Best way to charge to prevent battery degradation?

[johnny_cakes]

I've read this too... there are graphs posted somewhere on these forums of SoC studies that show higher degradation right around the 58% mark (oddly specific).

I believe this is the graph you're referring to:

It shows the calendar aging of batteries at different temperatures in the first 10 months. Calendar aging is the predominant form of battery degradation in the first 5 to 8 years, so minimizing this will minimize the overall degradation of your battery. For NCA cells, which is what all Model Ys use in the US, you will see a big drop at 57%, true SoC where the central graphite peak is. 57% true SoC is 55% display SoC (what our cars will show). At or below this SoC, degradation can be cut in half and this is why @TesslaBull suggests setting your limit to 55% or lower and charging as late as possible.

The rate of calendar aging will taper off in time by the square root of time (i.e. degradation at 10 months will double by 40 months).

All of this info is from the research and reading that @AAKEE 's been doing. Search his name and calendar aging for more info.

 

[AAKEE]

Charging right before you leave is also the most wasteful (needs the most battery Re-heating). Charging when you get home from a drive takes advantage of an already heated battery. Letting the battery cool and later reheat it, is pure waste.

The car does not heat the battery for home charging (AC) if the battery is about 10C or warmer.

The battery heating thing is only valid in cold weather, and if having a Tesla with a heat pump the extra heat in the battery comes in handy to heat the cabin. So charging late in cold climates is the best when having a Heat Pump/Octovalve car, it reduces the energy consumption by using the “waist” heat in the battery.
In really cold climate like -20C I see below 200Wh/km with a battery that the heat pump can use the heat from, and like 260 Wh/km when the battety is cold and the heat pump have not useful source for grabbing heat from.

Also letting the battery cool and reheating it causes more temperature swings. Heating and cooling cycles tends to age electronics quicker.

Its not valid in this case.

The battery is better of cold when not used, and warm when the car is in use.

 

[DB288]

sorry…

how much if this is supposition and urban legend and how much of this is proven battery degradation in an actual tesla in the real world over multiple years…

people treat there cars very differently…how come we don’t see wide variations in battery degradation in the real world in the past 10 years…why would tesla not recommend 55% if it really mattered….i think they care deeply about the battery issue…

i would not be surprised if after 10 years a car whose owner obsessed about this stuff is pretty similar to a car whose owner never thought about it…

 

[father_of_6]

how come we don’t see wide variations in battery degradation in the real world in the past 10 years…why would tesla not recommend 55% if it really mattered….i think they care deeply about the battery issue…

I think we actually *do* see wide variations in battery degradation in 10 year old vehicles, but those would be Model S... and some of those had their own battery design issues that further complicate things.

Tesla isn't going to recommend charging to 50% officially because it doesn't sell well, and because the general public won't understand, and because they don't really care if your battery loses another 10% of it's range in 10 years.

The point is, there are definitely factors that increase or decrease battery degradation. Those that have done the research (not me) see a strong correlation between charging above 50ish percent and an increase in degradation.

 

[AAKEE]

sorry…

how much if this is supposition and urban legend and how much of this is proven battery degradation in an actual tesla in the real world over multiple years…

Its actually the other way around.

The urban legends is like:

”Charging to 80 (or 90%) is the best for longevity because Tesla says that”
—> IRL Tesla say ”less than 90%

”If you charge to 100% you need to drive asap, otherwise the battery get hurt”
—> IRL there is no data suggesting 100% is much worse than 80-90%. In extreme temperatures the rate is higher but not by far. (This doesnt mean I recommend leaving it there for long periods)

“Going below 20% is bad for the battery.”
—> IRL there is no data that support this myth. Actually, the lower the better down to 0%.

people treat there cars very differently…how come we don’t see wide variations in battery degradation in the real world in the past 10 years

We do see differences.

First, I started to use the low SOC strategy more or less directly after delivery. I have about 18-20% Supercharging energy wise (~50 sessions) and about 30 charges to 100%.
2 yrs 4 months (61K km) and the difference is clear.
There is quite a few cars here and at a swedish forum that adopted the low SOC stategy, the low range drop is seen by virtually all of the one I know of.

I started to learn about lithium batteries about 2006-2007, because tgere was myths already then. After reading research I adopted the low SOC during storage.
I still have lithium polymer batteries from 2009 that works fine today but most of my friends have to throw their batteries after a few years.
The science /research is agreeing very much on how lithium ion batteries work and what cause them to degrade.

There really is not much to be uncertain about if lokking into the sum of all research results.

…why would tesla not recommend 55% if it really mattered….i think they care deeply about the battery issue…

Tesla off course want to give the owner as few restrictions as possible. It should be easy to own and use an EV.

If Tesla on one hand said EPA range = 358 miles, and on the other hand said “please do mot charge more than 55%, they probably would be sued for non true advertisement.

Teslas advise will not be the ones maximizing battery longevity. They will ensure that the batteries in general will not need warranty replacements (100.000 miles and eight years is the law mininum warranty in US).

i would not be surprised if after 10 years a car whose owner obsessed about this stuff is pretty similar to a car whose owner never thought about it…

Its quite safe to say that you can reduce the degradation to half (or better) by staying low in SOC (as much time as possible below 55%).

If you tell me:
-What tesla you have (for knowing original capacity and range).
- how old it is, down to months ( X yrs Y months) since delivery or build date.
- To what SOC you charged most times.
-End of day SOC (before next charge)
- when /time on the day you start the charge
- The climate where you live, average temp.
- if you park it in a garage or outside.

Then I’ll tell you your expected degradation, expected range today.
(This assumes you owned it since new or know this data for the previous owner as well).
You do not even need to tell me the miles driven.
Tested on quite a few cars so far and it mostly hit quite close.
(This is because calendar aging is predictable and also the main degrading factor for the first 5-8 years.)

Try me!

 

[TesslaBull]

sorry…

how much if this is supposition and urban legend and how much of this is proven battery degradation in an actual tesla in the real world over multiple years…

people treat there cars very differently…how come we don’t see wide variations in battery degradation in the real world in the past 10 years…why would tesla not recommend 55% if it really mattered….i think they care deeply about the battery issue…

i would not be surprised if after 10 years a car whose owner obsessed about this stuff is pretty similar to a car whose owner never thought about it…

The nice thing about choosing to optimally minimize battery degradation, is that there is absolutely no obsessing about it at all. I have my charge limit set to 55%, and charging automatically begins about 2 hours before I depart in the morning. All I do is take 5 seconds to plug the car in when I get home. I don't think about it at all. I wake up with 195 miles range for my daily 60 mile round trip commute. Even if I forget to plug in, I can commute 3 times, especially since I can plug in when I wake up if needed. Simple. Easy. Optimal.

 

[804son]

Its actually the other way around.

The urban legends is like:

”Charging to 80 (or 90%) is the best for longevity because Tesla says that”
—> IRL Tesla say ”less than 90%

”If you charge to 100% you need to drive asap, otherwise the battery get hurt”
—> IRL there is no data suggesting 100% is much worse than 80-90%. In extreme temperatures the rate is higher but not by far. (This doesnt mean I recommend leaving it there for long periods)

“Going below 20% is bad for the battery.”
—> IRL there is no data that support this myth. Actually, the lower the better down to 0%.

We do see differences.

First, I started to use the low SOC strategy more or less directly after delivery. I have about 18-20% Supercharging energy wise (~50 sessions) and about 30 charges to 100%.
2 yrs 4 months (61K km) and the difference is clear.
There is quite a few cars here and at a swedish forum that adopted the low SOC stategy, the low range drop is seen by virtually all of the one I know of.
View attachment 932605

I started to learn about lithium batteries about 2006-2007, because tgere was myths already then. After reading research I adopted the low SOC during storage.
I still have lithium polymer batteries from 2009 that works fine today but most of my friends have to throw their batteries after a few years.
The science /research is agreeing very much on how lithium ion batteries work and what cause them to degrade.

There really is not much to be uncertain about if lokking into the sum of all research results.



Tesla off course want to give the owner as few restrictions as possible. It should be easy to own and use an EV.

If Tesla on one hand said EPA range = 358 miles, and on the other hand said “please do mot charge more than 55%, they probably would be sued for non true advertisement.

Teslas advise will not be the ones maximizing battery longevity. They will ensure that the batteries in general will not need warranty replacements (100.000 miles and eight years is the law mininum warranty in US).

Its quite safe to say that you can reduce the degradation to half (or better) by staying low in SOC (as much time as possible below 55%).

If you tell me:
-What tesla you have (for knowing original capacity and range).
- how old it is, down to months ( X yrs Y months) since delivery or build date.
- To what SOC you charged most times.
-End of day SOC (before next charge)
- when /time on the day you start the charge
- The climate where you live, average temp.
- if you park it in a garage or outside.

Then I’ll tell you your expected degradation, expected range today.
(This assumes you owned it since new or know this data for the previous owner as well).
You do not even need to tell me the miles driven.
Tested on quite a few cars so far and it mostly hit quite close.
(This is because calendar aging is predictable and also the main degrading factor for the first 5-8 years.)

Try me!

Hey @AAKEE
I have an interesting one.... I have a MYP and a M3LRAWD with some quite different degradation results. Maybe you can shed some light on.....

Case 1: 2021 MYP
-What tesla you have: 2021 MYP
- how old it is, down to months: Purchased 8/26/2021
- To what SOC you charged most times. 50%
-End of day SOC usually 45% ish
- when /time on the day you start the charge: Charge/precondition before leaving 7:00 am
- The climate where you live, average temp. Denver CO. US Varies from -10f to 100f
- if you park it in a garage or outside. Always Garaged at home. Work, parked outside
This one is currently showing about 4.5% degradation

Case 2: 2022 M3LRAWD
-What tesla you have: 2022 M3LRAWD
- how old it is, down to months: Purchased 2/26/2022
- To what SOC you charged most times. 50%
-End of day SOC usually 40% ish
- when /time on the day you start the charge: Charge/precondition before leaving 6:00 am
- The climate where you live, average temp. Denver CO. US Varies from -10f to 100f
- if you park it in a garage or outside. Always Garaged at home. Work, parked outside
This one is currently showing about 0.0% degradation

Here's what I find interesting is that the M3LRAWD shows No degradation and yet the MYP shows 4.5%. They're of course 6 months difference in age, but the MYP showed it's degradation quite some time ago. probably last summer. I've struggled to identify why
Here's a screenshot of the Tessie Usable capacity graph:

Maybe you can shed some light on the difference.

 

[AAKEE]

Hey @AAKEE
I have an interesting one.... I have a MYP and a M3LRAWD with some quite different degradation results. Maybe you can shed some light on.....

Case 1: 2021 MYP
-What tesla you have: 2021 MYP
- how old it is, down to months: Purchased 8/26/2021
- To what SOC you charged most times. 50%
-End of day SOC usually 45% ish
- when /time on the day you start the charge: Charge/precondition before leaving 7:00 am
- The climate where you live, average temp. Denver CO. US Varies from -10f to 100f
- if you park it in a garage or outside. Always Garaged at home. Work, parked outside
This one is currently showing about 4.5% degradation

This is the value I get:
(i found data about the average temp in Denver is about 50C, so heating from garage and charging might put the average cell temp between 15 and 20C, or so)

I did put in 82.1kWh, I guess the MYP in US did get the new 2170L by then.
(It can be debated what number to use as the initial, I know many M3P start at 80.5 or so with that battery.)
82.1 give 78.9kwh and 296-297 miles range
For me, using 82.1 kWh is spot on
(Using 80.5 kWh as initial gives 77.3kWh and 290-291 miles range.)

Case 2: 2022 M3LRAWD

-What tesla you have: 2022 M3LRAWD
- how old it is, down to months: Purchased 2/26/2022
- To what SOC you charged most times. 50%
-End of day SOC usually 40% ish
- when /time on the day you start the charge: Charge/precondition before leaving 6:00 am
- The climate where you live, average temp. Denver CO. US Varies from -10f to 100f
- if you park it in a garage or outside. Always Garaged at home. Work, parked outside
This one is currently showing about 0.0% degradation

This gives:

The degradation threshold on your M3LR is about 79 kWh and you still is above, this means the car should show full range.

You probably will start to se a decline in range in about 6 months (give or take a few months). In some cases the BMS can stuck high (like mine did). As the hotter period is in near future* it possibly can show earlier, specially if you do larger cycles with higher SOC.

Here's what I find interesting is that the M3LRAWD shows No degradation and yet the MYP shows 4.5%. They're of course 6 months difference in age, but the MYP showed it's degradation quite some time ago. probably last summer. I've struggled to identify why

Maybe you can shed some light on the difference.

The MYP has a higher degradation threshold. I havent looked it up but it probably is at about the same mark as the M3P, around 80.5-80.7kWh.
This means the range start to drop earlier with the MYP.


*) we got a few inches of snow yesterday, and also today. Doesnt feel like the summer is comming

 

[AAKEE]

Here's a screenshot of the Tessie Usable capacity graph:

I do not thrust the Tessie values*

Id prefer you perform a energy graph calculation. A range at 100% could also do it but the energy graph can be used at 55% also (less margin of error the higher the SOC is, but anyway more safe than Tessie)

Energy graph calc:

Average consumption x calculated range x 100 / SOC = total capacity (including the buffer).
For your M3LR the “capping” at full range means you most probably will not see a value above about 79 kWh even if the real capacity is higher.


I found some tessie *usable capacity* showing some 3kWh above the real nomimal full pack.

Usable capacity = In Tessie words meaning the whole capacity including the buffer.

 

[804son]

This is the value I get:
(i found data about the average temp in Denver is about 50C, so heating from garage and charging might put the average cell temp between 15 and 20C, or so)
View attachment 932661

I did put in 82.1kWh, I guess the MYP in US did get the new 2170L by then.
(It can be debated what number to use as the initial, I know many M3P start at 80.5 or so with that battery.)
82.1 give 78.9kwh and 296-297 miles range
For me, using 82.1 kWh is spot on
(Using 80.5 kWh as initial gives 77.3kWh and 290-291 miles range.)




This gives:
View attachment 932669
The degradation threshold on your M3LR is about 79 kWh and you still is above, this means the car should show full range.

You probably will start to se a decline in range in about 6 months (give or take a few months). In some cases the BMS can stuck high (like mine did). As the hotter period is in near future* it possibly can show earlier, specially if you do larger cycles with higher SOC.

The MYP has a higher degradation threshold. I havent looked it up but it probably is at about the same mark as the M3P, around 80.5-80.7kWh.
This means the range start to drop earlier with the MYP.


*) we got a few inches of snow yesterday, and also today. Doesnt feel like the summer is comming

So you think the higher degradation threshold in the MYP has essentially just "displayed" the degradation earlier. Seems logical, it will be interesting to see what happens when the weather finally turns warm in Denver. I would have like to have thought that I got lucky with the M3LRAWD battery, but knew that wasn't the case.

 

[AAKEE]

So you think the higher degradation threshold in the MYP has essentially just "displayed" the degradation earlier. Seems logical, it will be interesting to see what happens when the weather finally turns warm in Denver. I would have like to have thought that I got lucky with the M3LRAWD battery, but knew that wasn't the case.

Whats the range in the MYP, or how did you find the 4.5% loss?
( if its the Tessie value, 75.4kWh out of 82.1 is not 4.5%….)

 

[804son]

I do not thrust the Tessie values*

Id prefer you perform a energy graph calculation. A range at 100% could also do it but the energy graph can be used at 55% also (less margin of error the higher the SOC is, but anyway more safe than Tessie)

Energy graph calc:

Average consumption x calculated range x 100 / SOC = total capacity (including the buffer).
For your M3LR the “capping” at full range means you most probably will not see a value above about 79 kWh even if the real capacity is higher.


I found some tessie *usable capacity* showing some 3kWh above the real nomimal full pack.

Usable capacity = In Tessie words meaning the whole capacity including the buffer.

Thanks for the insight, there are some nuances that I had not considered. The Tessie values for "usable capacity" had been bothering me, they didn't seem to work out when I took what I believed was the total capacity and subtract the buffer. Makes sense that they're worded incorrectly.

 

[804son]

Whats the range in the MYP, or how did you find the 4.5% loss?
( if its the Tessie value, 75.4kWh out of 82.1 is not 4.5%….)

Here's the MYP latest values:

Timestamp (MDT)	Odometer (mi)	Max Range (mi)	Max Ideal Range (mi)	Usable Capacity (kWh)
4/25/2023 0:10​	18071​	282.38​	282.38​	75.11​

 

[804son]

Here's the MYP latest values:

Timestamp (MDT)	Odometer (mi)	Max Range (mi)	Max Ideal Range (mi)	Usable Capacity (kWh)
4/25/2023 0:10​	18071​	282.38​	282.38​	75.11​

Tessie showed initial capacity of 79.0kWh

 

[Art84]

When I am seeing discussions about batteries like this I always think about portable electronics like phones and laptops. For those, we don't care at all about battery SOC. We charge it to 100% every day, use it actively and charge to 100% again. Think about the phone... most of people drain the battery for the day and charge to 100% and this happens every day!
My phones (iPhones) usually last 3-4 years. The last one (iPhone 8) I used for 5 years. Charged to 100% every day. So I assume the battery did 1500 cycles or so and after 5 years it has 75% of capacity remaining. How much of a Tesla battery difference other than size.. I mean in general?
And we don't drain the Tesla battery daily. There is no way you can make charge/discharge 1500 cycles in 5 years unless you are an Uber driver. Most likely battery going to last over 200-300K miles if you use it however you want. How often do you keep the car for so long making more than 200K miles on it? If you are not an Uber driver or don't have daily long commutes - I don't think it's ever worth bothering about babysitting the battery. Just enjoy the car, work hard, make money to upgrade to a new car in 3-5 years ))

 

[TesslaBull]

When I am seeing discussions about batteries like this I always think about portable electronics like phones and laptops. For those, we don't care at all about battery SOC. We charge it to 100% every day, use it actively and charge to 100% again. Think about the phone... most of people drain the battery for the day and charge to 100% and this happens every day!
My phones (iPhones) usually last 3-4 years. The last one (iPhone 8) I used for 5 years. Charged to 100% every day. So I assume the battery did 1500 cycles or so and after 5 years it has 75% of capacity remaining. How much of a Tesla battery difference other than size.. I mean in general?
And we don't drain the Tesla battery daily. There is no way you can make charge/discharge 1500 cycles in 5 years unless you are an Uber driver. Most likely battery going to last over 200-300K miles if you use it however you want. How often do you keep the car for so long making more than 200K miles on it? If you are not an Uber driver or don't have daily long commutes - I don't think it's ever worth bothering about babysitting the battery. Just enjoy the car, work hard, make money to upgrade to a new car in 3-5 years ))

Some may not want the extravagant splurge of a new car every three years. Personally, I'd rather drive my car for ten years and invest the money others waste on a new car every three years. Over time, this will result in many years of early retirement i.e. freedom! Personally, its not worth it to me to work for years and years and years longer just to spend a lot of money on a new car every three years. Well maintained cars will run and drive like new for 10 years easily. 9-5 till your 65....no thanks.

I also don't waste a fortune on new phones every three years. When my iphone battery degrades enough, I pay $69 to have the battery replaced and keep using it for many years. Why waste over $1,000 on a new phone that does the exact same function?

 

[AAKEE]

Tessie showed initial capacity of 79.0kWh

Guess that is Tessie data?
(Try the energy app calculation instead)

 

[Art84]

Some may not want the extravagant splurge of a new car every three years. Personally, I'd rather drive my car for ten years and invest the money others waste on a new car every three years. Over time, this will result in many years of early retirement i.e. freedom! Personally, its not worth it to me to work for years and years and years longer just to spend a lot of money on a new car every three years. Well maintained cars will run and drive like new for 10 years easily. 9-5 till your 65....no thanks.

I also don't waste a fortune on new phones every three years. When my iphone battery degrades enough, I pay $69 to have the battery replaced and keep using it for many years. Why waste over $1,000 on a new phone that does the exact same function?

I am just saying, that after 200K miles on Tesla, there most likely will be other concerns (suspension, electronics, HVAC, etc) other then battery.
As with the phones... even battery is still running, the processor and memory just not enough for the modern apps so need to replace it for a comfort usage. I replaced iPhone 8 not because of the battery degradation.. because it was not enough memory and it could not handle well some of the apps

 

[Rocky_H]

As with the phones...

I hate seeing these comparisons to phones. You don't need to run the newest updated amazing new whiz-bang app that RandomCorp Inc. publishes. It's a car. It drives. It just needs to be able to drive. Tesla has already stopped sending a lot of feature updates to the older cars that don't support them.

 

[johnny_cakes]

If you are not an Uber driver or don't have daily long commutes - I don't think it's ever worth bothering about babysitting the battery. Just enjoy the car, work hard, make money to upgrade to a new car in 3-5 years ))

A counter argument to that is some people don't have the luxury of a large battery and need to drive in a non Supercharger dense area. Here's a trip I need to do this summer and ABRP is telling me that I'll arrive at the next Supercharger with 9% and 8% SoC. A battery with less degradation would leave more room for error.

ABRP Settings:

• 2019 M3 SR+
• Reference consumption at 110 km/h: 166 Wh/km
• Reference speed: 110% of speed limit
• Battery degradation: 14%
• Extra weight: 250 kg