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

[AlanSubie4Life]

Hopefully someone reads this at the end of all these pages of posts. Noobie so didn’t want to start new thread.
Bought used 2020 M3LR 19” sport wheels, June build Fremont. Has 32k miles. Read and watched battery degradation stuff till my eyes bled.
Car was reset to factory when used purchase was made. Been charging to 80% each night with Tesla Wall Charger. Today I wanted to see roughly him many miles I would get at 100% SOC as I bought for road tripping in retirement. See pictures attached. 277 miles at 100%. What am I not understanding or did I buy a used Tesla with major battery degradation?

Pretty normal. That's just 14%. You will probably find slower declines from here. Can try charging consistently to 50% instead but depends on use case. You're in a hot area in general so slightly higher capacity loss is normal. 10% is basically the norm at this stage, 14% is a little high, but also totally normal.

 

[RMannino]

Thank you for your quick response
Love the car anyway

 

[Candleflame]

Hopefully someone reads this at the end of all these pages of posts. Noobie so didn’t want to start new thread.
Bought used 2020 M3LR 19” sport wheels, June build Fremont. Has 32k miles. Read and watched battery degradation stuff till my eyes bled.
Car was reset to factory when used purchase was made. Been charging to 80% each night with Tesla Wall Charger. Today I wanted to see roughly him many miles I would get at 100% SOC as I bought for road tripping in retirement. See pictures attached. 277 miles at 100%. What am I not understanding or did I buy a used Tesla with major battery degradation?

thats similar to my 2019 car with 55k kms. seems slightly below average i.e. normal.

 

[AAKEE]

Been charging to 80% each night with Tesla Wall Charger.

You already got good answers from @AlanSubie4Life and @Candleflame but I’d like to emphasize the impact hot climat has on the degradation:
Most part of your cars degradation is not comming from the miles driven.
It is the calendar that is the main degrading factor during (at least) the five first years.

Calendar aging is driven by [Time x SOC x Temperature]

80% SOC during long time during high ambient temps will degrade the battery quite some. One good thing, after the first 3-4 years the rate will be much lower.

3.45 V is about 25% SOC
3.7 V is about 45% SOC
4.1 V is about 85% SOC

If you look at the 4.1V /cell to the right, having an average cell temp in the middle between 25 and 40C put you at about 8 % loss after two years.
Having an average cell temp of 40C and you are at about 11% loss agter two years.
To both examples above you have to ad about one percent or slightly more or so for each year from the cyclic aging (”the miles”).

Three years at the middle of 25 and 40C is about 12% loss, plus, lets say 1% cyclic loss year put you at 14%.

So, does it help to reduce the SOC to 70%?
- Not much. The calendar aging Curve is quite flat between 60 to 80%.

What do help then?

- Having a low average SOC helps.
Charging in the morning so the average SOC during the night is lower, helps. The time from the charging stops until the drive should be short

-Not charging more then needed for the day (plus a range-anxiety killing margin) also helps keeping the average SOC down.

(Your car has the NCA chemistry)

 

[RMannino]

Thank you guys for your reassuring words and explanations. I am so glad that we all have this forum! I am making a road trip into Sonora MX in January and accurate range and charging will be critical.

 

[AlanSubie4Life]

I am making a road trip into Sonora MX in January and accurate range and charging will be critical

Plan on roughly 150 miles between charges. That’s the (very) approximate “optimal” range for minimum trip time. (First leg can be a bit longer.)

 

[KenC]

Thank you guys for your reassuring words and explanations. I am so glad that we all have this forum! I am making a road trip into Sonora MX in January and accurate range and charging will be critical.

Highly recommend using ABRP in route planning. If you register for free, it'll pull the API data from your car and give you more accurate results. Also, you can test out some strategies to see what is and what isn't more efficient for road tripping. Most people naturally assume the goal is to maximize range between stops; but I find the fastest trip times are when I drive as fast as I am comfortable with and charge at the lowest SOCs I am comfortable with. That's because more supercharging is more time efficient than more slow driving.

 

[RMannino]

Great advice. Thank you.

 

[DownshiftDre]

In 2022.36.2 Service Mode looks like Battery Health and Health Test is shown. Have not run Battery Test.

Also note on second picture difference between battery SoC on top of screen and the graphic.

Thoughts?

 

[MP3Mike]

Also note on second picture difference between battery SoC on top of screen and the graphic.

Thoughts?

That the buffer below 0% is about 4%?

 

[AlanSubie4Life]

In 2022.36.2 Service Mode looks like Battery Health and Health Test is shown. Have not run Battery Test.

Also note on second picture difference between battery SoC on top of screen and the graphic.

Thoughts?

View attachment 863208
View attachment 863209
View attachment 863210

Yeah, that is fully expected. Can’t quite get the math to work out (I calculate true SOC to be 49.4%, with a 4.5% buffer and 47% of the 95.5% above the buffer available), but I may be making a dumb mistake in the calculation, or they may have a different definition here for true SOC %s.

Someone with SMT could easily do the comparison anyway. Lots of different SOC% there too, which have different definitions (SOC UI, SOC Expected, etc.).

Everything seems fine. Battery test seems relatively pointless and may as well just drive somewhere instead and measure your battery health. I guess you may prefer to put cycles on your garage queen while it remains in the garage. You can try it, though, for science.

 

[DownshiftDre]

Yeah, that is fully expected. Can’t quite get the math to work out (I calculate true SOC to be 49.4%, with a 4.5% buffer and 47% of the 95.5% above the buffer available), but I may be making a dumb mistake in the calculation, or they may have a different definition here for true SOC %s.

Someone with SMT could easily do the comparison anyway. Lots of different SOC% there too, which have different definitions (SOC UI, SOC Expected, etc.).

Everything seems fine. Battery test seems relatively pointless and may as well just drive somewhere instead and measure your battery health. I guess you may prefer to put cycles on your garage queen while it remains in the garage. You can try it, though, for science.

Lol Yes those pics were for my wifes MYP. My “garage queen” M3P was showing 6% between the different SoC displayed.

I thought the added battery test and a “battery health” was interesting. Would be curious to see if a higher mileage vehicles would show degradation in the health number. Could it also possibly recalibrate with the push of a button and get some peoples displayed range back. That would be interesting to find out.

I recall earlier iPhone OS maybe 10 years ago had a calibrate battery button.

 

[bossra95]

Hi Everyone

I am a new M3P owner and have a question about daily charging. I have a long commute to work about twice a week which is about 130-140 miles round trip from my apartment to my office. I have cheap Level 2 chargers at the office that are cheap, and I have a couple of superchargers by my apartment that I can use to charge my car as needed when I am not at the office. Since I drive a lot, I wondered if I should just charge to 80% and not 90% for daily charging. I know Tesla states 20% - 80%/90%, but I assume 80% for daily driving is best for battery health.

What are you thoughts? I am leaning towards 80% but having 90% is a nice buffer to have, I just rather have my battery health be the best in the long run.

 

[Bouba]

Hi Everyone

I am a new M3P owner and have a question about daily charging. I have a long commute to work about twice a week which is about 130-140 miles round trip from my apartment to my office. I have cheap Level 2 chargers at the office that are cheap, and I have a couple of superchargers by my apartment that I can use to charge my car as needed when I am not at the office. Since I drive a lot, I wondered if I should just charge to 80% and not 90% for daily charging. I know Tesla states 20% - 80%/90%, but I assume 80% for daily driving is best for battery health.

What are you thoughts? I am leaning towards 80% but having 90% is a nice buffer to have, I just rather have my battery health be the best in the long run.

The golden rule here is to do what AAKEE says....if you look just above at post #5364 he has summed it all up beautifully

 

[AAKEE]

I wondered if I should just charge to 80% and not 90% for daily charging. I know Tesla states 20% - 80%/90%, but I assume 80% for daily driving is best for battery health.

I think you are hit by forum thuths.

(Where does Tesla state 20-80% /90% ?)

I recommend reading the manual and following Teslas tips in the manual.
Teslas manual doesnt really say what people say it says (strange, huh?)

I just rather have my battery health be the best in the long run.

The battery will be fine just following Teslas manual.

Teslas tips in the manual is not made to minimize degradation though. Teslas tips is to make the car as useble as possible.

There is a lot of information written about minimizing degradation in this forum.

 

[AAKEE]

Yeah, that is fully expected. Can’t quite get the math to work out (I calculate true SOC to be 49.4%, with a 4.5% buffer and 47% of the 95.5% above the buffer available), but I may be making a dumb mistake in the calculation, or they may have a different definition here for true SOC %s.

Someone with SMT could easily do the comparison anyway. Lots of different SOC% there too, which have different definitions (SOC UI, SOC Expected, etc.).

As usual your calc is good. 47 on screen = 49.4% true SOC.

Of all the SOC values that show in SMT, SOC MIN is the same as the one we call ”True SOC”.
True SOC as we see it:
Nominal remaining / nominal full pack
This will give the same number as SOC MIN
So, we know what SOC MIN refers to.

The SOC MAX might have to do something with the CAC values (CAC Max and CAC min), maybe.
The SOC UI seems very high at low SOC, too big to be a real SOC.
I know the makers of SMT didnt know but kept the value showing in the app.
In my case, I didnt ever really care as these SOC numbers wasnt needed for anything.

I do not know at which voltage a Tesla shuts down and disconnects the battery but anyway it is not much energy left below the 4.5% buffer, so the big difference to the number we see on that.

It is possible (probable) that the difference between it is as easy as that the service mode shows the SOC in the same *percent unit size* as the on screen SOC does but also actually showing the buffer.
In this case, a full charge should be 104.7%
4.5% buffer is 4.7% in the on screen [percent size].

The 47% is rounded and could easily actually be 46.6%. Add the 4.7% buffer and the number on the service mode screen is 46.6 + 4.7 = 51.3%

 

[Joeblue83]

You already got good answers from @AlanSubie4Life and @Candleflame but I’d like to emphasize the impact hot climat has on the degradation:
Most part of your cars degradation is not comming from the miles driven.
It is the calendar that is the main degrading factor during (at least) the five first years.

Calendar aging is driven by [Time x SOC x Temperature]

80% SOC during long time during high ambient temps will degrade the battery quite some. One good thing, after the first 3-4 years the rate will be much lower.

View attachment 862522

3.45 V is about 25% SOC
3.7 V is about 45% SOC
4.1 V is about 85% SOC

If you look at the 4.1V /cell to the right, having an average cell temp in the middle between 25 and 40C put you at about 8 % loss after two years.
Having an average cell temp of 40C and you are at about 11% loss agter two years.
To both examples above you have to ad about one percent or slightly more or so for each year from the cyclic aging (”the miles”).

Three years at the middle of 25 and 40C is about 12% loss, plus, lets say 1% cyclic loss year put you at 14%.

So, does it help to reduce the SOC to 70%?
- Not much. The calendar aging Curve is quite flat between 60 to 80%.

What do help then?

- Having a low average SOC helps.
Charging in the morning so the average SOC during the night is lower, helps. The time from the charging stops until the drive should be short

-Not charging more then needed for the day (plus a range-anxiety killing margin) also helps keeping the average SOC down.

(Your car has the NCA chemistry)

View attachment 862535

Great post. I live in wisconsin and was wondering if battery degrades in much lower temps. Like less than 32f?? Thanks

 

[AAKEE]

Great post. I live in wisconsin and was wondering if battery degrades in much lower temps. Like less than 32f?? Thanks

Lower ambient ( = lower cell temps) means less calendar aging.
You can see that 10C cause less calendar aging than 25C.
32F is 0C and the line would probably be slightly above the 10C line. About 1/2 of the difference between 25 and 10C or so.
There is research showing that at -20C the calendar sging has virtually stopped.

Cycic aging is higher at low cell temps so it is not only good to lower the cell temp without lower limits.

 

[Bouba]

Lower ambient ( = lower cell temps) means less calendar aging.
You can see that 10C cause less calendar aging than 25C.
32F is 0C and the line would probably be slightly above the 10C line. About 1/2 of the difference between 25 and 10C or so.
There is research showing that at -20C the calendar sging has virtually stopped.

Cycic aging is higher at low cell temps so it is not only good to lower the cell temp without lower limits.
View attachment 863470

Am I willing to live in a country that is twenty celsius below freezing to protect my Tesla battery ?....YES!!!

 

[Apprunner]

Am I willing to live in a country that is twenty celsius below freezing to protect my Tesla battery ?....YES!!!

No freaking way. I'd rather change cars every 5 years then have to live in cold weather