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

[sjg98]

Yes, and without reading some real-world tests, people don't realize that different vehicles are optimized differently.
So it is not as simple as knocking 15% off the range of every vehicle when comparing.
Gearing, regen performance, drag coefficient, weight, torque, etc all impact how the vehicles range is impacted by speed, stop&go, etc.
Cars with heat pumps are not as impacted by cold weather for example.

Over time we will also see different vehicles age differently as well in terms of battery pack range due to a mix of (+ side) reserve/overprovisioning of cells by some companies, and (- side) poor BMS/heat management and/or overly aggressive DC charging curves in others.. We saw this already with Leaf batteries declining rapidly while the Tesla ones hold up pretty well (~2% loss/year).

 

[sjg98]

On a POSITIVE note I would add, the reason to get a Tesla, especially in the US is that they still have some of the longest range vehicles and a vastly superior charging network for when you do need to top off on the go.
While there are competitive vehicles I've been eying this year which on paper might get 50-75mi less range than my Tesla but in reality come closer to 25mi less... I just don't have confidence in the northeast region's non-Tesla charging networks.

 

[Icenks]

Calendar aging is the dominant degradation the first years of a battery aging. The higher the SOC is on average, the higher the degradation. The higher the temperature is, the higher the degradation.

I charge to 55% every night and use 25-35% daily. I set the timer to commence charging so the charging is done not that long before I leave for work. (Of course I charge more before a longer trip etc, when needed). I still have full range, after almost one year and 30000km.

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

This graph is exactly what I’m looking for. Looks like there’sa step at 55%. Do you have similar graph extended to higher mileage/life time?

 

[VT_EE]

Thanks. I suspect that’s the answer. The 375 is shown as an estimated range on a new vehicle with aerocaps fitted. I think this is wltp conditions though. I’ll check and see if my 100% (that’s the display percentage or 343 miles when you toggle between then) is based on a 90% limit.

I'm not sure about wltp testing, but EPA range is based on running the battery down until the car shuts down. I believe Tesla added ~2% buffer (in addition to the anti-brick buffer) to make it less likely you will actually run out of juice when the meter reads 0 miles. This means that the display will always understate the actual miles available, assuming you are driving in the same conditions as the EPA test.

 

[AAKEE]

This graph is exactly what I’m looking for. Looks like there’sa step at 55%. Do you have similar graph extended to higher mileage/life time?

Well, nope but it is easy to make one.
The researchers agree about that calendar aging decreases with square root of time.

To make one year from 9.6 months, use the square root of 12/9.6 times the point you found on the 9.6 mounth line.
( For simplicity, one can use the 9.6 or 9.5 month line ad one year. This line is probably not 100% correct for our panasonic 2170/2170L, but it probably is quite close).

To find the degradation for *any year* from new, take the square root of *any year* times either the 9.6 month line value, or the calculated value.

For example, my M3P is one year old since I picked it up( and tje car was built one month earlier so the batteries is probably about 13-14 months. Aging before the car dhips should be low( I guess panasonic/Tesla knows how to take care.

So, one year.
My average SOC when the car is not used is about 30-35%. The picture I posted do only have 25C and 50C lines, there is data from other tests that show 15C and 10C, and my year average is not above 15C.
For this example, I use the 25C line.

30%, one year(9.6months) and 25C show about 2.5-3%. Lets use 3%.

After 6 years my calendar aging will be about: Square root of 6 times 3 = 7.34%..

I would say that the research is good enough to be quite precise and most research cells do not show “bad luck or good luck in the battery lottery. They behave in a quite close manner.

But our average SOC and most common temperature can be har to estimate without some kind of log( I have teslafi + teslalogger).

The car will also have cyclic aging but for most which do not use the car very mych with a lot of miles, SuC and deep cycles the calendar aging will be the dominant part the first years( like 3-8 years depending on SOC and temps).

My battery seems to behave better than this, less degradation than I expected (about 2.5% first year in total, but I havent really seen any degradation yet).

I am currently screening the net for research about self healing/ reversible degradation from resting at low SOC.
There seem to be too little research about this.

 

[AlanSubie4Life]

I believe Tesla added ~2% buffer

4.5% for Model 3.

 

[Candleflame]

On a POSITIVE note I would add, the reason to get a Tesla, especially in the US is that they still have some of the longest range vehicles and a vastly superior charging network for when you do need to top off on the go.
While there are competitive vehicles I've been eying this year which on paper might get 50-75mi less range than my Tesla but in reality come closer to 25mi less... I just don't have confidence in the northeast region's non-Tesla charging networks.

Indeed. In europe third party networks are so good, the supercharging network isnt as strong. Same in Aus (both are crap here).

Also I find AP is useful on those long journeys in Aus and the USA too but probably less useful when you actually WANT to drive on europes prestine motorways. Certainly I dont use AP on what limited motorway we have here.

 

[VT_EE]

4.5% for Model 3.

Is that 4.5% plus the non-useable, anti-brick buffer, or does 4.5% include both buffers?

 

[AlanSubie4Life]

Is that 4.5% plus the non-useable, anti-brick buffer, or does 4.5% include both buffers?

The buffer appears to be completely used during the EPA test and there are YouTube videos showing it being used and it seems like the usable amount in those videos is about 4.5%.

Of course there would be additional unusable buffer below that, since the EPA test article is not bricked.

 

[Candleflame]

Is that 4.5% plus the non-useable, anti-brick buffer, or does 4.5% include both buffers?

multiplying the cell capacity in independent tests with the amount of cells in a 17/18/19 model battery the battery has a capacity of 80kwh or so, so that suggests with the available 78.8kwh inc. buffer that the car has a brick protection of around 1.2kwh.

 

[AAKEE]

multiplying the cell capacity in independent tests with the amount of cells in a 17/18/19 model battery the battery has a capacity of 80kwh or so, so that suggests with the available 78.8kwh inc. buffer that the car has a brick protection of around 1.2kwh.

The spec is 18Wh for the ”classic” 2170(5000mah x 3.6V nominal). That would be about 79.5 on the pack level.
Cycling tests seem to show just below 5000mah( 4950 or so mostly) which point to about 78.7 or so. A lower current than in the tests would cause slightly less heat loss, and slightly more capacity delivered.

The panasonic lithium batteries of these types always have a maximum voltage of 4.2volts and minimum voltage of 2.5Volts.
This is also valid for the 2170.

If we look at the maximum voltage reported by the BMS with Scan My Tesla, we will find the max/min to be the same.

Max 403V / 96 cells in series( ”96s”)= 4.198 rounding error, 4.20V would be max( 4.20V seen during charging).

Min pack voltage 241V / 96s = 2.51V. Probably rounding error here also.

My own conclusion: Tesla do not use any extra brick protection above the specified minimum discharge voltage for the lithium cells themself. The voltage curve is very steep at 2.5V/cell and there is not much energy left below 2.5V, maybe the 50 mah that is needed to reach 5000 in this test.

50mah at about 2.5V is about 0.5kWh on the pack level, IRL the voltage drops very much and the average probsbly would be 1.25V, making the ”brick protection” as low as 0.05 x 1.25 x 4416 = 0.276Wh.

I wouldnt really say that Tesla has X% or Y kWh brick protection. I would say that Tesla use all energy that is allowed to be used within the battery cells voltage range of 2.50V to 4.20V.
The brick protection is a minimum voltage, below that voltage the cell could be damaged and also, the voltage droop is so high that the car probably wouldnt even be able to keep a decent speed.

 

[Jeremy3292]

Interesting. Let us know with pictures of the energy screen. I guess you could do before and after, but we know the current situation, so before is not really necessary. I would though.

Finally got a new software update with the 2021.44.6 update and then the next day the holiday update 2021.44.25.2. My 2021 M3 LR now charges to 358 miles. Although the main charge screen does say charge limit of 359 miles, I never got to that. App says 358 miles too.

Another point of note is I have 7,600 miles on the car now with no signs of degradation, at least what Tesla let’s me see.

 

[AlanSubie4Life]

Finally got a new software update with the 2021.44.6 update and then the next day the holiday update 2021.44.25.2. My 2021 M3 LR now charges to 358 miles. Although the main charge screen does say charge limit of 359 miles, I never got to that. App says 358 miles too.

Another point of note is I have 7,600 miles on the car now with no signs of degradation, at least what Tesla let’s me see.

View attachment 748817

View attachment 748815

Energy Screen pictures (both display modes capturing all three numbers in each) would be nice.

Note that we expect this to just be a degradation threshold change, with no change in the constant (it’s rare for the constant to change so soon after vehicle release). The degradation threshold change makes sense since there was a pretty large discrepancy between full pack and the prior threshold.

I would expect early 2021s to see no change with this update (even if the threshold changed for them).

 

[Jeremy3292]

Energy Screen pictures (both display modes capturing all three numbers in each) would be nice.

Note that we expect this to just be a degradation threshold change, with no change in the constant (it’s rare for the constant to change so soon after vehicle release). The degradation threshold change makes sense since there was a pretty large discrepancy between full pack and the prior threshold.

I would expect early 2021s to see no change with this update (even if the threshold changed for them).

I took multiple pictures:

 

[AlanSubie4Life]

I took multiple pictures:

View attachment 748894

View attachment 748895

View attachment 748897

Thanks. Unfortunately need to capture that rated miles/% value as well (sorry to not have been more specific). Average Range mode is all that is needed.

it’s rare for the constant to change so soon after vehicle release

This was a typo - it’s rare for the constant to change, EXCEPT soon after vehicle release.

 

[Jeremy3292]

Thanks. Unfortunately need to capture that rated miles/% value as well (sorry to not have been more specific). Average Range mode is all that is needed.


This was a typo - it’s rare for the constant to change, EXCEPT soon after vehicle release.

 

[AlanSubie4Life]

View attachment 748937

Thanks for trying…need those rated km/miles as well…and ideally at a higher %. Anyway this shows the degradation threshold at about 78kWh just as before but there is a lot of rounding error. I suspect it is at 79kWh now like Model Y, but we’ll see.

 

[Jeremy3292]

Thanks for trying…need those rated km/miles as well…and ideally at a higher %. Anyway this shows the degradation threshold at about 78kWh just as before but there is a lot of rounding error. I suspect it is at 79kWh now like Model Y, but we’ll see.

Above 80% or higher? I will provide in the next few days when I charge that high again.

 

[AlanSubie4Life]

Above 80% or higher? I will provide in the next few days when I charge that high again.

Yeah, 80% should be ok. Tap the battery to switch to km/mi as well. (Both % and mi/km are good.)

 

[Candleflame]

The spec is 18Wh for the ”classic” 2170(5000mah x 3.6V nominal). That would be about 79.5 on the pack level.
Cycling tests seem to show just below 5000mah( 4950 or so mostly) which point to about 78.7 or so. A lower current than in the tests would cause slightly less heat loss, and slightly more capacity delivered.

The panasonic lithium batteries of these types always have a maximum voltage of 4.2volts and minimum voltage of 2.5Volts.
This is also valid for the 2170.

If we look at the maximum voltage reported by the BMS with Scan My Tesla, we will find the max/min to be the same.

View attachment 748803

Max 403V / 96 cells in series( ”96s”)= 4.198 rounding error, 4.20V would be max( 4.20V seen during charging).

Min pack voltage 241V / 96s = 2.51V. Probably rounding error here also.

My own conclusion: Tesla do not use any extra brick protection above the specified minimum discharge voltage for the lithium cells themself. The voltage curve is very steep at 2.5V/cell and there is not much energy left below 2.5V, maybe the 50 mah that is needed to reach 5000 in this test.

50mah at about 2.5V is about 0.5kWh on the pack level, IRL the voltage drops very much and the average probsbly would be 1.25V, making the ”brick protection” as low as 0.05 x 1.25 x 4416 = 0.276Wh.

I wouldnt really say that Tesla has X% or Y kWh brick protection. I would say that Tesla use all energy that is allowed to be used within the battery cells voltage range of 2.50V to 4.20V.
The brick protection is a minimum voltage, below that voltage the cell could be damaged and also, the voltage droop is so high that the car probably wouldnt even be able to keep a decent speed.

View attachment 748805

maybe it was a fluke set of cells? it was a youtube video where someone bought a few cells and tested them. Also the problem with lithium ion is always to determine what voltage counts as a complete discharge and i cant remember what he used. Particularly at low current draws you can quite significantly discharge them which is obviously detrimental to battery health...