Tell that to the Prius owners that sued because their gas tanks couldn't hold as much fuel as they did originally because the bladder in the tank shrunk after years of use and cold temperatures. The court rejected their suit and said that they were delivered the capacity advertised, and that the design decision that resulted in the bladder shrinking wasn't a defect.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health
- Thread starter KK_RedM3
- Start date
Regarding the app as a measure of degradation I found this over on reddit.
The variation is because at low SOCs, the math, due to rounding, results in wide variation.
If you look at each screenshot, you'll see:
7:04, 7% SOC, gives a range of 243miles, because the range is 17 miles. 17/0.07 is 243.
7:07, 8% SOC, gives a range of 238miles, because the range is 19 miles. 19/0.08 is 238.
7:10, 8% SOC, gives a range of 250miles!!!, because the range is 20 miles. 20/0.08 is 250.
7:11, 9% SOC, gives a range of 222miles, because the range is 20 miles. 20/0.09 is 222.
Because the car or app is rounding at low SOC levels, you can see how a 1% SOC variation at 7% SOC gives you up to 14% variance, or 32 miles of variance. If you notice, the variance was 28 miles. If you take enough data points, you'll find that the true estimate should be in the middle, so maybe about 236 miles. Obviously, as the SOC level increases, the variance will get smaller and smaller.
AlanSubie4Life
Efficiency Obsessed Member
Yep. Thanks for showing the math clearly. Best to avoid reading too much in to information on Reddit.
This is why it's always recommended to only pay attention to projections in the app at a relatively high SOC (and even then, be cognizant of the amount of error that may exist).
It's mysterious to me that they don't make an additional digit of precision on SoC available to the API. It would clean up a lot of this confusion (until getting to around 2-3% SoC - and then the extrapolation error would start to become significant again). Maybe it's not possible for some reason, but in the end it leads to a lack of app quality (confusing to end user) to have such widely varying estimates.
Last edited:
stopcrazypp
Well-Known Member
What you are doing is not the recalibration procedure, which is why it makes no difference. It needs high SOC readings (with the car asleep) at various SOCs and can take months:
How I Recovered Half of my Battery's Lost Capacity
Like many others, I have been concerned with loss of 100% indicated battery range on one of my Model 3s. My P3D (build date 9/13/2018, delivery date 10/8/2018) had gotten down to 270.3 miles at 100% charge on January 20, 2020, at about 30,700 miles, which is a loss of 40.8 miles since the car...
teslamotorsclub.com
Candleflame
Active Member
What you are doing is not the recalibration procedure, which is why it makes no difference. It needs high SOC readings (with the car asleep) at various SOCs and can take months:
How I Recovered Half of my Battery's Lost Capacity
Like many others, I have been concerned with loss of 100% indicated battery range on one of my Model 3s. My P3D (build date 9/13/2018, delivery date 10/8/2018) had gotten down to 270.3 miles at 100% charge on January 20, 2020, at about 30,700 miles, which is a loss of 40.8 miles since the car...
my car also gets frequent high and mid readings. I often let it sit at 80%, 90% and 3 months ago i also let it sleep for 4h at 100%.
I havnt let it sit at 90% for a few weeks because its just too hot here for that, but i will do that when i move south next year and will obviously report back.
But I have let it sit at 75% and 80% for a couple of weeks.
My car gets good readings at various SOCs.
with my mate up here sitting at 90% all the time and only having 407km (252 miles) we got some definite evidence that 90% is poison if the battery sits at 25-30C all the time.
Last edited:
Candleflame
Active Member
From traditional lithium ion understanding, if you live in cold climates then its almost irrelevant. I.e. If your car sits at 8C (45f?) then you get the same batterystress sitting at 100% as I do in the tropics at 100F/35C sitting at 78%.
I think from a practical perspective I'd recommend 85% in winter (when its 0-10C) and maybe 75-80% in standard summer with coolish nights and 75% in Texasstyle summer. To be honest if you charge at home and do scheduled charging prior to departure then I'd set it to 90% in winter and 80% in summer. That said, if you only drive medium distances, why not set it to 70% for most of the time and every couple of weeks charge to 90% instead or smth like that.
If you have a new iron battery SR+ then 90% is by far the best and even leaving it at 100% is ok. Need to also frequently charge to 100% for battery SOC reading.
CubedRoot
Member
Would you guys consider this odd? In the Teslafi screenshot below, you can see a pretty significant drop after my car hit 45k miles, back in July of this year.
Some backstory: I bought this car from Tesla used in May of this year. It had 40k miles on it. It's a 2018 Model 3 Long Range RWD. I drive this thing a lot for work, and I'm up to about 52k miles on it now, since I purchased it in May of this year.
Theres a second drop on that screenshot around the 51k mile mark and the curve is continuing downward a what seems an odd pace. My charging habits are: Charge to 90% daily, car is garage kept and the garage doesnt get hotter than about 80F. I live in South East TN. Every 3 or 4 weeks, I will do the BMS recalibration mambo, where I charge to 90, and then drive it daily, with each day drawing about 10% from the pack. The car enters a sleep every night for about 8 - 10 hours. Then I charge to 90 when I get the pack down below 10%, and repeat this a few times. After doing this BMS procedure a few times, I will go back to charging to 90 daily.
I do road trips pretty frequently and that means supercharging. I try to only charge when I get to a low SOC, and then only supercharge enough to get to my destination (even if thats the next supercharger. I typically stay in hotels with destination chargers, so I like to arrive there with a low SoC and charge slowly overnight. Heres a screenshot of my supercharges: Charge Totals 2021-10-22 at 12.19.20 AM
I have been using Teslafi since day one of ownership on this car, and I do so to try and keep all the data from the drives and charges. Does anything on this look out of spec or odd?
Some backstory: I bought this car from Tesla used in May of this year. It had 40k miles on it. It's a 2018 Model 3 Long Range RWD. I drive this thing a lot for work, and I'm up to about 52k miles on it now, since I purchased it in May of this year.
Theres a second drop on that screenshot around the 51k mile mark and the curve is continuing downward a what seems an odd pace. My charging habits are: Charge to 90% daily, car is garage kept and the garage doesnt get hotter than about 80F. I live in South East TN. Every 3 or 4 weeks, I will do the BMS recalibration mambo, where I charge to 90, and then drive it daily, with each day drawing about 10% from the pack. The car enters a sleep every night for about 8 - 10 hours. Then I charge to 90 when I get the pack down below 10%, and repeat this a few times. After doing this BMS procedure a few times, I will go back to charging to 90 daily.
I do road trips pretty frequently and that means supercharging. I try to only charge when I get to a low SOC, and then only supercharge enough to get to my destination (even if thats the next supercharger. I typically stay in hotels with destination chargers, so I like to arrive there with a low SoC and charge slowly overnight. Heres a screenshot of my supercharges: Charge Totals 2021-10-22 at 12.19.20 AM
I have been using Teslafi since day one of ownership on this car, and I do so to try and keep all the data from the drives and charges. Does anything on this look out of spec or odd?
Last edited:
Candleflame
Active Member
Would you guys consider this odd? In the Teslafi screenshot below, you can see a pretty significant drop after my car hit 45k miles, back in July of this year.
View attachment 724193
Some backstory: I bought this car from Tesla used in May of this year. It had 40k miles on it. It's a 2018 Model 3 Long Range RWD. I drive this thing a lot for work, and I'm up to about 52k miles on it now, since I purchased it in May of this year.
Theres a second drop on that screenshot around the 51k mile mark and the curve is continuing downward a what seems an odd pace. My charging habits are: Charge to 90% daily, car is garage kept and the garage doesnt get hotter than about 80F. I live in South East TN. Every 3 or 4 weeks, I will do the BMS recalibration mambo, where I charge to 90, and then drive it daily, with each day drawing about 10% from the pack. The car enters a sleep every night for about 8 - 10 hours. Then I charge to 90 when I get the pack down below 10%, and repeat this a few times. After doing this BMS procedure a few times, I will go back to charging to 90 daily.
I do road trips pretty frequently and that means supercharging. I try to only charge when I get to a low SOC, and then only supercharge enough to get to my destination (even if thats the next supercharger. I typically stay in hotels with destination chargers, so I like to arrive there with a low SoC and charge slowly overnight. Heres a screenshot of my supercharges: Charge Totals 2021-10-22 at 12.19.20 AM
View attachment 724194
I have been using Teslafi since day one of ownership on this car, and I do so to try and keep all the data from the drives and charges. Does anything on this look out of spec or odd?
Normal.
stopcrazypp
Well-Known Member
You don't need to let it sit for a few weeks at high SOCs (which is not good for the battery, especially in higher temps), only long enough at a range of SOCs that you are sure it gets a reading at each one (which above post claimed was 3+ hours after contactor disconnects). The OP in that thread did it for 6 hours for 95% every month or so. And his regular routine cycles him from 80% to 60% to 40% to 20% throughout the week, which gives him a nice variety of readings.
Candleflame
Active Member
AlanSubie4Life
Efficiency Obsessed Member
Yes, and to be clear, it's not like the LFPs aren't going to lose capacity - it's fully expected that they will (no one knows how much but @AAKEE recently posted some representative plots of calendar aging on that chemistry). The capacity loss is just not going to happen due to what SOC the LFP packs are left at. So that contributor (whatever it may have been) goes away for the most part (I guess - just parroting what others have stated here).
There’s no evidence this helps except for a case where the estimate is far off, though. In most (not all!) cases that does not appear to be the case - exactly as you would hope! The BMS is pretty good.
stopcrazypp
Well-Known Member
Sure, if your regular drive cycle already gives you a variety of readings, this isn't going to help much. The OP in that thread had a more extreme example of charging to 90% every night (which to be fair, is Tesla's default recommendation) and cycling roughly 20% per day, so he's only cycling between ~90-70% SOC, so it made a big difference for him. And to be clear, this only improves the estimate, it doesn't really "add capacity" in the sense it repairs the pack in some way (I believe in other threads it was mentioned the BMS is always balancing, so there is no need to force a particular SOC for it to balance).
For all recent test of LFP I have seen, they are NOT not sensitive for the SOC regarding calendar aging - they degrade more with higher SOC.
The only really big difference I have seen is that the DOD( Depth Of Discharge) can be 100% and still have very many cycles.
This is good for smaller batteries, as one probably need to use a higher SOC and DOD.
It is possible that the ones used in SR+ by Tesla have new ”features” still mot seen in research reports.
I guess we do not know but I would guess leaving a SR+ at 100% will degrade the battery in about the same manner as the NCA cells.
In all tests I have seen, NCA have been at least as good as LFP when it comes to calendar aging.
LFP need much more space for the same capacity/range so it cannot be used in a LR.
Also, they are much heavier so a Performance wont perform.
AlanSubie4Life
Efficiency Obsessed Member
I stand corrected. I guess I should have paid closer attention to your plots - which I think actually showed this, now that I think about it.
I guess it sounds like perhaps the effect of high SOC is not as strong as for NCA, but maybe that is not even valid for very high SOC %?
So seems like departure time scheduling for 100% charge on the LFP packs to minimize time there would be a good idea, since you do need to get them to 100% for proper SOC estimation (right?).
I would not say that you stand corrected.
I should have been more clear that I have not specifically searched for information about LFP’s. They are more or less always in the tests, as most research tests NCA, NMC and LFP and then compare them.
So from what Ive seen, NCA holds up well.
There might be recent research reports showing other things than I have seen.
The same day when there is lithium batterys that both not degrade from calendar aging/high SOC and also can do 100-0% DOD’s, we will know about it from the news.
My guessing point is that a SR+ that is parked with high SOC at elevated temperatures will show noticable calendar aging.
So that guy that had a LR that was on 10-15% degradation (which degradation actually was beginning to slow down to a maximum of 15-20%) and then bought a SR+ with LFP instead because he was furious about the degradation, then got a car that had lot less range to begin with and still lost range from that point.
With regards to my recent posts in this thread, in the image above:
- The timeframe shown as “1” is where I had been charging immediately when getting home for the day/night (range estimates were pretty poor).
- In “2”, I switched to scheduled charging at 3 AM (approx 6-10 hours after a typical last drive for the day), and my range estimates were > 290.
- In “3”, I was driving lots of miles in short periods of time, supercharging, and charging otherwise sporadically as I attempted to regain my 100 safety score, which caused my range estimates to go down considerably.
- Finally now in “4”, I reverted back to scheduled 3 AM charging, and my range estimates are starting to return to > 290.
Last edited:
Candleflame
Active Member
thats not true. iron batteries do degrade initially more being kept at 90% compared to 50%, however, the high SOC forms a protective film (at least thats the theory) at the anode which prevents further degradation so eventually 90% SOC vehicles degrade actually less than vehicles kept at 50%.
Similar threads
