Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health

[KenC]

Does this look normal?
View attachment 750691View attachment 750691One year and 9,200 miles? 2021 LR AWD.

Wow, you take lots of short trips. You're on the low-end of what most would consider normal deg, particularly since it seems to be slowing or bottoming out. It might not be too far different after two years.

 

[conv90]

For that we need to go back on the cars history. Some here says theres a battery lottery, but s far as research is concerned, there seem to be a very little lottery part to all of the research. There is variations, in many reports the variation is marked on the charts. Mostly maxmimum one percent or so up and down for individual cells. Between the reports( = not the same batch, or even the same cell brands or cell type) the variation is qiute small. There is no report showing 5 or 10% loss in one year if the cells had a SOC below 55% if the temperature was reasonable. One test I saw killed the cells at 60 degrees in six weeks, but constantly supplying energy so the cells stayed at 100% SOC. Not supplying voltage, the self drain lowered the SOC and helped the cell stay alive much longer. But there is not research report that really differ from the picture. Different methods make cause small differences etc, and the conclusions somtimes is really funny to read, when they made a mistake they did not realize. But the raw dtata is very clear in the reports.

What range did your car show at 100% SOC when new?
When did you get SMT and did read the first NFP?
When was your car built, and when did you get it( you are the first owner?)
Describe your charging schedule, from day one until now. How much driven daily, nighlt SOC etc. Also describe the average temperatue, for winter, summer spring and autumn. Is the car outside or inside a garage ?@AA

@AAKEE We spoke also in private message about my battery and the fact my battery is low respect yours.
But i reply to your question to let other user know.
1)What range did your car show at 100% SOC when new?
my car started at 79,6 kWh NFP (with FUll Pack When New at 82.1kWh like any other E3LD 2021 Performance battery), so the battery started UNDER the thresold degradation of about 80.7 kWh to shows full range of 505-506 km.
2)When did you get SMT and did read the first NFP?
The day One after 150 km of delivery in March 2021 i connected to SMT
3)When was your car built, and when did you get it( you are the first owner?)
It's a 2021 Model delivered in March 2021 and I'm the first owner
4) Describe your charging schedule, from day one until now. How much driven daily, nighlt SOC etc. Also describe the average temperatue, for winter, summer spring and autumn.
Charged from 30-40% to about 80% and more when needed for long trips from march to august and I had 0% degradation (at least NFP remained at 79,6 kWh). The fact that the range stayed the same (around 500-505 km) is irrilevant because my car already starded UNDER the thresold degradation of about 80.7.
Then I had a drop of about 1,5-2 kWh after an update that I never recovered, so I started to charge it fron 25-30% to 50-55-60% . This as normal routine. Obviously I made many long trips where I used Supercharger and charged to max or 90% just the time to re-start the trip.
I'm in Italy and the temp are quite hot during summer but usually the car in summer rested under 50% SOC.
Autumn and Spring are in the 10°C -20°C range ambient temp
Winter varies from -5°C to 10°C
5) Is the car outside or inside a garage ?
The car is stored OUT (under a canopy).

 

[AAKEE]

Well, if we play with about 4 months where you used more than 60% SOC during the hot period, and temperatures affecting the battery is about 40C( I’d guess 30C outside + sun shining directly on the car):

From this we see that 40C causes degratation about the middle between 25 and 50C

Knowing that, we look at this chart:
Between 60% and 80% if we use the average between 25C 4.0 months and 50C 3.8 months we will get about 5 to 6% calendar aging, from those 4 mounts only.
Of course nights is less hot and no sunshine but as the battery cool quite slow we maybe have quite hogh average temp during a 24h cycle.

I think the most common initial NFP for the M3P ‘21 is cirka 80.5kWh, at least the average is not higher from those we have seen. I think the charging schedule, usage etc have a quite big impact of the early NFP.
If we play with the idea that you bat started with an actual capacity, or “actual NFP” of 80.5, 5-6% loss would put your battery capacity at about 75.7 to 76.5kWh.
I do not know for how long you used 30-40 to 80% and what SOC you had during nights.

You know the SOC, and the ambient temps during the first year of your car. If you use the chart above you could use parts of the summer, for example if June mostly had 30C days and you car stood at 80% mostly you could use half the 2.1 month at 25C, thats about 1% loss for that month.
Do the same for the first six months, and see where you end up.

Calendar aging lessens with time but for the first six months it will not end up very wrong. If you not count the cycles and SuC etc( this probably did wear 1% or less anyway), you will have a calendar sging number that probably is not very long from the probable reality.

 

[AAKEE]

Another way of look at it is to use the teslafi average.

If your car is at about half my mileage, you should be at about 480-485 km range.
The ”constant” is about 159Wh/km

482km x 159wh/km =76.6 kWh NFP is the average around ODO 15.000km
So if you see about 76kWh you’re actually more or less on the mark.

The difference between my car and your car is not because your car is different or broken. The difference comes from my car being different from most others.
My charging scedule is a big part but also our climate, up here at the polar circle sure helps to reduce the calendar aging.

 

[conv90]

Thank you @AAKEE .
The explanation is Exemplary.
The strange thing is that I had no Degradation in the period where I charged to from 30-40 to 80% and the hot climate was an important factor.
I had degradation only when rested at less 20%.
I have no TeslaFi and no range graph, but I have a NFP history on Excel.
Every drop of NFP is an Update (little drops) or car left under 20% (the bigger ones).:
RED are Updates and YELLOW are car left under 20% (usually 15%)
The graph is updated to today with 77,4kWh NFP.
See the battery started at 79,6 kW and in the HOT summer climate it lost nothing.
SMT says 488-492 km (today)
Tha car has 19.000 km

 

[AAKEE]

Thank you @AAKEE .
The explanation is Exemplary.
The strange thing is that I had no Degradation in the period where I charged to from 30-40 to 80% and the hot climate was an important factor.
I had degradation only when rested at less 20%.
I have no TeslaFi and no range graph, but I have a NFP history on Excel.
Every drop of NFP is an Update (little drops) or car left under 20% (the bigger ones).:
RED are Updates and YELLOW are car left under 20% (usually 15%)
The graph is updated to today with 77,4kWh NFP.
See the battery started at 79,6 kW and in the HOT summer climate it lost nothing.
SMT says 488-492 km (today)
Tha car has 19.000 km

View attachment 751524

Well, as a good guy here (@Candleflame) wrote
“degradation happens in chunks”.
He was refering to the BMS reported range/capacity.

yes, normal. degradation isnt gradual as its usually software based whenever the car "recalibrates" which happenes in chunks.

Real degradation is progressive. For example each Supercharge from 10-100% will cost about the same 0.0X% each time.
The calendar aging also, but reducing the rate with time.

The BMS calculated capacity(NFP) will need to be a guesstimate as it cannot discharge it to 0% and charge it to 100% each day. The BMS has data of what SOC a open voltage reading is, and it can count the energy between measurements, and calculate the capacity.
Lack of 0% and 100% readings introduce a error. In my case my low cycles 55 to about 25% introduce a overestimation of the capacity. I have natural needs of higher charging every now and then, which restore the NFP. So far I havent really seen any bigger chunk, currently at 80-80.5kWh NFP and I started with 80.7, so…dont ask me about chunks( yet )

But Im sure the BMS sometimes suddenly find a difference between the earlier estimate and the new percieved “truth” and readjust.
I have seen “loss” of NFP with new software versions but also recovery after a while, and I think a increased NFP after one updated software.

 

[AAKEE]

Heres my NFP graph since I did get Teslalogger. I have the NFP data from the car was new, manually saved.
Red dotted lines = software updates. Just precise installed 2021.44.30.
The update late in September did cut a part of the NFP as it seems.

 

[sunhead21]

I am a remote worker and I use my Model 3 primarily for short drives (groceries etc). Most of my drives are less than 10 mins round trip.

My neighbor believes that because they are short drives and I still charge every night to keep it charged at 70% that it might have a negative effect on battery life.

I don't see the relationship between regular use and Tesla battery life.

Does anyone have any experience or thoughts on this?

 

[jjrandorin]

I am a remote worker and I use my Model 3 primarily for short drives (groceries etc). Most of my drives are less than 10 mins round trip.

My neighbor believes that because they are short drives and I still charge every night to keep it charged at 70% that it might have a negative effect on battery life.

I don't see the relationship between regular use and Tesla battery life.

Does anyone have any experience or thoughts on this?

There is no correlation that we are aware of that says short drives + charging every night has any specific impact at all.

 

[Apprunner]

I am a remote worker and I use my Model 3 primarily for short drives (groceries etc). Most of my drives are less than 10 mins round trip.

My neighbor believes that because they are short drives and I still charge every night to keep it charged at 70% that it might have a negative effect on battery life.

I don't see the relationship between regular use and Tesla battery life.

Does anyone have any experience or thoughts on this?

Maybe he thinks that you aren't keeping your battery near 50% enough? If you read through this very long thread, calendar aging is much slower at 55% or lower for lithium ion batteries.

 

[milesr3]

Tue chart below shows degradation for a Panasonic NCA cell depending on SOC, time and temperature.
Low SOC is also benificial for cyclic aging, so doulbe win from low SOC.
Small cycles degrade the battery less so charge often(every night) is better than charge on a SOC basis.

View attachment 745352

Thank you for posting this graph. If I am reading it correctly, there is a step in relative capacity loss above 55% storage SoC from circa 3% to 5% degradation at 25C after 9.6 months? Thereafter the relative capacity loss is pretty flat from 65% to 80%, then just starts to tail off but at worst it is less than 6% at 100% SoC.

Multiplying by the SQRT of time gives the following relative loss of capacity (degradation);

So, at 8 years the degredation would be 8%, 14% and 17% at <55%, <80% and 100% SoC respectively? The difference between <80% and 100% is less than I expected, given the advice to only charge the car to the range you need and the functionality of the app which distinguishes between daily and trip charging levels.

Unless the average storage temperature is actually higher than 25C if the vehicle is used/charged frequently? In the UK our average daily temperature is 11C and <20C even in summer, which ought to flatten the degradation curve even further.

 

[AAKEE]

Thank you for posting this graph. If I am reading it correctly, there is a step in relative capacity loss above 55% storage SoC from circa 3% to 5% degradation at 25C after 9.6 months? Thereafter the relative capacity loss is pretty flat from 65% to 80%, then just starts to tail off but at worst it is less than 6% at 100% SoC.

Multiplying by the SQRT of time gives the following relative loss of capacity (degradation);
View attachment 751749So, at 8 years the degredation would be 8%, 14% and 17% at <55%, <80% and 100% SoC respectively? The difference between <80% and 100% is less than I expected, given the advice to only charge the car to the range you need and the functionality of the app which distinguishes between daily and trip charging levels.
Unless the average storage temperature is actually higher than 25C if the vehicle is used/charged frequently? In the UK our average daily temperature is 11C and <20C even in summer, which ought to flatten the degradation curve even further.

Remember that the degradation in your table is calendar aging. We also have cycle aging. Fir most this is not a huge part, perhaps 1% per year. The cyclic degradation is more or less a straight line(not square root).
For smaller cycles and maybe 0.5-1% per year it will still not be mire than the calendar aging after 5 years
But if using big cycles and often charge to 100% the cyclic aging will be bigger and maybe be as big as calendar aging after a few years.

We had a discussion recently in a swedish forum with a guy that already have 50.000km on the same car as me( M3P ’21 with the 2170L / 82kWh battery). His range is down to 482km, still he get home with 10% and charge to 90% but just before using the car. He seem to have lost about 5% capacity and most part of this is probably cyclic aging( as it stand with low SOC duting the night).
Not a problem at all. The teslafi average is 482km at 15000km so he is well above that.

Yes, that step comes from the central graphite peak. ( This is a good read about that: Calendar aging NCA )

Teslas recommendation for max 90% for daily use might very well be set due to the fact that smaller cycles at lower SOC reduce the wear. By limiting the charge to 90% the cycle life is doubled.
Most of the research reports show a sign of that the calendar aging actually lessens a bit above about 80%. There is one report showing a big reduction above 80%, but the brand of the 2170 NCA cells is not disclosed. I have deliberately “withheld” to show pictures from that report as it probably would make some peoples mind troubled. In that report, 100% is about as bad(good) as using a SOC below the step (about 55% or so). That report clearly shows that 80% is the worst SOC for calendar aging. The brand/exact version of NCA is not disclosed, it might be possible to find out but its probsably not the panasonic ”Tesla cells”.

I would not go on that data and start storing at high SOC. We do not know the exact battery brand/model and most other research show about the same calendar aging from 70 to 100% in normal temperatures.

Still, below 55% is better or at least as good, and smaller cycles is much better, low SOC cycles also.

 

[CarlThompson]

I've found when discussing this topic many people make two key incorrect assumptions that may affect their reasoning:

1. Assuming that a battery pack with a complex array of thousands of cells managed by a sophisticated battery management system will behave and react similarly to a single cell on a test bench. Statements like "degradation due to cycle wear is linear" fall into this trap. Each individual cell will act like a single cell. But the group may not.
2. Assuming that 0% and 100% on the Tesla's screen exactly correlate to 0% and 100% at the cell level, respectively (however those levels may be defined). Statements like "it's really bad for your battery to drive under 20% charge" fall into this trap.

 

[AAKEE]

I've found when discussing this topic many people make two key incorrect assumptions that may affect their reasoning:

1. Assuming that a battery pack with a complex array of thousands of cells managed by a sophisticated battery management system will behave and react similarly to a single cell on a test bench. Statements like "degradation due to cycle wear is linear" fall into this trap. Each individual cell will act like a single cell. But the group may not.
2. Assuming that 0% and 100% on the Tesla's screen exactly correlate to 0% and 100% at the cell level, respectively (however those levels may be defined). Statements like "it's really bad for your battery to drive under 20% charge" fall into this trap.

For the:
1) Researchers most often use multiple cells at each measuring point, and they present the spread between single cells. This spread is often not more than a single percent up and down from the average. This shows that the spread between cells are not big.
Between research we also see quite small difference, mostly not more than a few percent.
If we take four thousand cells of the same cell and use them together they will probably behave quite close to the middle of the spread, thats the average line in the research report. For some tests the heating/cooling system vill preserve the cells better but for all normal tests where the temperature do not spike and need cooling the test and the real world probably is quite close.
And degradation is more or less linear.
For example if a 100-0% SOC with X C current during the cycles produve a very straight line( until 20% degradation as I have written about before, at 20% the line will droop and the battery is considered used up, by industry standard and by researchers).

2) 100% SOC is 4.20V per cell, this is the same as Tesla use for 100% SOC on our screens.
Tesla use a 4.5% buffer in the bottom, so 0% on our screens is about 4.5% SOC on the cell level.
0% is 2.50V/cell set by the cell manufacturers.
With SMT I can see Max battery voltage= 403 volt, which is 4.20v/cell( 403/96s)
Min battery voltage 241V, which is very close to 2.5V/cell ( 2.51V).

The statement to go below 20% is crap, as lithium oion batteries of this type degrade less the lower SOC you have, both during cycles and during not used.
The BMS keeps the pack safe buy disconnecting it before it get below the minimum voltage.

 

[AAKEE]

This is an example of a cycling test in a research report. The Red line is the outcome, we can see that the degradation is more or less linear.
For our purpose of understanding, we can think of it at linear.

Big cycles more or less look linear, but small cycles at low SOC( which I use in my M3P for daily driving) lessens with time.
This is 20-80% SOC with 1C and 2C.
Red/blue is about 39-40degrees, the other high temp/high C-load. ( this is not Tesla cells, and not NCA. just got the first picture i had available)

 

[sunhead21]

Maybe he thinks that you aren't keeping your battery near 50% enough? If you read through this very long thread, calendar aging is much slower at 55% or lower for lithium ion batteries.

I do maintain my SoC at 70% and I charge every night as it says in the manual.

But from now on I will maintain the SoC at 55%. Thanks for the pointer.

 

[AllSmiles]

my dual motor LR purchased in Sept 2019 has 37000 km. my 80% charge range currently reads 348km range or 217miles. That equates to a full charge range of 435km compared with 518 when new. If my math is correct, that is a 16% drop in range. I have only charged to 100% a few times for a trip, and normally charge at 48A to 90% daily after using about 10% of my battery. In the last 3 months I started charging to 80% and letting the battery drop to about 50%. My W/km lifetime shows 175 (109W/m?), but as most owners know that figure is misleading because that number does not include heat for the battery, cabin, seats, defrost etc. My commute in Vancouver BC Canada is 38km return and in the summer I use about 8-10% of my battery and in winter about double that.

 

[conv90]

my dual motor LR purchased in Sept 2019 has 37000 km. my 80% charge range currently reads 348km range or 217miles. That equates to a full charge range of 435km compared with 518 when new. If my math is correct, that is a 16% drop in range. I have only charged to 100% a few times for a trip, and normally charge at 48A to 90% daily after using about 10% of my battery. In the last 3 months I started charging to 80% and letting the battery drop to about 50%. My W/km lifetime shows 175 (109W/m?), but as most owners know that figure is misleading because that number does not include heat for the battery, cabin, seats, defrost etc. My commute in Vancouver BC Canada is 38km return and in the summer I use about 8-10% of my battery and in winter about double that.

A Model 3 September 2019 LR AWD never showed 519 km at 100% . all 2019 showed (when new) 499-500 km at 100% with E3D battery

 

[jyavenard]

My 2019 performance that for almost all of 2020 and 2021 read 68.5kWh decided to jump back to 70.6kWh over the last 1.5 months.

Not sure if it’s related to a software update, or I’m just lucky.

Anyone else seeing such increase in range over the last 2 months?

 

[jyavenard]

A Model 3 September 2019 LR AWD never showed 519 km at 100% . all 2019 showed (when new) 499-500 km at 100% with E3D battery

Was about to say the same. Never heard of a 2019 showing more than 500km range