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Battery health tracking SS
- Thread starter msinfo
- Start date
I did read, lets say 150 reasearch reports.
Excluded about 10 of these when I found appearent faults. (Some researchers make mistakes in the setup that hides thing causing the result to be wrong. Or just like my favorite, make a very strong (faulty) assumption that offsets everything crazy. Like, if you keep the SOC at 100% the batteries will hold up much more than 100 years).
The rest, most of them have data that can be used and put togheter.
This is not the “truth” but very close to the data I have used: so far the formulas is for NCA, but its not very big differences so it will be possible to add the others.
From a few other reoorts se have data for what happens at 10C and 0C, that can be interpolated into this NCA graph (they are very alike otherwise as well).
Some tests show that 80% wear more than 100%, that data is not put into this, but as we can see 80-90-100% cause about the same calendar aging for normal temperatures.
All this is converted to formulas, so you input the SOC and the temperature and get a reference calendar aging for 10 months.
Using any value 25 or 50c hit the graph on the spot, also setting time (square root formula) to for exampke 2.1 months hit the line very well.
For cyclic aging the same is done, the spread is wider (much wider) between different research reports, but I made it a average that fits good in most reports.
(Calendar aging is small compared to the cyclic so it wont be very of).
In total it works quite fine and almost any case has been close.
There are two outliers. @KenC and a Swedish M3, living in the very cold mountains parked outside. These cars
are not very very of but enough to see that it differs.
There is a few calendar aging
Research tests showing very low degradation below 10C for the cells that by
Judgment only (did not try to calculate) which would probably make these cars fit very well. I did not exclude that data when making the formulas but I made a softer slope that tones down these reports data slightly. (A few other reports do not show that the degradation reduces that much, so I think it is good enough). One thing that can be hard to judge is the average cell
Temp.
I know I had 13.46C average over two years, but for other cars its the thing taking time to find a probable average cell
Temp.
Yup.
No, the initial capacity probably was around 80.7 but the range doesnt drop until about 79.0 kWh (judging by model 3 lr, no expert on mylr).AAKEE
Sorry, once again I think I am answering my own q's ...
Based on what you said I should be using 80.7
View attachment 970762
313 it is.
What about charging to 100% if ypu have a not that short drive soon after, to see the real BMS-data for range at 100%?
I have not done a 100% yet. The closest I have is 95% and let the car sleep for 3 hours once. This is BMS capture after 220 miles trip and 95% initial charge.
and next day with 50% L2 charge
PS I did it to see if I'll see any impact on BMS since car was mostly short cycling 40-50% and based on what I've read that could confused the BMS a bit
This is very helpful - thank you for sharing! Is this a good article to read more details - ShieldSquare Captcha? I found it searching for the graphs in your post.
No, I did not do anything. It was there since I picked up my MYLR.
PS My brother helped me to setup the car at the SC. Perhaps he renamed it ...
Where does ANYTHING that lists cars for sale list the current battery state? At this point, it effectively has NO IMPACT on the resale price. Sure, there may be a few people that look for it. But there's more that will turn the car down because of the tread depth.
And how much did the trade-in price change because of your degradation?
So, the amount of degradation didn't impact you?
Not really, My numbers are better than AAKEE and I don't pamper my battery.
And where do you balance this against the problems with ICE vehicles? What about the degradation of efficiency and range and the need for tune-ups to help fix some of it? What about the non-recoverable loss of efficiency and range as non-tune-up items wear?
What about the inability to use all the gas, because the inlet valve won't let you?
If you want to compare apples to apples, then compare then as apples. I haven't seen you post an equivalent loss vs time between tune-ups chart!!
zoomer0056
Active Member
This is an EV in question, not an ICE ages vehicle. If one doesn't care about battery health, we'll that's just dumb.
AlanSubie4Life
Efficiency Obsessed Member
You seem to be about in line 11-12% or so as I recall (295 miles). But you have not provided the confirmation of that.
Here you go. I have never tuned up my Highlander. My Subaru had approximately the same steady (horrible 18.5MPG) efficiency over 13 years. Did not matter what I did to it.
Anyway it’s a silly argument. We’re talking about an unavoidable capacity loss. This does not happen in ICE vehicles. The whole “efficiency gets worse over time” is just not a thing in modern ICE vehicles in decent working order. Tires make a difference though.
But there are a lot of other problems with ICE vehicles, which is why 2/3 of my vehicles are EVs. I have had a Spark EV for 7 years and have not done service on it once (this is great). It is about at 70% of its original capacity, going 55-60 miles rather than 85. 13-14kWh rather than initial 19+kWh. This does matter and has reduced its utility - but it is useful still.
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@outdoors I'm going to make a very apt analogy here to car paint. In the first few years, when I was on the old forum at the Tesla.com site, before it went away, there were a lot of threads about most ideal perfect car washing by hand strategies. There were ridiculously extensive LOOOONG discussions of the methods and the products people used. It was insanely OCD.
I hate washing my car and will never do it by hand and never want to have my life dictated by how my car is washed. I will take the four minutes to ride through the car wash, with those big industrial cloths sweeping back and forth across it. For some of those hand washing obsessives, that would probably give them a heart attack, because they really care about that.
So it's about the same thing. I acknowledge that gentle hand washing is the best, most ideal thing for my paint. It is not "disinformation" or "FUD" or misleading, like the accusations you have been making about ideal charging procedures. But I want to practically USE my car, so I don't do the most ideal car washing method or charging method. But discussing those doesn't hurt people.
I hate washing my car and will never do it by hand and never want to have my life dictated by how my car is washed. I will take the four minutes to ride through the car wash, with those big industrial cloths sweeping back and forth across it. For some of those hand washing obsessives, that would probably give them a heart attack, because they really care about that.
So it's about the same thing. I acknowledge that gentle hand washing is the best, most ideal thing for my paint. It is not "disinformation" or "FUD" or misleading, like the accusations you have been making about ideal charging procedures. But I want to practically USE my car, so I don't do the most ideal car washing method or charging method. But discussing those doesn't hurt people.
IMO very well put and love the analogy. So true!
PS I hand wash or touch-less only. And "YES" I do cringe every time thinking about those sweeping brushes leaving scratches on the paint LOL
@msinfo
Now this is interesting.
It looks like the day after your 95% charge, your battery capacity calculation went went up by ~ 2kWh. Am I reading your tables correctly?
Would be interesting to know if driving immediately after the 95% charge (instead if waiting for 3 hr, as you did) would yield the same result.
Yes, you are reading it right. Personally, I've noticed that often after I've used SC the BMS numbers are lower following quick recovery next time(s) I charge at home and drive locally. But it does not make much sense! Well, at least to me. So, I wrote off this observation to coincidence or not enough statistics or BMS approximation or simply something I just don't understand ...
Looks like cell balancing may have taken place, giving the BMS a better idea of the real capacity.
I am shooting from the hip, though ...
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