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

[Candleflame]

weird. I was on 460km and dropped to 453km gradually over a few days too in mid march. early april i dropped to 450km and then hit this strange recalibration event and i can go up to 455km extrapolated again. In fact when I checked with SMT earlier today the car predicts now 456km. so im just letting my car sit at 60-70% at the moment and will do a 100% charge in 7 days.

 

[KenC]

funny coz thats pretty much what i do. my car sits most of the time around 60%... But I have 10% degradation haha.

That could just be the Arrhenius equation at work like Dave said. You’re in a lot warmer clime than me.

 

[Dave EV]

It's what Tesla is now documenting. Charge the MIC 2021 SR+ car with a LFP battery to 100% at least once a week.

That's only because LFP has a very flat voltage as discharged, so Teslas BMS was having a hard time keeping track of actual state of charge and balance of the pack, not because 100% is good for the cells. If it were good you would do it all the time.

I understand that a firmware update has mitigated this suggestion.

 

[AAKEE]

There is. All three 18”, 19”, and 20” Performance were sold in the US as 2020 models and they all had different ranges as I listed.

If there is ever any question you can go to the EPA website fueleconomy.gov and look it up. Everything is there.

As I have understood it, all LR and Performance earlier had 499km as the full range when new on the screen batttery indicator. My ’21 P also had it, until late jsnuary or early february when I got about 507km which is the EPA range for mine(315mi)

As for Teslafi, I dont know how teslafi calculated the range but it doesnt seem to be the battery meter range. I see variations in SMT full rated range, but the variations is a lot smaller than teslafis battery degradation report.
For my car, the last week the nominal full pack has increased linear from 80.1 to 81.0 kwh.

This thursday teslafi showed about 505km range but SMT showed 508,67km.
During the week the nominal full has increased steady togheter with the range but teslafi generally show a lower number and jumps around a bit, so it did this week despite SMT showed a steady increase.
(The increase probably cones fron i creasing ambient temps...

As you say, the rated range or the teslafi range in battery degradation doesnt seem to be a transparent.

 

[AAKEE]

Yeah, it crossed my mind, but after waiting for it for 4 months, and with the $7500 tax credit expiring in 2 weeks; I decided to keep it, though I had the driver note the ZERO SOC. And, as AlanSubie has noted, I lucked out, as I still have 310 miles of estimated range. Seems like cold weather is much gentler on battery aging than hot weather. It would be interesting to compile a list of deg by geography, since anecdotally, it seems that owners in hot weather locales have suffered more deg. I know there's that chart at BatteryU where it shows storage at 40C vs 25C or something along those lines, but real world data would be fascinating.

Low SOC is not bad for the battery cells in general. For storage the age(degrade) slower the lower the SOC is. May be bad for the 12v bat but not for the batterys.
The do not like to have to produce high currents at low SOC though.
I will drive carefully below 20% SOC.

 

[Candleflame]

That could just be the Arrhenius equation at work like Dave said. You’re in a lot warmer clime than me.

yeah i was shocked, it was a nice day yesterday and i was shocked that my battery was 29.5C in the shade at like 10 in the morning (when its like 23C at nighttime).

That said, jyavenard has same gen of model 3 and he has same degradation as me which also behaves the same. Despite him being in Melbourne which is considerably colder.

 

[Phlier]

yeah i was shocked, it was a nice day yesterday and i was shocked that my battery was 29.5C in the shade at like 10 in the morning (when its like 23C at nighttime).

That said, jyavenard has same gen of model 3 and he has same degradation as me which also behaves the same. Despite him being in Melbourne which is considerably colder.

What kind of temps do you see in the summer where you're at, Candleflame? Just curious to compare your summer temps to where I'm at.

We hit 100f for the first time in mid May, then from June 1st through the end of September, we're 100F+ every day. Curious what your temps are during.. say... January and February.

We console ourselves by saying "at least it's a dry heat." Which does make a difference, honestly. I'd rather spend a day in 100F+ and low humidity here in the dry desert than 90F in the humidity of the east coast. Although when it hits 110F (which is pretty much the daily temp for July and August) it's just brutal... low humidity or not!

 

[Candleflame]

Low SOC is not bad for the battery cells in general. For storage the age(degrade) slower the lower the SOC is. May be bad for the 12v bat but not for the batterys.
The do not like to have to produce high currents at low SOC though.
I will drive carefully below 20% SOC.

i do switch to chill mode below 20% but I did post a paper before which suggested that flogging a battery at 4C at 5% SOC is more healthy for longevity than a 1C draw at 70%.

 

[Candleflame]

What kind of temps do you see in the summer where you're at, Candleflame? Just curious to compare your summer temps to where I'm at.

We hit 100f for the first time in mid May, then from June 1st through the end of September, we're 100F+ every day. Curious what your temps are during.. say... January and February.

We console ourselves by saying "at least it's a dry heat." Which does make a difference, honestly. I'd rather spend a day in 100F+ and low humidity here in the dry desert than 90F in the humidity of the east coast. Although when it hits 110F (which is pretty much the daily temp for July and August) it's just brutal... low humidity or not!

not too hot actually, its mainly the humidity which gets you and makes 30 feel like 45.

I'd say summer is 33C and 25C at night, winter 26C and 18C at night. summer is for like 6months, then winter for like 4-5months.
Outback is usually summer 45C daytime 35C nighttime and 28-30C winter and down to 5C at night.

I find our 33C feels worse in many ways than the 45C in the outback haha. humidity.

 

[Phlier]

not too hot actually, its mainly the humidity which gets you and makes 30 feel like 45.

I'd say summer is 33C and 25C at night, winter 26C and 18C at night. summer is for like 6months, then winter for like 4-5months.
Outback is usually summer 45C daytime 35C nighttime and 28-30C winter and down to 5C at night.

I find our 33C feels worse in many ways than the 45C in the outback haha. humidity.

Sounds pretty nice! A desert rat like me might fit in pretty well there, although my accent probably wouldn't.

Man, I want to visit Australia so bad...

Sorry for the OT posts, Gents, and thanks for that, Candleflame! Enjoy your oncoming cool season.

 

[Candleflame]

something which doesnt fit with the heat theory is that there are heavy fleet vehicles with i.e. 200k km on the clock which dont have that much degradation. And the Tesla Battery operating temperature is 45C. So with 200k km on the clock and no ideling and an average speed of 80kmh (which is very high, in reality the fleet average speed is much lower i bet) the battery spends over 100 days at 45C.

 

[jyavenard]

What kind of temps do you see in the summer where you're at, Candleflame? Just curious to compare your summer temps to where I'm at.

Candleflame's average is definitely much warmer than Melbourne. However temperature here will exceed 47C several times in the year (116.6F) ( and typically drop to below 20 that same evening)

 

[jyavenard]

That's only because LFP has a very flat voltage as discharged, so Teslas BMS was having a hard time keeping track of actual state of charge and balance of the pack, not because 100% is good for the cells. If it were good you would do it all the time.

I understand that a firmware update has mitigated this suggestion.

LFP batteries have been used for many years for energy storage, they are typically used in a setup that charge them constantly at 100%.

So while there's no doubt Tesla recommended the car to be charged to 100% to help calibrating the BMS, they wouldn't have done so if that would lead to premature degradation.

 

[Dave EV]

they wouldn't have done so if that would lead to premature degradation.

"Premature" is relative and subject to interpretation.

 

[AlanSubie4Life]

all LR and Performance earlier had 499km as the full range when new on the screen batttery indicator. My ’21 P also had it, until late jsnuary or early february when I got about 507km which is the EPA range for mine(315mi)

This is a coincidence. The reason the 2021 Performance ended up at 499km originally is because 481km (299mi) was the 2020 range, and 299mi*~80.6/77.8 = 310 miles. Note that the LR AWD 2021 vehicles were nowhere near this value (much higher, though variable - separate topic).

It's a complete coincidence that the 2021 Performance ended up the same as the 2018/2019 vehicles initially (remember, NONE of the 2020 vehicles had 499km of range except for a brief period when they were brand new in late 2019, before Tesla updated the constant).

Basically, the 2021 Performance were assigned the same constant as the 2020 20" wheel version of the Performance, and were given a larger battery. So that ~299miles went to ~310 miles (ratio of new and old capacity). And then subsequently they updated your constant to give you the rated 315 miles (no change in capacity).

Pure coincidence; that 310 miles is quite different than the 310 miles on the 2018/2019 Performance, for a couple reasons. This just shows again that comparing miles degradation across model years (and even within the same model year if the software changed the constant, which does happen, but very rarely, and only at the very initial part of a model year as Tesla software catches up) has to be done extremely carefully. And personally I would separate out different packs so they could be compared to one another, not combine them.

 

[Candleflame]

This is a coincidence. The reason the 2021 Performance ended up at 499km originally is because 481km (299mi) was the 2020 range, and 299mi*~80.6/77.8 = 310 miles. Note that the LR AWD 2021 vehicles were nowhere near this value (much higher, though variable - separate topic).

It's a complete coincidence that the 2021 Performance ended up the same as the 2018/2019 vehicles initially (remember, NONE of the 2020 vehicles had 499km of range except for a brief period when they were brand new in late 2019, before Tesla updated the constant).

Basically, the 2021 Performance were assigned the same constant as the 2020 20" wheel version of the Performance, and were given a larger battery. So that ~299miles went to ~310 miles (ratio of new and old capacity). And then subsequently they updated your constant to give you the rated 315 miles (no change in capacity).

Pure coincidence; that 310 miles is quite different than the 310 miles on the 2018/2019 Performance, for a couple reasons. This just shows again that comparing miles degradation across model years (and even within the same model year if the software changed the constant, which does happen, but very rarely, and only at the very initial part of a model year as Tesla software catches up) has to be done extremely carefully. And personally I would separate out different packs so they could be compared to one another, not combine them.

indeed, i never think of range as range. When I see rated range I just see a kwh constant which is more palatable on a quick glance.
Tbh I wouldnt even mind if there would be a switch from rated "typical" to rated "kwh".


Also dont know if I mentions this on Teslafi you can display fleet data to be within certain C of your charging temperature. And If i limit mine to i.e. 6C (so most people have ambient temperatures above 25C) average range does go down slightly, perhaps by 4-5km. But not as much as you would expect and sample size is lower.

 

[jelloslug]

Low SOC is not bad for the battery cells in general. For storage the age(degrade) slower the lower the SOC is. May be bad for the 12v bat but not for the batterys.
The do not like to have to produce high currents at low SOC though.
I will drive carefully below 20% SOC.

You cannot hurt your battery when the indicator on the screen says that your SOC is low. The threshold where battery damage can occur is far below where the car will turn off to protect itself.

 

[Earl]

The threshold where battery damage can occur

This is wrong. There is no threshold.
Its a continuum from minimum damage at about 50% SoC with more damage occurring as the SoC moves beyond 50% either high or low.
Between about 10% and 90%, the 'badness' isn't too bad but there is a 'knee' in the curve below 10% and above 90% where the damage becomes more pronounced. At or beyond the cutoff point, you're really hurting your battery.

 

[jelloslug]

This is wrong. There is no threshold.
Its a continuum from minimum damage at about 50% SoC with more damage occurring as the SoC moves beyond 50% either high or low.
Between about 10% and 90%, the 'badness' isn't too bad but there is a 'knee' in the curve below 10% and above 90% where the damage becomes more pronounced. At or beyond the cutoff point, you're really hurting your battery.

There is zero proof of what you are saying. There absolutely is a buffer at the top and the bottom. If there was not, people would be bricking their batteries all the time. The only thing that causes wear on the batteries is the actual usage of it. How you charge it, especially on L1 & L2 charging equipment, has no effect at all. Short of leaving your battery a 0% for months, there is nothing you can actively do to damage the battery. There is almost a decade of evidence to back me up.

 

[jelloslug]

Hey Rocky_H, if you are just going to disagree with everything, why don't you back it up with some actual info?