If you fast charge, Tesla will permanently throttle charging

[Max*]

@Max*

Oh I know this is not the first time JonMc has not given us all the info.

I find it perfectly possible Tesla decides to limit the peak rate in all cars.

After all, that was their solution to fixing the Ludicrous launch counters.

What I don't agree is that the fleet taper is the whole story like the Danish SC has now reported.

But it may be the NEW story. Possibly.

Why does it have to be a "story" and not the "truth"?

 

[AnxietyRanger]

Why does it have to be a "story" and not the "truth"?

Occam's razor is JonMc would have told us if this was just a fleet-wide taper change. Instead he and several SCs have talked of DC charging related issue affecting certain users. JonMc specifically mentioned less that 1% and a ~5min slowdown.

Now an SC in Denmark tells some completely different explanation that all these cars are actually going through an ECU-by-ECU Supercharging taper change? We are supposed to ignore all the past reports and find this the real reason and rest was all false?

No, IMO. The simplest explanation is that if the new story is true, it is a pivot or a change, not the old story explained...

Both old story and new story can be true. But I am not buying that only the new story is true and everyone else, JonMc included, were wrong...

 

[Max*]

We'll have to agree to disagree.

 

[Naonak]

My car is at 30% SOC at the moment... I'm waiting on a new bluetooth dongle (my old one is a little weird) which should arrive tomorrow. I will get a TM-Spy dump of a SC session after that. Hopefully I can avoid charging between now and then... if not, I'll just top it up enough to get over to the SC (which is about 40 miles away unfortunately).

Maybe we'll get some interesting data on the taper for my vehicle.

 

[AnxietyRanger]

We'll have to agree to disagree.

I'm not sure what we are disagreeing with because your hypothetical JonMc quote is exactly how I think it might well have gone down. But even in that quote certain user's problems were what came first... which is my point.

It is quite possible Tesla later decided/decides to introduce the limitation/new taper to everyone, but that is separate from the original fault...

 

[Ugliest1]

We'll have to agree to disagree.

Somehow, there's a lot of that going around!

 

[tls]

I think given how many testimonies we've seen from uncapped 85'ers, one thing is for sure: they aren't affected. The one reported exception may be something else entirely.

Yeah, the guy has a Chademo charger at home!

Seems to me there's a decent chance this is just a plain, simple software bug. Either a "DCFC charge count" that includes both low-rate (Chademo) and high-rate (Supercharger) sessions when it probably ought to just include Supercharging, or a "time spent on DCFC" counter that similarly massively overcounts Chademo time (because it'll all be at 48kW or below with current-generation batteries and chargers).

Not many people use Chademo primarily so not many people report it. But there are a few -- PoCo employees with Chademo at work, people with homebrew Chademo in their garages, people in Norway (Chademo all over the place there, my sister says) -- and that's who's getting nailed. Not by any malice on Tesla's part, not by any wrongdoing on their part, but by a plain and simple bug. Software has those, you know?

Another possibility is that Tesla's learned of some obscure issue which degrades batteries at charge rates between 0.5C and 1.2C. That seems a lot less likely to me.

I occasionally hit one fairly busy SC that's right next to a free Chademo unit. When I charge there, I sometimes move over to the Chademo when my charge rate hits 40kW or so to free up the SC spot...that, I think I'll stop doing.

 

[tls]

The additional bytes report the lifetime number of kWh added by external (non-regen) charging broken down into categories. On my car there are two categories. My 240V AC charging is in one group and my Supercharging is in the other group.

If there isn't a 3rd category for Chademo (the car does know it's on Chademo and not a Supercharger; the instrument cluster says so) this will significantly overestimate the amount of time the battery's spent at high charge rates. Chademo with a nominal "50kW" charger on a Model S peaks at 48kW and only gets there once the battery's hit a moderate state of charge, then falls off quickly. Most kWh input from a Chademo unit will be at rates 36kW and below -- well below the 0.8C threshold often cited as the optimal charge rate, 1/3 of the Supercharger peak rate, and less than 2 times what the onboard chargers can source.

Mmmmm, overly simplistic heuristics.

 

[SMAlset]

I'm probably about 10 pages or so behind in this thread to get to this point in reading but thought I would add a link to a lecture I saw referenced on the Model 3 forum by omgwtfbyobbq (the link below is of higher video quality than the one linked there). Sadly the thread there has had only several hundred views. Thought it would be appropriate to the discussion here in providing some understanding especially to those not familiar with battery technology and the testing procedures to try to determine the batteries longevity under various conditions. Really is cutting edge technology. The professor is Jeff Dahn of the Dalhousie University and the lecture is from 7/30/2013 on the topic of "Why do Li-Ion batteries die and can they be immortal?"

One of the guys who created some of their testing equipment went to work for Tesla. Professor Dahn was hired by Tesla under an exclusive 5-year contract to work on battery cell R&D last June. In any event even being a non-technical person I found his presentation very interesting and informative.

Two other videos you might find interesting:
Interview with Professor Dahn 2/17/17 -

His 2016 TED talk -

 

[AnxietyRanger]

Seems to me there's a decent chance this is just a plain, simple software bug. Either a "DCFC charge count" that includes both low-rate (Chademo) and high-rate (Supercharger) sessions when it probably ought to just include Supercharging, or a "time spent on DCFC" counter that similarly massively overcounts Chademo time (because it'll all be at 48kW or below with current-generation batteries and chargers).

I agree home or otherwise frequent CHAdeMO chargers seem to be a fairly large segment of the problem population. Whether a bug, Tesla's system lacking granularity to distinquish between these things properly or CHAdeMO has a real reason (different charge characteristics of CHAdeMO?), or CHAdeMO simply being a facility that more often allows frequent DC charging for more people, that seems to be anyone's guess at this point... it could also just be a co-incidence.

@Ugliest1 As for agreeing and disagreeing, I too agree this is a good time to wait for more data. The debate I think has been well hashed out. What makes one become a "less than 1%er" is the important question, as well as are there some future changes on-going at Tesla as @torvalstrom 's SC info suggested. Without more data, all we can do is wait and try and find out when possible.

Thank you for the videos @SMAlset!

 

[Candleflame]

And before there is another outrage thread, I just wanted to add this here:

For typical/most supercharger usage, the cap is somewhat irrelevant. It's about the shape of the curve. To be exact, the area under the curve is more important than the peak of the curve.

from what we can see the integral DOES seem to be smaller though. Under the old curve you could go from 10 - 80% in around 40min whereas now it is 45ish min i think. (on the 90kwh models)

 

[Candleflame]

maybe charging at 50kw is just as bad as 100kw and hence they are together?

 

[eye.surgeon]

It would be nice if someone could present a summary of facts as we know them for those that don't have time to read 60+ pages...for example which batteries are known be be affected. I have an 85, and as far as I can tell, it has not shown be be affected due to different battery chemistry. True?

 

[Max*]

from what we can see the integral DOES seem to be smaller though. Under the old curve you could go from 10 - 80% in around 40min whereas now it is 45ish min i think. (on the 90kwh models)

It's definitely possible. I'm not arguing that. But we don't have enough data to reach that conclusion yet - just 1 data point.

 

[Max*]

It would be nice if someone could present a summary of facts as we know them for those that don't have time to read 60+ pages...for example which batteries are known be be affected. I have an 85, and as far as I can tell, it has not shown be be affected due to different battery chemistry. True?

The current theory is: It's 90kwh batteries, that have been fast charged 250+ times.

Could be all the new chemistry batteries, could be a lower count trigger, could be higher, could be Chademo + Supercharger, could be a lot more possibilities.

 

[stopcrazypp]

It would be nice if someone could present a summary of facts as we know them for those that don't have time to read 60+ pages...for example which batteries are known be be affected. I have an 85, and as far as I can tell, it has not shown be be affected due to different battery chemistry. True?

I think there is one case of an 85, but people are speculating the cause is something else. The rest are all 90kWh as for as I can tell.

 

[Kant.Ing]

The cause is Supermarketing

 

[supratachophobia]

It's definitely possible. I'm not arguing that. But we don't have enough data to reach that conclusion yet - just 1 data point.

Two, I think Bjorn just posted his 90kw limit on his X.

 

[Max*]

Two, I think Bjorn just posted his 90kw limit on his X.

I didn't mean the cap data point, the shape of the taper not changing data-point.

Did he also do the charge in 43minutes vs. the advertised 40 minutes? (I didn't see his thread)

 

[tls]

maybe charging at 50kw is just as bad as 100kw and hence they are together?

That doesn't make much sense -- and the charge rate for most of a Chademo session on today's equipment with today's batteries is a lot lower than 50kW, more like 30-40kW. An HPWC on 277V 3-phase is 22kW...