If you fast charge, Tesla will permanently throttle charging

[MikeBur]

You guys are lucky to be at SC's that allow you to see the degradation and slowdowns. We took 6 trips requiring Superchargers in our 85D, now sold, and every stop said "Approximately 20 Minutes", as an example, and we were there at least 40 minutes or double the time estimated because of slow Superchargers. We never got anywhere close to the rates of charge you guys are seeing even with battery degradation.

What was the response from Tesla, presuming you reported these?

 

[ohmman]

Some people took that number as fact, sort of seemed to me including you, and ran with it. It is my view that we know far too little about that number to tout it as a fact. (Indeed, from Denmark we already heard of 7 minute delays as a practical example.)

Since you're a self proclaimed "truth seeker," let's see if you can focus on this one item. We have a single semi-scientific test done on a 90kW limited pack vs. a 120kW capable pack. The test was done by @Owner and they did their best to control for the multitude of variables that impact charge rate. They recorded a 5 minute difference, with the 90kW limited pack tapering on a standard curve. If the new limit doesn't affect the tapering curve (that is, its flat and then lines up with the unlimited curve), it should be significantly shorter.

Observational anecdotes of longer or shorter times are not very useful due to the myriad of variables that can affect charge rate. Also, user perception appears to skew to the negative. For instance, OP quoted a ten minute longer charge time on a similar route, but analysis showed 3.5 minutes. This isn't surprising to anyone who has asked a person who was stuck in traffic about the length of their delay. The answer is quite often longer than the actual time. I've certainly been guilty of this bias in estimating.

What makes you think it should be longer? Is it possible it's even shorter? You don't seem to entertain both sides - that is what a truth seeker does. A drama seeker, on the other hand...

 

[NerdUno]

Being the suspicious fellow that I am, my takeaway from this is that folks with older Teslas haven't experienced the problem because they had cars with a very different battery chemistry. And NONE of those cars ever got throttled and probably never will. What changed? Tesla apparently came up with a new battery magic potion (probably cheaper) and guess what? They immediately started seeing battery degradation and had to do something about it or risk having to replace thousands of Tesla batteries before the warranties expired. None of this, of course, was revealed until one or two customers happened to mention it when taking their Teslas in for service. So then we all get treated to 40+ pages of denials and personal attacks before Tesla finally admits an itty-bitty part of the full story. Doesn't exactly inspire confidence moving forward, does it?

 

[TexasEV]

Well at the end of the day the implications go a bit farther than people thinking it's nbd or not. People buying a used Tesla are going to worry now. "Is my supercharging going to work well on this used car? Who knows what kind of charging they've done. " that means resale value drops. People buying CPOs like me who weren't told about this anywhere will feel cheated.

There are so many variables controlling how long it takes to supercharge, that a 5 minute difference over a 40 minute charging session under certain circumstances (arriving to unpaired stall with low state of charge) is almost meaningless for most people. No, you weren't cheated. You are buying a car with a battery management system that controls charging rate to protect the battery. That's what's important, that you get the range you think you're getting when you buy a specific battery size. Even if a car's charging rate never tops 90kW, that's a far cry from supercharging "not working well". That's the peak rate on my 60, for example, and I think supercharging works just fine.

Or you could just buy a different EV that guarantees it will always start charging above 90kW while protecting the battery from degradation. Oh, wait...

 

[AnxietyRanger]

You don't seem to entertain both sides - that is what a truth seeker does. A drama seeker, on the other hand...

I do entertain both sides. There is just overwhelming response on one side of my commentary making it seem otherwise. Even you just pick points of contention from my responses, instead of responding to the bigger picture or the multiple acknowledgements and disclaimers I continue to put an effort into.

For example, I keep bringing up the counter-examples on 85 kWh batteries all the time. I am not seeking drama where none exist, but I also don't shy away from where it does for the sake of any mission or adoption or company. So far there seems to be some suggestion of drama around the 90 kWh pack - the rest even I am willing to consider less important outliers at this point (subject to change if more data appears).

We have a single semi-scientific test done on a 90kW limited pack vs. a 120kW capable pack. The test was done by @Owner and they did their best to control for the multitude of variables that impact charge rate. They recorded a 5 minute difference, with the 90kW limited pack tapering on a standard curve.

Yes.

Observational anecdotes of longer or shorter times are not very useful due to the myriad of variables that can affect charge rate. Also, user perception appears to skew to the negative. For instance, OP quoted a ten minute longer charge time on a similar route, but analysis showed 3.5 minutes.

Agreed.

This isn't surprising to anyone who has asked a person who was stuck in traffic about the length of their delay. The answer is quite often longer than the actual time. I've certainly been guilty of this bias in estimating.

No doubt.

What makes you think it should be longer? Is it possible it's even shorter?

It is not necessarily longer. I do find it unlikely the effect is significantly shorter than ~5 minutes, because that is also confirmed by Tesla and I see no motivation for them to claim a longer time that has been happening and also because every data point so far, including the rough practical esimates hover +/- 2 minutes around the 5 minute mark. I think I used the range of 3-7 minutes in one of my recent posts in this thread.

The point I was making about it getting longer, though, was that we do not seem to know enough to exclude the possibility of another peak-rate adjustment downwards as the DC charging counts go up. It is quite possible - perhaps even probable - no such thing ever happens, but we would need to find out a lot more to know with more surity.

For the sake of completeness, it is also possible the peak rate is adjusted upwards in the future. How probable that might be, I have no idea.

 

[ODE90D]

I agree it would be nice for Tesla to be more transparent. But considering my wife and I have over 150,000 miles on Tesla vehicles and have used SCs with most of them, and have experienced no throttling, I have no anxiety over this.

I see you have a S70D and a X90D. How many miles in your X ?

 

[tomas]

There are many reasons that could happen. Most likely you plugged into a Supercharger stall that was shared with another car. Each Supercharger unit has two stalls, and if you're the second one to plug in you will get lower current until the first one ramps down.

Tip: if a car is plugged into 1A, avoid plugging into 1B and use a different unpaired stall if you can.

Thanks @Doug_G, for putting aside all the clamor and giving some facts to a new owner who could easily be misled by all this noise.

This demonstrates a problem that Tesla has to deal with as the pioneer of long range BEVs. They want to sell cars powered by batteries, but they don't want to make it all about batteries or make batteries sound complex and confusing. According to some members here, threads like this do a great "service" of "holding Tesla's feet to the fire" etc. regarding transparency. But they also present new owners and owners who just want the car to work with a bunch of confusing and conflicting information, and drum up unnecessary anxiety. If Tesla published the code to their BMS, it might make <1% of owners very happy, but do you think for a minute that would reduce the debate and FUD generated on this forum? I don't. It would increase it.

 

[AnxietyRanger]

But they also present new owners and owners who just want the car to work with a bunch of confusing and conflicting information, and drum up unnecessary anxiety.

Who decides what anxiety is unnecessary and what is necessary?

 

[JRP3]

Tesla apparently came up with a new battery magic potion (probably cheaper)

More energy dense as well, hence the change from 85 to 90kWh.

 

[tomas]

Who decides what anxiety is unnecessary and what is necessary?

Why the Anxiety Ranger!!! Who else?!?!?!

 

[JRP3]

Who decides what anxiety is unnecessary and what is necessary?

Obviously an Anxiety Ranger

Tomas beat me to it

 

[AnxietyRanger]

OK, good we got an answer. I'm cool with that.

 

[ohmman]

I do entertain both sides. There is just overwhelming response on one side of my commentary making it seem otherwise. Even you just pick points of contention from my responses, instead of responding to the bigger picture or the multiple acknowledgements and disclaimers I continue to put an effort into.

For example, I keep bringing up the counter-examples on 85 kWh batteries all the time. I am not seeking drama where none exist, but I also don't shy away from where it does for the sake of any mission or adoption or company. So far there seems to be some suggestion of drama around the 90 kWh pack - the rest even I am willing to consider less important outliers at this point (subject to change if more data appears).



Yes.



Agreed.



No doubt.



It is not necessarily longer. I do find it unlikely the effect is significantly shorter than ~5 minutes, because that is also confirmed by Tesla and I see no motivation for them to claim a longer time that has been happening and also because every data point so far, including the rough practical esimates hover +/- 2 minutes around the 5 minute mark. I think I used the range of 3-7 minutes in one of my recent posts in this thread.

The point I was making about it getting longer, though, was that we do not seem to know enough to exclude the possibility of another peak-rate adjustment downwards as the DC charging counts go up. It is quite possible - perhaps even probable - no such thing ever happens, but we would need to find out a lot more to know with more surity.

For the sake of completeness, it is also possible the peak rate is adjusted upwards in the future. How probable that might be, I have no idea.

So we agree that 5 minutes is an appropriate number for the current ground truth, yes? You said we know "far too little to tout it as fact." I would argue that it's an appropriate number to reference that is corroborated both theoretically and with actual timed observations. Whether it's possible that the future holds changes only muddies the water here. What we're discussing currently is a change that will cause a difference of 5 minutes at most (since higher states of charge will compare more favorably to uncapped vehicles) in conditions that are ideal - not hot, not cold, not paired.

I still want to hear exactly how this is triggered and what Tesla found was happening to the battery. I'd like to know which packs are affected, if only specific ones are. I also would like to know more about the tapering curve on limited vehicles, and how they plan to account for this on CPOs or open market used vehicles. However, context is incredibly important. And the context is a 5 minute max number in ideal conditions, until we see evidence to the contrary.

 

[sorka]

More energy dense as well, hence the change from 85 to 90kWh.

That's what the Silicon does. It allows the anode to absorb more lithium ions but the side effect is the anode grows and shrinks a lot more over the SOC range causing much faster anode fracturing.

 

[JRP3]

That's what the Silicon does. It allows the anode to absorb more lithium ions but the side effect is the anode grows and shrinks a lot more over the SOC range causing much faster anode fracturing.

Well yes, but one would presume they figured out how to mitigate that effect before using the material in production cells for EV's.

 

[AnxietyRanger]

So we agree that 5 minutes is an appropriate number for the current ground truth, yes?

Yes. For 90 kWh packs. For other packs we lack data perhaps to say even that.

You said we know "far too little to tout it as fact." I would argue that it's an appropriate number to reference that is corroborated both theoretically and with actual timed observations. Whether it's possible that the future holds changes only muddies the water here. What we're discussing currently is a change that will cause a difference of 5 minutes at most (since higher states of charge will compare more favorably to uncapped vehicles) in conditions that are ideal - not hot, not cold, not paired.

There are two different issues here, though. What is the reality of today and what is the overall impact of frequent DC charging for someone considering what action to take. The latter is where I am not ready to jump to the conclusion that 5 minutes is the end of that story.

The thing is, if we accept 5 minutes as the final truth, we can say to someone: this will affect you by 5 minutes tops, don't worry about it, DC charge as much as you like, buy a CHAdeMO home etc. But I am not confident we can say that to a person yet. Are you?

I am confident in saying the number we know today is ~5 minutes. Sure. We don't know for sure if it ends there.

I still want to hear exactly how this is triggered and what Tesla found was happening to the battery. I'd like to know which packs are affected, if only specific ones are. I also would like to know more about the tapering curve on limited vehicles, and how they plan to account for this on CPOs or open market used vehicles.

I do too. Preferably with third-party confirmation that follows. @wk057 etc. in mind.

However, context is incredibly important. And the context is a 5 minute max number in ideal conditions, until we see evidence to the contrary.

Well, context indeed is important. "5 minute max" sounds innocent enough by itself, but attached to this sentence perhaps not so much: "The impact during the lifetime of your car is 5 minutes max, don't worry about using DC charging as much as you want."

 

[apacheguy]

I will add my unique situation:

2015 85D - one of the first to be delivered
I got the single charger and installed chademo at home. My thinking is it would be more practical for my uses.

I drive a lot, it's normal for me to charge 3 times in a single day. I sometimes get home and have to leave 1-2 hours later. My neighbor with a dual-charger tesla has a similar work/commute and sometimes comes over to "fast charge".

I'm like the OP, over 70k miles and I've maybe charged 300 miles with level 2

I have a photo of my first supercharger session which was 115kw, for a long time I have never had a supercharger go over 87kw

On my first visit to a service center, the advisor said to not use the supercharger because of degradation. I asked him if the chademo was the same, he wasn't sure, but later called me back and told me it was.

This just confirms what I've long suspected. Doesn't surprise me, it would have been nice to know before I spent $100k, but I've adapted to it.

Wait, what? How can a chademo be the same as a supercharger if it's capped to less than half of the max rate? Doesn't add up.

@wk057 @Ingineer need to comment on these recent revelations.

 

[Skipdd]

You're right, of course. I used 'time for tea' since my Nissan colleague and his TEPCO friend, while discussing CHAdeMO, suggested that 'time for tea' was the best translation of the intent, which was to imply that one might have sufficient time for a charge while having a leisurely tea. Since NISSAN itself meant essentially 'Japan daily manufacturing company' they can hardly be accused of being masters of a clever turn of phrase, especially when they're trying to make it work in multiple languages. Despite having worked in Japan frequently during the last 50 years, since 1967, I am accustomed to both ambiguity and unintended consequences in language, worsened because I lack personal expertise by which to judge such issues.

We agree, I think, that in the case of CHAdeMO they wanted to imply fast and easy charging.

Thanks for the explanation. A nice flower amongst a lot of weeds..

 

[apacheguy]

Hi Everyone -

The peak charging rate possible in a lithium-ion cell will slightly decline after a very large number of high-rate charging sessions. This is due to physical and chemical changes inside of the cells.

Our fast-charge control technology is designed to keep the battery safe and to preserve the maximum amount of cell capacity (range capability) in all conditions. To maintain safety and retain maximum range, we need to slow down the charge rate when the cells are too cold, when the state of charge is nearly full, and also when the conditions of the cell change gradually with age and usage.

Can you clarify further? So if a owner is down to 87 kw peak from a 115 kw max when new are you saying this is purely due to resistance increases in the cell and that is physically their limit? Or is the BMS enforcing the lower rate through software?

 

[jelloslug]

I think the 75KWh battery are also affected. There are some here saying they use to get over 100KW, now less than 100KW.

As for the 100KWh pack, it might be more resilient because of the higher capacity. But I suspect eventually even the 100KWh pack will show this problem just at a later time.

100 is the highest I have ever gotten on my pack. I have almost 21k on it now with many DC charges and I still can get 100kwh on it.