Is it better for my car to spend more time at 50% or have shallower discharge cycles but spend more time at a higher state of charge.

[J-a-x]

Except that isn’t correct. Did you not read posts 15 and 17. To be precise, if you have a NCA battery, it’s best to be below 55% SOC as long as possible. Please look at the charts in post 15 and note the plateau at 55%.

The video was mainly enlightening about the mechanisms of degradation but it seems to support your conclusions generally (he says to store below 30, and you say to store below 55 which are both technically correct I think). I find it interesting that your figure show that very low state of charge being ok. It’s actually really good to know that if I arrive home at 10% charge and don’t feel like charging before I go to bed there’s no harm done (I do have a charger in my garage but its a very slow shared community charger which is often busy and so its not always convenient to charge immediately after arriving home). That part is very interesting and useful and I think different from what was presented in the video.

From all this, it seems that storing at somewhere around 50% seems like a good compromise between less degradation than storing at a higher charge, while also leading to lower depth of charing cycle compared to always storing my car at 5% and then needing to charge it up to 90% before a long trip. So seems like I’m in good shape.

There will obviously be some times when I don’t store it below 55%. For example right now it’s at 75% because I had a chance to charge for free and I am not going on a long drive until Saturday. I assume that’s ok for a few days here and there, just not for the majority of the life of the car.

 

[LikesToys]

Except that isn’t correct. Did you not read posts 15 and 17. To be precise, if you have a NCA battery, it’s best to be below 55% SOC as long as possible. Please look at the charts in post 15 and note the plateau at 55%.

Congratulations, your negativity has managed to stop all discussion, well done. I hope your happy.

 

[KenBlub]

Sorry. Carry on. I only wanted to point out that almost all of the information you could want to know about taking care of your battery is contained in posts 15 and 17 with scientific data

By all means don’t let me stop you.

 

[Owner4523]

That is not correct.

Calendar aging for NCA is reduced quite much at or below 57-58%, but still lower SOC is better.
(Teslas buffer makes 57% real SOC to be 55% displayed so we should use 55% as the reference for upper limit if we like to reduce the degradation).

This has been tested many times in research. In general calendar aging vs SOC look like this: (Panasonic NCR18650 in this test). This picture is a specific test, but very good to use as a common way to look at calendar aging.
View attachment 1018271

Here is cells taken from a Tesla model 3 cells (Panasonic 2170, NCA-cells):
View attachment 1018272

This is actual model S cells, taken from a almost new ’16-17 S:
View attachment 1018274

We can see that low SOC is very good to reduce calendar aging.
We also can se that 100% SOC is not at all as bad as the common myth.



As you could see above, the above 80 or 90% being very bad is not true.

High SOC is worse at high temperature.




That is not correct. The batteries does get hur from low SOC.

If looking at small cycles, the lowest degradation from cycles happens around 35-55% SOC for actual Tesla model 3 cells.

This picture is from cycling Tesla model 3 cells in different SOC ranges.
It might look like the lower SOCs are very bad but, if we look at 5-15%, and 1000 FCE cycles (which in this case is 10.000 charges/discharges) we loose about 15%.
1000 FCE is about 400K km or 250K miles.
This means that driving the normal average 20K km or 15K mi we loose about 20/400x 15 = 0.75% per year in cyclic aging.

At the same time we loose about 5 % from calendar aging during the first year and about 10% in total after 4 years if mostly using SOC above 55% displayed.
Using 55% displayed mostly or at least having the car at or below 55% will cost about 2.5-3% the first year and 5-6% in total after four years.

View attachment 1018276

So we can look at the uppermost picture above and see that as we reduce calendar aging at very low SOC, the slightly increased cyclic aging is more or less compensated by the lower calendar aging.

@AAKEE - I have a 2023 MY AWD 4860 battery. I have a level 2 charger at home. My car only has 2,500 miles or so. I have a very short drive to the office and mainly pick my kids up from school and drive around our town with my car. So I set my charge to 50% each day, and when I go out I probably only drive to the 40%'s or maybe the 30%'s and then charge it back to 50% each night. On the weekend when we have various activities I'll bump it to 70-80% to be able to get me to where I need to go. How does this charging plan work to maximize long term battery health?

 

[E90alex]

@AAKEE - I have a 2023 MY AWD 4860 battery. I have a level 2 charger at home. My car only has 2,500 miles or so. I have a very short drive to the office and mainly pick my kids up from school and drive around our town with my car. So I set my charge to 50% each day, and when I go out I probably only drive to the 40%'s or maybe the 30%'s and then charge it back to 50% each night. On the weekend when we have various activities I'll bump it to 70-80% to be able to get me to where I need to go. How does this charging plan work to maximize long term battery health?

I would say that’s perfect and exactly what I do.

 

[Owner4523]

I would say that’s perfect and exactly what I do.

Nice. Do ever charge to 90 or 100% (such as before a road trip?)

 

[E90alex]

Sure. I’ll charge to whatever is needed to complete the trip comfortably. But haven’t done many long road trips personally. I’ll also crank up the limit if there’s a free public charger so I get as much free juice as I can

 

[AAKEE]

@AAKEE - I have a 2023 MY AWD 4860 battery. I have a level 2 charger at home. My car only has 2,500 miles or so. I have a very short drive to the office and mainly pick my kids up from school and drive around our town with my car. So I set my charge to 50% each day, and when I go out I probably only drive to the 40%'s or maybe the 30%'s and then charge it back to 50% each night.

On the weekend when we have various activities I'll bump it to 70-80% to be able to get me to where I need to go.

If you like to really minimize the degradation you could charge ”late” on the weekends, thats charging so the charge is finished shortly before the drive.
In this weekend context it doesnt mean you need to plan to drive at the exakt time when the charging is finished, but if you for example donnit drive before 9 am on saturday, ypu could schedule the charging to be finished in the morning, perhaps 8am or so.

The charge late could be done every night (I do), but the biggest difference comes from reducing time at higher SOC (like > 60% for the NMC’s).

How does this charging plan work to maximize long term battery health?

No problem, it’ll work fine. If you really like to minimize degradation you can consider the charge late tip above.

 

[J-a-x]

Sure. I’ll charge to whatever is needed to complete the trip comfortably. But haven’t done many long road trips personally. I’ll also crank up the limit if there’s a free public charger so I get as much free juice as I can

I have that problem too. If the charge is free I’m more likely to go past my typical charge limits and if I’m paying for the energy I keep it more or less around 50% for most of my weekday idles.

 

[Owner4523]

If you like to really minimize the degradation you could charge ”late” on the weekends, thats charging so the charge is finished shortly before the drive.
In this weekend context it doesnt mean you need to plan to drive at the exakt time when the charging is finished, but if you for example donnit drive before 9 am on saturday, ypu could schedule the charging to be finished in the morning, perhaps 8am or so.

The charge late could be done every night (I do), but the biggest difference comes from reducing time at higher SOC (like > 60% for the NMC’s).


No problem, it’ll work fine. If you really like to minimize degradation you can consider the charge late tip above.

Thanks, I do this already!

 

[Owner4523]

@akkee -

If you like to really minimize the degradation you could charge ”late” on the weekends, thats charging so the charge is finished shortly before the drive.
In this weekend context it doesnt mean you need to plan to drive at the exakt time when the charging is finished, but if you for example donnit drive before 9 am on saturday, ypu could schedule the charging to be finished in the morning, perhaps 8am or so.

The charge late could be done every night (I do), but the biggest difference comes from reducing time at higher SOC (like > 60% for the NMC’s).


No problem, it’ll work fine. If you really like to minimize degradation you can consider the charge late tip above.

 

[Owner4523]

A few more questions as I'm learning: is it bad to let the car sit at a low rate of charge (25% or maybe even 15%?) until the charge kick in over night? For example, if I charge to 50%, and come home with 25 or 15%, is it ok to leave it at the SoC, plugged in, but with a departure time and off peak hours selected so that it doesn't go back to 50% until early in the morning? Or should I let it start charging as soon as I get home and stay there?

Also, yesterday I charged up more than Joe al thinking I had a road trip, but had the wrong day, so my car sat last night at 65 or so %. I assume that is ok, and that we are really looking at the general charging pattern over time?

Finally, I'm headed on a road trip next week. Any problem charging to 100% as I start the trip, or would you suggest only going to 90 or 95?%

Thanks!

 

[E90alex]

Low charge overnight is fine. 100% before a trip is also fine. You just don’t want to have it sit at 100% overnight or for days on end.

 

[Owner4523]

Low charge overnight is fine. 100% before a trip is also fine. You just don’t want to have it sit at 100% overnight or for days on end.

Thanks. If I come home with 60-80% charge for some reason (maybe I didn't use as much as I thought I would) is there an issue letting it sit overnight with that SoC? Also, If I know I'm going to need to 70-80% of battery around 3pm and I start charging around 10 am, is there any issue letting it sit for a few hours at that state of charge before I leave? (I'm pretty new to Tesla and I'm wanting to keep my battery as healthy as possible for as long as possible, so I'm trying to get up to speed.) Also, I have the 4860 battery in case that changes anything charging wise.

 

[Owner4523]

@AAKEE - Sorry for the all of the questions, but I have another one. Do you know how degradation works In regards to what part of the battery actually experiences the degradation? If I only charge my battery to 50% every day and in a few years my battery degrades by 15% does that just mean 85% is not my new 100% and I'll get the same range charging to 50% regardless of the degradation? Does the degradation come 'off the top' so to speak? Thanks for all of your very helpful information.,

 

[E90alex]

Thanks. If I come home with 60-80% charge for some reason (maybe I didn't use as much as I thought I would) is there an issue letting it sit overnight with that SoC? Also, If I know I'm going to need to 70-80% of battery around 3pm and I start charging around 10 am, is there any issue letting it sit for a few hours at that state of charge before I leave? (I'm pretty new to Tesla and I'm wanting to keep my battery as healthy as possible for as long as possible, so I'm trying to get up to speed.) Also, I have the 4860 battery in case that changes anything charging wise.

There is no need to overly obsess or worry about specific charge levels or the battery health. Don’t worry about charging to 100% if needed or running down to even single digit % if needed.

Just keep in mind the rule of thumb to try and have the car spend most of its time at lower charge levels whenever you can to minimize battery degradation, but don’t inconvenience yourself to do so.

If you can’t then you can’t. Eg arriving home at 80% one day, it will be fine. People charge their car to 80-90% everyday and it’s fine. They will just have a bit more degradation when it’s all said and done, but it’s not like the battery will fail or explode or lose half of its capacity.

 

[Owner4523]

There is no need to overly obsess or worry about specific charge levels or the battery health. Don’t worry about charging to 100% if needed or running down to even single digit % if needed.

Just keep in mind the rule of thumb to try and have the car spend most of its time at lower charge levels whenever you can to minimize battery degradation, but don’t inconvenience yourself to do so.

If you can’t then you can’t. Eg arriving home at 80% one day, it will be fine. People charge their car to 80-90% everyday and it’s fine. They will just have a bit more degradation when it’s all said and done, but it’s not like the battery will fail or explode or lose half of its capacity.

Thanks. These forums (and all of info out there) is a bit overwhelming.

 

[AAKEE]

A few more questions as I'm learning: is it bad to let the car sit at a low rate of charge (25% or maybe even 15%?) until the charge kick in over night? For example, if I charge to 50%, and come home with 25 or 15%, is it ok to leave it at the SoC, plugged in, but with a departure time and off peak hours selected so that it doesn't go back to 50% until early in the morning? Or should I let it start charging as soon as I get home and stay there?

Low SOC is nice for the battery. It will not be bad for the battery to be at low SOC overnight, it avtually is better to have low SOC.

It is a really good choice to charge late so the battery spend more time at low SOC.

Also, yesterday I charged up more than Joe al thinking I had a road trip, but had the wrong day, so my car sat last night at 65 or so %. I assume that is ok, and that we are really looking at the general charging pattern over time?

There is no single SOC number that kills the battery like the myth says.

Calendar aging is the degradering effect from time and it looks like this:

We can se that it is about the same at or below 55%.
We can also se that it’s about the same from 60-65% and above, but doubled compared to 55% and below.

This means that one hour at 60-65% and above will ”wear” like two hours at 55% and below. It is nothing worse than that.
You can leave the car at 100% overnight and it will not brake the battery, just cause degradation compared to two nights at or below 55%.
Mostly, there is not a reason to leave the car at 100%, so because of that we can avoid it mostly. If you end up charging to 100% and then for some reason don’t go on the trip there is not need to start discharging the car. (Most forum myths tell the people do drive it down to maximum 90% but as we see from the chart there is not a big win doing it. Not bad bit really doesnt change anything).

Finally, I'm headed on a road trip next week. Any problem charging to 100% as I start the trip, or would you suggest only going to 90 or 95?%

Thanks!

100% is fine!
Avoiding 100% when you would need 100% or just like to try it is a redult of the myths.

On my new Plaid I have about 10 charges to 100% so far, after 8 months. -> still full range and probably one of the cars with the best battery capacity.

On my old ‘21 M3P i had about 35 full charges and 55-60 supercharging sessions after 2.5 years and 66K km. My cars degradation / range loss was about 1/3 of the average for 2021 M3P.

Last charge showed 78.4 kWh and 492 km range out of 507 km where the average for the same car/year was around 462km.

Charging full when needed will not noticable degrade the battery.
Supercharging when needed will not do that either.

Having a SOC above 55% most of the time will noticable degrade the battery compared to having a SOC at or below 55% most of the time.

 

[AAKEE]

@AAKEE - Sorry for the all of the questions, but I have another one. Do you know how degradation works In regards to what part of the battery actually experiences the degradation? If I only charge my battery to 50% every day and in a few years my battery degrades by 15% does that just mean 85% is not my new 100% and I'll get the same range charging to 50% regardless of the degradation?

You will always be able to charge to 100% but each percent will be less worth.

The range indication by the battery symbol that you can use instead of % will drop.

For a 3 LR it might start at for example 358miles. (Just grabbing a number as I do not se your cars spec).
When you have lost ~2% battery capacity the range will start to decrease for a full charge. After loosing 12% battery capacity , you will have lost 10% of the range (as the forat 2% are hidden from displayed range loss).
In this case you still have 100% on a full charge but each percent give you 12% less range.

 

[Owner4523]

Low SOC is nice for the battery. It will not be bad for the battery to be at low SOC overnight, it avtually is better to have low SOC.

It is a really good choice to charge late so the battery spend more time at low SOC.

There is no single SOC number that kills the battery like the myth says.

Calendar aging is the degradering effect from time and it looks like this:
View attachment 1022579

We can se that it is about the same at or below 55%.
We can also se that it’s about the same from 60-65% and above, but doubled compared to 55% and below.

This means that one hour at 60-65% and above will ”wear” like two hours at 55% and below. It is nothing worse than that.
You can leave the car at 100% overnight and it will not brake the battery, just cause degradation compared to two nights at or below 55%.
Mostly, there is not a reason to leave the car at 100%, so because of that we can avoid it mostly. If you end up charging to 100% and then for some reason don’t go on the trip there is not need to start discharging the car. (Most forum myths tell the people do drive it down to maximum 90% but as we see from the chart there is not a big win doing it. Not bad bit really doesnt change anything).



100% is fine!
Avoiding 100% when you would need 100% or just like to try it is a redult of the myths.

On my new Plaid I have about 10 charges to 100% so far, after 8 months. -> still full range and probably one of the cars with the best battery capacity.

On my old ‘21 M3P i had about 35 full charges and 55-60 supercharging sessions after 2.5 years and 66K km. My cars degradation / range loss was about 1/3 of the average for 2021 M3P.
View attachment 1022587
Last charge showed 78.4 kWh and 492 km range out of 507 km where the average for the same car/year was around 462km.

Charging full when needed will not noticable degrade the battery.
Supercharging when needed will not do that either.

Having a SOC above 55% most of the time will noticable degrade the battery compared to having a SOC at or below 55% most of the time.

Thank you for all of this great info. I read somewhere that when you change to 100% you can physically see the battery swell or stress or something like that, which caused me to be a little anxious to change to 100 as I don't want to stress the battery casing or anything.