# How much does Supercharging damage my battery?



## FRC

About a year ago, when we added a second Model 3 for my wife(wish we could've waited for the Model Y), I changed my charging habits. I gave up my NEMA 14-50 because my wife has greater charging needs(actually and emotionally). For a while I slow charged at 115v which is fine most of the time. But since I have the time, and free supercharging, and I pass a supercharger at least once a week, I've gotten in the habit of supercharging exclusively. My local supercharger is a 150 that is almost always empty, I've never seen more than two other cars in the 10 stalls. So I'm not inconveniencing anyone. I probably charge about every 10 days from, say, 15% to 70%. I read a book, make phone calls, or clean the car; so it's no inconvenience for me either.

I've noticed that lately I don't even get the "excessive supercharging can damage you battery" warning. And I don't think any of us know for certain, but what's your opinion? How much is my $10/week savings over home-charging really costing me? I doubt this car will last me beyond 300K anyway, and as long as my real world range stays at 200+ miles, I'm content. Just curious, how short-sighted do you think I'm being?


----------



## iChris93

FRC said:


> 've noticed that lately I don't even get the "excessive supercharging can damage you battery" warning.


I'm assuming that means you had seen that message on the 3? That is news to me.


----------



## Ed Woodrick

It's not the best thing to do. But it's not the worse. Why not plug in the 120V at home and then only top of at Supercharger every few weeks?

Some folks Supercharge almost daily, so weekly isn't a huge deal.


----------



## garsh

Based on the few reports we have of "abused" Model S batteries, I don't think you'll have much to worry about. 

Tesloop is some kind of Tesla Taxi service. They started out with Tesla Model S vehicles that came with unlimited, free supercharging. So they supercharged them - exclusively. And they would also supercharge them all the way up to 100%. Several times a day, every day. They've written a few articles about their experiences.

TESLOOP'S TESLA MODEL S SURPASSES 400,000 MILES (643,737 KM)

Model S 90D: 6% degradation over the first 194k miles (battery replaced). 22% degradation over the next 125k miles.
Model X 90D: 10% degradation over first 300k miles
TESLA CHARGING FAILS AND BATTERY LESSONS (MODEL S, MODEL X & MODEL 3)

"Changing to a practice of keeping the Charge Limit set at 95% slowed the rate of degradation to nearly nothing."


----------



## FRC

iChris93 said:


> I'm assuming that means you had seen that message on the 3? That is news to me.


Yes, I used to get it regularly, but not in the last couple of month's.


----------



## FRC

garsh said:


> Based on the few reports we have of "abused" Model S batteries, I don't think you'll have much to worry about.
> 
> Tesloop is some kind of Tesla Taxi service. They started out with Tesla Model S vehicles that came with unlimited, free supercharging. So they supercharged them - exclusively. And they would also supercharge them all the way up to 100%. Several times a day, every day. They've written a few articles about their experiences.
> 
> TESLOOP'S TESLA MODEL S SURPASSES 400,000 MILES (643,737 KM)
> 
> Model S 90D: 6% degradation over the first 194k miles (battery replaced). 22% degradation over the next 125k miles.
> Model X 90D: 10% degradation over first 300k miles
> TESLA CHARGING FAILS AND BATTERY LESSONS (MODEL S, MODEL X & MODEL 3)
> 
> "Changing to a practice of keeping the Charge Limit set at 95% slowed the rate of degradation to nearly nothing."


Thanks for that info @garsh, anybody have any experience with Tesloop's Carmiq?


----------



## JWardell

I don't think supercharging harms the Model 3 battery. This was a thing with the Model S, but the Model 3 battery was designed to handle much more current. Aa garsh said, I don't think the warning exists in the 3 [checks files...nope].
Of course it's a different story if you are always supercharging in the top or bottom 5%. Don't do that often.


----------



## FRC

JWardell said:


> I don't think supercharging harms the Model 3 battery. This was a thing with the Model S, but the Model 3 battery was designed to handle much more current. Aa garsh said, I don't think the warning exists in the 3 [checks files...nope].
> Of course it's a different story if you are always supercharging in the top or bottom 5%. Don't do that often.


Thanks, @JWardell. But I'm confused, are you saying that you see no evidence that the Model 3 ever has displayed a supercharging warning? I know mine has, it's what prompted me to author this thread. If you're telling me I'm crazy, you wouldn't be the first!


----------



## JasonF

FRC said:


> Thanks, @JWardell. But I'm confused, are you saying that you see no evidence that the Model 3 ever has displayed a supercharging warning? I know mine has, it's what prompted me to author this thread. If you're telling me I'm crazy, you wouldn't be the first!


I don't know why you would have gotten the warning, because once a week isn't really excessive as far as I know.


----------



## Ed Woodrick

A couple of points over the last few posts....

Everything damages a battery, in some people's view. But other points of view say that it is just normal wear and tear. 
(Just like humans aging, Is a 60 year old "damaged" or just normal wear and tear?)

If I remember correctly, the car has prompted that multiple fast charging sessions can be harmful in the past. I think that now it just says that multiple 100% charging can be an issue.

But, heat isn't a friend to a battery. Supercharging causes more heat than slower charging. 

So I guess a better way to put it is that lots of Supercharging isn't the friendliest thing for a battery. It doesn't damage it, it doesn't hurt it, but the batteries would much rather be not warm.

I Supercharge whenever I need to, without hesitating. But given the option, I charge slower.


----------



## FRC

Ed Woodrick said:


> I charge slower.


But slower charging is less efficient, so where's the balance? Faster more efficient charging w/degradation or slower, less efficient charging with lesser degradation?


----------



## Ed Woodrick

FRC said:


> But slower charging is less efficient, so where's the balance? Faster more efficient charging w/degradation or slower, less efficient charging with lesser degradation?


I really could give a flip about the efficiency.


----------



## Alighieri256

TLDR: What they said ^^^

I think the term 'damage' is not the right word for it. Looking at lithium ion battery service life / charging strategy studies, you'll see that it's really a continuum of degradation where charging faster generally increases degradation to one degree or another, as does utilization of the upper and lower limits of charge. 

A Tesla Urban Charger charges a Model 3 LR at 72kW, compared to its ~75kWh capacity. That's around 0.96C. For comparison, my phone has a 12.5Wh battery, and charges at 15W, which works out to 1.2C. If you think of the car's battery as a massively scaled up version of a phone battery, you'll see that I'm actually charging the phone more harshly on a day to day basis than a Model 3 LR at an Urban Charger. At 150kW, that number increases to ~2C, and at a 250kW SC V3, it's 3.3C. There are many LI ION battery types that can be charged safely (safely meaning with minimal chance of catastrophic failure) at 5C. 

There are definitely differences between the car's battery and the one in your phone:
- Custom chemistry / electrode, whose characteristics are not well known outside of Tesla
- Active cooling during charging and discharging
- Varying charge rate based on %. - Most LI ION chargers supply a set amount of current while the battery is between 0-~80%, then taper off near the top because the battery just doesn't want any more. The Tesla BMS varies the applied power continuously to apply the max safe amount of current.

I haven't seen any studies on how much of a battery's degradation is due to charging / discharging in and of themselves vs. the heat generated by those processes. Heat generally accelerates most chemical reactions, so active cooling is probably a major benefit. *I say probably because I don't have the data, not because I believe it to be a question. 

At the end of the day, all of the LI ION chemistries we know of exhibit this same inverse relationship between charging speed and service life. But while 150kW sounds huge, it's not really leaps and bounds faster than charging strategies used for other LI ION batteries. From Tesloop's data, added above by Garsh, we can see that even if you treat a Tesla the same way as you treat your cellphone: with deep, rapid, daily charge and discharge cycles (which is abysmal for both), the battery still lasts hundreds of thousands of miles.

Also, Tesla has to honor their warranty. As a company, they have a direct incentive to make sure that the number of packs that fail within the warranty period is as small as possible. Even if they were to try to impose some arbitrary limit of Supercharging that would void the warranty, it wouldn't hold up in court. Any judge would rule that use of Tesla Superchargers is an implied part of owning a Tesla vehicle. I realize that your question isn't related to warranty period battery failure, but whomever calculated the warranty period didn't just throw a dart at a numbered board. Because warranty coverage is an anticipated cost of doing business, it's typically carefully calculated from known failure rate. My best guess is that the original Model S and X unlimited mileage warranty was more a statement of "We don't yet know how long these are going to last, but we promise to get it done for you." The newer mileage limits are likely calculated based on the findings from that experiment.

So, in conclusion (This turned out way longer than I thought), you probably don't need to worry about your Supercharging activities. It would be "better", whatever that means, to charge slowly at home, but in the grand scheme of things, there isn't any reason to think it's going to cut the battery life by any huge amount.


----------



## Ed Woodrick

Alighieri256 said:


> TLDR: What they said ^^^
> 
> There are definitely differences between the car's battery and the one in your phone:
> .


Very different battery chemistries and usage.

Most importantly, phone batteries have lives of about 3 years. At that point, they've often swollen and busted the case open.

Car batteries are more like 10 years before becoming unusable.

It's really hard to compare the two.


----------



## iChris93

Ed Woodrick said:


> Very different battery chemistries and usage.





Alighieri256 said:


> There are definitely differences between the car's battery and the one in your phone:
> - Custom chemistry / electrode, whose characteristics are not well known outside of Tesla
> - Active cooling during charging and discharging
> - Varying charge rate based on %. - Most LI ION chargers supply a set amount of current while the battery is between 0-~80%, then taper off near the top because the battery just doesn't want any more. The Tesla BMS varies the applied power continuously to apply the max safe amount of current.


----------



## FRC

Ed Woodrick said:


> I really could give a flip about the efficiency.


My suspicion is that you are in the vast minority amongst members of this forum on that one, Ed.


----------



## Ed Woodrick

Are you really concerned about less than 10% added cost for electricity?

My suspicion is that the vast minority are the ones that are even aware of the difference in efficiency. Most people still are trying to figure out what a NEMA and J-1772 is.

And I think that I can easily say that significantly less than 1% of all Tesla owners know the difference. 

So let's let you bring us up to date, what it the current efficiency numbers for a Model 3 or Model Y. Make sure that you discount the basic phantom drain that occurs no matter what. So just counting what's goes in vs mileage usage isn't accurate. 

From what I've seen, it's only a few percent difference. And knowing how much power costs in Georgia, you may be able to buy a meal at McDonalds each year for the difference.


----------



## FRC

Ed Woodrick said:


> Are you really concerned about less than 10% added cost for electricity?
> 
> My suspicion is that the vast minority are the ones that are even aware of the difference in efficiency. Most people still are trying to figure out what a NEMA and J-1772 is.
> 
> And I think that I can easily say that significantly less than 1% of all Tesla owners know the difference.
> 
> So let's let you bring us up to date, what it the current efficiency numbers for a Model 3 or Model Y. Make sure that you discount the basic phantom drain that occurs no matter what. So just counting what's goes in vs mileage usage isn't accurate.
> 
> From what I've seen, it's only a few percent difference. And knowing how much power costs in Georgia, you may be able to buy a meal at McDonalds each year for the difference.


Personally, I try to keep an eye on all the money I earn, spend, save, and invest. EVERY SINGLE PENNY. I don't obsess over it, and perhaps I'm wrong in thinking that others think like me, but if I see a way to save money with no downside, I'm probably gonna do it. But, to each his own.


----------



## JWardell

FRC said:


> Thanks, @JWardell. But I'm confused, are you saying that you see no evidence that the Model 3 ever has displayed a supercharging warning? I know mine has, it's what prompted me to author this thread. If you're telling me I'm crazy, you wouldn't be the first!


Pics or it didn't happen 
I just wish I was plugged in and logging when you got that. Would love to see what triggered it exactly.


----------



## garsh

FRC said:


> But slower charging is less efficient, so where's the balance? Faster more efficient charging w/degradation or slower, less efficient charging with lesser degradation?


The decision point is basically AC versus DC (aka super-) charging.

Even AC charging at 80 amps (the maximum supported by a Tesla Wall Connector, but only a few Model S versions support going that high) is considered pretty "low" by Tesla battery packs (reference).
The heat generated in the battery (which "ages" the battery) by AC charging is apparently pretty constant no matter the charge rate. Therefore, _faster _AC charging will be better for battery life than slower AC charging (reference).
So it's pretty much always a better decision to AC charge as fast as possible. There may be other reasons for wanting to tell your car to charge more slowly than what an EVSE will allow, but efficiency and battery life are not valid reasons for doing so.


----------



## garsh

Ed Woodrick said:


> I really could give a flip about the efficiency.


I care about it enough that I want to understand it so I can make informed decisions.

For example, charging from a regular outlet (12 amps @120v) is about 78% efficient, while charging at 40 amps @240v is about 91% efficient (reference).
If I drive 20,000 miles/year, at about 250 W•h/mile, then the car is using 5,000 kW•h per year.
At 78% efficiency, the car is pulling 6400 kW•h per year. At 91% efficiency, the car is pulling 5500 kW•h per year. That's a difference of 900 kW•h per year.
If I pay 7¢/kW•h for my electricity, then that's a difference of $63 per year.

From that, I can see that:

A $500 Wall Connector, installed for an additional $500, would pay for itself in about 15 years. Probably not worth it _from a purely economic viewpoint._
A $35 NEMA 14-50 adapter for my Mobile Connector will pay for itself within a year. That becomes a no-brainer upgrade.
That said, I ended up getting a wall connector from the referral program, so I went ahead and installed it anyway.


----------



## FRC

Since my electricity costs a bit more than 50% more than yours, my annual savings would approach $100 per year. That's a solid happy meal per month!
But more seriously, I assume that most Tesla owners have at least some interest in the green aspect of EV ownership. And inefficiency is waste and waste is not green. So, my assumption(right or wrong) is that most Tesla owners care about their efficiency.


----------



## garsh

FRC said:


> I assume that most Tesla owners have at least some interest in the green aspect of EV ownership.


That becomes less and less true as Tesla continues to become more mainstream.

And we all have our cutoff points for worrying about waste and efficiency. For instance, we bought brand-new Teslas instead of continuing to drive our older cars, which would have arguably been less wasteful and more efficient overall.


----------



## iChris93

garsh said:


> For instance, we bought brand-new Teslas instead of continuing to drive our older cars, which would have arguably been less wasteful and more efficient overall.


Sure, it may have been better not to mine or build anything new, but it's not like I sent my previous car to the junkyard to be crushed like cash for clunkers did. Someone else is now driving it to be less wasteful and more efficient overall.


----------



## garsh

iChris93 said:


> Sure, it may have been better not to mine or build anything new, but it's not like I sent my previous car to the junkyard to be crushed like cash for clunkers did. Someone else is now driving it to be less wasteful and more efficient overall.


In my case, I doubt anyone ended up buying and driving my Leaf (I gave it to CarSense for a six-pack and some smokes). It was down to a 30 mile range - tough to even use it for commuting at that point.


----------



## FRC

garsh said:


> In my case, I doubt anyone ended up buying and driving my Leaf (I gave it to CarSense for a six-pack and some smokes). It was down to a 30 mile range - tough to even use it for commuting at that point.


So...no waste there!


----------



## MMMGP

FRC said:


> So...no waste there!


That all depends on what beer they gave him.


----------



## Ed Woodrick

FRC said:


> Since my electricity costs a bit more than 50% more than yours, my annual savings would approach $100 per year. That's a solid happy meal per month!
> But more seriously, I assume that most Tesla owners have at least some interest in the green aspect of EV ownership. And inefficiency is waste and waste is not green. So, my assumption(right or wrong) is that most Tesla owners care about their efficiency.


Take a look at your electric rates, I'm pretty sure that they aren't twice as much. They do get more expensive, but only during summer months.

But remember folks, aren't we saving a lot more than that by going electric?


----------



## FRC

Ed Woodrick said:


> Take a look at your electric rates, I'm pretty sure that they aren't twice as much. They do get more expensive, but only during summer months.
> 
> But remember folks, aren't we saving a lot more than that by going electric?


I think I said 50% more than your stated rate, not twice as much. No off-peak for me either. But you're right, still much cheaper than gas.


----------



## ULEWZ

FRC said:


> I assume that most Tesla owners have at least some interest in the green aspect of EV ownership.


I am sorry to say that this has never crossed my mind. I wanted a fast, good handling car, and the ability to carry 4 adults. That was my criteria for buying a Tesla over another Corvette. Not having to pay California taxes at the gas pump was another great reason to go electric. Who knows, I may change my mind some day and buy some birkenstocks.


----------

