Used 2019 Model 3 Standard Range Plus - Does it need a new battery?

[whiteskulleton]

I'm looking to buy a used Tesla. I went to a dealership and sat in a car and took a picture of the Energy screen. Am I correct to assume that it's battery is not good?
2019 Model 3 Standard Range Plus
Odometer: 47,651
209 Wh/Mi for 30 miles average range
183 miles projected
SOC: 88%

That would gives us 209*183/.88=43.5 kWh @ 100% charge
The original battery capacity is 54.5kWh, correct? That would then be 43.5 kWh / 54.5 kWh = 79.7% capacity, correct? This battery is not looking good, correct? Did I use the wrong capacity number? Did I do the math wrong? Could it be that the car was sitting at the dealership and not moving so that had an impact on it's battery degradation?

 

[AlanSubie4Life]

In order to use a supercharger, don't you have to use the Tesla app and have a car on the Tesla app?

You do but you should make sure you have the car in the Tesla app.

 

[whiteskulleton]

You do but you should make sure you have the car in the Tesla app.

And I hear it takes at least a day for it to be on the Tesla app. I need to drive out of state with a friend and then I would like to drive it back. It won't make the journey without a supercharge so I need a way to charge it on the way back.

 

[father_of_6]

And I hear it takes at least a day for it to be on the Tesla app.

Hmm... shouldn't be. I drove 7 hours to pick mine up, drove back right away and Supercharged 3 times.

 

[father_of_6]

So it's likely that the battery won't degrade any more? Usually with batteries in things like computers and stuff, it will keep degrading until it has difficulty holding a charge and will just suddenly shut off at 20%. Is it wrong to assume that with a Tesla battery?

I don't mean to imply that it won't degrade any more... but they say it's non-linear - you might lose more the first year than years 2 and 3 combined.

I believe the batteries in Tesla's current cars are much better than their earlier cars, but they still haven't been around for decades.

What I meant was... if the battery continues to degrade slowly, you'll still get a good 10-15 years out of it (assuming no other issues). The bigger concern would be that the battery entirely dies out of the blue in a year and you're out of warranty. Currently a replacement remanufactured battery for the Model 3 is like $13k.

It's worth doing the math on a new Model 3, since there's a full $7,500 credit plus likely lower interest rate.

 

[ucmndd]

Worst is 80% which is actually worse than 100%.

where to you guys come up with this stuff

 

[whiteskulleton]

you might lose more the first year than years 2 and 3 combined.

Exactly, it's been 3-4 years already and at 105k miles the battery is very good and better than that of the other 2. It's right in line with expectations so I would assume that it should hold to 300k miles. Replacing the suspension, drive train, and electronics seems like the biggest issue. I just watched a video on someone replacing the suspension and it looks like it will be easier than trying to my 2006 rusted Ford Taurus which I attempted but had issues due to rust weld of the ball joints. I am worried about that stuff failing.

 

[johnny_cakes]

I recently bought a used 2019 Model 3 SR+. This is what the energy screen showed when I went to see the vehicle on January 23. The SoC was 97% and mileage was 70,343 km.

144 Wh/km * 313km / 0.97 SoC = 46.5 kWh

Based on @AlanSubie4Life's original 52.5 kWh capacity, the degradation is 11.5%. I haven't measured it using the Energy screen since, but based on the Tessie App, my degradation (now at 72,594 km) is 10.7% (assuming original 51.6 kWh capacity, which Tessie seems to think is the norm for my configuration). Also according to Tessie, the battery capacity is just slightly below the fleet average. I'm not sure which fleet they're referring to, but I assume it's a group of 2019 M3 SR+ Tessie users. Screenshot from Tessie:

As a side note, I don't know how the previous owner achieved 144 Wh/km, as I've never gotten anywhere near that and I'm driving around the same town that they did.

 

[AAKEE]

So it's likely that the battery won't degrade any more? Usually with batteries in things like computers and stuff, it will keep degrading until it has difficulty holding a charge and will just suddenly shut off at 20%. Is it wrong to assume that with a Tesla battery?

I will try to make an answer that covers a few things:

I’m from Europe and googled the North Carolina climate. It seems quite warm (?)

A large portion of the degradation comes from calendar aging. Calendar aging increases with:
-High temperature.
-High SOC.

With the car outside in the sun the battery will be warmer than the ambient, perhaps 5C or 10F. Charging also increases the cell temp, as well as driving it.
A car that was parked outside might have a average temp that’s 5-10C above the ambient.

We can calculate a calendar aging/degradation on the battery.
In the central North Carolina the annual average is 19C, so just for making an example we can use 30C as the annual average cell temp.
At 80-90% SOC the calendar aging for 10 months will be about 6.5% which will be about 7% for the first year ( square root (12/10) x 6.5).

Calendar aging reduces with the square root of time so this will be the total calendar aging (rounded numbers):
After one year 7%
After two years 10%
After three years 12%
After four years 14%
After five years 15.5%
After six years 17%
After seven years 18.5%
After eight years 20%
After 16 years 28%

To the numbers above we need to add the cyclic aging which is much less. The standard range will have bigger average dept of discharge than a Long range that cause more cyclic sging but still we could set it to approximately 1% each year.

So this answers the question if the battery will continue to degrade; yes it will but at progressively smaller rate.

Also, in all lithium battery research the degradation is very foreseeable and follows the known degradation rates. This is even for single cells and the variation of degradation between single cells is some 1% or so.
A big pack with a lot of cells will follow the known rates.

“The battery lottery” is not really existing when it comes to degradation. For some part maybe one car may start slightly below another, but mostly it will be a BMS estimating error that we see.

You will not find a three-four year old SR+ ifrom north carolina with a true degradation of only 5%. There might be one with the BMS fairly off stating that but a real degradation test would show up closer to the numbers above.

 

[AAKEE]

where to you guys come up with this stuff

Research with actual tests of a lot of lithium batteries of the same make and chemistry.
Actually a lot of different resesrch reports, there is not a single report supporting the idea of that 100% is very bad.

The [must drive asap at 100%] is a myth.
(This does not mean that I leave my car st 100% for extended times, but I do not leave it above 55% for extended times either)

At lower cell temperatures (about 30C or below) in some cases we see the highest degradation at around 80% SOC. In many other the degradation is the same between 75-100%.
At really high ambient, in most cases it is worse the higher the SOC is.

Below two charts of calendar aging for panasonic NCA :

This is from a recent report of a 21700 NCA, brand/manufacturer “not disclosed” but we know there is only a very few manufacturers of 2170 NCA.

 

[Candleflame]

thanks i was sweating i had to look up the papers. Tbh these are not just lab studies.
This has been a TMC mistery for years - there was an old survey here where people would put their SOC% (back then it had to be done via a timer as the model s just had day charge 92% and tripcharge 100%) and their degradation in. And by far the least amount of degradation was in people who charged to 92% every day with 80% bizarrely having the most.

 

[father_of_6]

And by far the least amount of degradation was in people who charged to 92% every day with 80% bizarrely having the most.

But that's a BMS issue then, right?

 

[AAKEE]

But that's a BMS issue then, right?

Not for sure.

The BMS tries constantly to estimate the correct capacity, but it is not fault free or does not always estimate correct.

I had the BMS estimate the capacity as 81.4 kWh, in one month down to 75.7 kWh as the bottom estimate. A 100-0% drive during this time did show the capacity as 79 kWh, (75.2 kWh used, and 3.8 kWh still in the battery).

Even if the BMS can be off I would guess that if we have several cars showing us something it is probably not the BMS:es that is off.

 

[father_of_6]

The idea that there's this "magic 80% number" that causes faster degradation seems very counterintuitive to me... so I tend to think that this is more of an issue with the BMS never seeing the battery at > 80%, which causes it to underestimate due to lack of data.

It just seems like if degradation is associated with a given state of charge, it would be at one end or the other (high SoC or low), not at some seemingly arbitrary point in the middle.

That said, it's chemistry so perhaps there are some other factors at play that could cause 80% to be worse than 92%... I'm no chemist.

 

[ucmndd]

Research with actual tests of a lot of lithium batteries of the same make and chemistry.
Actually a lot of different resesrch reports, there is not a single report supporting the idea of that 100% is very bad.

I am generally a fan of your myth busting and bringing data to the table in response to the increasingly ridiculous forum lore and mental gymnastics about battery care. I applaud your efforts.

However, I suggest that extrapolating results from a single study and turning them into definitive context-lacking statements such as “worst is 80% which is actually worse than 100%” risks simply substituting one myth for another.

 

[AAKEE]

The idea that there's this "magic 80% number" that causes faster degradation seems very counterintuitive to me... so I tend to think that this is more of an issue with the BMS never seeing the battery at > 80%, which causes it to underestimate due to lack of data.

In plain text, the degradation is about the same from 75-100%. Thats the simple way to see it. In some cases 100% causes less degradation than 80%. This is not seen in all research but in at least 50% of the research, and at normal ambient temperature or slightly higher.

The reason is deemed in some research at that the creep current counteracts degradation (lithium plating and SEI build up).
Lithum batteries have much higher self discharge above 80%, so all togheter the theories might be true.

Anyway, there is very many research where hundreds of cells in each research was tested and the degradation messured.
100% is about the same as 80%, or worse.
There is not a single report showing that 100% is very bad at normal temperatures.
None.

By research we know how batteries degrade.

It just seems like if degradation is associated with a given state of charge, it would be at one end or the other (high SoC or low), not at some seemingly arbitrary point in the middle.

The large step at about 58% for NCA chemistry is verified over and over and over again.
The reason for that step is that the central graphite peak (this is over the relevant level of knowledge for the average TMC-forum member).
ShieldSquare Captcha

 

[AAKEE]

I am generally a fan of your myth busting and bringing data to the table in response to the increasingly ridiculous forum lore and mental gymnastics about battery care. I applaud your efforts.

However, I suggest that extrapolating results from a single study and turning them into definitive context-lacking statements such as “worst is 80% which is actually worse than 100%” risks simply substituting one myth for another.

If you did read my post you should know that it was not a case of extrapolating a single study. All my statements are the sum of > hundred reports thourughly read, and even questioned.

You sited me for your answer with this:

I do not really see how you can read that I try to sell the idea that 80% is much worse than 100%.

Heres the rest of the text I wrote, that followed what you cited me:

At lower cell temperatures (about 30C or below) in some cases we see the highest degradation at around 80% SOC. In many other the degradation is the same between 75-100%.
At really high ambient, in most cases it is worse the higher the SOC is.

I did feel that I had to answer this, but at the same time we are dragging away from on topic with the risk that the OP misses the point of hus question?

[Edit]I forgot to write that I would appreciate feedback If anyone find that I am starting to create new myths, as per the subject of @ucmndd’s post. In this case I could really see this happening, but I appreciate the feedback. We need no more battery myths

 

[AlanSubie4Life]

Usually with batteries in things like computers and stuff, it will keep degrading until it has difficulty holding a charge and will just suddenly shut off at 20%. Is it wrong to assume that with a Tesla battery?

It’s not clear at all to me what happens with the pouch cells in electronics. You are right that they can become very unreliable in cold temperatures as they age, and it is not just a BMS thing as far as I can tell (happens even after cycling the battery a few times).

Anyway the Tesla batteries seem different and seem to degrade more predictably and don’t have the rapid cliff dropoff at 20% that is often seen in consumer electronics. BMS is also quite good of course.

Lots of issues with those pouch cells it seems. E.g. One of my MacBooks swelled up (would not sit flat on a table anymore!) and I had to swap the original battery, which was blown up like a balloon. Extremely common.

Hopefully this does not happen with EVs (do any use similar cells?). Would be bad for ground clearance!

on topic with the risk that the OP misses the point of hus question?

Fortunately questions have been answered I think.

 

[AAKEE]

It’s not clear at all to me what happens with the pouch cells in electronics. You are right that they can become very unreliable in cold temperatures as they age, and it is not just a BMS thing as far as I can tell (happens even after cycling the battery a few times).

Anyway the Tesla batteries seem different and seem to degrade more predictably and don’t have the rapid cliff dropoff at 20% that is often seen in consumer electronics. BMS is also quite good of course.

All lithium batteries at least of the main chemistries degrades very predictable If you ask me.

The 20% degradation limit thing is a branch standard, as the predictability is reduced below 80% capacity.
The branch use 80% as the standard, partly because of this and for some part that if a battery is used in a system and has lost too much of the capacity, the low capacity might start to cause issues like needing charge too early.

Tesla has set the warranty threshold at 30% degradation. For one part the regular charging power (C) is lower than the standard charge used in the 80% branch standard and also the (C-)load during cycles is lower.
If we look at low load cycles it is very common for lithium batteries to continue to be somewhat predictable below 80% capacity.

I would say that the 70% warranty limit (30% degradation) is ok, as the batteries might function quite well below 80%, but as 70% is reached we could say that the battery has passed the practicle life limit threshold.

Below, cycles 100-0%, 90*-0% and 80* to 0%, looking at the lower C cycles like 0.7A and 0.5 is more like EV cycles for the load but still very large cycles. We can see that the wear per cycled reduces slightly and these will not drop off quickly at 80% capacity.
Using smaller cycles at lower SOC increase the bend towards lower degradation per cycle, Which we see in the next picture.

*) Not exactly, but for easy reference as most people can not estimate the SOC from cell voltage by heart.
4.1V is about 90%
4.0V is about 80%.

 

[ucmndd]

I do not really see how you can read that I try to sell the idea that 80% is much worse than 100%.

I am actually not trying to attribute any particular statement to you at all. My initial response in this thread was to Candleflame, who stated definitively, and without context, that “worst is 80% which is actually worse than 100%”. This is the stuff that leads to more forum lore, not less, and as you pointed out paints a different picture to the casual reader than what the data is likely telling us - that “the degradation is about the same from 75-100%”.

 

[AAKEE]

I am actually not trying to attribute any particular statement to you at all. My initial response in this thread was to Candleflame, who stated definitively, and without context, that “worst is 80% which is actually worse than 100%”. This is the stuff that leads to more forum lore, not less, and as you pointed out paints a different picture to the casual reader than what the data is likely telling us - that “the degradation is about the same from 75-100%”.

Yes, if we should remember anything from this is is that degradation isa about the same from 75 to 100%.

The differences is in most part small anyway and there is no large win in calendar aging before we go below the step that is located at about 58% for NCA.

If going into details, we actually see that in many cases 80% is worse than 100%, but this is not a very big difference.

I would say though, that if there is a lot of cars that had more degradation (according to the BMS) charged to 80% then a lot of cars charged to 90% or more we should not dismiss this as a BMS error without further investigation.

One year ago I bought two batches of Panasonic NCA cells (25+10cells)
These have been cycled to find the capacity and then stored. After some long time I have cycled them again a couple of times and checked the capacity, charge them to the same SOC and stored them again. I just performed the 1 year check with the foirst batch.
I have no interrest in extreme temperatures so it is about 25C And about 10-15C. A few is placed in a warmer place that is about 30C.

I can more or less confirm this picture. For me, 100% causes less degradation than 80% In both batches.
I might be back with more data later on.
(The cells with 20% and less actually gained capacity in my case, delivered with 30% SOC and stored below increased the capacity after 3-7 months with 1-2%).