Battery Degradation: Tale of Two Teslas

[BizJet]

I've been tracking battery range degradation religiouslyon my two Teslas -- a four-year-old Model X and a two-year-old Model 3, and differences in battery performance versus the fleet average are truly remarkable.

My Model X 90D, delivered in June, 2016, started at 264 miles of range, but is now down to 227 miles -- a degradation of 14% over 82,671 miles. Tracking this against the fleet average on TeslaFi, you can see that this car has always run well below the fleet average, despite the fact that I've always "babied" the battery -- rarely charging to 100%, minimal supercharging, etc. In the chart below, my Model X is the blue line, and the fleet average is the green line:

Compare that disappointing performance on my Model X to the experience on my Model 3, which, except for two brief periods (roughly corresponding to winter, interestingly) has been consistently well above the fleet average. After 33,200 miles, my Model 3's battery has only degraded by 3% -- well above the fleet average. Again, very similar careful battery management. My Model 3 is the blue line, and the fleet average is the green line:

The differences are quite remarkable, especially since the things I would most often associate with variations in battery degradation -- climate, driving patterns, and charging management -- were quite similar between the two vehicles.

With my new Model Y due to arrive in a few weeks (replacing the Model X), I can't help but wonder whether I'll be lucky like I was with my Model 3, or unlucky as I have been with the Model X.

 

[manttium]

Interesting post, thanks!

I don’t normally use TeslaFi - I assume “the fleet” limited to 90D model X’s? These are known to have poor battery degradation, but if it’s an apples to apples comparison, then indeed it looks like your X has it worse than average.

Curiously, I am in nearly the exact same situation. I have a Model X 100D that has 14% degradation over 80k miles, and a P3D with 2% degradation over 10k miles.

One thing to note: when I did use TeslaFi for my free trial, I found that “the fleet” at my mileage was one other vehicle. So not very statistically significant ;-) it did show, however, that my X was well below “the fleet”.

 

[BizJet]

Thanks for that reply, @manttium. Yes, it is definitely apples-to-apples -- at least in the first 2/3 of the chart. At least until 50,000 miles, the fleet benchmark is 13 other vehicles; by 70,000 miles there were just 3 other vehicles, and the flat line after 80,000 miles suggests that I'm the only X90D on TeslaFi that has logged that many miles. Nonetheless, the consistency of the deficiency in the earlier parts of the curve suggest something wrong here. Maybe a couple of dead cells? What else would cause this consistent deficit?

 

[P85_DA]

I have a 2018 X P100D with over 350 supercharging sessions in 77k miles early on I would say I “babied” the battery but now I don’t worry to much about that ...my TeslaFi stats show ~9% degradation and compared to fleet average im about 1mile range below ..what had happened was now my max supercharge speed is capped at 108kw ..the taper is the same once it reaches 50% ..

 

[mpkelly20]

Why did you supercharge speed get capped? You can never go above 108kW not even for a few mins?

Any rhyme or reason to who gets capped and why?

 

[P85_DA]

Why did you supercharge speed get capped? You can never go above 108kW not even for a few mins?

Any rhyme or reason to who gets capped and why?

the Tesla. BMS will Cap it ..not sure what formula is but I drive heavily and supercharge a lot ..I have a 100battery probably the best one with the 186xx cells before the new 3/Y 2170 cell batteries came out ....when I started charging at V3 SCs the max speed never held that long maybe few min ...not a time saver for me more of a marketing thing lol

 

[HostileHarry]

@BizJet

It's crazy how we both have complete opposite versions of the same story! I have a 2016 Model X 90D and I'm at 6% degradation as 50,000 miles. My 2018 Tesla Model 3 is at 13% degradation at 30,000 miles.... hah!

Wild.

 

[ElectricIAC]

Hoping our BTX5 (XSR Raven) car doesn’t degrade like this.

Showing around 3% degradation on my P3D since around 7K when I picked It up. Now at 31K.

 

[100XSCD]

I've been tracking battery range degradation religiouslyon my two Teslas -- a four-year-old Model X and a two-year-old Model 3, and differences in battery performance versus the fleet average are truly remarkable.

My Model X 90D, delivered in June, 2016, started at 264 miles of range, but is now down to 227 miles -- a degradation of 14% over 82,671 miles. Tracking this against the fleet average on TeslaFi, you can see that this car has always run well below the fleet average, despite the fact that I've always "babied" the battery -- rarely charging to 100%, minimal supercharging, etc. In the chart below, my Model X is the blue line, and the fleet average is the green line:

Compare that disappointing performance on my Model X to the experience on my Model 3, which, except for two brief periods (roughly corresponding to winter, interestingly) has been consistently well above the fleet average. After 33,200 miles, my Model 3's battery has only degraded by 3% -- well above the fleet average. Again, very similar careful battery management. My Model 3 is the blue line, and the fleet average is the green line:

I've been tracking battery range degradation religiouslyon my two Teslas -- a four-year-old Model X and a two-year-old Model 3, and differences in battery performance versus the fleet average are truly remarkable.

My Model X 90D, delivered in June, 2016, started at 264 miles of range, but is now down to 227 miles -- a degradation of 14% over 82,671 miles. Tracking this against the fleet average on TeslaFi, you can see that this car has always run well below the fleet average, despite the fact that I've always "babied" the battery -- rarely charging to 100%, minimal supercharging, etc. In the chart below, my Model X is the blue line, and the fleet average is the green line:

Compare that disappointing performance on my Model X to the experience on my Model 3, which, except for two brief periods (roughly corresponding to winter, interestingly) has been consistently well above the fleet average. After 33,200 miles, my Model 3's battery has only degraded by 3% -- well above the fleet average. Again, very similar careful battery management. My Model 3 is the blue line, and the fleet average is the green line:

The differences are quite remarkable, especially since the things I would most often associate with variations in battery degradation -- climate, driving patterns, and charging management -- were quite similar between the two vehicles.

With my new Model Y due to arrive in a few weeks (replacing the Model X), I can't help but wonder whether I'll be lucky like I was with my Model 3, or unlucky as I have been with the Model X.

The differences are quite remarkable, especially since the things I would most often associate with variations in battery degradation -- climate, driving patterns, and charging management -- were quite similar between the two vehicles.

With my new Model Y due to arrive in a few weeks (replacing the Model X), I can't help but wonder whether I'll be lucky like I was with my Model 3, or unlucky as I have been with the Model X.

Correct me if I am wrong, but the reason for Tesla selling 90kWh battery cars was so that they could unload the 100kWh batteries that failed to make the grade and so avoid the expense of scrapping them. This marketing policy would indicate that the quality of Tesla batteries is erratic and the failure rate high. So, it’s no surprise that there are wide discrepancies in battery performance, and that cells may continue to burn out or not perform or whatever at a high rate in a ‘bad’ pack.

One other explanation comes to mind and that is the charging software in your car is faulty or was badly set from the beginning and is simply not allowing the pack up to charge fully.

 

[Battpower]

I've been tracking battery range degradation

I am not at all sure that we fully understand what third party tools are showing us.

I copied this from another thread discussing 'degradation'. The title of the chart clearly refers to 'degradation' but if that is what it is really showing, then this lucky owner has managed to reverse degradation!

Not intending to be picky over symantics, but I'm not sure 'range' can 'degrade' but it can reduce or deminish. 'Condition' can degrade. (in contrast, weather can degrade but not really reduce or deminish. You can have degraded weather but voltage, range, temperature etc are just a measurement).

So what is the above graph showing? In this case, since it relates to a single car, while there could be some degradation contributing to the downward trend in range, by the end of the period shown there is virtually no change in the range value. I would suggest that this is showing a recalibration of some sort, or a change in the way the car is reading sensors or possible the effect of some external factor like a change in charging process or temperature.

My point is that we have to be careful how we interpret data that we don't fully understand, especially when it is presented in graph with a title that could mislead us.

 

[Battpower]

Just for comparison, here is a SMT graph from my MS LR showing various Range related info.

For some time, range showed steady around 350 miles. Then after a software update, range stepped up to around 370 ish. Recently, it has started dropping quite considerably. All with no obvious explanation. Certainly within other SMT logged data there is nothing obvious that correlates directly.

The next two are from the same graph, just to give exact figures for the recent max and min.

So on the face of it, over 10 days I 'lost' 10 miles of range, which might seem significant. Clearly some thing must be different giving rise to the data shown in the graph, but in reality, it is just as reasonable (given the remainder of the graph) to conclude that real battery condition and real range are not actually being represented here at all, and it is purely output from estimation algorithms that are chan ging for reasons we can't be sure of - including the possibility of Tesla changing the algorithm.

 

[Rocky_H]

Correct me if I am wrong, but the reason for Tesla selling 90kWh battery cars was so that they could unload the 100kWh batteries that failed to make the grade and so avoid the expense of scrapping them.

I'm pretty sure with this being a 4 year old Model X that this is actually a 90 kWh battery, not a downgraded 100. The 100 packs were actually redesigned internally with some of the cells oriented differently, and the cooling pipes arranged in a different way. Here's a breakdown of that with pictures of the new internal structure that the 100 packs were made with:
Pics/Info: Inside the Tesla 100 kWh Battery Pack

 

[forkee]

Let me know when you reach 219