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

[STS-134]

Define ”overdischarge” for your self.

The battery manufacturers and researchers define it as discharging the battery cell beyond the designed limit.

We can not discharge the battery beyond the limit as the car will shut down the battery via the cobtactors before we reach that limit. Thats also, correct, stated in the document STS-134 refers to:
View attachment 799747

The same document refers to this test:
View attachment 799748

Its only one of very many showing the same thing.
How come the battery cycled down to 0% SOC has the absolutely, by a wide margin, the lowest degradation?
Cycled down to 0% caused 3% degradation. Cycled down to 20% has 9% degradation.
How would the battery thats cycled to 20% have 3X degradation if the one cycled in the dangerous ”overdischarge” region ?

If you start reading resesrch reports you will find that:
100% SOC = the state with the maximum cell voltage
0% SOC = the state with lowest cell voltage(actually stopped discharging at lowest voltage, and regains voltage at rest after the discharge cycle.
Capacity = the energy delivered between 100 and 0% SOC.

Overdischarge= discharging the battery beyond the specified limit.

There is also research reports about overdischarge. For batterys with 2.5V discharge limit there was hardly any damage detected if discharged down to 2.0 Volts. The damage occured if dischsrged to lower than 2.0V.

ALL data show that 0% is safe. 0% is not overdischarge.

Huh, I took a look at Table 2 on page 7. It does appear that it's perfectly okay to store a battery at say 5% so long as you do not over discharge it. In the real world, a lot of people probably WILL over discharge it if they let it go that low and do not plug in so that's probably why all of the manufacturers say not to do it. But then again, that's for LFP, which Tesla apparently says is okay to keep at 100% all the time?!? Looks like high temperature/high SoC hurts LFP batteries as well.

 

[AlanSubie4Life]

But then again, that's for LFP, which Tesla apparently says is okay to keep at 100% all the time?!?

As I understand it, Tesla does NOT say this. I don't think there is anything in the Owner's Manual that says that. They just recommend keeping it at 100%. They don't say it's not going to result in capacity loss. I guess it depends on your definition of "ok."

Specific verbiage:
"If your vehicle is equipped with an LFP Battery, Tesla recommends that you keep your charge limit set to 100%, even for daily use, and that you also fully charge to 100% at least once per week. If Model 3 has been parked for longer than a week, Tesla recommends driving as you normally would and charge to 100% at your earliest convenience."

"Following the above guidance maximizes available range and improves the vehicle's ability to accurately determine the state of charge and estimated range."

And I read maximizing the available range as not suggesting that it will minimize capacity loss. I read that as it maximizing the energy stored in the battery (the "obvious" interpretation...). It's not clear at all whether this strategy will "maximize available range" after 5 years in the sense we mean here. We'll find out in a couple years!

Tesla doesn't care if your battery loses 15% capacity - they just want the car to be useful (convenient to use) to people, have maximum performance, and not have people running out of energy because of their OCD charging habits or a BMS that lost track of available energy (not a good look). So for them it makes sense to recommend to people to charge it as high as possible without limited regeneration being annoying. The capacity loss doesn't matter to them, or to the owners, for most owners.

 

[STS-134]

As I understand it, Tesla does NOT say this. I don't think there is anything in the Owner's Manual that says that. They just recommend keeping it at 100%. They don't say it's not going to result in capacity loss. I guess it depends on your definition of "ok."

Specific verbiage:
"If your vehicle is equipped with an LFP Battery, Tesla recommends that you keep your charge limit set to 100%, even for daily use, and that you also fully charge to 100% at least once per week. If Model 3 has been parked for longer than a week, Tesla recommends driving as you normally would and charge to 100% at your earliest convenience."

"Following the above guidance maximizes available range and improves the vehicle's ability to accurately determine the state of charge and estimated range."

And I read maximizing the available range as not suggesting that it will minimize capacity loss. I read that as it maximizing the energy stored in the battery (the "obvious" interpretation...). It's not clear at all whether this strategy will "maximize available range" after 5 years in the sense we mean here. We'll find out in a couple years!

If you lose capacity, you aren't maximizing available range, now are you? Especially if you aren't using most of the range on most days and the battery is degrading needlessly.

 

[AlanSubie4Life]

If you lose capacity, you aren't maximizing available range, now are you? Especially if you aren't using most of the range on most days and the battery is degrading needlessly.

Exactly, as I said, "in the sense we mean here." But I don't think that's what Tesla means, and it's certainly reasonable to interpret their statement in that other way.

 

[STS-134]

Exactly, as I said, "in the sense we mean here." But I don't think that's what Tesla means, and it's certainly reasonable to interpret their statement in that other way.

It's certainly inconsistent with how they tell you to use the NCA batteries. Apparently it will warn you to not constantly charge NCA above 90% due to capacity loss if you do it too many times in a row? (I've never done this but that's what I've seen reported).

 

[AlanSubie4Life]

It's certainly inconsistent with how they tell you to use the NCA batteries. Apparently it will warn you to not constantly charge NCA above 90% due to capacity loss if you do it too many times in a row? (I've never done this but that's what I've seen reported).

Yes but in the case of LFPs there's the significant issue of the BMS losing track if it doesn't see the 100% level, so it may be the lesser of two evils. Hard to know. In any case, Tesla is not particularly concerned about minor capacity loss of 15% over a couple years. They may have determined that constantly charging to 100% on non-LFP does open them up to higher warranty (or safety?) risk, which would explain that NCA warning - and it's an old warning, so they may be more comfortable with the LFPs now than they were with the NCAs a couple years ago - even if fundamentally they're not that different in overcharging capacity loss (they may also just be a bit different, with LFPs more tolerant of 100% than NCA - but different does not necessarily mean "immune" for the LFP).

Impossible for us to know, but for now I don't see any way to conclude that LFPs will be just fine being charged to 100% all the time, as far as calendar aging is concerned. We'll have to find out, in a couple years.

 

[FlatSix911]

Define ”overdischarge” for your self.
The battery manufacturers and researchers define it as discharging the battery cell beyond the designed limit.

We can not discharge the battery beyond the limit as the car will shut down the battery via the cobtactors before we reach that limit. Thats also, correct, stated in the document STS-134 refers to:
View attachment 799747

The same document refers to this test:
View attachment 799748

Its only one of very many showing the same thing.
How come the battery cycled down to 0% SOC has the absolutely, by a wide margin, the lowest degradation?
Cycled down to 0% caused 3% degradation. Cycled down to 20% has 9% degradation.
How would the battery thats cycled to 20% have 3X degradation if the one cycled in the dangerous ”overdischarge” region ?

If you start reading resesrch reports you will find that:
100% SOC = the state with the maximum cell voltage
0% SOC = the state with lowest cell voltage(actually stopped discharging at lowest voltage, and regains voltage at rest after the discharge cycle.
Capacity = the energy delivered between 100 and 0% SOC.

Overdischarge= discharging the battery beyond the specified limit.

There is also research reports about overdischarge. For batterys with 2.5V discharge limit there was hardly any damage detected if discharged down to 2.0 Volts. The damage occured if dischsrged to lower than 2.0V.

ALL data show that 0% is safe. 0% is not overdischarge.

I think we agree on the definition.

EV Table 3 - Do not leave the vehicle parked for longer than 14 days with a high voltage battery below 20% state of charge Mercedes-Benz [132] If allowed to discharge too much, the battery may become damaged.

5.3.2. State of charge recommendations
Just as high SoC places stress on a battery, so too does low SoC. A device's BMS will shut down a device before it reaches true 0%, to avoid overdischarge, which can permanently damage the battery. Despite this precaution, a device will still reach overdischarge if it is not charged for a long period of time. Battery users do not have a good understanding of the impact of extreme states of charge on their battery. Results from a 2017 survey, displayed in Fig. 5, show roughly equal numbers of people agreeing and disagreeing with statements that ask whether high or low states of charge can damage a battery [155]

 

[AAKEE]

Huh, I took a look at Table 2 on page 7. It does appear that it's perfectly okay to store a battery at say 5% so long as you do not over discharge it. In the real world, a lot of people probably WILL over discharge it if they let it go that low and do not plug in so that's probably why all of the manufacturers say not to do it. But then again, that's for LFP, which Tesla apparently says is okay to keep at 100% all the time?!? Looks like high temperature/high SoC hurts LFP batteries as well.

The self discharge from a lithium battery is very low. This means that when the battery disconnect itself by the contactors (as it also does during a sleep) the drain of the battery is very slow.
Tesla warns about the low voltage battery can be damaged, because it will discharge quite quickly when not charged. Lead acid batteries wear bad from discharging too much and I think some 50% SOC is the safe level for these.
So the lithium battery in a Tesla that shut down is safe for some further time(quite long time). I would not recommend trying to find the time though.

For calendar aging, lithium batteries is better of the lower the SOC is down to zero %. Note, that this is discharged to the safe level, 0% SOC but still within the minimum voltage level. From this they are left in that state for about a month or two in the research tests, then a few cycles and discharge is performed to find the capacity and after that they are charged or discharged to the SOC they use in the test.
In this test the battery cells is left as the test SOC( 0% for the 0% points) for two to three months without getting damaged, they actually have the least degradation despite 2-3 months a time at 0% SOC, and 10 months in total.

This picture show the calendar aging for NCA, NMC and LFP cells. While it is a recent test, and other tests show the same, we actually do not have data on the absolute newest battery cells. But as the basic chemistry do not change very much for each type we can use these results as a base for understanding the degradation frm time on these battery types. In some cases the newest cells might have slightly reduced (or increased) cyclic aging or calendar aging.


For LFP there is a need to charge full to reset the BMS energy counter on a regular basis. LFP has very flat voltage curve and the BMS counter of the actual remaining stored energy might drift and in the worst case you find yourself stranded when the battery goes empty despite the BMS did think there still was plenty left.

LFP suffer from calendar aging but as you can see the calendar aging is not that bad at 100% for specially shorter periods.

We can expect LFP cars to have slighty less degradation for the same use, just to give a number about half compared to LR and P cars. This because calendar aging is the dominant degradation factor for both types.

This is actually also possible to see in teslalogger.de/degradation. The LFP versions seem to loose about half the range per driven miles/km. In reality the calendar aging comes per time and not km/mile but there is no such graphs.
Its also a bit early to say for sure as LFP has not been around in Teslas for that long, but the facts we have from research points in that direction.

 

[Lauramye]

I'm going to try to articulate this the best I can. I've had my Model 3 for less than 2 months. I noticed that if my car states the charge is 100 miles - it's not accurate with the distance I'm driving. I know that from my house to the bottom of the hill is exactly one mile. In my Tesla it will be 2 - 3 milers - so now I'm at 97 miles.

Is the miles status in the car actual miles or an energy thing?

 

[glide]

I'm going to try to articulate this the best I can. I've had my Model 3 for less than 2 months. I noticed that if my car states the charge is 100 miles - it's not accurate with the distance I'm driving. I know that from my house to the bottom of the hill is exactly one mile. In my Tesla it will be 2 - 3 milers - so now I'm at 97 miles.

Is the miles status in the car actual miles or an energy thing?

Actual miles displayed are an estimate based on absolutely perfect driving conditions. You will very rarely ever get the displayed range.

 

[Arthur31]

It's based on your energy consumption. I have both of my Tesla's set to display % of battery remaining. You can tap on the numbers next to the battery icon to switch between % and miles.

 

[mangrove79]

I'm going to try to articulate this the best I can. I've had my Model 3 for less than 2 months. I noticed that if my car states the charge is 100 miles - it's not accurate with the distance I'm driving. I know that from my house to the bottom of the hill is exactly one mile. In my Tesla it will be 2 - 3 milers - so now I'm at 97 miles.

Is the miles status in the car actual miles or an energy thing?

Your trip display shows your actual miles driven (Control > Trips). Your SoC miles are estimates that can be more or less than your actual range depending on your efficiency (wh/mi number). For example in my MY, if my wh/mi number is around 220, the two numbers match almost exactly. If I can get it down to 200 wh/mi on a 20-mile local drive, then the SoC decrease will actually be less, maybe only 16 miles. On the other hand, if a 50-mile highway drive yields 300 wh/mi then I may lose 65 miles in my SoC number.

 

[EVRider-FL]

You'll get a feel for your actual range when you've driven more, and it doesn't really matter unless you're driving a long distance.

 

[Shelburne]

Try driving uphill! I regularly drive up a long steep hill. My 2020 M3 uses roughly 5 miles of estimated range over the course of 1.5 miles at 55MPH on that hill. Range is an estimate. Temperature, terrain, number of passengers and/or cargo, speed, and even had or tail winds will effect it. It's no different than the mileage you actually get in an ICE car vs. the EPA rated mileage.

 

[Lauramye]

Your trip display shows your actual miles driven (Control > Trips). Your SoC miles are estimates that can be more or less than your actual range depending on your efficiency (wh/mi number). For example in my MY, if my wh/mi number is around 220, the two numbers match almost exactly. If I can get it down to 200 wh/mi on a 20-mile local drive, then the SoC decrease will actually be less, maybe only 16 miles. On the other hand, if a 50-mile highway drive yields 300 wh/mi then I may lose 65 miles in my SoC number.

Thank you! That makes more sense. And I am driving uphill so that probably has something to do with it.

 

[hanswiththe3]

Hello to all, I'm looking for some clarification on the battery range of my car. (Side note I live in Arizona)

I have a Model 3 STR+ that I have been driving since Late December 12/20. I typically drive 40-60 Miles a day for commute to work plus whatever else I end up doing this is a good estimate. My first year I did not use my mobile charger because I had 0 knowledge about the effects of constantly supercharging. Almost every 1-2 days I would supercharge my car to about 80%.

Around August 2021 I received an error on my screen: Maximum battery charge level reduced/unable to charge battery to 100% (I am not sure what the error code was)
I then created a service appointment where they did this: Correction: HV Battery (Dual Motor) (Remove & Replace).
This all was covered by my Basic Vehicle Limited Warranty. Once this happened I was given a loaner for about a week which was pretty nice.

Eventually I was given back my car and I began super charging for like a month. Then I figured I can just try out the mobile charger because I did not want to go through the trouble of installing a wall charger.

I do not supercharge unless I go on trips now. I did go on a trip this weekend to LA and super charged about 5 times total there & back. I used the navigation on the tesla screen so It would tell me which supercharges to hit along the way.



Now that I am back I decided to take a look at my battery life and see how it's keeping up & I want to know if there's anything I should do.
My 90% Charge range is about 223 Miles. I believe my car is supposed to be capable of about 263 Miles.
So considering 90% of 263 is about 236 Miles.


This means I have about 13-15 Miles of degradation? Is there anything I should do to try to recover range?
I currently only use my mobile charger and top off my battery at night to 90%.

Currently at about 28k Miles.

Thanks for the help!

 

[Tenet]

Hi everyone,
About 2.5 months ago (February 19) I took delivery of a brand new 2022 RWD Model 3 with the LFP battery. Day 1 I read the instructions on the battery. It is recommended to leave the battery limit at 100% and to charge to 100% at least once a week. I have been charging to 100% twice a week. Have made 2 trips and have used the superchargers just a few times. I mostly charge at home and at my work place.

Initially after charging to 100% I would get about 276 miles of range. This was back in February. After some time it then started to go down to about 274,273,272.
It has reached the point where now I would at best get 270 miles. After charging today I got 268. Tomorrow I may get 269 or 270 (hopefully 270). The car has ~ 3.3k miles. The weather is typically between 80-95 in Florida so the car is always in warm weather.

The car has just been running about for 2 months since it was brought into this world in the Fresno Cali factory. Have any of you guys heard of varying range on the LFP Model 3?

 

[Tenet]

The strange part was getting 269 one day then the next 273. This has gone down to now getting 267 one day and then the next about 2-3 more miles. I no longer seen 271+ miles when charging to 100%

 

[fj_fan91]

The estimate is just that, an estimate. It is based on your driving habits, environment, etc. Don't sweat it. Some days my LR (I know it's not an LFP) gets 354, some days it's 360's.

 

[Tam]

The strange part was getting 269 one day then the next 273. This has gone down to now getting 267 one day and then the next about 2-3 more miles. I no longer seen 271+ miles when charging to 100%

The variation is normal and expected. That's why Tesla guarantees 70% capacity to ease your anxiety.

By the way, it's Fremont near San Francisco metropolitan and not Fresno where the farming in Central Valley is.