I can accept that. However…..if the sample size is too small, can we accept the conclusion as valid??
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Tesla battery longevity not affected by frequent Supercharging, study says
- Thread starter Apprunner
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I thought about this again and I think there is a potentially substantial confounder that should be taken into account in the data analysis: what is the typical level/distribution of state of charge between the groups?
I suspect that the group that frequently supercharges, on average, does so because they don't have charging at home. And as a result I bet their average state of charge (over time) is significantly lower than the other group that does, because most people will set their charge limit to 80 or 90% and cars will spend frequent time there.
We know from science that calendar aging is a dominant phenomenon in early life for battery degradation (which is what we see here, 3 years old or less).
So it could be two counteracting influences: lower calendar aging, but higher supercharger degradation, make the overall curves similar.
The sample size for those who don't supercharge frequently and yet keep their average state of charge low is very small---only a small number of nerds who have read the threads here, like myself. Even a poll here shows most people set charge limit to 80-90% and not 50% like me.
We also know from science that fast charging does degrade batteries faster than L2 charging, though we don't have numbers here directly how much, and in which temperatures they were done.
I suspect that the group that frequently supercharges, on average, does so because they don't have charging at home. And as a result I bet their average state of charge (over time) is significantly lower than the other group that does, because most people will set their charge limit to 80 or 90% and cars will spend frequent time there.
We know from science that calendar aging is a dominant phenomenon in early life for battery degradation (which is what we see here, 3 years old or less).
So it could be two counteracting influences: lower calendar aging, but higher supercharger degradation, make the overall curves similar.
The sample size for those who don't supercharge frequently and yet keep their average state of charge low is very small---only a small number of nerds who have read the threads here, like myself. Even a poll here shows most people set charge limit to 80-90% and not 50% like me.
We also know from science that fast charging does degrade batteries faster than L2 charging, though we don't have numbers here directly how much, and in which temperatures they were done.
Makes sense. Doubt people who use a SC go every day and set their limit to 50% like I do at home. Let's assume your analysis is correct. We know from @AAKEE that we can cut calendar degradation pretty much in 1/2 with a low SOC strategy. Does that mean the better interpretation of the data is that you can 2x your degradation by exclusively supercharging??? Definitely not the conclusion from the headline.
We don't know that it's 2x, but I'd say >= 1x is probable.
This is like a poorly done medical study on an area with underlying biochemical experimental results but little field data.
In a scientific world, the analysts would have made stratified tests and statistical methods to attempt to neutralize the phenomenon; there might be a cohort of people who supercharged frequently at mid-upper state of charge vs people who charged at home with a lower average charge and they could be compared. But this is obviously not a science research article but probably paid marketing test ("how to deceive with statistics that look truthy").
I think it's premature to say that "supercharging has no effect on battery life" since we know the scientific results. Tesla would like people to believe so to sell cars to people who have to use their own supercharger stations and pay for them. Would JD Rockefeller in 1910 support an article saying "gasoline-powered car use is correlated with poorer lung function"?
Well played. I’m reminded of the old adage: What do you get when you mix medicine and politics? Politics.
We know that periods of low SOC make the cells recover lost lithium (that was lost to lithium plating when fast charging).
So, if using the low SOC stategy the battery can recover some of the losses from SuC.
As lithium plating also causes short ciruits in (very) long term it is 2 x good.
Recover capacity and reduce the total amount of lithium plating.
Staying at high SOC do not offer this effect as it seem from the research.
In general it looks like supercharging do not cause very much degradation, at least not that is estimated by the BMS.
But it causes the very bad lithium plating, that probably not is an issue short term but in the very long run it kills battery cells (causing shorts).
Everyday supercharging is probably not the best, if there is an other option.
I am very happy supercharhing when I need it, and I’m also happy knowing my car will get the chance to recover from it.
I actually quite sure I have seen the effect, and maybe even have data from it (if teslalogger did not dump the old data when I changed car).
During long periods of low SOC i see the capacity + range increase.
When doing longer trsveling witj series of maybe 10 supercharging sessions or more, the capacity and range has gone down.
Retirning home to low SOC + AC Charging and smalker repetes cycles the capacity and rabge go up again.
Initially there was somecforum people telling me that low SOC ”fools” the BMS causing the range to go up.
After checking the capacity by delta SOC and used energy (described by me on TMC in a few other threads) I actually could see that the capacity was higher after returning home and using low SOC cycles for a week or two, the increase might be about 1kWh or so, sometimes s little more.
This most probably is the recovery effect seen.
Yes, to some extent.
Just search for lithium plating + recovery effect, or read here:
Peter Keil’s eminent report cover this as well
https://www.researchgate.net/public...ium_ion_cells_and_their_influence_on_lifetime
Obviously these are technical papers that are difficult to understand as they are not my field of expertise....but they say that lithium plating can be partially reversed with rest....but it needs a full 100% charge before the rest...and the rest is about one to two days .
Can you confirm this...because there were many provisos
No, it do not need to be fully charged.
Low SOC is better for this, but rest at high SOC also could give some recovery appearently.
But low SOC is the thing.
Thanks. I’m beginning to understand how using a lot of SC can lead to a lower average SOC. I’m going on my first long trip and working through ABRP noticing a lot of my stops are 15-60% or so then get in car to drive to the next SC. This would give a pretty low average SOC.
From the following interesting research papers, curtesy of AAKEE
This is a short extract, which is out of context and incomplete...but it is interesting and thought others might find it interesting also....
This is one of the critical issues when discussing battery accelerated aging tests and degradation patterns. One piece of literature [141] suggests that a 2-day rest period between every 50th cycle will double the battery's cycle life. In another piece of literature [142], the minimum duration required for a rest period is 2 h in order to noticeably recover capacity. ...
This is a short extract, which is out of context and incomplete...but it is interesting and thought others might find it interesting also....
This is one of the critical issues when discussing battery accelerated aging tests and degradation patterns. One piece of literature [141] suggests that a 2-day rest period between every 50th cycle will double the battery's cycle life. In another piece of literature [142], the minimum duration required for a rest period is 2 h in order to noticeably recover capacity. ...
Have you read about any means to reverse regular old calendar aging? I have never supercharged, and probably will rarely need to.
There is a little data on that but it do not seem to help really.
This was a test with both calendar aging and cyclic aging that had a forced pause due to the covid situation.
I think it was a three months break and they put the cells at 50% SOC and room temp instead of higher SOC (75%) and higher temp (45C?) or something like that during the pause.
What happened was that the after the break, the first test data showed a slight recovery but the next data point “erased” the recovery. This is seen by the steeper gradient on the last part.
There is a slight win as the three month period has lower calendar aging, but the temporary recovery itself is wiped out, so at least in this case no long term recovery.
For the cyclic aging its more or less the same. The cell that showed more recovery lost it until next data point.
From memory I think I have read a report where it actually showed some gains, but I didnt find that report now.
This is one reason that I haven’t started an aggressive program to recover some degradation (although it’s mostly because I haven’t had the time)....I have always feared that after making the effort and wasting the energy, the recovery (if there is one) will fade quickly
The only real capacity recovery we can get is when plated lithium returns to cyclable lithium after Supercharging as far as I have read.
From what I seen, low SOC and small cycles seems best for helping the lithium plating return to cyclable lithium.
Charge to 50% or so every day, and charge late so the car can rest at the end of the day SOC. ( just like *any other day* really).
So, from my point of view not agressive and the effort is 0%
I have been following that regime ever since I started reading your posts....of course that was to reduce future degradation from cyclic loss....now it looks like it can restore battery capacity by deplating lithium...so a double benefitThe only real capacity recovery we can get is when plated lithium returns to cyclable lithium after Supercharging as far as I have read.
From what I seen, low SOC and small cycles seems best for helping the lithium plating return to cyclable lithium.
Charge to 50% or so every day, and charge late so the car can rest at the end of the day SOC. ( just like *any other day* really).
So, from my point of view not agressive and the effort is 0%
If you did not supercharge and already stay low, you have probably not lost any capacity to regain.I have been following that regime ever since I started reading your posts....of course that was to reduce future degradation from cyclic loss....now it looks like it can restore battery capacity by deplating lithium...so a double benefit
I saw this. How does he know that his battery death was from Supercharging? Any number of things could have gone wrong that caused it. Also, he paid $9k for a refurbished battery with 14%? That was a bad purchase...would rather explore getting a new battery for $15k with a full battery warranty.
He is also the only one that i've seen have this issue. Are there any other ride share people out there that have battery death with Supercharging. Seems anecdotal.
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