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LFP to 100% Each Week—Assumptions?
- Thread starter PianoAl
- Start date
The reason I asked was because many people think they baby the battery by charging to 80% or so.
For keeping calendar aging low (which is the main degrading factor for at least the five first years), 80% is not very good.
The lower the SOC, the better. Even down to 0%. Low SOC is not bad, that is a forum myth.
I havent really babied my battery, as I have > 30 full charges and ~ 50 supercharging sessions. Its a M3P and I have used the power quite a few times.
But I have used a low SOC stategy, not charging more than needed and charging late so the car stands with low SOC over time. My standard charge is 55%.
My car is two years and thre months, 60K km (37K mi).
Out of the ”new car range”, 507km, my last full charge said 495km so thats a 2.5% drop in range.
For an NCA battery, wouldn't charging to 55% unless you need more for the day's driving be the best way to try to reduce degradation? For an LFP battery, substitute 70% for 55%, although the greater longevity of LFP batteries may mean that the difference it makes is smaller for an LFP batter than for an NCA battery.
Why do you even need to go to 100% once a week? Or even once a month? If you aren't using the bottom 20%, such that BMS drift could be a problem, you can just treat 20% as 0% and 50% as 30%. Then any time you do need to go below 20%, or once every 3 months if this does not happen, charge to 100% to recalibrate the BMS.
stopcrazypp
Well-Known Member
While that is true, it's pretty hard to separate the the two. I remember when I did research on the interaction between the two, it seems they cancel each other out somewhat (a highly cycled pack might see less calendar wear effects and vice versa), so it's not additive nor is it necessarily all based on the worst factor.
As a data point, during the first year of ownership (I got my car delivered last day of 2020), I supercharged exclusively to 90-100% SOC (although I use up the top part almost immediately), given I had free supercharging for the first year and basically deep cycled it (although I didn't go below ~50 miles or about 20% given that is when the bar turns yellow).
After that period, now being a weekend car, I settled to now charging to 70%, using it same or next day down to about 50% where it sits about a week, and then using it about down to 30% before I get back to my charging, where cycle repeats. So the average lifetime sitting SOC of my car should be now be pretty close to 50%.
Calendar degradation data from the manufacturer is harder to come by for the NCA cells, so I never did analysis of that though. I'm just not surprised about the cycle degradation given I did look at that previously.
Hi I have 2023 Model 3 and I don’t have place to charge at home. My question is since tesla recommend to charge once a week to 100% and my only option is SC. Should still charge 100% with Supercharger?
My concern is to damage the battery also realized yesterday I only have 268 mile range at 100% which supposed to be 273. Car have less then 1k on it and 4 months old so Im kinda worried and got confused.
2nd question Im not driving a lot and if I charge once a month is enough for me but should i just go and charge every week lets say even car at 70% with SC ?
Thank you for answers in advance
My concern is to damage the battery also realized yesterday I only have 268 mile range at 100% which supposed to be 273. Car have less then 1k on it and 4 months old so Im kinda worried and got confused.
2nd question Im not driving a lot and if I charge once a month is enough for me but should i just go and charge every week lets say even car at 70% with SC ?
Thank you for answers in advance
I would recommend to not worry about it and charge when it makes sense for your life. These other optimizations are for people who have garage charging and it is easy for them to do different charge profiles. A new Tesla will typically drop a few miles quickly, but then it stops dropping the miles.Hi I have 2023 Model 3 and I don’t have place to charge at home. My question is since tesla recommend to charge once a week to 100% and my only option is SC. Should still charge 100% with Supercharger?
My concern is to damage the battery also realized yesterday I only have 268 mile range at 100% which supposed to be 273. Car have less then 1k on it and 4 months old so Im kinda worried and got confused.
2nd question Im not driving a lot and if I charge once a month is enough for me but should i just go and charge every week lets say even car at 70% with SC ?
Thank you for answers in advance
Those data are not publicly available. Tesla could do a data analysis but their motivations are not the same as battery nerd's motivations. Very very few people in the world with LFP will be consistently charging up to 50-60% and no more other than the occasional BMS recalibrations. We're the tiny minority here.
Tesla cares about lowering service calls and bad experiences, not optimizing for 5-10 year degradation. Also, given the hostile press and clickbait journalism, any suggestion from Tesla to charge only to 50 or 60% will be spun into some horrible Tesla-specific major defect. This misinformation would seriously hurt sales. The way people here think and act is very different from the average person. I just helped a friend buy and setup a new EV, non-Tesla, and the knowledge and concerns were really different. In this population explaining something complex about LFP and half charging and charge once a week up to 100% seems so complex and a big turnoff. Seeing a low number really freaks them out. Someday, when EV penetration has been 90% for a decade or more, then average people will be more receptive to more nuanced scientific suggestions.
That's entirely not at all true. Do you know any?
The one thing that really deeply angers scientists is others faking data. The smell of maybe fake data sends them into a frenzy of righteous rage. At the moment this is happening in superconductor research where a group with a questionable history is now being deeply scrutinized because of their claimed new results and data and their past behaviors. There's a whole crowdsourcing of investigators all working for free, just because the idea of fake physics is deeply immoral to them.
As @DrChaos said, we won’t get access to some of the knowledge that Tesla have or gain.
We can se from teslaloggers data for LFP model3’s that they have about the same form on the degradation curve as the LR has. The rate of the degradation seems slightly less. As 100% in some cases does give less calendar aging than 80%, this is not completely unexpected.
We know both from CATL spec’s and cycle tests that modern LFP can stand very many cycles and that large cycles does not wear much at all.
I put in a caviat for BMS in LFP cars not being able to detect degradation as well as in Long range cars due to the issue of measuring the exact SOC. This might delay the real degradation/range loss.
Any obvious degradation the first years should be more or less calendar aging only.
From 424 to 403km at 60.000km.
This is 5% loss.
LR with NCA, from 499 to 458km at 60.000km. This is 8% loss.
The LFP’s seems to degrade less than NCA, but what we see is not degradation due to the miles, instead the most part is calendar aging. The curve describes a square root line which is most probable due to calendar aging.
This in turn tell us what se already knew, as there is no lithium batteries yet that does not behave about the same:
These LFP’s do suffer from calendar aging and it is extremely probable that these also follow the standard calendar aging route - less SOC = less calendar aging.
What we are starting to see on quite some ”low SOC stategy cars” is a clearly reduced degradation. This is valid both here and on a Swedish forum.
It is very likely that this is valid to LFP cars as well, if the low SOC stategy is used.
The BMS issue of keeping track of the SOC complicates things if you do not drive much. It’s (probably) wise to follow the 100% charge at least once a week. Doing that, if you can have the car standing most of the time at or below 70% this would most probably reduve the degradation.
As per the caviat listed above, it is possible that the real degradation is less but the BMS get harder to ”count” so we might not see the lower degradation thats really happening on a short term basis.
I’m just curious though would you still charge to 100% with Supercharger if you only charge once a week though for LFP ? Do you think that recommendation of Tesla, only for home charging because charging to 100% with SC might not good for battery life?
Scientist dissentions is not heard. They are silent for good reason. The ones that are brave enough to stand up and disprove the false assertions are ostracized with fundings eliminated. I can provide several examples of this happening in Anthropology, Astronomy, Climatology, and other historical Sciences. Most of these disciplines are based upon a foundation of assumptions. And those claims are skewed and not on objective findings.
Everyone can look up several examples for themselves of deception and form their own conclusions. But this forum is about Tesla and not junk science and I will leave it at that.
stopcrazypp
Well-Known Member
If you charge to 100% and use it up almost immediately, the impact on the battery is minimal. So it depends on how far away you drive after you supercharge. The battery cells just doesn't like being stored at high SOC long term.
The only logic Tesla has given for recommending weekly 100% is because the capacity estimate may drift and become inaccurate and there have been people stranded in LFP cars when indicated SOC fell below 10% and car shut off unexpectedly even when car said there was still charge. Because of the low capacity lithium LV battery in the Ryzen cars, the whole car computer shuts off also quickly afterwards (reported within 15 minutes). If you treat 10% indicated as 0% in your mind, you theoretically don't need to do the 100% (or only do it in months to recalibrate the capacity estimate as desired).
Just do whatever is convenient for you. When I was using superchargers exclusively, I did charge to 100%, but only because I was only doing the supercharger stop every 2 weeks, and I shop while it is charging. If you are going to superchargers weekly or more often (to cover your regular driving) charging to a lower SOC may make more sense, given charging to 100% takes a much longer time (charge rate slows down drastically at higher SOCs).
Agreed. I like the idea to just not dip below 10-15% and you should be fine. I will definite do 100% within a month timeframe but it it won't be a weekly occurrence. I just don't drive that much.
One of the reasons I went for the M3 is price and the LFP battery. LFP batteries are not bullet proof and will degrade. But they are hardier than NCA/NCM chemistry packs. Plus, they are made by CATL and they are thee premiere battery makers in the world. My confidence is weak when it comes to the Tesla's 4680 format, though. I would be hesitant on buying a car based upon it until the data points come out. There is a reason why it was delayed coming to the market. Now, I must go as the Tesla swarming Murder Hornets will be coming after me :
Hi I have 2023 Model 3 and I don’t have place to charge at home. My question is since tesla recommend to charge once a week to 100% and my only option is SC. Should still charge 100% with Supercharger?
My concern is to damage the battery also realized yesterday I only have 268 mile range at 100% which supposed to be 273. Car have less then 1k on it and 4 months old so Im kinda worried and got confused.
2nd question Im not driving a lot and if I charge once a month is enough for me but should i just go and charge every week lets say even car at 70% with SC ?
Thank you for answers in advance
Perhaps you can charge at a public L2 charger or at a low power DCFC; you can precondition the battery with the Tesla cellphone app.
What tires and wheel cover options are set in the car's menu? IIRC, 268 miles was the reported max range with 19in tires (without aero covers?).
I know this question is asked to death, but I just want to make sure I’m doing the right thing. And yes, I know what the manual says.
I have around a 40 mile round trip commute daily. I’m usually at 86-88% when I return home and I plug in and charge to 100% nightly. My question is this: with not losing much percentage, if I arrive home at say my normal 88% and set the charge limit to 88% and leave it plugged in as the manual says to do, would that be ok? Then after say 3 days of driving to work, and dropping to around 60%, then charging back up to 100% for the rest of the week? Is repeating that pattern OK or should I just not worry about it and charge to 100% daily?
I guess maybe it’s an unfounded worry, but I feel like only losing 12 percent during the day and then charging back to 100 would put strain on the battery.
Thank you.
I have around a 40 mile round trip commute daily. I’m usually at 86-88% when I return home and I plug in and charge to 100% nightly. My question is this: with not losing much percentage, if I arrive home at say my normal 88% and set the charge limit to 88% and leave it plugged in as the manual says to do, would that be ok? Then after say 3 days of driving to work, and dropping to around 60%, then charging back up to 100% for the rest of the week? Is repeating that pattern OK or should I just not worry about it and charge to 100% daily?
I guess maybe it’s an unfounded worry, but I feel like only losing 12 percent during the day and then charging back to 100 would put strain on the battery.
Thank you.
stopcrazypp
Well-Known Member
As mentioned above, if you don't drive your car down to 10% there isn't really a real need to charge to 100% daily. The charging to 100% for LFPs is to help the BMS get a more accurate capacity estimate, but generally it isn't good for the battery to keep it at high SOCs.
However, shallow charges are better for the battery, so daily charging does make sense if it is convenient for you, only I would set the charge limit (like maybe 70% or less given your commute so short), so your average SOC is lower. You can occasionally charge to 100% to recalibrate the battery if you feel like it.
There is some evidence that exclusive shallow discharges within limited SoC levels can cause reversible degradation due to "uneven storage" of lithium. Reversing this effect requires extended full charge/discharge.
Since LFP batteries are not affected by DOD for permanent degradation, my suggestion is to utilize it like a gas car, where you charge it up to 100% and refill it whenever it gets low (whatever remaining % makes sense for you). This is balancing different considerations like temporary vs permanent degradation, SOC accuracy etc.
As low SOC as possible is best for reducing permanent degradation.
Since the voltage curve for LFP batteries is no longer flat below around 15% (unlike in the 20-99% range), wouldn't an instance of going down to below 15% get the BMS to see a voltage that allows determining the true state of charge with less error?
Of course, a recommendation to "drive it down to 10% regularly" may result in more issues among the general public than "charge to 100% regularly".
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