ro_explorer
Member
And I did that today, to my surprise the nominal max is now 76.8, up from 76.1. Not doing anything special, just charging 60-80% every 2-3 days.
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MASTER THREAD: 2021 Model 3 - Charge data, battery discussion etc
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You know that the up-ing is the BMS value only and that the battery itself dont get better capacity?
What about trying to only charge below 60% ?
The LFP battery is made by CATL not LG, as already stated the 10 mile loss in EPA rated range is easily made up by the fact that you can charge to 100% routinely. I would say go for it, the only question mark surrounding the LFP pack is really cold weather performance but given your location that should not be much of a concern.
ro_explorer
Member
On the same philosophy the original "downing" is also the bms.
I'm aware these are just estimations and it's my OCD acting up.... but still I cannot go over the fact that the battery lost some capacity in only 3 months and less than 9k km.
The BMS:es are good but cannot bee 100% correct every day.
All batteries will degrade. How we use them is the main source to the level if degradation.
For most electric car owners the calendar aging is the main degrader and degradation from driving cycles is the least part.
Time x SOC is the main degradation driver.
Time x SOC x temperature is also a factor, but only in a noticable level for elevated temperatures.
Charging cycles causes wear to a lesser point.
Togheter, high SOC for long times causes higher calendar aging.
Big Depth of dischargeis worse than smaller ones.
The lower SOC the battery averages at rest/sleep, the better for the li ion battery.
Tesla has 20% as the amber batt level, probably to make sure SOC doesnt go to low because the 12V lead acid batt do not like to get discharged.
We can make the calendar aging to stay at or below half the value by usibg a lower charging targey(SOC) when possible, and also by not charging to high levels and leave the car charged at high SOC.
And we can limit the cyclic wear by charging often and keep the DOD small.
We can never make the battery better by doing the stuff the BMS like (and maybe our OCD’s) to get a higher NFP.
If you’re doing the best for the battery in the long run, a temporary high SOC or charging schedule to get the BMS on the track doesnt hurt the battery noticebly but if you always do it constantly it willdegrade your battery a little faster than needed.
ro_explorer
Member
I do not have my home charger installed yet in my garage (stupid bureaucracy - I live in an apartment building). I cannot afford to stay at 60% for the weekends. My typical charge cycle is to 80% and I'm using a local 50kw DC charger for that (0.7 C basically) and also I use an 11kw AC when time is not a problem. I do not consider these regimes as stressful for the battery (I'm working with li-ion batteries for quite some time, I'm very familiar with their behaviour in various chemistry implementation and charge/discharge situations).
AlanSubie4Life
Efficiency Obsessed Member
Why can’t you get over it? This seems like a completely normal thing. When would you expect a battery to start aging? Do you expect the aging to be fastest at first, or faster later in life?
Then, it is a little puzzling to me that you did not expect a relatively rapid capacity loss. You’re apparently doing worse than average, but still, capacity loss should be fully expected on every single vehicle.
I follow what I learned from about 15 years of lithium battery use in a hobby. I learned a lot from this, mainly from being interrested and reading reasearch reports.
I did draw out on the getting a Tesla, mainly hesitating between a S LR or a model 3.
Meanwhile I did read more reasearch so at least I knew what to expect.
I have the data to make a calculation of the degradation, and to make it work out very good I think( these calculations is present in a lot of the research reports).
At least for the 2170L cells, the big question is at what capacity does the battery start?
Is the BMS off because of the new low cobalt formula?
There seems to be quite big differences in the NFP and something causes this difference. I do not know what it is, but I suspect the BMS calculation and that the 2170L performs different than the older 2170. The lower cobalt levelcould be the answer.
My M3P ’21 is 8 months since delivery, 21400km/13300mi and I have been above the other M3P’s range using teslafi all time since new. I have charged mostly at home but 25% of total is SuC (from traveling).
I only have one Tesla so I cannot statistically prove this is the right way to do it but all the research reports support the outcome.
It would be possible to minimize the wear/degradation more but I have decided to only use the things that doesnt limit the easy living. For example, I could leve the car pver the weekend with lower SOC and charge before going to work the next week. But as it might put me in the situation of needing to use my other car( Audi, fossile) instead I do not do that. Ease of living comes before preserving the batt.
I did draw out on the getting a Tesla, mainly hesitating between a S LR or a model 3.
Meanwhile I did read more reasearch so at least I knew what to expect.
I have the data to make a calculation of the degradation, and to make it work out very good I think( these calculations is present in a lot of the research reports).
At least for the 2170L cells, the big question is at what capacity does the battery start?
Is the BMS off because of the new low cobalt formula?
There seems to be quite big differences in the NFP and something causes this difference. I do not know what it is, but I suspect the BMS calculation and that the 2170L performs different than the older 2170. The lower cobalt levelcould be the answer.
My M3P ’21 is 8 months since delivery, 21400km/13300mi and I have been above the other M3P’s range using teslafi all time since new. I have charged mostly at home but 25% of total is SuC (from traveling).
I only have one Tesla so I cannot statistically prove this is the right way to do it but all the research reports support the outcome.
It would be possible to minimize the wear/degradation more but I have decided to only use the things that doesnt limit the easy living. For example, I could leve the car pver the weekend with lower SOC and charge before going to work the next week. But as it might put me in the situation of needing to use my other car( Audi, fossile) instead I do not do that. Ease of living comes before preserving the batt.
As I understand it, you know what drives li ion degradation. I’m with you about the strange things that make your NFP way less than it should be, at least for a true 82.1kWh Full pack when new.
But still, the NFP is just a figure and the true capacity is always usable anyway. Probably in some cases the ”lost part” is part of the hidden capacity below 0%.
I would guess that the real capacity average in all 4416 cells doesnt vary much between cars when new. The NFP might vary more.
I see the urge for trying to up the NFP, but I wouldnt try all the time. Some day its better to accept NFP and to start the preserve the battery way of living.
If you cant, because of no home charcer etc, no problem at all except that you probably cause a little more degradation. No problem with that. Will you ever need the top 5% or could you live with the old 77.8kWh pack if you had that?
Its probably also so that we all sooner or later come to the 10% degradation point. If you reach it before me, you get a almost ”flat line”before me, and the status quo will make you happy and during these days I still have the degradation pitsuing me.
AlanSubie4Life
Efficiency Obsessed Member
Especially as it is a three-year lease, as I recall.
ro_explorer
Member
If I'd know why I can't control my OCD I'd probably be a millionaire by now
As for the "normal thing" .. yes, degradation is normal and expected ... but not in 3 months, not by 5%. The thing that bugs me is not understanding why. I can live with a lower capacity battery, that is not the issue .. the question WHY is the issue.
In my RC hobby I use some really high grade li-ion batteries, that can sustain 5C charge and 20C discharge ... and those I expect to lose capacity quite fast, and they do (I charge them at 1C and discharge them at 15C, always in 5-100% cycles). They are rated for max 300 cycles so, by 30 cycles (which can happen in a week time) I expect it to see the capacity down by 10% (which usually happens).
In a battery that is rated for 1500 cycles, I expect to see maximum 1% degradation after 30 cycles in less than 3 months and about 4% after a year. It is a matter of predictability, nothing else. So far, the predictability algorithm is kind of all over the place ... and that is my problem.
Once I would have understood the reasons and mechanisms behind what I see I will probably be able to rest and leave everything behind
Candleflame
Active Member
If I'd know why I can't control my OCD I'd probably be a millionaire by now
As for the "normal thing" .. yes, degradation is normal and expected ... but not in 3 months, not by 5%. The thing that bugs me is not understanding why. I can live with a lower capacity battery, that is not the issue .. the question WHY is the issue.
In my RC hobby I use some really high grade li-ion batteries, that can sustain 5C charge and 20C discharge ... and those I expect to lose capacity quite fast, and they do (I charge them at 1C and discharge them at 15C, always in 5-100% cycles). They are rated for max 300 cycles so, by 30 cycles (which can happen in a week time) I expect it to see the capacity down by 10% (which usually happens).
In a battery that is rated for 1500 cycles, I expect to see maximum 1% degradation after 30 cycles in less than 3 months and about 4% after a year. It is a matter of predictability, nothing else. So far, the predictability algorithm is kind of all over the place ... and that is my problem.
Once I would have understood the reasons and mechanisms behind what I see I will probably be able to rest and leave everything behind
but that is the thing you cant get your hand around. You have lost 19km or 2% in 3 months which IS completely normal.
What part of battery degradation being normal do you not understand?
Your degradation is completely average.
From research we know this:
Lithium Ion batteries of the NCA type that Tesla/Panasonic manufacture will loose capacity from calendar aging. Initially this loss will be much higher than the cyclic aging. The aging starts when the battery is manufactured, but I guess they ”storage charge” the cells just as you should with your RC li Ions. I dont know the SOC used during transport before delivery, but this still causes a little loss of capacity even if storage charged.
If you use the manufacturing date, your car is about on month older, or about 4 months?
4 months with high SOC during long time causes some calendar aging. 80% the first night, and a bit less the other night?
Calculate your average SOC when the car is sleeping, and check the calendar aging in this picture( from a research report):
Also take the aversge temps in account
My average SOC at rest is 30-40%. I charge late during the night to 55-57%, the charging is complete one or two hours before going to work. Temps average 15C.
I had my M3P( E3LD 82kWh) 8 months, but it is 9 months old.
I can expect about 2.5% degradation from this, even if the car wasnt driven at all.
( if I had averaged 70-80% I would expect about 4.5-5% from calendar aging).
The cycles, and rating. One Full Eqvivalent Cyccle (FCE) is the cycled energy of 100-0%, and for example two 100-50% equals one FCE. At smaller DODs a battery that is rated or can survive 1500 FCE, can survive 5000 or even 10000 FCE.
My average DOD is about 35%, or less. From research reports I se that I can expect a maximum of 10% loss for about 1000-1500 cycles so my cyclic loss should be in the ball park of 0.5% or less for my 62 FCE done during the 22000km done so far.
So my calendar aging should be about 2.5% and the cyclic only a fifth, 0.5%. The total degradation should be about 3% and I should have a capacity of about 79.6 kWh.
I did read a NFP of 79.9 today( it varies between 80.0 and 79.7 lately). It makes sence. My BMS showed very high values for some time and after that it fell fast to lower values(faster than realistic for degradation) but now it seems to be quite good at it.
For you, if it stands long times with high SOC 3% is not unlikely after four months. If you have elevated temperatures combined with high SOC 5% is not unlikely.
The good thing, calendar aging is highest in the beginning and reduces quickly, specially if the battery is not in a hot environment.
Right now the Performance is only certified with the 3L Panasonic, but it is still likely that in the first weeks of October we see the release of V20 and in it the introduction of an E5LD performance. Tesla won't ship those Panasonic's forever, if they can avoid it.
V20 might also include the list with the 2022 model year upgrades.
I think October will be an interesting months for us.
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