What should my ideal charge percentage be?

[zoomer0056]

I suspect that most people don't keep their cars for much more than 5yrs, so it probably doesn't matter

Many people say the same thing, that if you will keep the car a short time then don't think about the cars health long term. What about the idea of passing on the car to the next person with the healthiest battery possible? Not just for environment or the sake of not wasting because we don't have to waste, but also for resale value. A healthier battery has to be worth more.

 

[AAKEE]

I read through the thread, but it is long so I may have missed it. If one wants to preserve battery life, I suppose it is fair to say that one should charge to as little capacity as you can but enough for what you need.

Yes.

Charge late is good.

Does anyone have a good source for degradation as it relates to SOC, ie, 50% capacity no degradation; 75% capacity, 1%/yr of loss; 90% capacity, 2%/yr of loss, etc.

Just google *calendar aging* together with *lithium battery* or *NCA*
Look formeesearch reports and not EV site articles.

This is from a such report.

Calendar aging is reducing the rate with time so its considered [square root of time]

This chart is then monts so one year is square root (12/10) times this chart.

25C and 80% degrades about 5% for then
months, so it will be about 5.5% for one year. After two years= square root [2] times 5.5= 7.8. After three years = 9.5%
After four = 11%

I have ab logged average of just below 14C battery temp and about 48% avg SOC

This is my car after 2.25 years and 60K km plus:

Keeping low SOC works!

I suspect that most people don't keep their cars for much more than 5yrs, so it probably doesn't matter for the majority. However, if you are on this forum you probably like to know the data, just because.

Someone will buy the car after me and Im sure that a fresh low degraded battery wont bve bad when selling.

 

[tesluv108]

I want to keep my car another 9 years. By then it would be a 2015 in 2032. This will be the ultimate test to see if low miles really matter or if the battery will fail regardless after a given amount of time. I’m hoping the battery holds up as I currently have 8380 miles on the car.

 

[DayTrippin]

I read through the thread, but it is long so I may have missed it. If one wants to preserve battery life, I suppose it is fair to say that one should charge to as little capacity as you can but enough for what you need.

Does anyone have a good source for degradation as it relates to SOC, ie, 50% capacity no degradation; 75% capacity, 1%/yr of loss; 90% capacity, 2%/yr of loss, etc.

I suspect that most people don't keep their cars for much more than 5yrs, so it probably doesn't matter for the majority. However, if you are on this forum you probably like to know the data, just because.

There is an independent service that can monitor your battery health. Recurrent | Buy, Drive & Sell Your Electric Car, Positively

I have been pretty meticulous about taking care of my battery. Recurrent Auto has some good information and they try and quantify how much extra value you have in your car by managing degradation. In over a year, my S has seen 1% or less in degradation. In about the same time, my 3 has effectively seen no degradation or is better than some 3's that are brand new. My S has seen some supercharger use and my 3 none.

Early on I read what @AAKEE posted about battery degradation and came up with a simple plan to maximize my health. Recurrent auto has pretty much validated that approach works for me.

As I mentioned upstream, I keep my cars at 50% or less. I only charge up more when absolutely needed and only just before I go. I try and avoid supercharger use and typically only charge then from 15-65%. All in all it is pretty simple to do. The worst things you can do seem to be charge your car to a high level in hot weather and keep it there.

I basically never have any need to charge over 60% on my S because of its range. A big plus for it is even at a low charge level, it is still wickedly fast. The performance on the new S drops off very little until I am around 20% charge or under. The 3 is a little more obvious but even at a 25% I am still under 4 seconds 0-60.

 

[aerodyne]

TL;DR:

Store at around 55%, always in garage, operate 30-70% has had good but minor results for me over 5 years on two cars, see pics below.

More:

One should consider that MS and MX cell chemistry varies over the years of production, as well as BMS design and software.

Also, pack failure modes are not well correlated with degradation. Many pack failures reported here occur with cars with good range and low miles.

Unless you are going to put the pack in cold storage, and not use it, like Jeffery Dahn has done, 20 year life is not likely.

Also, if there were a method that would significantly increase pack life and reduce failures you can bet Tesla would have broadcast this.

Apart from the Elon tweet years ago (Operate 70-30%, store at 50-62%) guidance has varied and seems to be slanted to calibration of 2170 cells.

First image from '15 MS, second from '22 MS.

If you got this far, just garage and drive the car, and don't worry about the pack! Let the BMS do that!

 

[wayner]

My Model S is now about 8.3 years old. I don't drive a ton - about 100,000km in total over that time. I charge to 90% at home with a Tesla HPWC probably about once or twice a week on average. When I am going on trips I will occasionally charge to 100% but I probably have only done that 3-4 times per year on average.

When my car was new I had 400km of range. When I charge to 100% now the car says that I have 380km of range. So, assuming that the car is reporting the range in km correctly, my car has lost about 5% of range over that time. I only go on long trips occasionally - my longest trips would be about 450km in a single day which require at least one stop.

 

[12Pack]

in europe people keep their car frequently >10 years and in eastern europe >15 to 20 years.
Less consumerism and americanism over there. I mean most people there dont buy new cars anyway.

Not central to the topic, but this seems incorrect.

I spend equal time living in US, UK and Northern Europe. The last has virtually no “beaters” as they are termed in the US, given as all road cars have to meet certain standards and be checked annually. And the UK has a high proportion of new business-owned and leased cars for even relatively junior management levels.

It’s the US that keeps the cars the longest and of course also with the highest miles.

And what is Americanism anyway? It’s the most heterogeneous country in the world….

 

[maximizese]

For a lot of

Not central to the topic, but this seems incorrect.

I spend equal time living in US, UK and Northern Europe. The last has virtually no “beaters” as they are termed in the US, given as all road cars have to meet certain standards and be checked annually. And the UK has a high proportion of new business-owned and leased cars for even relatively junior management levels.

It’s the US that keeps the cars the longest and of course also with the highest miles.

And what is Americanism anyway? It’s the most heterogeneous country in the world….

I would say Cubans keep their vehicles on the road a whole lot longer than folks in the US. I'd say that Americanism hints at the idea that we like the latest and greatest or biggest new thing. We aren't too particular about waste or sentimental value. Many point to America's history of expansion without a major event of contraction, our innovative and pioneering history, but from an economic perspective I would say it stems from our shift from a manufacturing based economy to a service/consumption model. We have layers and layers of industry that are propped up and depend on Americans to buy new stuff and consume; we have financially engineered methods of debt to spur more consumption...including both fiscal and monetary policy, though I suppose other countries have done similar things.

Anyway, there are many folks who get new cars every 3 years since they insist on leasing. Dealerships are also known to entice leasees to turn their vehicles in a year or 2 year early to rope them into a new lease with a brand new vehicle. More transactions means more income and productivity to the dealership and the lease agent.

 

[Boza]

https://www.kbb.com/car-news/americans-driving-older-cars/

 

[DayTrippin]

My Model S is now about 8.3 years old. I don't drive a ton - about 100,000km in total over that time. I charge to 90% at home with a Tesla HPWC probably about once or twice a week on average. When I am going on trips I will occasionally charge to 100% but I probably have only done that 3-4 times per year on average.

When my car was new I had 400km of range. When I charge to 100% now the car says that I have 380km of range. So, assuming that the car is reporting the range in km correctly, my car has lost about 5% of range over that time. I only go on long trips occasionally - my longest trips would be about 450km in a single day which require at least one stop.

Cooler weather is a big plus for longevity when charging to higher SoCs. Also it would be interesting to see what your AVERAGE SoC is over the time you use the car. Do you charge to 90% and then leave it there, or charge to 90% and start driving right away? How deep do you discharge before charging?

As for Elon's comments, I trust them as much as when he says FSD will be ready. He is in the business to sell cars. As long as the battery packs make it out of warranty with little or no claims, I don't think he cares that much.

 

[aerodyne]

Cooler weather is a big plus for longevity when charging to higher SoCs. Also it would be interesting to see what your AVERAGE SoC is over the time you use the car. Do you charge to 90% and then leave it there, or charge to 90% and start driving right away? How deep do you discharge before charging?

As for Elon's comments, I trust them as much as when he says FSD will be ready. He is in the business to sell cars. As long as the battery packs make it out of warranty with little or no claims, I don't think he cares that much.

Not just Elon. His head of battery tech at the time agreed. The was circa 2017, pre Grimes, pre pot, pre production hell, and things were different then.

 

[OldPro]

I read through the thread, but it is long so I may have missed it. If one wants to preserve battery life, I suppose it is fair to say that one should charge to as little capacity as you can but enough for what you need.

Does anyone have a good source for degradation as it relates to SOC, ie, 50% capacity no degradation; 75% capacity, 1%/yr of loss; 90% capacity, 2%/yr of loss, etc.

I suspect that most people don't keep their cars for much more than 5yrs, so it probably doesn't matter for the majority. However, if you are on this forum you probably like to know the data, just because.

We recharge at home via our solar panels (Tesla) to 80%. So far recharge is coming in at around 260+ miles for a 2018 LRM3.

 

[PickledRamps]

Many people say the same thing, that if you will keep the car a short time then don't think about the cars health long term. What about the idea of passing on the car to the next person with the healthiest battery possible? Not just for environment or the sake of not wasting because we don't have to waste, but also for resale value. A healthier battery has to be worth more.

Over the lifetime of the vehicle the environmental impact is negligible. With respect to ownership over that lifetime, everyone has their own idea of what they value. There are plenty of buyers for whom 5-10% reduced capacity is worth the savings and plenty of sellers for whom the added convenience is worth the reduced value. The market takes care of the value issue.

 

[PickledRamps]

There is an independent service that can monitor your battery health. Recurrent | Buy, Drive & Sell Your Electric Car, Positively

I have been pretty meticulous about taking care of my battery. Recurrent Auto has some good information and they try and quantify how much extra value you have in your car by managing degradation. In over a year, my S has seen 1% or less in degradation. In about the same time, my 3 has effectively seen no degradation or is better than some 3's that are brand new. My S has seen some supercharger use and my 3 none.

Early on I read what @AAKEE posted about battery degradation and came up with a simple plan to maximize my health. Recurrent auto has pretty much validated that approach works for me.

As I mentioned upstream, I keep my cars at 50% or less. I only charge up more when absolutely needed and only just before I go. I try and avoid supercharger use and typically only charge then from 15-65%. All in all it is pretty simple to do. The worst things you can do seem to be charge your car to a high level in hot weather and keep it there.

I basically never have any need to charge over 60% on my S because of its range. A big plus for it is even at a low charge level, it is still wickedly fast. The performance on the new S drops off very little until I am around 20% charge or under. The 3 is a little more obvious but even at a 25% I am still under 4 seconds 0-60.

I generally did a similar thing which is to charge to 60-70% at home and rarely used a supercharger. However, my car has free lifetime supercharging which could probably save me $1,000+/yr but requires that I charge to higher levels - 80-90%. I had not been taking advantage of it, but am now experimenting with the later.

It sounds like 2-3% loss per year? Over 5-6 years, maybe 12-13%?? Several people have made the point about resale value. I suspect that it is small and probably overshadowed by the $17,000 mi/yr driven. It's not about hiding the issue from buyers. The market dictates the value based on multiple factors, battery degradation being only one, and relatively small compared to others; probably still worth the savings of free charging.

 

[DayTrippin]

Latest Model S degradation looks encouraging. About 12% after 200k miles.

Tesla gives update on battery degradation: only 12% after 200,000 miles

Tesla has released a rare update on the battery degradation in its electric cars. The automaker claims its batteries only...

electrek.co

 

[aerodyne]

For those that spend effort to rarely supercharge, or AC charge at low rates, consider that every time you let off the accelerator, you are DC charging, perhaps as much as 60kw.

 

[DrGriz]

For those that spend effort to rarely supercharge, or AC charge at low rates, consider that every time you let off the accelerator, you are DC charging, perhaps as much as 60kw.

Interesting to think about. Of course, A supercharger starts out at 150 or 300 kW, so 60 isn't so much of a hit. But I am sure that you are right, and those little charge cycles probably do a miniscule amount of damage. Certainly worth the cost, in my mind.

If you don't use it, what's the point?

 

[STS-134]

For those that spend effort to rarely supercharge, or AC charge at low rates, consider that every time you let off the accelerator, you are DC charging, perhaps as much as 60kw.

One factor that determines degradation is how long this charge rate is sustained. Quick bursts of energy, such as when you decelerate and regenerate, don't really stress the battery, because remember you have just been moving ions and electrons in the opposite direction to get the car up to speed in the first place and there's plenty of "room" for the reverse chemical reaction to occur. And in the case of the battery in a Tesla, 60 kW isn't much, especially below 50-60% SoC, and is less than 1C.

 

[aerodyne]

One factor that determines degradation is how long this charge rate is sustained. Quick bursts of energy, such as when you decelerate and regenerate, don't really stress the battery, because remember you have just been moving ions and electrons in the opposite direction to get the car up to speed in the first place and there's plenty of "room" for the reverse chemical reaction to occur. And in the case of the battery in a Tesla, 60 kW isn't much, especially below 50-60% SoC, and is less than 1C.

According to my SMT data, Regen accounts for 20+ percent of charging. That's a lot, even if only in short bursts.

In the old cars such as the one I had, 60 KW is near peak.

My point is if you SuC moderately and occasionally say between 30-70%, one should not be too concerned.

 

[STS-134]

According to my SMT data, Regen accounts for 20+ percent of charging. That's a lot, even if only in short bursts.

But that's the point. Short bursts do nearly nothing in terms of chemical stress. What did you do to the battery just before you had the burst of regen? You got the vehicle going, using what? The battery of course. So all of those ions and electrons had just moved in the opposite direction and now you're reversing the flow. There's plenty of them to "move" back into their previous positions because you just took them out of those positions not too long ago.

My point is if you SuC moderately and occasionally say between 30-70%, one should not be too concerned.

SC is completely different, because it's pushing ions/electrons through the battery in the same direction for a sustained period of time. Part of the reason why you want a warm battery before you SC is that it makes it easier for the ions to "move around". You're forcing stuff into areas where it has not recently been, and this causes chemical stress. This scenario doesn't really apply for short bursts of charging after long periods of discharging.

Did you ever have an almost dead battery and put it into a toy or flashlight and turn it on, and for the first few seconds, you get almost normal operation? This is because the battery had been "at rest", and at first, there were plenty of electrons you could pull from it. As the seconds pass however, the battery has trouble "keeping up" with the demand of the toy or flashlight, and the toy slows or the light dims. That's kind of what happens too when you're charging: it's very easy to push those electrons for the first few seconds or even tens of seconds, especially if the battery has been running in reverse (discharging) for a while, but as time goes on, the chemical stresses build.