8 month old battery degradation

[ucmndd]

And considering that right now we are frequently making a trip that requires maximum range due to very limited Superchargers along our route

“Very limited” or “none”?

What about other DC fast chargers? I’m frankly surprised there are any 200+ mile gaps at all along a US interstate in 2024…

 

[AAKEE]

I'm shocked at how fast our 2024 Model Y Long Range is losing capacity. According to Scan My Tesla the BMS system reports that the battery original capacity is 82.1 kWh. When we took delivery with 4 miles on the odometer it showed 81.9 kWh

Panasonic 2170L, the 82.1 kWh pack has a bit higher degradation rate than the first gen 2170.
Still, 81.9 kWh is very good.
Nominal Full Pack or Nominal Remaining at a full charge?

At average ambient temps you could expect to loose 5.5-6.5% or sometimes more the first year from calendar aging only when having the car above 55% SOC mostly.

Calendar aging is most rapid initially and reduces the rate with the swuare root of time.
With 6.5% first year, you would expect to loose ~ 3.75% the first four months.
78.4 out of 82.1 is ~ 4.5% so not very far from what to expect. The BMS could be out in the blue as well.

For normal driving we charge typically to 60-75% & don't discharge below 35%. Occasionally for long drives we have to charge to 100%, but I try to time the charging with our departure & limit the time parked at 100% after charging is completed to less than 1 hour, often less than 30 mins.

You could search for some of my numerous posts about calendar aging.
Calendar aging will be the thing that degrades the absolute most part of your battery for the first 8 year or so.

The most important thing is to keep the SOC at or below 55% as often as possible.

You can see that low SOC is better for reducing the calendar aging, all the way down to 0%. (But as 0% gives limited range, 55% displayed SOC cut the calendar aging to half but still offers 55% of the range. This is the sweet spot for range vs degradation.

The usual thing people have problem with is the low SOC part. The usual myth talk about not going below 20% but that is - right - a myth.
The battery is happy all the way down to 0%

For cyclic aging, we need to first remember that cyclic aging will only be responsible for a minor part of the degradation the first 8 years or so.

These cycles are from the voltage in the chart down to 2.5V ( = true 0%)
We can see that a lower charging voltage ( = lower SOC) causes less degradation.
4.2V = 100%
Then around 0.1V decrease = 10% which means that 3.7V ~ 50%.

This chart shows actual model 3 cells taken from a almost new model 3.
Cycled in 10% Depth of discharge in different SOC ranges.

If we look at the cycling range causing the most cyclic aging which is 5-15% SOC (this transfers to ~ 0-10% in Teslas display, as Tesla has a 4.5% buffer in the bottom).

In this case we loose ~17% after 3000 FCE cycles (which actually is 30.000 actual 10% cycles).
3000 FCE would be around 3000 x 250 miles real range so around 750.000 miles.
Still we only loose 17% so with an normal annual driving of ~ 12500 miles we would loose 12500/750.000x17 = 0.28% each years in cyclic aging. Despite cycling the battery in the very low end. (Which by the myths is said to be very bad to the battery)

So using the battery in a low SOC range will reduce both the calendar and cyclic aging.

I did use the low SOC stategy with my M3P 2021 with the same 82.1 kWh battery. I had a lot less degradation than most people, after 2.5 years and 66K km the battery capacity was 78.0-78.4kWh (last full charge 492 km range out of 507km).
The man owning that car now has not been interrested in using the low SOC strategy but it still has a good 76.8 kWh capacity after 3.5 years.

My BMS was on a bad estimation tour in the summer of 2022, but I did a 100-0% drive to test the capacity and it was 79 kWh at that time, so the correct range should have been around 498 km then. The dip seen is the BMS Being off.

I use the same on my ‘23 MSP, which still show full range after 1 year ownership and 20K km plus (97.1 kWh nomimal full pack today, close to what the most see as the top value.). Full pack when new = 99.4kWh but most packs show 97-97.5 kWh as the top value.

Our previous 2016 Model S 90D was down about 14% after 7.5 years & 125k miles. This loss on the Y seems very fast. And considering that right now we are frequently making a trip that requires maximum range due to very limited Superchargers along our route this 3+ kWh (10+ miles) loss has already put us in a bind where we had to reduce our speed to 65 MPH on the interstate so as to not get stranded in a rural area with no Superchargers.

You do not need to worry about using full charge, that will not kill your battery.
Use full charge whenever you want/need to.

I did have more than 30 full charges on my M3P (exact number forgotten, but possible to check…I think 35) I also had around 55 Supercharging sessions on that car, still low degradation.

I have around 12-15 full charges on my ‘23 MSP and ~ 20 Supercharging sessions.
The car has very low degradation despite this.

Its not the full charges nor the Supercharging sessions that will reduce the capacity very fast. It is calendar aging that get the rate set by [SOC x Temperature].

 

[hybridbear]

“Very limited” or “none”?

What about other DC fast chargers? I’m frankly surprised there are any 200+ mile gaps at all along a US interstate in 2024…

Well, from our current home to our destination we use 65-75% depending on wind & weather right now during summer. For the return trip we have an SC 20 miles away or 90 miles away. If we make it at 35% remaining we can make it to the one 90 miles away. If we are lower then we have to go to the close one & charge more slowly because of a higher arrival SOC. Both of these SCs are V2 so 150 kW max. The 4% capacity loss is pushing those arrival SOCs the wrong way.

 

[boulder.dude]

“Very limited” or “none”?

What about other DC fast chargers? I’m frankly surprised there are any 200+ mile gaps at all along a US interstate in 2024…

Some Tesla owners want to drive on non-Interstates as well. Add a headwind, rain, or elevation gain and things get dicey. (Blanding UT -> Flagstaff. AZ for example.)

 

[AlanSubie4Life]

Some Tesla owners want to drive on non-Interstates as well. Add a headwind, rain, or elevation gain and things get dicey. (Blanding UT -> Flagstaff. AZ for example.)

There are vast expanses of the American West which are basically inaccessible (for convenient use, not involving sitting charging for hours solely reliant on RV outlets or whatever) to Teslas due to major deficiencies in the Supercharger network. Mainly in Nevada, but certainly also in places in Arizona and Utah.

They’re not places a lot of people go, but they are places people go.

 

[ucmndd]

Some Tesla owners want to drive on non-Interstates as well. Add a headwind, rain, or elevation gain and things get dicey. (Blanding UT -> Flagstaff. AZ for example.)

My question was to OP, who explicitly mentioned traveling on the interstate.

 

[hybridbear]

My question was to OP, who explicitly mentioned traveling on the interstate.

And I tried to give you more details about the challenges in this particular area of rural MN & IA.

 

[Mrbrock]

Well, from our current home to our destination we use 65-75% depending on wind & weather right now during summer. For the return trip we have an SC 20 miles away or 90 miles away. If we make it at 35% remaining we can make it to the one 90 miles away. If we are lower then we have to go to the close one & charge more slowly because of a higher arrival SOC. Both of these SCs are V2 so 150 kW max. The 4% capacity loss is pushing those arrival SOCs the wrong way.

If you are worried about a higher arrival SOC slowing down your charge at the closer SC then you can start with lower SOC. Also, complaining about time spent at a supercharger due to HIGH SOC at arrival goes against you saying you need MAX range to maker the trip. You can also start with an even lower charge and charge at the site 20 miles from your destination and then fully charge to be able to get to your destination and back home without needing to stop on the return trip. It sounds like you actually have a lot of options for the trip.

 

[AAKEE]

If you are worried about a higher arrival SOC slowing down your charge at the closer SC then you can start with lower SOC. Also, complaining about time spent at a supercharger due to HIGH SOC at arrival goes against you saying you need MAX range to maker the trip. You can also start with an even lower charge and charge at the site 20 miles from your destination and then fully charge to be able to get to your destination and back home without needing to stop on the return trip. It sounds like you actually have a lot of options for the trip.

Arriving with a higher SOC is not negative, actually. It should be seen as energy already charged reducing the charging time at that session.
Of course we would adjust that charge to arrive with low SOC at the next charge.

 

[flai54]

Panasonic 2170L, the 82.1 kWh pack has a bit higher degradation rate than the first gen 2170.
Still, 81.9 kWh is very good.
Nominal Full Pack or Nominal Remaining at a full charge?

At average ambient temps you could expect to loose 5.5-6.5% or sometimes more the first year from calendar aging only when having the car above 55% SOC mostly.

Calendar aging is most rapid initially and reduces the rate with the swuare root of time.
With 6.5% first year, you would expect to loose ~ 3.75% the first four months.
78.4 out of 82.1 is ~ 4.5% so not very far from what to expect. The BMS could be out in the blue as well.


You could search for some of my numerous posts about calendar aging.
Calendar aging will be the thing that degrades the absolute most part of your battery for the first 8 year or so.

The most important thing is to keep the SOC at or below 55% as often as possible.

You can see that low SOC is better for reducing the calendar aging, all the way down to 0%. (But as 0% gives limited range, 55% displayed SOC cut the calendar aging to half but still offers 55% of the range. This is the sweet spot for range vs degradation.

The usual thing people have problem with is the low SOC part. The usual myth talk about not going below 20% but that is - right - a myth.
The battery is happy all the way down to 0%
View attachment 1053810


For cyclic aging, we need to first remember that cyclic aging will only be responsible for a minor part of the degradation the first 8 years or so.

These cycles are from the voltage in the chart down to 2.5V ( = true 0%)
We can see that a lower charging voltage ( = lower SOC) causes less degradation.
4.2V = 100%
Then around 0.1V decrease = 10% which means that 3.7V ~ 50%.
View attachment 1053812

This chart shows actual model 3 cells taken from a almost new model 3.
Cycled in 10% Depth of discharge in different SOC ranges.

If we look at the cycling range causing the most cyclic aging which is 5-15% SOC (this transfers to ~ 0-10% in Teslas display, as Tesla has a 4.5% buffer in the bottom).

In this case we loose ~17% after 3000 FCE cycles (which actually is 30.000 actual 10% cycles).
3000 FCE would be around 3000 x 250 miles real range so around 750.000 miles.
Still we only loose 17% so with an normal annual driving of ~ 12500 miles we would loose 12500/750.000x17 = 0.28% each years in cyclic aging. Despite cycling the battery in the very low end. (Which by the myths is said to be very bad to the battery)
View attachment 1053813

So using the battery in a low SOC range will reduce both the calendar and cyclic aging.

I did use the low SOC stategy with my M3P 2021 with the same 82.1 kWh battery. I had a lot less degradation than most people, after 2.5 years and 66K km the battery capacity was 78.0-78.4kWh (last full charge 492 km range out of 507km).
The man owning that car now has not been interrested in using the low SOC strategy but it still has a good 76.8 kWh capacity after 3.5 years.
View attachment 1053826
My BMS was on a bad estimation tour in the summer of 2022, but I did a 100-0% drive to test the capacity and it was 79 kWh at that time, so the correct range should have been around 498 km then. The dip seen is the BMS Being off.

I use the same on my ‘23 MSP, which still show full range after 1 year ownership and 20K km plus (97.1 kWh nomimal full pack today, close to what the most see as the top value.). Full pack when new = 99.4kWh but most packs show 97-97.5 kWh as the top value.

You do not need to worry about using full charge, that will not kill your battery.
Use full charge whenever you want/need to.

I did have more than 30 full charges on my M3P (exact number forgotten, but possible to check…I think 35) I also had around 55 Supercharging sessions on that car, still low degradation.

I have around 12-15 full charges on my ‘23 MSP and ~ 20 Supercharging sessions.
The car has very low degradation despite this.

Its not the full charges nor the Supercharging sessions that will reduce the capacity very fast. It is calendar aging that get the rate set by [SOC x Temperature].

What is the advice for those that have a M3 RWD LFP battery. What SOC should the car be sitting at most of the time to be in the happy medium and reduce calendar aging and degratdation?

 

[AlanSubie4Life]

What is the advice for those that have a M3 RWD LFP battery. What SOC should the car be sitting at most of the time to be in the happy medium and reduce calendar aging and degratdation?

Below 70%

(Follow the link for info.)