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Not a problem.How about being in a short band? From 55% to 40% work days? Never going too low?
That is where our M3 LR spends most of the time since new. I basically set it at 50% and charged up above that only when needed and just in time to leave. The car is coming up on 2 years old (Feb) and about 15k miles. It has been in hot temps since new which are worse for the pack. Overall degradation is less than 1% when I last checked it.How about being in a short band? From 55% to 40% work days? Never going too low?
The largest source for difference between ”In” and ”Out” is probably that the battery efficiency is not 100%.2020 MSLR+ here, with 50k miles.
The car has a handful or superchargers (2MWh total). Charging at home every day to 60% (14MWh total). For road trips to 90%. Never above 90%, never below 10%. The cycles are mostly 50%-60%. The garage is about 75’F, consistently.
I am using “scan my Tesla” with OBD. Would appreciate help with:
1. It shows 212 discharge and 221 charge cycles. How do I explain that?
Yes it is included. Nominal full pack is “total”.2. It shows 91.7kWh nominal full pack. Is the 5kWh reserve on top of that or included?
If it is included then that is almost 9% degradation for 3 years only. Given that I was taking care of it, it seems rather high. Am I doing something wrong? Is the daily “top on” bad?
Thank you - very informative!The largest source for difference between ”In” and ”Out” is probably that the battery efficiency is not 100%.
If you charge 100 kWh, the battery will not deliver 100 kWh.
The efficiency is lower at lower cell temperatures, so the delta will increase with low cell temps.
(Self discharge and cell balancing will also cause losses that’s not messured but fir modt people this would be low numbers. Often have the car above 80% will increase the self discharge and often above ~90% will increase the balancing losses. Remember that these are small losses so not important but could explain differences between different owners if you start to compare).
I had 2.5 years of logged data on my M3P but I can not reach it after the switch to the MSP. Might still be there, but not easy available today. I’ll try to find data from that one before I sold it.
My MSP has 3247 kWh charge total, and 3117 discharge total. But it is parked with 34kWh total remaining. (Charge total includes the regen).
This makes the delta about 3% so far. The car is ~8 months since build, and 11 K km.
Also remember that the energy stored in the battery give an extra difference, specially early in the cars life. Fully charged we have 95-99 kWh more charged than discharged.
SMT do calculate and present some data by itself, that is not BMS-data.
The # charge cycles is the total energy divided by the Nominal Full Pack (if they did nit change the principle for this) but acutalky it should rather be divided by the initial capacity. As the NFP is an estimate that can change, this number will change as a result. This will mean that the charge cycle changes and would get lower when the BMS estimate for NFP increases. Charge cycle numbers is handy but have those limitations so looking at total charge and total discharge will take the induced issues away.
Yes it is included. Nominal full pack is “total”.
Did you charge to 60% daily from day one or did you charge higher earlier?
60% is on the edge between ”good” and ”bad” so you might have had a slightly higher calendar aging initially.
If we assume an 25C average cell temp the calendar aging should be about about 4.5% for 10 months, which calculates to ~ 8.5% after three years using the graph below.
(Calendar aging is reducing the rate with time). 5% for one year will be square root (3) x 5 for 3 years.
Your average SOC would be lower, depending on when in the day you charge and the normal end of day SOC.
So you probably have slightly less calendar aging but a (1-2?) percent cyclic aging, that set your toral degradation to a out 9%. Not bad at all for ypur car, and just about as expected.
If you had charged to 50- (max) 55% instead, and charged late you would have been at about square root (3) x 3 = ~5% calendar aging so maybe 6% total today.
View attachment 1002394
Thank you - very informative!
The car was set to charge to 60%, starting at 10pm every day, since the beginning.
Interestingly, looking at TeslaFi graphs, I should be having only about 5% degradation.
Contine as before.Hence, my concern.
Do you think I should go for less frequent charging and deeper cycles? E.g. from 50-60% to 30-50%?
Yep!Is the 55% and under still best for an older Tesla Model S? I have a 2014 Model S P60D and I'm trying to make it last as long as possible. It has 100k miles. Thanks.
Thanks a ton. I'm a newbie here so I can't like the post but it definitely is an amazing help.Yep!
To be perfectly clear most of the graphs shown is from batteries a few year and back (because a research report need to first have the cells available for test, then like one to two years for the test and maybe another half to one year to produce the report and get it accepted.
View attachment 1002893
This report is from 2018 if I remember it correct. The tests in this case was about a half year so I guess the cells was taken from a 2017-2018 model S.
For the NCA cells from Panasonic they have been behaving about the same for ten years.
So just remember it like this picture vaöid as the principle for Panasonic NCA:View attachment 1002894
After several years the rate is very low but still about half at or below 55% compared to above.
The 55% safe number increases with calendar aging and decreases with supercharging. So after a cell has lost 5% from calendar aging, the safe level is 55/0.95 if no supercharging etc was done. To make it easy it might be wise to still use 55% and only charge more when needed.
I have written a lot about this during ~ three years. Most often with references and links to research reports.Thanks a ton. I'm a newbie here so I can't like the post but it definitely is an amazing help.
So looks like 35-55% range is the least followed by 55-95% if I'm reading right? With 5-25% being even worse.Still you use about the worst SOC when it comes to calendar aging.
I’ll post a few graphs from different research relort, that tested the calendar sging at different SOC.
Panasonic NCA (virtually model S/X cells), the two first pictures.
View attachment 1001299
View attachment 1001300
Actual model 3 cells taken out of a 2018 model 3.
View attachment 1001301
Not Panasonic cells but a easy to read graph:
View attachment 1001302
Again Panasonic NCA.
View attachment 1001303
Calendar aging takes the very largest bite of our batteries the first fice years.
Cuclic aging is almost negligible for the most owners. 100K miles might cost 5% degradation but the first year only might cost 5% by being long time at around 70-90%.
Cyclic aging also wear less at lower SOC’s.
This is actual model 3 cells tested in 10% depth of discharge in different SOC regions:
View attachment 1001305
The wear is slightly more between 5-25%, but as we still get 1000 Equivalent Full cycles for 15% loss we get about 400K km (250K mi) for 15% loss, thats about 0.75% cyclic loss each year.
Calendar aging, if the battery is most often at 70% or more, we loose about 5% the first year.
The cyclic aging is very small anyway.So looks like 35-55% range is the least followed by 55-95% if I'm reading right? With 5-25% being even worse.
I charge to 55% at any time thats enough until next charge. I did not select 55% before 50% to reduce low SOC, as low SOC down to 0% is not bad.I see your post now about 55% being your target now.
Does it depend on how much you drive a day? Meaning if you end day with 20% would you charge daily maybe to 65% or something? Thanks.
Damn!Charged to 100% before the drivre here due to 300km in extreme cold (-41C right now).
And I'm worried if the car gets below +40F....Damn!
Our average annual temp is below thatAnd I'm worried if the car gets below +40F....
Amperage / speed of charging how does it matter? At home I only have 30amp so that’s how I charge. (With my old car’s charger)