reference new pack usable kWH, account for the few miles left in the battery, and there is your answer.

And BTW, tracking the range number/GOM could be useless as the car updates driving history, changes firmwares, etc... Better to think in terms of sheer battery capacity loss.
In my early Tesla days, I thought this would all be simple math and I had done several calculations focused more on the kWh used and/or added, such as you suggest. KWh just seems a better unit than rated miles. But I never found those calcs to be very satisfying as they didn’t cleanly square away. After reading your post, tho, I decided to revisit current battery capacity from this vantage point, using my vast data collected by Teslafi for both my model 3 and my model X. I chose charges in which I had added at least 50% of the battery capacity, which was plentiful for the model X and I judged to be adequate for the model 3. I extrapolated the full battery value from the “kWh added” (Teslafi value that is pulled directly from Tesla API) based on SOC that was added (e.g., 10% to 90% is 80% added.) I did not do any intentional battery balancing routines (except last model 3 data point), but my cars’ batteries are not typically cycled through narrow ranges, which is apparently a root concern for accuracy of BMS calcs.

I found that the kWh calc has even more chatter in it than the rated mile calculation. I’m not sure that focusing on kWh separates one from the BMS algorithm, since this still relies on the BMS definition of what % charge the kWh corresponds to. Obviously if I would get close to 100% added, that component would go away. The closest I got was 93% added for the model 3 and 84% for the model X.

The largest thing I learned from this exercise: I was very puzzled by the recent apparent significant increase in kWh for the model X. Those correspond to charges starting in 2020. They were at superchargers. In all cases, I had the heater or a/c on while charging. According to https://insideevs.com/news/392775/tesla-adjusts-supercharger-billing/, Tesla changed their kWh added data for superchargers to include these other energy uses. Although the energy is not going to the battery, the change was made to capture the extra kWh for billing. As a side note, tho, that change doesn’t seem to have been applied to superchargers at Ft Wayne, IN. That is the location of the 2 lowest recent data points at 96 and 98 kWh.

Plots are below, should anyone care to look at them. Blue points are the kWh calcs (for >50% battery capacity added) on the left axis and reddish points on the right axis are from Teslafi (all charges), normalized to the initial rated miles (310 for model 3 and 295 for model X). Also plotted the starting and ending SOC for each of the charging sessions included in the blue kWh calculation.
EFCD6750-FDAC-4BFB-AF44-2525B878D38A.jpeg
00A315D9-C085-4A64-A6AF-6B9DEBCF2AFF.jpeg
 

garsh

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Where is this suggestion to let it sit at 100% for day(s) coming from?
+1
Ed has a good point that many people worry too much about how to protect a battery. Most of the things we talk about end up making very small differences. Tesla has designed their batteries very well, and they usually won't degrade any more than 10% over their lifetime.

But charging to 100% is one of the things that Tesla has ALWAYS said to avoid unless required for a trip. When you do so, the car will even pop up a message on the screen telling you that you should only do so for long trips. Charging to 100% and leaving it sit there is not good advice.

https://www.tesla.com/support/home-charging-installation/faq
What percentage should I charge the battery to?
Adjust how full the battery charges from the charge settings menu. For regular use, we recommend keeping your car set within the 'Daily' range bracket, up to approximately 90%. Charging up to 100% is best saved for when you are preparing for a longer trip.
 

eyedrop0

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I agree about letting it sit at 100%, not a good idea for battery health.

I never charge to 100% unless I have to. But for the sake of getting the best possible balance/accurate predicted range, giving the cells as much time as possible to charge/ as much voltage as possible will always give the most accurate BMS numbers.

Its also my theory that charging fast or charging to very high SOC can help "shake" those dendrites loose and actually can do some good to the battery.

But on the daily, of course I dont recommend charging to 100%.
 

eyedrop0

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Nothing other than personal anecdotal expierence messing around with old 18650's that dipped below the 2v threshold. Sometimes shocking them with high currents can bring them back to life if a trickle charge wont bring it above your desired threshold.

I guess its like the old "Italian tuneup" for ICE where you run it hard to "clear the cobwebs". Probably nothing to back this theory either...
 

mcmoyer

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I swear that 285 - 290 is where I see most people saying their 100% charge is nowadays. At least the 2018-2019 model 3's. Unironically, that's where mine is as well. I switched to % battery about a year ago and quit stressing about it. That said, I just got back from a round trip from DFW to Denver and I did miss that extra few kilowatts from the long dry run from Amarillo to Trinidad, CO. If I go by my charging calculations, my battery capacity is around 69.6 kWh. Has anyone established what the official capacity is supposed to be? I know 75 is floated a lot, but do they hold off a few kWh is reserve?

The extra power would have been helpful, because it was quite embarrassing to be going 60mph in a 75mph zone and being passed by gravel haulers.

Oh, and I really hate when you're driving and it says,

"stay below 80mph to get to your destination"

then a few minutes later, "stay below 75mph..."

then a few minutes later, "stay below 70mph..."

then a few minutes later, "stay below 65mph..."

you start to think at some point you're going to be traveling around 25mph to limp into a charging station.
 

Hdez

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I wonder whether software updates have something to do with this loss in battery range. I've lost 2% of estimated battery range since 2020.28.5 a little over 3 weeks (7/26/20). My estimated range with 2020.24.6 was 316.25 and I'm now down to 309.51 with 28.6 according to Teslafi. I'm not complaining though. Basically my LR RWD M3 is back to the original estimated range of 310 miles after 16 mos. and 17,217 miles. Down only 5.38% from the range boost of 326.17.
 

tencate

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I know, I know, we all love to talk about displayed range and I generally ignore all the discussion about battery degradation with the latest software update, etc.. But lately I've noticed mine APPEARS to have dropped too. Didn't bother me, mine's a 2017 car with nearly 70k miles on it. So I'd expect to see some degradation. Today I made a nice round trip to Albuquerque, did some errands, and got back home seeing yellow on the battery. I'd charged up to 80% the night before, didn't do anything special, sorta stayed near the speed limit (75 mph) and used A/C most of the way (it was 100F in ABQ today). Used up that 80% charge nicely. Tonight I plugged in and for grins ran the charging limit up to 100% to see what range would be displayed. 307 miles. I paid for 310 miles of range back in 2017 :) I can't honestly tell you what my battery degradation is because Tesla keeps tweaking everything about the car so they can squeeze out more and more range from a battery pack. Gotta love over-the-air software updates and big batteries too. :) Seeing 307 miles made me smile.
 
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Hdez

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I know that this is supposed to level off at some point, but it keeps going down. I'm getting anxious :confused:. It's been down hill since 2020.12.6 Just installed '20.36.10 this evening. I'll keep watching and worrying.


Bat Deg.JPG
 

GDN

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I know that this is supposed to level off at some point, but it keeps going down. I'm getting anxious :confused:. It's been down hill since 2020.12.6 Just installed '20.36.10 this evening. I'll keep watching and worrying.


View attachment 35527
You're still in great shape compared to many others including me. I'll start by saying this, if it is SW related, just know Tesla will get ahold of that and fix it. They are really bad at breaking things and then fixing them. So if SW, it'll be back.

Here is my thread - https://teslaownersonline.com/threads/how-do-i-charge-next-to-regain-range.16703/post-290589. and to be honest, I'm not as worried now that JWardell has weighed in. He really understands this stuff and after I took some longer drives, I saw upticks on my range both times as he noted it would to help get the BMS back on track. Read the thread and then likely take some longer consistent speed drives, especially if you have just taken a lot of short drives close to home recently.
 
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