If you fast charge, Tesla will permanently throttle charging

[AnxietyRanger]

It may be helpful to consider a little history here. The Model S was designed assuming that the primary means of charging would be 240V AC at 40-80A. The ability to DC charge was included to enable road trips, and the first superchargers were 90kW max. The expensive CHAdeMO adapter was made later to accommodate those owners who traveled in areas where CHAdeMO was prevalent before the supercharger network was built out enough. I can't imagine that anyone at Tesla considered that owners would use CHAdeMO as the primary means for charging their Model S. That's not just an edge case, as Elon might say, but far over the edge. Even three years after the CHAdeMO adapter became available, the number of cars using it as their primary means of charging must still be a rounding error in the size of the Tesla fleet.

So to those who use CHAdeMO for your routine charge, if after several hundred of those charges your supercharging sessions don't go over 90kW in order to protect the battery (which is what my 60 is limited to anyway), I just don't get the outrage.

I have no problem with that description, though I'd add we have a data point of 1% affected, so not a rounding error anymore?

That said, if it really is no problem in the big picture, why not just readily describe and disclose? We still don't know who and how this affects people, so that they can beware. Why no warnings anywhere in the wider materials? Tesla obviously has known about this since we know of three, four cases of techs at Service Centers talking about this to customers.

Just post it sufficiently clear and big somewhere, people can beware DC charging within some stated tolerances and that's it.

 

[TexasEV]

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.

You do know what Tesla recommends for home charging, and it's not CHAdeMO, right?

 

[SageBrush]

I wonder if the group of people doing their part to clog up Superchargers to save pennies in places like California are drawing the rational conclusion that they should stop. Not only is their time probably more valuable in other pursuits, but resale value may well be affected.

Tesla's throttling was not done to discourage this group from their perverse behavior but it is a hopefully awesome unintended consequence.

 

[jdw]

Two observations -

1) Heat, aging and range charging all affect the battery, increasing internal cell resistance; fast charging does heat the battery more than slow charging
2) The charging taper curve seems to change in affected vehicles; initial charge rates are lower but mid-curve rates are hgher

Net result: batteries with higher internal cell resistance are charged with a different taper curve than batteries with lower internal cell resistance. Seems to me this would happen naturally to some degree and Tesla is proactively trying to slow this aging by switching at risk batteries to this different curve. A few extra minutes of charging seems a reasonable alternative to damaging long term battery capacity.

As long as this change results in relatively minor changes to a relatively few vehicles it does fall into exactly the same category as slowing charging in temperature extremes. It would be good to know what behavior is considered "bad" for the battery, but I can see that explaining any detail that sounds like a limitation is very difficult to publicly communicate without it being reduced to "you can't charge a Tesla when it is hot/cold" or "fast charging will kill your battery".

Jon's explanation makes sense to me, plus there are probably a number of other battery management methods going on that are also not publicly disclosed.

 

[electracity]

Why does chademo count as fast charging? It's below 0.8C.

I suspect the primary issue is 30,000 miles in one year. If the car is going to be driven hundreds of thousands of miles in eight years, the algorithm becomes a bit more conservative for charging.

 

[AnxietyRanger]

You do know what Tesla recommends for home charging, and it's not CHAdeMO, right?

He knows now. Obviously he did not know before being throttled. I think I follow Tesla pretty closely and I did not know before this thread.

An example of Tesla needing to educate us better on this, IMO.

 

[scottf200]

I have a 90kWh Model X. I have about 32K miles on it in 1.2 yrs and I'd guess 25K was roadtrips using SuCs. Probably 150 charges.

The chart below is a from a common trip I take. Not many data points but certainly my latter two charge tapers are very different than my first two. Former have higher max and latter have sustained ~80 kW rate for 20 minutes.

7.1 -- 2.13.120 -- 935 mi -- Fri Mar 11 2016
7.1 -- 2.13.120 -- 4009 mi -- Fri May 13 2016
7.1 -- 2.30.61 -- 14600 mi -- Fri Aug 19 2016
8.0 -- 2.44.121 -- 20700 mi -- Tue Nov 15 2016

i.imgur.com/LOebxsO.jpg

 

[thefortunes]

I have no problem with that description, though I'd add we have a data point of 1% affected, so not a rounding error anymore?

That said, if it really is no problem in the big picture, why not just readily describe and disclose? We still don't know who and how this affects people, so that they can beware. Why no warnings anywhere in the wider materials? Tesla obviously has known about this since we know of three, four cases of techs at Service Centers talking about this to customers.

Just post it sufficiently clear and big somewhere, people can beware DC charging within some stated tolerances and that's it.

Clarification - no we don't. Jon McNeill said "less than 1% of our customers..."

 

[AnxietyRanger]

Clarification - no we don't. Jon McNeill said "less than 1% of our customers..."

Fair enough. Accuracy is good.

However, it did not sound like a rounding error.

 

[TexasEV]

I have no problem with that description, though I'd add we have a data point of 1% affected, so not a rounding error anymore?

Actually I believe Jon said less than 1%. And I was referring specifically to the CHAdeMO issue, not all DC charging as he was. So yes, CHAdeMO as primary means of charging is still a rounding error.

 

[thefortunes]

I have a 90kWh Model X. I have about 32K miles on it in 1.2 yrs and I'd guess 25K was roadtrips using SuCs. Probably 150 charges.

The chart below is a from a common trip I take. Not many data points but certainly my latter two charge tapers are very different than my first two. Former have higher max and latter have sustained ~80 kW rate for 20 minutes.

Scott - do you happen to know which firmware you were on for each (or can you get that info)?

Also (I suppose I could do the math but...) since the later charges have a shallower taper, is the net effect about the same?

 

[TexasEV]

He knows now. Obviously he did not know before being throttled. I think I follow Tesla pretty closely and I did not know before this thread.

An example of Tesla needing to educate us better on this, IMO.

Really? Have you ever seen CHAdeMO mentioned on Tesla's home charging web pages?

 

[AnxietyRanger]

Actually I believe Jon said less than 1%. And I was referring specifically to the CHAdeMO issue, not all DC charging as he was. So yes, CHAdeMO as primary means of charging is still a rounding error.

Fair enough. I agree CHAdeMO as a primary charging is a much smaller amount than those affected.

After this news, it will remain so.

 

[AnxietyRanger]

Really? Have you ever seen CHAdeMO mentioned on Tesla's home charging web pages?

My point was: nowhere until now was it said CHAdeMO as home charging was not recommended either.

 

[SageBrush]

Why is it "perverse"?

Because he saved ~ $600 by sitting at ChadDemo chargers for 150 hours, and he did it for the money. This is the same guy who is now up in arms over the ~ 3 - 5 minutes he now loses on the occasions he uses a SuperCharger.

Since no rational person who makes more than half of US minimum wage in his locale would use ChaDemo this way, his behavior is perverse.

per·verse
pərˈvərs/
adjective

1. (of a person or their actions) showing a deliberate and obstinate desire to behave in a way that is unreasonable or unacceptable, often in spite of the consequences.
   • contrary to the accepted or expected standard or practice.
     "in two general elections the outcome was quite perverse"
     synonyms: illogical, irrational, unreasonable, wrong, wrong-headed
     "a verdict that is manifestly perverse"

 

[jerry33]

But all charging is DC charging, the only difference is whether it goes though the onboard chargers, to convert AC to DC, or not. The only difference to the battery cells would be from the rate at which the charging occurs.

 

[AnxietyRanger]

I wonder if it could become a selling point for used Teslas:

- Only hand-washed
- Ludicrous mode never used
- Never been DC charged

 

[JRP3]

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.

What counts as a high rate charging session? What is the cutoff? 50kW Chademo, 24kW Chademo? Is Chademo somehow worse than Supercharging?

Tesla is not slowing down charge rates to discourage frequent Supercharging – quite the opposite. We encourage our customers to use the Supercharger network at their discretion and we committed to doubling the number of worldwide chargers just this year.

Are you informing customers of the possible accelerated effects and slowed charging rate which may occur from extensive use of Supercharging and/or Chademo at the time of purchase?

 

[SageBrush]

My point was: nowhere until now was it said CHAdeMO as home charging was not recommended either.

There are an infinite number of omissions in the user manual ... although it is already quite a big volume, in part due to fools who try to avoid taking responsibility for their behavior on this pretext you keep falling back on.

 

[Electricfan]

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.

This change due to age and usage may increase total Supercharge time by about 5 minutes and less than 1% of our customers experience this.

Tesla is not slowing down charge rates to discourage frequent Supercharging – quite the opposite. We encourage our customers to use the Supercharger network at their discretion and we committed to doubling the number of worldwide chargers just this year.

We also want to ensure that our customers have the best experience at those Superchargers and preserve as much vehicle range as possible even after frequent usage.

Thanks,

Jon

Since this is new information - to quote you - "The peak charging rate possible in a lithium-ion cell will slightly decline after a very large number of high-rate charging sessions" - are you going to put this on the website so it can be considered when making the purchasing decision?

I was told the opposite of this in 2013 when I bought my first Tesla - supercharging would not have any effect on battery life is exactly what I was told. Tesla is supposed to be a new and better car company than the traditional manufacturers - GM, Ford, etc. - but not disclosing a fact like this puts you down on their level, in my opinion.

IMO, Tesla should put a disclaimer on the website such as:

"The Tesla battery pack is intended to be charged at home using lower power charging and not to be regularly charged by DC Fast Charging methods. Use of DC Fast Charging as the primary charging method will eventually lead to a lowered charging rate enforced by Tesla at supercharging stations, to avoid damage to the battery."