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Degradation is happening too quickly

Hello all,
I have a Model S 90D that was shipped to me in December of 2017.

At that point the range was sold to me and marketed as 296 miles and I would top off at either 296 or even 297 at times.
Per everyone's suggestions, I would rarely charge it to 100% as to preserve the longevity of the battery.

However, I started noticing after about 8 months or so that the most I could charge to was about 290, and by December of 2018 (which was the time for my first Tesla service) it was down to 287. So a total of 9 miles over one year was lost. It's gotten even worse as I charged it all the way up the last two times back in February and topping out at 284. So, 12 miles lost in a little over a year!

At service I brought that issue up and I received quite possibly the most unsatisfactory responses ever: "well, Tesla may have just changed the algorithm to more closely reflect what it should be getting," and "well, it's rare for the vehicle, or any vehicle, to get exactly what it was suggesting anyway so losing a few miles off the top doesn't really affect anything. Like for example, when it's cold you lose miles anyway."

The problem with those rationales is that for the first I really feel like that would be considered false advertising then. What's stopping Tesla in that scenario from saying due to a "new algorithm" your vehicle that you just spent a small fortune on is going to drive 50, or 60, or 100 miles fewer than what you originally thought. And for the second, it does make a huge difference on certain trips as sometimes those extra 10 or 12 miles means one fewer stop, or giving you just a little bit of extra comfort knowing you'll be making home when it starts getting low. And yes, I know I already lose miles when it's colder, why in the world would I want to start off with fewer miles when topped off then?


Anyway, is anybody suffering from this alarming pace of degradation?

And does anybody have ideas as to what I can do about this?

Thanks!
 

TexasEV

Well-Known Member
Jun 5, 2013
7,650
8,914
Austin, TX
It’s not abnormal degradation. Batteries have less capacity in the cold. Also the range displayed is the EPA rated range, not exactly how many miles your car will go. Battery capacity can’t be measured directly and the algorithms give an estimate. The estimate may be more or less accurate depending on your recent charging history.

Bottom line, don’t worry about it.
 
However, I started noticing after about 8 months or so that the most I could charge to was about 290, and by December of 2018 (which was the time for my first Tesla service) it was down to 287.

replace "was" to "will". :p

degradation is pretty bad for the first year. so it's actually normal that you lost 12 miles. and it's winter time, so the consumption will be about 20% higher.
 

MorrisonHiker

Well-Known Member
Moderator
Mar 8, 2015
10,481
10,423
Colorado
I think you listed both years incorrectly. Do you mean you got it in December 2016 and took it in for service in December 2017?

I took delivery of my S90D in December 2016. When I would charge to 100% in the winter, it would get 293 miles. In the summer, it was up to 295 miles. I charge it more often to 90% and in the winter, I still get the original 263 miles (but it quickly drops to 262). Last summer, I was still getting 265 miles.

There are several threads discussion degradation on the 90 battery but most of them are for earlier versions of the battery. How many miles have you put on your car? What is your Wh/mile over the lifetime of your car?
 
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sorka

Well-Known Member
Feb 28, 2015
8,601
6,447
Merced, CA
For most it's normal to see the biggest degradation in the first year. I didn't. My P85Ds rated range at new is 253 and after two years and 30K miles, it only dropped to 251. Then in the last year, mostly during the period my cooling system failed with a busted cooling louver that took 6 months for them to diagnose, my range dropped from 251 to 245 which is where it is now.

That said, the early 90 packs were known to have way worse degradation than what you're seeing do to the silicon the added to the anode to increase capacity. The 90s had the same cell count and weight as the 85s. The only way they increased the range was to add silicon.

In the hobby world, we pick lithium ion batteries based on application. When we want batteries that last for many charge cycles but don't need the maximum capacity, we pick batteries that have no silicon. The more silicon you add, the more charge each cell holds but the faster the degradation. The silicon allows the annode to suck up more ions which causes the anode to change in size. The larger the swelling, the faster the degradation.
 
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David99

Active Member
Supporting Member
Jan 31, 2014
4,875
7,225
Brea, Orange County
Degradation happens fast in the beginning of the life of a battery and then slows down. In the first 6-12 months you will see a 'dramatic' drop, then it will be less in the same amount of time/use. On the other hand the 90 battery pack is known to show more degradation than other battery packs. Keep in mind, many things contribute to degradation. I lost 9% in 4 years and 150k miles. A loaner car I had recently was the same age as mine (VIN was close) but only 30k miles. The degradation was only half of mine. Not charging to 100% is good advice, but it's not really as dramatic as people make it sound. The average temperature of where you live makes a good difference as well as how many times you Supercharge vs normal AC charging.

Here is the degradation data from hundreds of Teslas. You can see how the degradation drops fast at first and then slows down and seems to go linear.
degrad.GIF
 

techmaven

Active Member
Feb 27, 2013
3,618
9,768
Hello all,
I have a Model S 90D that was shipped to me in December of 2017.

At that point the range was sold to me and marketed as 296 miles and I would top off at either 296 or even 297 at times.
Per everyone's suggestions, I would rarely charge it to 100% as to preserve the longevity of the battery.

However, I started noticing after about 8 months or so that the most I could charge to was about 290, and by December of 2018 (which was the time for my first Tesla service) it was down to 287. So a total of 9 miles over one year was lost. It's gotten even worse as I charged it all the way up the last two times back in February and topping out at 284. So, 12 miles lost in a little over a year!

...

Anyway, is anybody suffering from this alarming pace of degradation?

And does anybody have ideas as to what I can do about this?

One of the first questions is whether or not your battery pack is balanced and if the range estimator is on track. The best way to find out is to drive it down to less than 20 miles of range, then charge it back up to 100% and let it top balance. Then repeat. And maybe do it another time. It usually isn't worth doing this just to get the electronics calibrated and the cell voltages balanced, but if this is really bothering you, maybe you can do the process once to put yourself at ease.

The degradation is going to be the highest in the first part of ownership.. then it pretty much levels off for quite a while. My 4+ year old 85 kWh pack now charges to full at 254 miles instead of 265... about 4% degradation. It has been 254 at full for about 2-3 years now.
 

croman

Well-Known Member
Nov 21, 2016
5,073
7,860
Chicago, IL
90 and 75kwh are prone to increased degradation and poor supercharger performance as compared to both the older 85/60kwh packs and particularly the new 100kwh packs.

There is a giant thread where wk057 lays it down. Sucks and Tesla doesn't even warranty against extreme degradation though usually extreme degradation is due to a module or cell failure.

So older owner experiences with degradation is not particularly useful for judging how much you might lose. Its worth searching for and finding the wk057 thread (sorry, hard to do on mobile or I'd link to it).
 

David99

Active Member
Supporting Member
Jan 31, 2014
4,875
7,225
Brea, Orange County
90 and 75kwh are prone to increased degradation and poor supercharger performance as compared to both the older 85/60kwh packs and particularly the new 100kwh packs.

We don't have long term data from the 100 packs so it's too early to say they are holding up better.

The 90 pack will limit the peak power at Supercharging after x amount of DC charging sessions, which the old 85 pack doesn't show. The 85 does suffer from poor Supercharging performance as well, though. The degradation is gradual so people don't notice it like the sudden cap in power on the 90 packs, but it's significant. Based on my data my old 85 now (4 years, 150k miles) takes 20-25% longer at the Supercharger to charge the same amount of energy compared to when it was new. The peak power rate is the same but it taper off faster. When you plug in you see the same peak power thus you think it's as fast as ever. Unfortunately it drops down earlier causing it to be slower overall. If I had the choice I'd actually prefer to have the peak limited 90 pack than the faster tapering 85 because in a real world situation, the capped 90 still tapers off much less giving it the edge over the 85.

In terms of pure range loss the 90 packs definitely seem to drop faster.
 
Thanks all for all of the information.
I feel kinda* a little better, and hopefully the degradation does slow down from here on out.

To answer some questions:
I did mess up on the years, it was built in December 2016, not 17!
I do a full charge, on average, once a month. Some months twice, but a lot of months never
I've not checked whether my battery pack is balanced but I did have them check on the degradation during my service inspection in December and that's when they told me after supposedly running tests and analytics on it that everything was fine.
I've put 21k on the car but not sure what lifetime wh/mi is
 

David99

Active Member
Supporting Member
Jan 31, 2014
4,875
7,225
Brea, Orange County
I've not checked whether my battery pack is balanced ...

Unless you have a CAN bus reader you can't check for that. Based on monitoring several Teslas over the last three years I can say with confidence that balancing is not an issue. Tesla's BMS is really good and keeps the pack well in balance all the time. I have never seen a situation where the differences between the cells would have been big enough to make any significant difference in range. Doing a full cycle does not balance the pack. It helps to recalibrate the algorithm that calculates the remaining capacity. Battery capacity can't be measured directly. Only a full cycle allows you to measure the energy that went in or out of the battery and that gives you an idea how much the battery can hold. When you use a car normally, the battery gets charged and discharged partially thus the capacity is calculated based on a mathematical model that can be off a little. That's why a full cycle can sometimes bring back some range. It has nothing to do with balancing
 

sorka

Well-Known Member
Feb 28, 2015
8,601
6,447
Merced, CA
Isn't the jury still out on supercharging vs normal charging? On a
We don't have long term data from the 100 packs so it's too early to say they are holding up better.

The 90 pack will limit the peak power at Supercharging after x amount of DC charging sessions, which the old 85 pack doesn't show. The 85 does suffer from poor Supercharging performance as well, though. The degradation is gradual so people don't notice it like the sudden cap in power on the 90 packs, but it's significant. Based on my data my old 85 now (4 years, 150k miles) takes 20-25% longer at the Supercharger to charge the same amount of energy compared to when it was new. The peak power rate is the same but it taper off faster. When you plug in you see the same peak power thus you think it's as fast as ever. Unfortunately it drops down earlier causing it to be slower overall. If I had the choice I'd actually prefer to have the peak limited 90 pack than the faster tapering 85 because in a real world situation, the capped 90 still tapers off much less giving it the edge over the 85.

In terms of pure range loss the 90 packs definitely seem to drop faster.

My 85 had a couling lover failure that doesn't show as an error on the console that caused it to drop off from 115KW down to 64KW pretty quickly resulting in about a 25% longer charging time.

Are you sure this isn't what happened to yours?
 

Bebop

Active Member
Jun 25, 2017
1,193
733
Midwest
was it ever 296-7? I remember hearing like 100% is 290. That has been my impression since I got my car. I get like 292-3 at 100%

I'm really curious as to how the new drive units affect range and efficiency. Since they were only released back in July it hasn't been a full year and probably not enough data.
 

David99

Active Member
Supporting Member
Jan 31, 2014
4,875
7,225
Brea, Orange County
Isn't the jury still out on supercharging vs normal charging? On a


My 85 had a couling lover failure that doesn't show as an error on the console that caused it to drop off from 115KW down to 64KW pretty quickly resulting in about a 25% longer charging time.

Are you sure this isn't what happened to yours?

For a while I (and many others) had the issue where the charge rate dropped to aprox 60 kW for no apparent reason. I definitely checked my louvers and they work fine. That issue has been going on for a while but recently it seems to be fixed. I believe it was a safety feature that was just set to be a little too aggressive and caused the charge rate to drop in situations where it would be safe/fine to charge normally.

Anyways, the slower charge rate I'm experiencing is not related to that at all. I have recorded and compared a lot of data from the time my car was new to now and it shows clearly that the taper is happening faster. Combined with the loss of capacity it adds up to 20-25% slower charging. I talked to Tesla's service center about it a few times but they say it's normal. That's what happens as the battery gets older.

I posted about it here 25% slower Supercharging due to degradation
 

AmpedRealtor

Well-Known Member
Jun 30, 2013
6,414
4,111
Phoenix, AZ
Hello all,
I have a Model S 90D that was shipped to me in December of 2017.

At that point the range was sold to me and marketed as 296 miles and I would top off at either 296 or even 297 at times.
Per everyone's suggestions, I would rarely charge it to 100% as to preserve the longevity of the battery.

However, I started noticing after about 8 months or so that the most I could charge to was about 290, and by December of 2018 (which was the time for my first Tesla service) it was down to 287. So a total of 9 miles over one year was lost. It's gotten even worse as I charged it all the way up the last two times back in February and topping out at 284. So, 12 miles lost in a little over a year!

At service I brought that issue up and I received quite possibly the most unsatisfactory responses ever: "well, Tesla may have just changed the algorithm to more closely reflect what it should be getting," and "well, it's rare for the vehicle, or any vehicle, to get exactly what it was suggesting anyway so losing a few miles off the top doesn't really affect anything. Like for example, when it's cold you lose miles anyway."

The problem with those rationales is that for the first I really feel like that would be considered false advertising then. What's stopping Tesla in that scenario from saying due to a "new algorithm" your vehicle that you just spent a small fortune on is going to drive 50, or 60, or 100 miles fewer than what you originally thought. And for the second, it does make a huge difference on certain trips as sometimes those extra 10 or 12 miles means one fewer stop, or giving you just a little bit of extra comfort knowing you'll be making home when it starts getting low. And yes, I know I already lose miles when it's colder, why in the world would I want to start off with fewer miles when topped off then?


Anyway, is anybody suffering from this alarming pace of degradation?

And does anybody have ideas as to what I can do about this?

Thanks!
Sorry to hear that. I've read here that the 90 kWh battery has some charging and degradation issues. My 2013 P85 has lost 17 miles of range in 5 years.
 

Bebop

Active Member
Jun 25, 2017
1,193
733
Midwest
I also heard supercharging helps a lot actually, in fact the irony is the more you supercharge the slower the degradation. Someone posted a photo with data and I wish i can find it so I can post it here.

As an example, someone who supercharges at least once a week vs someone who does once a month suffers slower degradation over time if I can remember correctly.
 

Viking1

Member
Oct 24, 2016
255
104
CA
Not unusually for a 90 (85s are better due to different cell chemistry). One suggestion is to not let the SOC drop too low. I try to keep mine > 30% when possible. That has stopped my rapid degradation.

I also have a Dec. 2016 S90D. 13k miles. I usually charge to 90%. That is 256 at 90%. That equals around 285 for a 100% charge.
 
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