Some new data from research on Tesla model 3 cells

There has recently been released a series of new research reports containing tests on Tesla Model 3 Cells (Panasonic 2170 NCA).
This is the calendar aging test from one of them (25C, 15, 50 and 85% SOC. Checkup once a month):
Using the datapoints from these and putting them in the old charts I ususally post, these match the olds ones quite good. As there is only three points, it do not show the real form of the curve, but all three points match the usual graphs.

For the cyclic tests, they did use rather high currents, not really respresentative to normal EV use. (To the researchers defense, the currents used is sort of the most EV-battery manufacturers current in the specifications but still not close to the regulkar EV usage).
Charged with 0.33C which would match about a 25kW DC charger, or double to four times the usual rate EV owners use mostly. Probably not offsetting the result much, but to be clear this is how it was done.

Discharged with 1C, which would be 78kW, about enough to drive constant at 200kph. This is way above the average power used from a regular EV. Driving at higway speeds at 120kph/80mph or so, we normally use like 1/4 of that power.
The average car often has a average speed longterm of about 50-60kph, meaning we often use 1/8-1/4 of the power in these cyclic tests.
From other tests we can se that lower power reduce the wear, the degradation often reduces to somewhere down to 0.5-0.7C.

In this report the author was a bit surprised over the increased wear at 5-15% SOC and 15-25% SOC. I would say that it it a very high probability of that this is induced by the 1C discharge rate, and that our normal power rates used IRL would make this look different. This is nothing I can promise but from several other research tests we can see that there ususally is a tendency to slightly increase the cyclic degradation at the lowest SOC ranges.

According to this chart, the best cycling range is 55 % down to 35%( see note below about true SOC).

Note: These are “True SOC”. 0% in this chart is where the car already has stopped, and 5% in-chart is about 0% displayed and 55% in-chart is is about 57% displayed.

As I said above, there is a high probability that the low SOC range wear much less with a lower C-rate. Anyway, due to the high impact of calendar aging we most certainly benefit from staying low in SOC.

For the first two years, we would loose about 9-9.5% from calendar aging if staying at high SOC.
During these two years, if we drive 15-20K km annually (10-15Kmiles), and stay in the very low regime cycling (5-25% true SOC, thats 0-20% displayed SOC) we would loose about 1% from ~ 75-100 FCE cycles during these two years/30-40K km.

IRL its not possible to stay that low in SOC without actively stopping the charging, as 50% is the lowest setting (but for reference to low /high SOC).

To reach the same level of cyclic degradation from low SOC cycling according to the chart we would need about 700FCE, or about 280K km, but that is not really possible to do and at the same time stay at 5-25% SOC.

So, a car charged to 80-90%, and used as most EV’s is used, will mostly be above 55% SOC and have a calendar aging close to the 85% graph.
After two years, it will be around 10% degradation if the average cell temp is about 25C.

If the car was charged to 50-55% it would have a calendar aging around 6%, and the cyclic aging would be half the high SOC car, so more or less negligeble.

Link to one report

[Edit]For what its worth, if someone is worried about the low SOC below 20% (I am not, but I’m aware of the classic forum rumors), charging to 50-55% and charging for the daily drives at or above 20% (not talking longer traveling here) all aspect of this report if ticked-in-the-box.

I will not change any of my charging behavior because of this report. There is from time to time small differences in the reports and usually the reason for that can be found by thorougly comparing with other tests. We need much more than one report to state a “fact”.

 

[fhteagle]

In that case, how about charging to 50%, and then just before leaving go to 65 or 70%? The calendar aging from that should be close to nothing, as it will be at > 55% for a very short time.

That's very close to what my charging strategy is evolving to. Charge when solar is abundant in the local grid, up to ~60% or so. If I do come home at less than 30%, it does charge to at least 30% immediately though. Fortunately HomeAssistant makes that very straightforward to set up, monitor, and override via calendar entries. I've also added a temperature adder to let the solar charge target be about 10% higher in our winter months. This is acceptable to me because the battery will be staying quite cool (<5*C usually), and the SOC needed to reach DCFC stations on an unplanned trip in the winter goes up too.

 

[AAKEE]

@AAKEE @DrChaos

Great feedback and dialogue. Especially when its data driven.

Yes, facts / tests / data is good things discussing batteries

I think the fact that I live in hot desert area makes me look for how to optimize the crap out of my cycle usage for both my wife’s Tesla and mine to offset that. Couple that with being an engineer (aerospace related so not afraid of commercial flights @AAKEE lol) and its a recipe for overthinking but its fun.

I’m a ATP Pilot so maybe it got unsafe-r to fly now

Always looking for any ounce of decreasing degradation to compensate and offset for the high temperatures the battery goes through in summer.

Hot weather, then low SOC is your thing.

Calendar aging will cause the very most part of your cars degradation.

High battery temp and cyclic aging is a rather good mix. In many cases the lowest cyclic aging happens at 25-35C.

Cyclic aging will be low anyway, so that is not where you should concentrate.

PS: Wish I can change the Battery TMS logic to less passive cooling and more active cooling of battery.

For the driving part, there very small or no difference by cooling the battery.

For the parked car, if using the battery for cooling the battery (I only think cars with heat pump / octovalve can do active cooling of the battery) it would probably deplete quite fast, and it would be a high cost to keep the battery cool during a summer.

By having the SOC low you can about cut the degradation in half compared to high SOC (like 70-80-90% or so), this without any extra cost in energy.
Charging late keeps the average SOC low and it also put the extra heat from charging before the drive to the drive where we actually do not have a ”problem” with heat.

To cool the battery to achieve the same, you need to cool it about 15C from 35-40C to cut the degradation in half.

You can easily compare SOC vs Temps here:

As calendar aging is so much higher the cyclic aging can be completely distegarded and if possible, charge to 50 or 55% and drive on the low side, which means parking where calendar aging is low.

(Calendar aging reduces with square root of time so the first 10 months causes much more degradation and it wont be doubled until about 40 months total time. )


I you like to do both, I suggest you move North. I live close to the artic circle and had, I think a average cell temp of 13.46C for about two years in my M3P.
Still, I had it in the warm garage. Leaving it outside during the winter would have kept the cell temp much lower…but its not fun when -30- -35C.

No, just joking.

But you can have the car out of the direct sun if possible. I think I saw about 5C increase of cell temp when the car was in really sunny weather outside.
I have a insulated garage that also stay about 5C or slightly more or so below the OAT during hot days if the doors are kept closed.
It would be possible to use a AC to cool a garage, probably a better idea than using the cars system and battery to cool the battery. But I think it would be to “overdo it”.

 

[DayTrippin]

Most studies have shown that the smaller the DoD cycle the better. Basically keeping the average SoC around 50-55% and keeping the discharge cycles small are the way to go. So if you have a chance to top up from 45 to 55 rather than wait a few days and go from 25 back to 55%, that is ideal.

I've been following this strategy for about 19 months now. My M3 LR has less than 1% degradation. My MS LR at 15 months when I sold it was at less than 1% degradation. My MS Plaid is at about 2% degradation but I didn't buy it new but I've put most of the miles on it. It was already at 2% when I got it. All these cars have been in hot climates, TX, FL and NV. They have all seen a lot of full throttle runs which stress the batteries more due to the high discharge rate.

My simple rules are ones derived from what AAKEE posted a long time ago. Here is my basic strategy.

• I set my charge level to 50-55%. I only charge above that when I need it for a trip OR I will return to the house significantly below 20%.
• I keep my car plugged in at all times.
• I see tup charging typically to complete just before I leave, especially if I am going to need a substantially higher charge level than 55%.
• I top off my charge when I get back to minimize the DoD. Back to the many small charges rather than a big one.
• I will typically charge in the morning when cooler since the temps are very high here in the summer and high SoC and high temps are bad for the Li-ion cells. It is still unclear what Tesla does to manage the battery temps when the car isn't running. So I am playing it safe here so to speak. I may keep it as low as 30% at night when it is still 100F/38C and charge when it drops down to the cooler temps just before leaving in the morning. Even today it was still up to 95F/35C so not cooling off yet.

I have found that this regimen isn't difficult to achieve now that my wife and I have adapted to it. I haven't got caught out yet with a lack of charge. My S can easily go 100+ miles while going from 50% to 20%. Our 3 is pretty close to that. There are enough supercharges near by that I can stop if I think I might drop well below 20% and a 3 minute blast will give me more than enough to get home. I haven't had to do that yet.

I typically set the charging time the night before (if I didn't top it up as it was very hot) to charge the car just before I typically leave. I will typically set the charge level for departure to hit 55% as I almost never will use less than 5%. I know that with my 3 the wall charger recharges at about 12% per hour on and the S about 10% per hour so very easy to determine when I need to start charging.

It didn't take long to become accustomed to this approach. For me the dividends are obvious with this strategy. It is even more critical since I am in a very hot climate to minimize calendar aging.

If my performance suffered substantially I might not be as strict at following this regime. The M3 LR w/boost is still quicker by far at 40% charge than it was without boost at 100%. It does fall off at higher speeds but still pretty good. The Plaid is still a monster even at 20% charge. At that low SoC though full power runs can take more of a toll on the pack but it is still very quick if needed. If I had my MY LR and it was stock, I'd probably be hating the car. Oh wait, I did hate it when it had low SoC and didn't have boost. It was pretty darn slow TBH.

 

[zoomer0056]

My M3 LR has less than 1% degradation.

How are you measuring degredation?

 

[thefrog1394]

@AAKEE any data on different depth of discharges? I don't currently have home charging, so my typical pattern is to wait to charge as long as possible to increase time spent at low state of charge. I'll typically charge to 80% and wait until I'm around 10-15% to recharge, so while I'm likely spending more time at low SOC than many folks on here who charge nightly to 90%, I'm also doing 60%+ discharges every cycle.

The other interesting factor for no-home-charging drivers is supercharging vs L2. Riding the fast part of the charge curve to 50% once/week is probably similarly convenient to leaving my car at the slow charger overnight to 90% every 2 weeks. I typically do the latter in the name of decreasing battery degradation, but I'm not actually sure it's better.

 

[AAKEE]

@AAKEE any data on different depth of discharges? I don't currently have home charging, so my typical pattern is to wait to charge as long as possible to increase time spent at low state of charge. I'll typically charge to 80% and wait until I'm around 10-15% to recharge, so while I'm likely spending more time at low SOC than many folks on here who charge nightly to 90%, I'm also doing 60%+ discharges every cycle.

First thing, almost hovewer you do it, cyclic aging will not come close to calendar aging for the first five years. So your plan should be to minimize high SOC if you like to try to reduce the degradation.

These is a better tests than the actual model 3 tests, as they use 1A on tests with NCA cells of 2.9Ah so about 0.34C. This C-rating is closer to our actual use but still higher.

This is discharges down to 0% buth from different charhing levels.
(4.2V = 100%, 3.7V = about 50% and each 0.1V represents about 10% at all SOC’s but the lowest).

We can se that the lowest 50-0% is slightly worse than 60-0 and 70-0%.
But look at the next picture before making up the mind!

This is a checkup test to see that the test above is valid (a very professional way to include controls of the tests in the same research report):
Here we can see that the smaller the cycle the less cyclic aging.
The lowest 3.7V (~50-0%) is not better than 3.8V(60-0%) but as the cycles are smaller we would expect slightly less cyclic aging.
But as 1000FCE is about 400K km, the annual degradation for this 50-0% is about 0.5% (20.000km / year).
Even using the first chart/tests data with higher degradation put it at about 1% each year.

The above tests reduce the upper voltage (Starting SOC) but all tests discharged to 0% true SOC.

Here is the other way around, using high SOC but reducing the end of discharge voltage:
4.1V = about 90%
We can see that reducing the depth of discharge reduces the cyclic aging here as well. These are still quite large cycles.

Smaller DoD reduce the cyclic aging.
Cyclic aging is mostly not an issue, compared to calendar aging.

Here we can se the difference between 2.5V and 3.2V end of discharge voltage.
Remember that Teslas has a 4.5% buffer so our 0% is about 4.5%.
10% displayed SOC is about 3.25-3.3V
So even if using low displayed SOC we do not end up that low.
= its safe to go low.

The other interesting factor for no-home-charging drivers is supercharging vs L2. Riding the fast part of the charge curve to 50% once/week is probably similarly convenient to leaving my car at the slow charger overnight to 90% every 2 weeks. I typically do the latter in the name of decreasing battery degradation, but I'm not actually sure it's better.

Supercharging leads to lithium plating which AC charging don’t.
The wear is different. The charge to high SOC at low power as L2 do not cause any noticable wear at all. But the time at high SOC will cause calendar aging.

The lithium plating from SuC can to some extent be recovered if the battery spends time at low SOC and possibly better, is cycled at low SOC.

If you use only a little SOC each day the battery will stay above the 55% “limit” for extended time, causing higher calendar aging.

My advice is to not even try to think ”cyclic aging” but to put the effort into reducing calendar aging.
Hunting cyclic aging might be like straining mosquitoes and swallow camels.

If the cyclic aging is low, then the calendar aging is also low or doesnt matter.

 

[DayTrippin]

How are you measuring degredation?

There are several apps and websites you can use. I tend to use several and see how they agree (or not). You can also go through the service menu and do the same test Tesla does but that can take 24 hours or so for your car and you can't use it during that time.

Tessie app can do it. May not be super accurate but close enough, especially for trends.
TezLab can do it somewhat indirectly.
Stats can do it somewhat indirectly.
Reccurretauto.com and teslafi.com also track it.

I think there are other apps that do I just don't recall off the top of my head. They all may slightly very in how the check it such as comparing to total capacity vs usable capacity. If they all agree pretty closely, then I feel fairly comfortable but know it may not be exact. It is more than close enough for me to use and for trend analysis. Since I've used most of these apps since I bought the car, I have a good baseline.

For comparison as well. My MY LR w/boost that I sold has about 70k miles on it. I hadn't refined my charging strategy yet. It degraded about 4% in the first 7k miles and I had just adopted my charging strategy that I use to today. The person who bought it and I are friends. I explained to him how I changed my charging approach and he adopted it. The car has about 70k miles on it and is in the 6% degradation range now. So only another 2% degradation in 2 years and over 63k miles.

 

[dakhlkt22]

There are several apps and websites you can use. I tend to use several and see how they agree (or not). You can also go through the service menu and do the same test Tesla does but that can take 24 hours or so for your car and you can't use it during that time.

Tessie app can do it. May not be super accurate but close enough, especially for trends.
TezLab can do it somewhat indirectly.
Stats can do it somewhat indirectly.
Reccurretauto.com and teslafi.com also track it.

I think there are other apps that do I just don't recall off the top of my head. They all may slightly very in how the check it such as comparing to total capacity vs usable capacity. If they all agree pretty closely, then I feel fairly comfortable but know it may not be exact. It is more than close enough for me to use and for trend analysis. Since I've used most of these apps since I bought the car, I have a good baseline.

For comparison as well. My MY LR w/boost that I sold has about 70k miles on it. I hadn't refined my charging strategy yet. It degraded about 4% in the first 7k miles and I had just adopted my charging strategy that I use to today. The person who bought it and I are friends. I explained to him how I changed my charging approach and he adopted it. The car has about 70k miles on it and is in the 6% degradation range now. So only another 2% degradation in 2 years and over 63k miles.

How do we know these apps are accurate? TeslaFi estimates battery range, but so far it seems to swing up and down which makes it seem like it's a rough guess rather than a precise definitive view on degradation.

 

[AlanSubie4Life]

How do we know these apps are accurate? TeslaFi estimates battery range, but so far it seems to swing up and down which makes it seem like it's a rough guess rather than a precise definitive view on degradation.

Usually this is because they are doing extrapolation of some form which introduces additional rounding error.

In the end it is exactly what you see on the car screen, with extra error potentially added.

Just important to realize it is a precision error, not an accuracy error. (These two concepts differ; if the app produces an estimate of either 100 or 300 miles for a car that has a 200-mile rated range, that is very accurate - it is just not very precise.)

SMT and similar show a more direct & precise view (but also align perfectly with the screen in the car when the car is charged to high SOC).

 

[shahryaran]

Are there any research on batteries at different SoC with the same C rating output different capability?
For example at 90% SoC 1% use gives 5 miles, but at 60% Soc 1% gives 8 miles.
I would assume it is intuitive as a general rule that lithium batteries show better capability within a balance Soc (40%-60%). In another term, anything at high Soc has a kind of fake charge.

 

[DrChaos]

Are there any research on batteries at different SoC with the same C rating output different capability?
For example at 90% SoC 1% use gives 5 miles, but at 60% Soc 1% gives 8 miles.

If that were the case then the battery management system would be faulty. I don't know if state of charge refers to current or to energy, but if were energy then 1% of energy should be 1% of energy at any part of the scale. If it were current then there would be somewhat more energy per cent of displayed SOC as the voltage of that would be somewhat higher at high state of charge, but in a typical NCA/NMC battery that would mean going from 4.2 V to 3.3V at 100% to near 0% displayed SOC so the difference isn't that big, and it declines monotonically with voltage vs capacity curve (which is based on chemistry)

I would assume it is intuitive as a general rule that lithium batteries show better capability within a balance Soc (40%-60%). In another term, anything at high Soc has a kind of fake charge.

That isn't intuitive to me. What makes you think that?

 

[AAKEE]

Are there any research on batteries at different SoC with the same C rating output different capability?
For example at 90% SoC 1% use gives 5 miles, but at 60% Soc 1% gives 8 miles.
I would assume it is intuitive as a general rule that lithium batteries show better capability within a balance Soc (40%-60%). In another term, anything at high Soc has a kind of fake charge.

It should not be like that. Use the energy graph to read the energy consumed within each percent and then it would be about the same.

The reason that we know should be like your question is that the car can not measure the SOC when driving.
SOC during a drive is calculated, but using [known SOC before the drive], the [estimated capacity] and the used energy(like the energy graph).

[known SOC before the drive] x [estimated capacity] = initial energy.

Initial energy - used energy = current energy.

Current energy is converted to SOC and displayed. If the BMS capacity estimation is dead spot on, the estimated SOC and the actual SOC will be the same after the drive. But if the BMS is a little off on the capacity estimation, the estimated SOC will be a wrong and after parkiong, at rest the SOC will be updated to the measured real SOC. ( SOC is measured by open contactor voltage, when no load is put on the battery, thats the reason for the SOC can not be measured during a drive).
Sometimes, the SOC can be adjusted during a drive if it is fairly off and the load is low so the BMS can realise that it is wrong and need to be adjusted.

 

[randall_s]

The cycles is causing a very small part of the degradation.
Calendar aging is the thing causing the bigger losses. So you might be 10-15% of after 3-5 years.

Your 3000 FCE is from cycling at 55-45% 30.000 times. That wont happen, you will use larger cycles causing more degradation if you need to drive the length of 3000 FCE.

Same set of cells, picture from same report but in depth in another (sister) report:
R = room temp, 22C

R 50-100% give you 1000 cycles for 20% loss. 1000 cycles is well above needed itself but batteries tend to start getting unpredictable at about total degradation.
If you have 15% calendar aging, you do not have very much room for cyclic aging.
I think there are a lot of model S batteries getting troublesome because of the cells being tired.
View attachment 974607

It would be a good idea to consider degradation from real usage. For instance, my 2016 P90DL has a usable capacity of 74 kWh. It was 81.8 new. That's roughly 10% degradation over 90k miles and nearly 8 years. I charged to 90% the first year in a hot climate and 80% since then. According to this data, I should have hit 10% degradation after 2 years, which is not the case. For the older NCA based cars, the degradation tends to be 5% in year 1 and 1% each year after. In a recent presentation, Jeff Dahn recommended cycling 75% to 50%. If I remember correctly, that's how he charges his car.

 

[AAKEE]

For instance, my 2016 P90DL has a usable capacity of 74 kWh.

How did you establish that number?

 

[randall_s]

Currently using Tessie, but I got 75 in TM--spy previously as well as original 81.8 using OBD2. My 75% rated range is 180 miles, which matches the 310 wh/mi rating. So this is the capacity the BMS reports.

How did you establish that number?

 

[randall_s]

Yes, facts / tests / data is good things discussing batteries

I’m a ATP Pilot so maybe it got unsafe-r to fly now



Hot weather, then low SOC is your thing.

Calendar aging will cause the very most part of your cars degradation.

High battery temp and cyclic aging is a rather good mix. In many cases the lowest cyclic aging happens at 25-35C.

Cyclic aging will be low anyway, so that is not where you should concentrate.

For the driving part, there very small or no difference by cooling the battery.

For the parked car, if using the battery for cooling the battery (I only think cars with heat pump / octovalve can do active cooling of the battery) it would probably deplete quite fast, and it would be a high cost to keep the battery cool during a summer.

By having the SOC low you can about cut the degradation in half compared to high SOC (like 70-80-90% or so), this without any extra cost in energy.
Charging late keeps the average SOC low and it also put the extra heat from charging before the drive to the drive where we actually do not have a ”problem” with heat.

To cool the battery to achieve the same, you need to cool it about 15C from 35-40C to cut the degradation in half.

You can easily compare SOC vs Temps here:
View attachment 978532
As calendar aging is so much higher the cyclic aging can be completely distegarded and if possible, charge to 50 or 55% and drive on the low side, which means parking where calendar aging is low.

(Calendar aging reduces with square root of time so the first 10 months causes much more degradation and it wont be doubled until about 40 months total time. )


I you like to do both, I suggest you move North. I live close to the artic circle and had, I think a average cell temp of 13.46C for about two years in my M3P.
Still, I had it in the warm garage. Leaving it outside during the winter would have kept the cell temp much lower…but its not fun when -30- -35C.

No, just joking.

But you can have the car out of the direct sun if possible. I think I saw about 5C increase of cell temp when the car was in really sunny weather outside.
I have a insulated garage that also stay about 5C or slightly more or so below the OAT during hot days if the doors are kept closed.
It would be possible to use a AC to cool a garage, probably a better idea than using the cars system and battery to cool the battery. But I think it would be to “overdo it”.

This is fascinating, but I'm wondering if #1. These results have been independently reproduced and #2. How were temps measured? Tesla BMS uses active cooling with cooling tubes? physically contacting cells. If the experiment uses passive cooling and temps are ambient, cell temps might be much higher than ambient, especially considering the relatively high charge and discharge currents.

 

[AAKEE]

Currently using Tessie, but I got 75 in TM--spy previously as well as original 81.8 using OBD2. My 75% rated range is 180 miles, which matches the 310 wh/mi rating. So this is the capacity the BMS reports.

The Tessie value is the total capacity.
This means including the buffer.

(We know this as a fact, both from discussions with the James@Tessie in the Tessie thread and by using Scan my tesla and reading the nominal full pack together with the Tessie capacity values. Tessie change the term “usable capacity” to “capacity” after the discussion in the Tessie thread.)


—> So your car had 85.8 kWh total capacity when new now it has 74kWh.
Thats ~14% degradation counted on the whole capavity.

Thats not far from 5% for the first year which means 5 x (square root 8 years)= 14% like the research results.

 

[randall_s]

The Tessie value is the total capacity.
This means including the buffer.

(We know this as a fact, both from discussions with the James@Tessie in the Tessie thread and by using Scan my tesla and reading the nominal full pack together with the Tessie capacity values. Tessie change the term “usable capacity” to “capacity” after the discussion in the Tessie thread.)


—> So your car had 85.8 kWh total capacity when new now it has 74kWh.
Thats ~14% degradation counted on the whole capavity.

Thats not far from 5% for the first year which means 5 x (square root 8 years)= 14% like the research results.

Tessie reports 9.7% degradation. 81.8 new vs 74 now - neither of these is total. I'm certain 74kWh is the usable capacity. Again, my P90DL efficiency used for range calculations is 310 wh/mi. 74 kWh * 75% charge / 310 wh/mi = 179 miles, which is what my BMS reports as my range at 75% charge. I occasionally travel around 200 miles so the BMS gets a good look at different SOCs.

I only brought this up because of the chart you posted. There is no way to properly test battery degradation in a car over 8-10 years without using the batteries in a car for 8-10 years. What is typically done in labs is a projection based on some form of coulomb tracking. I'm just suggesting that you factor in some real world data instead of relying 100% on this lab study. If you comb through other threads you'll find several reports of earlier cars with less than 10% degradation, some of which performed actual discharge-charge tests.

Jeff Dahn is pretty much the GOAT when it comes to battery expertise. Like you, he suggests lower SOCs to limit degradation. For instance, he recommends 30% SOC if you are to leave a EV for months. But I think it's telling that he personally has no qualms about recommending 75%.

EV Battery Health with Dr Jeff Dahn Dalhousie U - Worth watching the entire presentation if you can.

 

[AlanSubie4Life]

Tessie reports 9.7% degradation. 81.8 new vs 74 now - neither of these is total.

FYI in the EPA test they extracted at least 84kWh from the pack.

2016 90D 384mi at 218.57Wh/mi
Or 405.2mi at 208.02Wh/mi

The data isn’t as nice as newer submissions but that’s the “new” pack capacity.

No idea what buffer percentage is, etc.

 

[David99]

One thing that always makes me look at these studies with some skepticism is their test method. They always charge linear and discharge linear. No EV charges linear and definitely doesn't discharge linear. A German battery expert said that regen braking is one of the most important factors extending the life of EV batteries. Of course this doesn't invalidate the results done using linear discharging, but it reduces the effect on degradation. My point is, that regen braking will reduce the difference in degradation between the cycle tests. If you would factor in the effects of regen braking, the real world difference won't matter much if you charge to 55% and drive to 20% or charge to 80% and drive to 45%.