[Rumor]Tesla is reducing speed of Supercharging as your Tesla gets older

[bonaire]

It's not an electrical system we are cycling, it's a chemical system.

Heat x time are the two key factors and you can find some things out by increasing heat and hoping its the same as a lower heat x a longer time but you can't increase time and sometimes time is the difference maker.

For a purely unrelated example leaf or piece of paper ages differently at different temps but you can't simulate 10 years in a day by making it 3650 times hotter because it'll catch fire and that isn't aging, not even close to the same result. Even getting it close to ~451F changes the nature of the situation too much to allow any huge amount of time compression.

Similar things with battery chemistry. Heat and time interact but you can't simulate everything without just waiting. You can do hot box tests but they only predict a trend and that prediction can be wildly inaccurate.

I would second this situation.

Batteries going through cycles endure some level of Lithium-Ion plating. Ions that get attached to anode and cathode and become immovable. Lithium Battery Research: Plating and https://www.sciencedaily.com/releases/2014/09/140903105638.htm

This causes some increases in IR (Internal Resistance).

Higher levels of IR cause higher levels of heating in the battery during charge cycles that are continuous at near or over 1C charge rates. Plating also happens at cold conditions. This is why Tesla does not allow high-speed charging in the winter until the battery core is warmed.

So, I could say that the OP is possibly saying older chemistry NCA batteries used may have seen some degradation over 500 cycles that the Ion Plating causing some concerns to limit the charging speed at SuperCharger sites due to the extra heating caused during full power charging. But Tesla would definitely have to clarify this and if they did put out a public notice, it could hurt the stock price, company view by the public and demand profile of new purchases. Even if they said "we made it better, so no worries" it just indicates they took a chance with the early Panasonic cells just to get things rolling in the earlier years.

However, this doesn't mean Tesla is slower-charging older battery packs. Maybe they taper earlier in some cases if the core temperature is rising too fast or they sense higher ambient air temps outside? I wouldn't want to force a faster charge under hot conditions (outside the proper healthy operating temperature range of the cells).

As dhanson856 states - this is a chemical reaction process, not just a battery. People should realize that it is far more complicated than is implied by the "plug and play" nature of EV ownership. One day, batteries may be more hardened without these idiosyncracies. Without the parasitic nature of Ion Plating, batteries could last nearly "forever". Well, at least 5000 cycles would be nice. Some LTO batteries now offer far more, as do some LiFEPO4 products (8000 cycles with 80% capacity remaining).

Most data is also available from Jeff Dahn, now associated with Tesla. Many here have watched his video(s).

Why do lithium-ion batteries die? (long)

 

[bonnie]

It is pretty clear from the posts some people are only reading the title. Based on that the title of this thread should be changed to "Data needed: Evidence of slower supercharging on higher mileage 90 kWh cars".

That's a great suggestion.

 

[bonaire]

One point about this thread - how often is someone supercharging "anyway"? Isn't SC for long distance travel between cities and not for around-town use? Should this even matter to anyone other than a travelling salesman or cross-country adventurist doing 25,000 miles a year? Just avoid range-charging often in hot weather and things will be ok. And for those with leased cars, will they care "at all" since the car goes back before warranty ever runs out?

 

[AmpedRealtor]

The message I got was that Tesla had reduced it intentionally to protect the battery.

Please post the contents of this purported "message"...

 

[Yarder]

Well, if Tesla is applying charging parameters based on my particular car, it's mileage, charging history, particular degradation, the battery temperature, and the ambient outside temperature to customize the charging rate to extend the battery life and maintain power characteristics, then I'm grateful for their engineering and operations programming that went into the chargers and the car! To me, that's a good thing.

The Tesla charging system is clearly superior to the dumb plug in home charger for my 18650 flashlight battery.

 

[ODE90D]

I really appropriate the posts from those of you taking me seriously and I understand I could have made my point more clear by choosing another title for my post. Basically all I wanted was your help to collect some data about the charging pattern and how it changes over time/milage - and especially for the new battery chemistry found in 90D and onwards.

I drive approx 220 miles at around 80 mph in average every day - so speed of charge for gaining the 10-20% I need to get all the way home welI above 0% is really important to me which is why I am making a big deal out of this. I understand that it isn't important for the majority of Tesla owners and based on the responses I got from my post I think I will create a new post ....with a less provocative headline and clear message - it is all about collecting data and not accusations of fraud.

Several of you asked for proof and I can give you what I have although I am sure some may accuse me of forgery as it isn't signed by a federal judge and 10 witnesses. The response I got from Tesla was by email and in Danish as it came from a Product Specialist at Tesla Service in Copenhagen (there is no reason to put him on display as he is only the messenger). His response was the result of an analysis of the logs pulled from my Tesla when I filed a complaint over slow charging a couple of months earlier. When I first wrote about this in the danish Teslaforum.dk a while back another 90D owner responded that he had received the exact same message from Tesla.

I have pasted a screenshot of the email response in Danish into this post but I also ran it though Google translate for your convenience and the text is as follows:

Hi Christian,

Sorry for the late reply, it took its time because. I wanted to make sure that any error could be excluded.

There are no errors in your battery or your car.

The reason you experience a lower max, charging speed entirely on supercharging than previously because with time limited top speed of supercharging, this is a security that automatically carried out because the vehicle protects the battery. The good thing is that it influences only the beginning of charging, ie during the period of charging, where the car receives the most power. You may want to take time on how long it takes you and charge 20% -80%, with a car that has run 100km before.

The conclusion is that there is an error on your car, it behaves exactly as it should.

and now the screen shot of the danish email:

After having recieved his response I asked ino the specifics, but he was unable to give me details. So my mission with this initiative is to make Tesla come out and explain themselves - officially. That will take some hard evidence and I hope some of you 90' owners will help me collecting it. At some point your Tesla will also reach this point and wouldn't you like to understand what brought you there? Maybe you could have changed you charging habits to preserve the battery (beyond what we are already told). The sheet to update is here: Tesla Supercharging Speeds

 

[bonaire]

The email states: "The good thing is that it influences only the beginning of charging, ie during the period of charging, where the car receives the most power."

Aren't you saying you want the higher max charge speed because you are adding charge in order to get home at the higher rate of speed? The benefit you get with that is you can "boost" your range with the max charge rate at the original max charge rate - but you perceive it now to charge slower during the "max" charging period (lower battery state of charge). And you must know that you get max charge when nobody is sharing the supercharger "other" side of the A/B configuration, correct? If you share charging on an A/B configuration with another, you share the total throughput of that SC unit.

 

[malcolm]

You may want to take time on how long it takes you and charge 20% -80%, with a car that has run 100km before.

Thanks for this. Would make an excellent opening post btw.

Gives other owners clear instructions of the parameters for data collection.

 

[ODE90D]

The email states: "The good thing is that it influences only the beginning of charging, ie during the period of charging, where the car receives the most power."

Aren't you saying you want the higher max charge speed because you are adding charge in order to get home at the higher rate of speed? The benefit you get with that is you can "boost" your range with the max charge rate at the original max charge rate - but you perceive it now to charge slower during the "max" charging period (lower battery state of charge). And you must know that you get max charge when nobody is sharing the supercharger "other" side of the A/B configuration, correct? If you share charging on an A/B configuration with another, you share the total throughput of that SC unit.

I typically charge 10-30 kWh to make it home and arrive at the supercharger with a 10-30% SoC. I only charge enough to make it home. So for me it is important to peak in the lower part of the scale as I used to and not in the middle.

I am very well aware of all the parameters influencing charging speed including sharing a "pair". I used to reach a max of around 115 kW but that is now down to 96 kW and 2 other danish 90D owners have experienced the same drop after some 50K km. You can see this is the google sheet. But it would be great with more data.

 

[stopcrazypp]

Something must be lost in translation, but the message doesn't refer to aging specifically, but can be talking in general terms (for example the observation that supercharger speeds in general have been dropping in some areas regardless of battery age). Temperature may also play a part.

Whatever data gathering happens needs to factor in the supercharger location too (perhaps the specific stall too).

 

[ODE90D]

Something must be lost in translation, but the message doesn't refer to aging specifically,.

Exactly - he wouldn't/couldn't elaborate on this which is why I would like to find the "pattern" with your help.

 

[stopcrazypp]

Exactly - he wouldn't/couldn't elaborate on this which is why I would like to find the "pattern" with your help.

Well, that is why you got backlash for your title and OP. You already wrote the conclusion without having the data. There would need to be more data gathering to make sense of things.

 

[malcolm]

You already wrote the conclusion without having the data.

I believe this is Alt-Science.

It appears to be trending.

 

[sorka]

I read the referenced post. I charge at home and at 40 amps the battery hardly ever gets above 35 C (even in the summer). In contrast, supercharging most often results in the battery riding at 45 C. I understand the claim you are making, but in my experience the battery runs much warmer after supercharging compared to L2.

You've just made my point for me. There's very little difference between 35C and 45C yet one takes 4 hours to get you 50% SOC while the other takes 20 minutes.

Add that to the fact that the 20 minute 50% bump is back to back with driving where it's already going shoot up to well past 40C in warm weather from driving alone.

Plus if you charge at home in the middle of the night, the battery spends more hours after the battery has been charged warm. When you're charging and driving at the SC, the battery is already warm from charging so you're not piling on extra hours of the battery being warm in between.

This is why when I do charge at home, I try to set the timer so charging will end either when I'm scheduled to leave or when off peak TOU ends. If I end up leaving 30 minutes after TOU off peak ends, then I've added an extra 30 minutes the battery is sitting hot but I'm willing to accept that for not paying far higher electricity rates.

 

[abasile]

Particularly now that the OP has posted some specifics, it seems to me that "Rumor" should be removed from the thread title. I'm not sure why some are considering this to be so controversial. In general, as Li-ion batteries age, they should be used a bit less aggressively. As others have stated, I'm very pleased that Tesla's battery management algorithms work to prolong the lives of our batteries, as evidenced by the very moderate rate of degradation that most Tesla batteries have shown. Tesla has done a great job in this area!

 

[scottf200]

As your Tesla gets older the maximum kW you experience while charging at the SuC will drop and charging take longer. Unofficially several Tesla employees have explained this as a limitation that has been implemented to protect the battery, but the details of the "algorithm" seem to be unknown and officially Tesla has never explained themselves in this matter.

Personally I find it unacceptable Tesla makes such changes to my car post purchase. What is next - reduced acceleration when they get concerned about the wear and tear from too many quick starts?

It seems that something happens once you pass approx. 30-40.000 miles. The charging curve changes and especially those with the new battery chemistry introduced in the 90D back in 2015 seem to be hit hard by the preventive measures. Several 90' owners report a drop from a max of 115 kW to 96 kW once they passed approx 50.000 km.

I have prepared a Google Sheet in which I hope those of you with a high milage (+30.000 miles) will maintain your SuC charging statistics at least once - and especially those with 90Ds. Note there are 2 tabs, one for metric (km) and another for imperial (miles) - just make your pick. Make sure the battery is warm and not sharing a pair of stalls.

Tesla Supercharging Speeds

Please do no highjack this thread with all the usual comments about battery temperature, sharing stalls etc. I know how all these things influence charge speed and can assure you it has been taken into account.

Here are 3 data points for you that you are welcome to enter on my behalf. I could probably export this data I think if you want to PM with an email address to send to. I guess it could be graphed overtop each other then too. Tesla Model X P90D(L) picked up 03-Mar-2016. Sorry but I have other things to do and you may need to extrapolate (i.e. want 20% where my snapshots may have 19% and 21%).

All 3 of these are at the same supercharger and likely the same unit as I have a favorite parking spot and others are not normally charging (no one on my pair). These are all from the drive back from dropping someone off at a 100 mile away town so the battery is certainly warm.

My max kW rate has dropped coincidence or not.

2016 03 11 OBD 00935 - Max kW: 115.1
2016 11 29 ODO 21500 - Max kW: 106.0
2017 03 17 ODO 28098 - Max kW: 102.4

 

[apacheguy]

You've just made my point for me. There's very little difference between 35C and 45C yet one takes 4 hours to get you 50% SOC while the other takes 20 minutes.

Add that to the fact that the 20 minute 50% bump is back to back with driving where it's already going shoot up to well past 40C in warm weather from driving alone.

Plus if you charge at home in the middle of the night, the battery spends more hours after the battery has been charged warm. When you're charging and driving at the SC, the battery is already warm from charging so you're not piling on extra hours of the battery being warm in between.

This is why when I do charge at home, I try to set the timer so charging will end either when I'm scheduled to leave or when off peak TOU ends. If I end up leaving 30 minutes after TOU off peak ends, then I've added an extra 30 minutes the battery is sitting hot but I'm willing to accept that for not paying far higher electricity rates.

Where do you get that there is "very little difference" between 35 C and 45 C? One study shows a 33% increase in degradation at 45 C compared to 35 C after 250 cycles (Figure 5). I would not classify that as very little.

Effect of Temperature on the Aging rate of Li Ion Battery Operating above Room Temperature : Scientific Reports

 

[widodh]

Not true in my case. Model S from Sep 2013, 166.000km on the ODO and still 118kW peaks until 35% SoC

 

[apacheguy]

Not true in my case. Model S from Sep 2013, 166.000km on the ODO and still 118kW peaks until 35% SoC

I believe the OP is specifically referencing 90 kWh packs due to the difference in cell chemistry. Your experience with an 85 kWh is not necessarily applicable.

 

[sorka]

Where do you get that there is "very little difference" between 35 C and 45 C? One study shows a 33% increase in degradation at 45 C compared to 35 C after 250 cycles (Figure 5). I would not classify that as very little.

Effect of Temperature on the Aging rate of Li Ion Battery Operating above Room Temperature : Scientific Reports

Did you miss the part where the battery spends 1200% more time (4 hours vs 20 minutes) at the slightly lower temperature