Early Model S owners - remember the supposed Supercharger penalty? Not a problem.

AnOutsider said:

I wonder if this is one of those "it still degrades, but not by as much and we don't want the public worrying about it" things. Last thing they need is for people to be worried about using the SCs that Tesla is touting as a benefit.

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That's not impossible by any means, but another explanation might be that they've changed the algorithm, possibly because of more real world data and the existence of much higher initial current from the upgraded Superchargers. All of this is speculation of course.

I get the impression that battery degradation is still not very well understood, and a lot of the theory around it is more guesswork than knowledge. Take for example the changes Nissan has made to the Leaf's charging. Originally they made it hard to charge to 100% to prevent degradation, but now they seem to have decided that this isn't a problem, and apparently make it hard not to charge to 100%.

I wouldn't be surprised if supercharging were a similar situation. The original guesswork was that it would hurt, but real-world data has since disproven that. The one thing that really seems to be bad for batteries is extreme temperatures (such as getting too hot because of waste heat from fast charging), and the Model S's active temperature management more or less solves that.

This is, of course, complete speculation on my part.

I read this as supercharging is no worse for battery life than any other form of charging.

According to this (not from Tesla) ultra-fast charging kills Li-ion battery quickly:

Do not ultra-fast charge batteries if possible and charge at a more moderate rate of 1C or less. (A maker of the 18650 Li-ion recommends 0.7C.) Makers of electric cars prefer if EV owners charge at an eight-hour or 16-hour charge, both of which are below 1C.

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Tesla has probably solved much of the problem with their algorithm but it's hard to believe they would have solved it completely.

Panu said:

According to this (not from Tesla) ultra-fast charging kills Li-ion battery quickly:

Tesla has probably solved much of the problem with their algorithm but it's hard to believe they would have solved it completely.

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Superchargers charge at about 1.4 C at their peek, but much of the time is spent at less than 1C.

The article talks about ultra-fast charging at as high as 10C. We're nowhere near that, so I would not worry about it.

liuping said:

Superchargers charge at about 1.4 C at their peek, but much of the time is spent at less than 1C.

The article talks about ultra-fast charging at as high as 10C. We're nowhere near that, so I would not worry about it.

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OK that's good to know. In the chart in that page the fastest charging is 3C.

Panu said:

OK that's good to know. In the chart in that page the fastest charging is 3C.

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Also, remember most of the charging is done at home, at way below 1C. For 85kWh battery owners, the HPWC charges at less than .5C and the UMC charges at less than .25C.

The relatively few slightly higher than 1C charges while traveling should not be a problem at all.

liuping said:

Also, remember most of the charging is done at home, at way below 1C.

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Not necessarily. If you live near a SC you may want to save money by charging there daily.

It also depends on the battery chemistry. Some batteries can take well over 2C charging. Some are designed to perform well at 10C discharges. It's a balance between energy density, power density, battery life, charge rates, and discharge rates. I'm sure active cooling also plays a significant role. Tesla and Panasonic are probably constantly looking at these graphs and chemistries to see if they can improve one or more of these values while minimizing the impacts on the others.

mikeash said:

I get the impression that battery degradation is still not very well understood, and a lot of the theory around it is more guesswork than knowledge.

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Actually, Tom Saxton from Plug-In America has been collected a fair amount of empirical data on battery life (you should all fill out the battery survey to help gather data points Plug In America) and the Model S data looks promising - Tom did a session at TMC Connect to review initial results. His blog is here Tom Saxton's Blog

Personally, I use a SC at least once a week and my pack degradation is minimal - S85 w/ ~44K miles will max charge to ~262 rated miles.

omarsultan said:

Personally, I use a SC at least once a week and my pack degradation is minimal - S85 w/ ~44K miles will max charge to ~262 rated miles.

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Do you mind me asking what you charge to on a daily basis, 60%, 80%, 90%?

RyanT said:

Do you mind me asking what you charge to on a daily basis, 60%, 80%, 90%?

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Sure. On a daily basis, I charge to 90%@80A. Twice a week, I head into the Bay Area for work, so I max charge at least twice a week and usually end up SC-ing at least once per week. My MS is my daily driver so I cannot afford to coddle it - I know some folks baby their battery packs, but I am part of the use it hard and put it away wet crowd.

Panu said:

Not necessarily. If you live near a SC you may want to save money by charging there daily.

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A degraded battery is the karmic penalty of using superchargers daily to save a few dollars but inconveniencing travelers who have to charge there

Six said:

A degraded battery is the karmic penalty of using superchargers daily to save a few dollars but inconveniencing travelers who have to charge there

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Do you have ANY evidence to support this or is it just a SWAG? Everything I have ever read indicates charging at a supercharger is equally as safe as charging on an HPWC.

RyanT said:

It also depends on the battery chemistry. Some batteries can take well over 2C charging. Some are designed to perform well at 10C discharges. It's a balance between energy density, power density, battery life, charge rates, and discharge rates. I'm sure active cooling also plays a significant role. Tesla and Panasonic are probably constantly looking at these graphs and chemistries to see if they can improve one or more of these values while minimizing the impacts on the others.

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You forgot manufacturing cost.

Simplified to power density, energy density, durability and cost the saying is "Pick 3 of 4."

Tesla sets a baseline target for durability (10 years) and power density.
Since they use large capacities, the power density requirements are lower than some other vehicles. (They seem to limit to 4C for discharge and up to 1.5C for DC (when empty)).
They do a lot of work with their BMS to keep temperatures controlled and even through the battery.

With the baseline set and aided by BMS, they then focus on lowering cost and raising energy density. It seems to be that US manufacturers understood early that the use of a BMS would help them drive the cost down and extend the life of the battery. Part of that might have been reaction to the competitive car market and the extreme environments found across the country.

Updated:
As energy density increases Tesla I'm sure that Tesla will try to increase the maximum capacity of batteries in their cars. I'm sure Tesla would already be able to build a 200 mile mid-size, but because capacity ~ range ~ performance ~ charging mph ~ 1/C, Tesla wants to be able to sell S85-equivalent or better Model 3s and progressively higher range and faster charging cars, because the better they can make the cars, the more of the better cars they can sell, the less challenge there would be for the Supercharger networks.

Six said:

A degraded battery is the karmic penalty of using superchargers daily to save a few dollars but inconveniencing travelers who have to charge there

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I agree, those bastards get what they deserve (and that's my opinion as long as there are no superchargers near me!) :biggrin:.

Panu said:

Not necessarily. If you live near a SC you may want to save money by charging there daily.

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With all of the money you save, you can start buying a few solar panels at a time, then add a few more, until they pay off (usually 6 - 8 years) and you can charge at home all the time for the same price as going to the supercharger. Then you won't get stuck waiting for a charger with all those new models coming out wanting to charge for free.

If you had thought of this a few years ago (Like I did, way before buying Tesla) your charging could be free at home even now! Or, if you, like my neighbors, keep saying that solar is too expensive, they can't afford it, wait until the bugs are worked out, whatever, you might still be trying to charge at superchargers the rest of your life.

Saving money happens by planning ahead more than hoping Tesla will put in a supercharger near you.

roblab said:

With all of the money you save, you can start buying a few solar panels at a time, then add a few more, until they pay off (usually 6 - 8 years) and you can charge at home all the time for the same price as going to the supercharger. Then you won't get stuck waiting for a charger with all those new models coming out wanting to charge for free.

If you had thought of this a few years ago (Like I did, way before buying Tesla) your charging could be free at home even now! Or, if you, like my neighbors, keep saying that solar is too expensive, they can't afford it, wait until the bugs are worked out, whatever, you might still be trying to charge at superchargers the rest of your life.

Saving money happens by planning ahead more than hoping Tesla will put in a supercharger near you.

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Yes I'm interested in solar panels although Finland is far up north and the sun is usually not shining. I've read about them for some time and will have to learn more. I'll probably post some questions to solar panel threads here. Right now my first hope is to get my S85 and the second one is to get the first supercharger in Finland!