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How I Recovered Half of my Battery's Lost Capacity
- Thread starter SomeJoe7777
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- battery degradation Range
Adding further, many people look at battery capacity similar to fuel tank capacity, but it's really quite different. Unlike a float gauge in a fuel tank, there's no way to directly measure the capacity of a battery. In addition, the capacity depends on the discharge rate and the battery temperature.
Imagine a fuel tank where you can't measure the fuel quantity and the amount of fuel changes based on how quickly it's being used and its temperature, and you have an idea of the challenge associated with predicting battery level.
Imagine a fuel tank where you can't measure the fuel quantity and the amount of fuel changes based on how quickly it's being used and its temperature, and you have an idea of the challenge associated with predicting battery level.
AlanSubie4Life
Efficiency Obsessed Member
Yeah, it's a difficult problem, but the BMS in general does a remarkably accurate job of measuring capacity. Of course there are exceptions, and occasionally people report that (as seen here). But throwing around the word "degraded" in the referenced case above is entirely appropriate. It's highly likely that 205 rated miles reflects an accurate estimate of the battery's actual capacity (about 45kWh in this case for a 2019 SR+, probably, if it started with 240). If the user is in doubt, they can try some of the strategies here, but in most cases the estimate will end up being pretty close. In this case, it's extremely likely there is substantial capacity loss, even if it has "actually" only lost capacity to 210-215 rated miles after a couple charge cycles.
There are really very few counterexamples in "normal" temperatures that I have seen. They do exist. Just not that common.
It's not negative, obsessed, or a reflection of poor battery health. It just "is."
That is one point of view. I can understand the use of degraded in a sentence.
My biggest issue are the many, many folks who read about degradation and presume its permanent (and bad) as opposed to a temporary condition.
As you say - it just "is"
AlanSubie4Life
Efficiency Obsessed Member
There are exceptions, but I would not tell people it is temporary. In general batteries degrade. It is part of ownership of any EV, and it should be expected.
What is the case, in any case, is that a lower number of available miles indicates you have less available energy for the trip in question. So, it “is.”
And as AlanSubie says, the BMS most often is on spot.
Techniques that restore range only put the BMS back on track, if its a bit off. This to a cost of a little further degradation fo the battery, I guess. So in most cases it wouldnt really be worth it to gain miles on the display, as it actually mostly dont increase the thrue range, if charged full and driven to 0%.
Techniques that restore range only put the BMS back on track, if its a bit off. This to a cost of a little further degradation fo the battery, I guess. So in most cases it wouldnt really be worth it to gain miles on the display, as it actually mostly dont increase the thrue range, if charged full and driven to 0%.
So what one can do is to try to keep the battery degradation to a minimum. Or just relax and do the easy living and accept the battery degradation as it comes. At lest for Model S, most of the cars, the degradation is very slow below 10%, and for most people 10 or 15% isnt that important. Longer trips, where supercharging is available still in most cases isnt done with a 100% SOC goal, I guess. What will happen is that the charging time to the same real range needs higher SOC in %, causing it to take a bit longer time. A small cost, after some years.
I’m quite interrested in technical stuff, and have aboiut 15 years or lithium battery experience, so I think I know quite much about how to best preserve the battery. Of course I will use this knowledge but I dont think it is worth trying very hard to preserve the battery as the battery anyway will degrade so slow that It wont affect my use of the car at all.
Lithium batterys degrade less from time by being about 50 to 60 % SOC.
They degrade less if the are kept cool during storage.
They degrade less if the cycles are small, and preferebly cycled centered around the 50 to 60% SOC.
They degrade less if kept at 50-60% until they need to be charged to be finished just before starting the trip.
If I followed this, I would charge less each night, but I would have slight low SOC coming home from work= maybe limit a non planned evening drive after work.
And, for the weekend, I preferably would set it to 55% charge if I think it wont be used during the weekend. But I might be limited for a unplanned drive during the weekend. So, I charge to 70% on friday night also.
I’m quite interrested in technical stuff, and have aboiut 15 years or lithium battery experience, so I think I know quite much about how to best preserve the battery. Of course I will use this knowledge but I dont think it is worth trying very hard to preserve the battery as the battery anyway will degrade so slow that It wont affect my use of the car at all.
Lithium batterys degrade less from time by being about 50 to 60 % SOC.
They degrade less if the are kept cool during storage.
They degrade less if the cycles are small, and preferebly cycled centered around the 50 to 60% SOC.
They degrade less if kept at 50-60% until they need to be charged to be finished just before starting the trip.
If I followed this, I would charge less each night, but I would have slight low SOC coming home from work= maybe limit a non planned evening drive after work.
And, for the weekend, I preferably would set it to 55% charge if I think it wont be used during the weekend. But I might be limited for a unplanned drive during the weekend. So, I charge to 70% on friday night also.
Interestingly, that's essentially what I've been doing the last year and a half. Keep SOC at 60%; ~30mile commute so cycle between 50% and 60%; and here in Maine, it's generally quite cool. No garage, my 3 sits outside. The nice thing about cycling between 50 and 60%, is when I get home, I can toggle the fuel gauge and see that 50% is usually about 156 to 154 miles. Easy math.
Here's the recent Stats data showing the estimated range of 312.9miles, which is odd since it has been a very cold February. I would normally expect the estimates to be in the 304 to 306 mile range, and the upswing in the trend not to happen until April/May.
AlanSubie4Life
Efficiency Obsessed Member
So envious of your battery, as usual. People should do what you do!
Stats has a lot of noise on it here of course, due to your charge level. But that is a healthy pack! Will be interesting to see how it settles this summer. I wonder whether the recent irregularity is due to the recent software updates which I perceived as maybe impacting range (negatively) a little. But in your case they helped, of course.
I’m at 281. 22k miles ~Oct 2018 pack. 80% a lot. Shallow cycles, usually. 30-40 Supercharges. Don’t mind flooring it, also tracked once and then they removed Qualcomm
. Sits in a garage which can get pretty warm (80+) in the summer time. Basically never left outside to get hot.I'm guessing it's the parking lot at Qualcomm Stadium where you could autocross.
Yeah, I saw the comment thread about the software updates affecting the range estimates, negatively, but it made no sense, since my estimates were going up.So envious of your battery, as usual. People should do what you do!
Stats has a lot of noise on it here of course, due to your charge level. But that is a healthy pack! Will be interesting to see how it settles this summer. I wonder whether the recent irregularity is due to the recent software updates which I perceived as maybe impacting range (negatively) a little. But in your case they helped, of course.
I’m at 281. 22k miles ~Oct 2018 pack. 80% a lot. Shallow cycles, usually. 30-40 Supercharges. Don’t mind flooring it, also tracked once and then they removed Qualcomm
AlanSubie4Life
Efficiency Obsessed Member
Yes. It's now gone forever. Qualcomm stadium nearly completely gone, too. Was used for autocross. Picture was taken there.
Ome could start to wonder if there was a software changing the projected range, because if you disregard the trendline which os softening the change, it sire looks like either a projelted range change or a BMS software change that thinks the battery is better now.
I did get a software changed range about one month ago for my ’21 M3P.
When new the max projected range was 500km(310-311miles) and after the update its 507 or 508km(315miles, the EPA range for ’21 M3P).
And yes, that battery low degradation graph looks very nice!
SageBrush
REJECT Fascism
@SomeJoe7777 ,
Now that some time has passed since you started this thread, how much of the lost capacity has been regained ?
Now that some time has passed since you started this thread, how much of the lost capacity has been regained ?
wildguess
Member
I am wondering if this is even working.
There is a sudden increase in the rated range at the end of the graph which if disregarded makes the end result questionable.
It has been hanging out at the recovered level with some variance.
So it appears that I have recovered some from the low point at around 30,500 miles, and it doesn't appear to be wanting to go down any further. Not a bad result.
Not really sure what you're getting at here. It sounds like "Well, if you disregard the evidence then this is meaningless".
Well. Ummm. Yes. I guess?
Doctor comes in and says "well the MRI shows you have a large cancerous tumor". Hmmm. Well I guess if I disregard the MRI results then everything should be OK.
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