Battery degradation???

[Kevin-rf]

Last time I back calculate (miles displayed / %charge displayed) I was back up to 294 miles. It had been down to 288 miles.... 2018 AWD 64k VIN 38k miles.

I just keep it at 70% in the summer, 80% in the winter using mostly a wall connector.

It is what it is, OCD be darned.

 

[MMBTUS]

Note this should say constant divided in to, not divided by. It is the power divided by the constant, not vice versa. It won't let me edit the original post.

For what it's worth, my 2018 with only 7k miles on it has no degradation to speak of. I 100% charged it late last week and it estimates 325 miles remaining still. I leave it set at 90%, and plugged in all the time. It seems that these weird scenarios happen for folks who have weird charging habits and don't leave their car plugged in all the time when at home.

In winter months my 100% charge is 2-3 miles lower and my 90% charge is 1 or 2 miles lower. This vehicle is in an uninsulated garage.

My M3 was built in July 2018, 76XXX off the Fremont line, LR RWD. Battery capacity since delivery has degraded by 9.5%, now at 280 miles. And that’s based on the high starting range of 309 mile when new. I never saw a ratings bump to 325. Of 113 M3s in the TeslFi database at my mileage level (low at less than 15k miles) 113 have better degradation results.

I charge whenever the SoC is more than 10% below my 80% SoC target. I leave the car plugged in to a HPWC between charges. I have supercharged only once in 24 months (at the SC). I’ve never dropped below 20% SoC, and rarely drop below 50%. I’m being very gentle and yet the battery is declining.

So outlier battery degradation cases like mine can definitely happen without charging weirdness.

I will give the recalibration process a try. It’s been a while since deep discharge.

 

[jjrandorin]

My M3 was built in July 2018, 76XXX off the Fremont line, LR RWD. Battery capacity since delivery has degraded by 9.5%, now at 280 miles. And that’s based on the high starting range of 309 mile when new. I never saw a ratings bump to 325. Of 113 M3s in the TeslFi database at my mileage level (low at less than 15k miles) 113 have better degradation results.

I charge whenever the SoC is more than 10% below my 80% SoC target. I leave the car plugged in to a HPWC between charges. I have supercharged only once in 24 months (at the SC). I’ve never dropped below 20% SoC, and rarely drop below 50%. I’m being very gentle and yet the battery is declining.

So outlier battery degradation cases like mine can definitely happen without charging weirdness.

I will give the recalibration process a try. It’s been a while since deep discharge.

as has been said many times, "charging only to 80%" confuses the BMS over time, so your "charging only to 80"% is likely why your rated miles looks the way it is. You ARE being "gentle" to the battery, but you are also guaranteeing that your BMS never sees the voltage of a higher 90% charge, so never really gets to see whats "actually" there.

If you want the number to appear higher, stop charging to "only 80%" and set it to 90% and let it sit there for a while (measured in several days, not hours, or "one charge to 90%". The pack will balance itself. You will likely (after a week or so) see a higher number reported in your car, while simultaneously putting a little more actual wear on your battery.

Or, keep charging to 80%, and be secure in the fact that you are actually babying your battery, but your car likely does not know its true pack range, so your reported number may keep going down.

I think for my own sake, I likely shouldnt look at, read or post to any more of these "battery degradation" threads, since my car seems to be "so different" than everyone who is following some specific charging regimine that isnt in the manual.

(I charge to 90% all the time, and my car only recently adjusted range down when they stated that Model3Ps with 20 inch wheels had 299 range and not 310). My car shows 298-299 range. Its a 2018 model 3P with 23.5k miles on it, always charged to 90%, always plugged in when not driven).

 

[golfpilot]

My Model 3 gets an estimated full charge of 281... 47k miles on the car. Everyone else posting looks to be doing pretty well in comparison

 

[tomas]

This is about the thousandth thread like this where people start dropping in with their data points absent car spec expecting that to be of value. Appreciate that some at least put in mileage.

if any one really cared about this, rather than posting random data points, they would harvest these threads, get back to those who report to confirm standardized data, and create a database. Or at least post a shared google doc for people to log their data. Absent 1,000 real data points, this is all noise.

 

[texas_star_TM3]

July '19 M3 AWD ... getting to 296 miles on a 100% SOC charge after 10k miles. Never saw the 310 miles from the beginning ... maxed out at 305 miles initially.

 

[camalaio]

But the real issue is what difference does it make? The car is going to travel whatever distance it’s going to travel. No sane person will depend on using the range counter to zero. And no one has ever posted numbers that approach a warranty coverage situation.

(emphasis mine)

There have been at least two people on here that have posted, been beyond the 30% threshold, and contacted Tesla regarding battery replacement. Sadly I don't think they followed up on these forums. But warranty coverage situations have definitely been posted here. There's a few active cases of being around 20% degraded, which is indeed approaching a coverage situation.

Never heard of this. Haven't seen any TSB's about related to M3 battery packs. What VIN range is impacted?

Ah shoot, now I gotta look it up.

I think it's this one, but I'll stop digging here (can continue on the NHTSA website if interested): https://static.nhtsa.gov/odi/tsbs/2019/MC-10154513-9999.pdf

They give a date range, not a VIN range: "Approximately" Aug 24 to Sept 10, 2018. Would have to be confirmed by Tesla on a case-by-case basis.

Quick Note to all: Do not abuse TSBs. Don't bring these all to Tesla claiming a whole bunch of stuff needs fixing on your car simply because the documents exist. In addition to being a good way to annoy your local service team, many of the documents probably don't apply to your specific vehicle (due to either date and/or VIN range).

 

[KenC]

This is about the thousandth thread like this where people start dropping in with their data points absent car spec expecting that to be of value. Appreciate that some at least put in mileage.

if any one really cared about this, rather than posting random data points, they would harvest these threads, get back to those who report to confirm standardized data, and create a database. Or at least post a shared google doc for people to log their data. Absent 1,000 real data points, this is all noise.

I started a thread, what seems like a year ago, where I asked people who had zero or minimal deg to provide their charging regimen data, etc. So many of these threads are by people with large amounts of deg, and very few are about people with little deg, so I was trying to see if there were any winning battery strategies.

What did I find? Basically, there was little to no pattern in what people did to achieve zero or minimal deg, according to what the BMS reports. My recommendation to people unhappy with what their BMS is reporting for range, is to change up their charging strategy. That's the only thing that seemed to help some people.

I've been charging to only 61% since last Fall, and while I haven't driven much, ~12k, my battery still shows 310 miles of rated range. One would think being parked outside in a cold clime I would have lots of BMS drift, but that doesn't seem to be the case. My rated range variation has been almost all temperature-related.

 

[jim0266]

Get ScanMyTesla. The Nominal Full Pack and Energy buffer reading will tell you your degradation amount.

 

[tomas]

Get ScanMyTesla. The Nominal Full Pack and Energy buffer reading will tell you your degradation amount.

Yes, that’s a more definitive approach than rated range. But the next question everyone asks is “is mine normal?” There is a pat answer to that: -5% in first year -1% for each year thereafter. All +/- 2%. If you are in that tolerance, you are normal.

But if you are going off of rated range rather than actual battery metrics, you have to start with the correct rated range for your specific vehicle and wheels. And you have to keep the BMS calibrated by occasionally going >90% and <20%. And you have to keep pack balanced by charging to 90% for a week straight every now and then.

99% of the people on this forum fretting about supposed degradation are in fact normal if they measured it correctly and measured against real data sets. Hint: google “battery degradation graph”.

 

[camalaio]

Yes, that’s a more definitive approach than rated range. But the next question everyone asks is “is mine normal?” There is a pat answer to that: -5% in first year -1% for each year thereafter. All +/- 2%. If you are in that tolerance, you are normal.

But if you are going off of rated range rather than actual battery metrics, you have to start with the correct rated range for your specific vehicle and wheels. And you have to keep the BMS calibrated by occasionally going >90% and <20%. And you have to keep pack balanced by charging to 90% for a week straight every now and then.

99% of the people on this forum fretting about supposed degradation are in fact normal if they measured it correctly and measured against real data sets. Hint: google “battery degradation graph”.

"Actual battery metrics" are exactly what rated range is based off of. Calibration, balancing, etc., if applicable to rated range, are also applicable to the figures seen via Scan My Tesla and similar OBD-II data apps. The only difference is you can look at both a temperature-influenced and temperature-independent number for pack energy (which as long as the battery is above 25C, these are pretty much the same anyways).

I'm only pointing this out because it sounded like you were saying SMT data is accurate regardless of BMS estimation on range. I'm not certain if that is how you meant it, just how it read to me.

 

[tomas]

"Actual battery metrics" are exactly what rated range is based off of. Calibration, balancing, etc., if applicable to rated range, are also applicable to the figures seen via Scan My Tesla and similar OBD-II data apps. The only difference is you can look at both a temperature-influenced and temperature-independent number for pack energy (which as long as the battery is above 25C, these are pretty much the same anyways).

I'm only pointing this out because it sounded like you were saying SMT data is accurate regardless of BMS estimation on range. I'm not certain if that is how you meant it, just how it read to me.

Thanks, Yes, I understand that. The OBD-II tools, as I understand it (I’m happy to be educated if wrong), provide base values that relate directly and only to battery, whereas rated range numbers numbers reflect the same battery data, factored by drivetrain and wheel size. So using the scanmytesla data makes it easier to accurately compare across cars. But since most people on this forum worry and post about rated range... to analyze a meaningful sample, you need the following info: Model (RWD,Dual,P), wheel size, age, mileage, rated range@100%. Plus, IMO the rated range @ 100% needs to be actually AT 100% Immediately at the end of a charge. Not the guesstimate from the Tesla app slider!

 

[Justin27]

I like how everybody here is suddenly a battery electrical engineer, lol.
I have another great idea just drive the damn thing and quit worrying about it... it's still a lot better deal than gas.

 

[AKinDC]

I like how everybody here is suddenly a battery electrical engineer, lol.
I have another great idea just drive the damn thing and quit worrying about it... it's still a lot better deal than gas.

I understand what you’re saying, but that’s not the point.
The battery size/range is a HUGE selling point for Tesla...so when you don’t get the range you were expecting, it’s incredibly frustrating, even if it really doesn’t matter that much in the general scheme of things.

 

[SageBrush]

Get ScanMyTesla. The Nominal Full Pack and Energy buffer reading will tell you your degradation amount.

How are these values calculated ?

 

[camalaio]

How are these values calculated ?

Tesla secret sauce. But it takes everything into account: bad bricks of cells, imbalance, reduced capacity, internal resistance, etc.

Unless by "how" you are asking how it's read from the car. In that case, the values we think are these values are interpreted with the scale we think they use. These appear to be correct interpretations. That said, SMT once reported my LR pack was suddenly 100kWh. I mention this simply because while there's high confidence in these values, there may be more factors to them than we know from outside Tesla (and thus no one should be holding Tesla responsible for any third-party app's representation of car data).

Happily, it's easy to back up degradation claims without SMT/OBD-II data simply because the same data is used to calculate the available rated range.

I understand what you’re saying, but that’s not the point.
The battery size/range is a HUGE selling point for Tesla...so when you don’t get the range you were expecting, it’s incredibly frustrating, even if it really doesn’t matter that much in the general scheme of things.

I wish folks here were more understanding of this point. We're all very used to this, being on the forums. But someone new to EVs is in for a hell of a shock when the primary selling point of a Tesla starts ticking down soon after purchase. The 499km rating of the LR (at the time we got it) was already cutting it close for some trips, but it was basically the best range EV available at a <$80,000 price tag and a large part of the reason we got a Tesla specifically (there's personally a lot of things I like about the Chevy Bolt, if it didn't have that "Chevy" bit to it).

 

[tomas]

I understand what you’re saying, but that’s not the point.
The battery size/range is a HUGE selling point for Tesla...so when you don’t get the range you were expecting, it’s incredibly frustrating, even if it really doesn’t matter that much in the general scheme of things.

For 99% of the people who have posted in the various threads, if you don’t get the range you expected it is because your expectations were wrong because you didn’t do your homework. The typical loss is well documented: 5% in first year, 1% or less per year thereafter. Plus lower range in cold weather or if you have a lead foot. No sympathy here.

 

[camalaio]

For 99% of the people who have posted in the various threads, if you don’t get the range you expected it is because your expectations were wrong because you didn’t do your homework. The typical loss is well documented: 5% in first year, 1% or less per year thereafter. Plus lower range in cold weather or if you have a lead foot. No sympathy here.

This thread is regarding someone's displayed range which is indicative of real battery pack capacity, not driving behaviour or additional usage due to speed/climate/etc. The loss is well-documented on fan forums which are a small subset of owners, and thus not common knowledge for existing or new owners.

Tesla Official Statement on Range

Why is my displayed estimated range decreasing faster than miles driven?
The range displayed is not adapted based on driving pattern or other factors that impact range. When fully charged, the driving range displayed is based on regulating agency certification (Environmental Protection Agency - EPA). To view estimated range based on average consumption, open the Energy app.​

 

[SageBrush]

there's personally a lot of things I like about the Chevy Bolt, if it didn't have that "Chevy" bit to it

I feel much the same, although I also get a bit nauseated by the coloring book display

simply because the same data is used to calculate the available rated range

This is the key point I try to remember. I'm still unconvinced that the battery needs to calibrated/charged to 100% etc to know rated miles. So far as I know, people have not been bothered by the question enough to provide anything more than anecdotal data heavily seasoned with battery temperature uncertainty.

 

[tomas]

The loss is well-documented on fan forums which are a small subset of owners, and thus not common knowledge for existing or new owners.

everyone I know who bought a Tesla, and that’s probably >100 I’ve talked to or corresponded with over last 8 years, had range as a significant concern... and did their homework. What kind of person buys an entirely new type of vehicle without researching? I think you are describing a very small subset. And, I’ll add, of friends who bought Teslas, the least fanatic who don’t even get on sites like this are also the least worried about range. Maybe the people I know are atypical, but I don’t think so. That’s why Tesla’s customer satisfaction is so high and this forum is so negative. The obsessive will obsess. (Me included I guess) The rest just live happily with their purchase.