Is the 80% recommended charge real?

[Beetlebug62]

This is an in depth look at charging. Worth a watch. I go with ABC = Always Be Charging. It seems that more frequent smaller charges are better for the LiOn crystal and prevents cracking. So my daily is 60% but will gust up to 100% as needed for road trips. Just completed a 250 mile trip that was about 80% highway on FSD (Standard mode). Arrived at destination with 15% in the battery.

Thanks for the video link. I haven't looked at battery charging in 6yrs. There's not much new in NMC chemistry apparently. But for LFP batteries, I'd treat them just like NMC, except once a month, if I were going out of town, I'd charge up to 100% just before leaving. That will give you the best longevity while also keeping the BMS up to date. That's just my takeaway.

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[henchman24]

Thanks for the video link. I haven't looked at battery charging in 6yrs. There's not much new in NMC chemistry apparently. But for LFP batteries, I'd treat them just like NMC, except once a month, if I were going out of town, I'd charge up to 100% just before leaving. That will give you the best longevity while also keeping the BMS up to date. That's just my takeaway.

I wouldn't say the bolded is true, NMC is maturing but has some of the most experimental chemistries being applied which have impacts on charging. 811 chemistry just became mainstream in the last couple years, which has dramatically reduced costs and increased energy density at the expense of a narrower temperature window and less tolerance for higher states of charge. The CT is the first mainstream vehicle running 955 chemistry, and either is or will be the first to run 973 chemistry (unknown if that chemistry is currently being used). Which takes the drawbacks of 811 to a higher extreme (while having much better energy density). Around the corner in NMC is Silicon carbide anodes that will push back on the drawbacks of higher nickel chemistries. This is likely ~1-2 years away, but that battery is likely to unlock 15-20% more density and thus range. The 400mi CT will probably be due to the NC30 cell and given the roadmap will be late 26 to mid 27.

 

[Beetlebug62]

I wouldn't say the bolded is true, NMC is maturing but has some of the most experimental chemistries being applied which have impacts on charging. 811 chemistry just became mainstream in the last couple years, which has dramatically reduced costs and increased energy density at the expense of a narrower temperature window and less tolerance for higher states of charge. The CT is the first mainstream vehicle running 955 chemistry, and either is or will be the first to run 973 chemistry (unknown if that chemistry is currently being used). Which takes the drawbacks of 811 to a higher extreme (while having much better energy density). Around the corner in NMC is Silicon carbide anodes that will push back on the drawbacks of higher nickel chemistries. This is likely ~1-2 years away, but that battery is likely to unlock 15-20% more density and thus range. The 400mi CT will probably be due to the NC30 cell and given the roadmap will be late 26 to mid 27.

I mean, there's not much new to recommend for owner behavior with regards to MNC batteries. I'll charge the same way I've been doing it since 2018.

 

[henchman24]

I mean, there's not much new to recommend for owner behavior with regards to MNC batteries. I'll charge the same way I've been doing it since 2018.

In the real world and with the average use case, while there is a difference, it simply isn't big enough for manufacturers to change recommendations.

That said (and all feel free to ignore these weeds I'm diving in), given what we know with 811 chemistry, they probably should be setting the 'daily' at 75% and the calendar aging of that cell has a knee point around 65% (instead of the ~70/75% of the 721 cell). With 955 those should trim a bit further down too (70% daily and 55% for the calendar aging knee point). IMO the reason they don't 'recommend' a change from previous is the higher degradation is simply because it is unlikely to cause issues within the warranty period. The battery might 'only' last 900 cycles vs 1100 before dipping below 70% capacity and that is still enough cycles to extend past the 150k warranty.

We can see this in real time too... If you look at the data with the M3 with the Panasonic NCA chemistry 2018-2020 vs the 22+ you'll see the 18-20 hold up to degradation a good bit better than the 22+ cells. This is mostly due to being a slightly lower nickel with higher cobalt chemistry. Giving a bit more protection to the cells at a higher state of charge. Excluding the 21 pack cars because that pack is filled with issues. Now the new LG pack NCMA cell cars offer a bit less capacity (and charge significantly worse) than the Panasonic 22+ cars, but they have the best degradation results of all of those packs. Those should realistically last 1500 cycles based on the data we have. Now all that nuance is too much for the everyday consumer to sift through... and the 80% recommendation still hits warranty goals.

The rule of thumb is as nickel increases and cobalt decreases (the manganese and aluminum are mainly there for thermal stability and can perform similarly... though aluminum does increase longevity over manganese when using one or the other), the lower SoC the battery prefers in day to day usage and in storage. Ideally the 955 or 973 chemistry cells would be stored at 40-45% and not charged above 70% for daily use. Which is drastically different than 622 or 721 cells that could be stored upto 65-70% and charged to 90% daily without a huge hit to degradation (early S/X used NCA in this chemistry).

 

[Gigahorse]

Agree, Musk has casually stated that battery range is = to your bladder.

He's never known a truck driver and why they have Gatorade bottles!

Yea and when pulling a trailer my bladder can make it more than 60-70mins and does not take 90mins to empty while charging, hopefully they can get the curve and 500kw charging here yesterday.

 

[Beetlebug62]

In the real world and with the average use case, while there is a difference, it simply isn't big enough for manufacturers to change recommendations.

That said (and all feel free to ignore these weeds I'm diving in), given what we know with 811 chemistry, they probably should be setting the 'daily' at 75% and the calendar aging of that cell has a knee point around 65% (instead of the ~70/75% of the 721 cell). With 955 those should trim a bit further down too (70% daily and 55% for the calendar aging knee point). IMO the reason they don't 'recommend' a change from previous is the higher degradation is simply because it is unlikely to cause issues within the warranty period. The battery might 'only' last 900 cycles vs 1100 before dipping below 70% capacity and that is still enough cycles to extend past the 150k warranty.

We can see this in real time too... If you look at the data with the M3 with the Panasonic NCA chemistry 2018-2020 vs the 22+ you'll see the 18-20 hold up to degradation a good bit better than the 22+ cells. This is mostly due to being a slightly lower nickel with higher cobalt chemistry. Giving a bit more protection to the cells at a higher state of charge. Excluding the 21 pack cars because that pack is filled with issues. Now the new LG pack NCMA cell cars offer a bit less capacity (and charge significantly worse) than the Panasonic 22+ cars, but they have the best degradation results of all of those packs. Those should realistically last 1500 cycles based on the data we have. Now all that nuance is too much for the everyday consumer to sift through... and the 80% recommendation still hits warranty goals.

The rule of thumb is as nickel increases and cobalt decreases (the manganese and aluminum are mainly there for thermal stability and can perform similarly... though aluminum does increase longevity over manganese when using one or the other), the lower SoC the battery prefers in day to day usage and in storage. Ideally the 955 or 973 chemistry cells would be stored at 40-45% and not charged above 70% for daily use. Which is drastically different than 622 or 721 cells that could be stored upto 65-70% and charged to 90% daily without a huge hit to degradation (early S/X used NCA in this chemistry).

Thanks for all the interesting info!

 

[HaulingAss]

Yea and when pulling a trailer my bladder can make it more than 60-70mins and does not take 90mins to empty while charging, hopefully they can get the curve and 500kw charging here yesterday.

Do you have a picture of your trailer?

 

[TyPope]

It's plugged in, but with no charge schedule. If it drops below 3% I'll remotely start a charge session to avoid total shutdown. (I'm curious if it will decide to charge anyway at some point, but not curious enough to let it try lol)

Been almost 2 days, still at 15%

letting it run down before charging again is pretty bad for the battery long-term, apparently.

How To Ruin Your Electric Car's Battery - NMC Edition!

Short version:
In a study, they found this:
Charging every day from 40-60% every day = after 400 days, battery can fall to 85% capacity
However,
Charging every 5th day from 0-100% (same overall amount of energy put into the battery as the other test) = after 100 days, the battery fell to 50% capacity.

TLDR: Better to stay in a 20% range and also below 100% regularly.

 

[CyberGus]

letting it run down before charging again is pretty bad for the battery long-term, apparently.

The cells prefer a shallow Depth of Discharge (DoD). They also prefer a low SoC for storage, and mine is sitting for 2 weeks in the heat.

I normally only charge to 50% anyway ?‍

 

[Beetlebug62]

letting it run down before charging again is pretty bad for the battery long-term, apparently.

How To Ruin Your Electric Car's Battery - NMC Edition!

Short version:
In a study, they found this:
Charging every day from 40-60% every day = after 400 days, battery can fall to 85% capacity
However,
Charging every 5th day from 0-100% (same overall amount of energy put into the battery as the other test) = after 100 days, the battery fell to 50% capacity.

TLDR: Better to stay in a 20% range and also below 100% regularly.

Yep, I've been charging my 2018 Model 3 from 40% to 60% for the last 6yrs. Deg is 5-8%. Can't avoid time-aging.

 

[TyPope]

The cells prefer a shallow Depth of Discharge (DoD). They also prefer a low SoC for storage, and mine is sitting for 2 weeks in the heat.

I normally only charge to 50% anyway ?‍

That's probably decent. I keep mine above 50% because we lose power often and I use 34% each day to commute... Forgot to plug it in yesterday though so I'm happy with keeping her at 80% when at home.

 

[PungoteagueDave]

Elon says all the charging level angst is BS - just drive it’s like a rented mule. With 450k miles of EV driving experience, including over 200k on our ‘14 P85D’s original battery with less than 5% degredation, and now over 250k miles to the second owner, I go with Franz’s 2015 recommendation - the BMS needs to see both ends of the battery to maintain accuracy - so every couple months, run it to near zero, and give it a full 100%(at that time called “Range”) charge.

That’s been my approach ever since. We use the entire range of battery, keep the daily charge at 8%, do a 100% charge every couple weeks, and have no problem going down to 5 miles remaining while on road trips. Loss of range has never been a serious consideration for our 13 years of EV driving, and isn’t about to become a concern. My issue is the CT’s limited range towing my largest boat, compared to the original promise, and considering the loss of a previously contracted range extender option.

 

[CyberGus]

Being the thrill-seeking rebel that I am, I left town for two weeks with a 16% SoC.

I hope that phantom drain is low!

After a week, the SoC dropped from 16% to 14%... and then we got a software update that woke it up for a couple of hours, and now it's at 12%.

How come features like Sentry et al are disabled below 20% SoC, but a non-critical software update is OK? ?

 

[Dubes]

In the real world and with the average use case, while there is a difference, it simply isn't big enough for manufacturers to change recommendations.

That said (and all feel free to ignore these weeds I'm diving in), given what we know with 811 chemistry, they probably should be setting the 'daily' at 75% and the calendar aging of that cell has a knee point around 65% (instead of the ~70/75% of the 721 cell). With 955 those should trim a bit further down too (70% daily and 55% for the calendar aging knee point). IMO the reason they don't 'recommend' a change from previous is the higher degradation is simply because it is unlikely to cause issues within the warranty period. The battery might 'only' last 900 cycles vs 1100 before dipping below 70% capacity and that is still enough cycles to extend past the 150k warranty.

We can see this in real time too... If you look at the data with the M3 with the Panasonic NCA chemistry 2018-2020 vs the 22+ you'll see the 18-20 hold up to degradation a good bit better than the 22+ cells. This is mostly due to being a slightly lower nickel with higher cobalt chemistry. Giving a bit more protection to the cells at a higher state of charge. Excluding the 21 pack cars because that pack is filled with issues. Now the new LG pack NCMA cell cars offer a bit less capacity (and charge significantly worse) than the Panasonic 22+ cars, but they have the best degradation results of all of those packs. Those should realistically last 1500 cycles based on the data we have. Now all that nuance is too much for the everyday consumer to sift through... and the 80% recommendation still hits warranty goals.

The rule of thumb is as nickel increases and cobalt decreases (the manganese and aluminum are mainly there for thermal stability and can perform similarly... though aluminum does increase longevity over manganese when using one or the other), the lower SoC the battery prefers in day to day usage and in storage. Ideally the 955 or 973 chemistry cells would be stored at 40-45% and not charged above 70% for daily use. Which is drastically different than 622 or 721 cells that could be stored upto 65-70% and charged to 90% daily without a huge hit to degradation (early S/X used NCA in this chemistry).

Thanks for the info!!
How would I know which chemistry is in my FSCT and 2019 MX too?
FYI my MX has 160k miles. It currently has 289 mi range of original 325 for 11% loss. This is consistent with expected loss of 5% at 50k, 10% at 150k, then slower yet. I commonly discharge to below 5% and even lower. I just don't leave it below 20% ever. (Love the free lifetime supercharging!)

 

[henchman24]

Thanks for the info!!
How would I know which chemistry is in my FSCT and 2019 MX too?
FYI my MX has 160k miles. It currently has 289 mi range of original 325 for 11% loss. This is consistent with expected loss of 5% at 50k, 10% at 150k, then slower yet. I commonly discharge to below 5% and even lower. I just don't leave it below 20% ever. (Love the free lifetime supercharging!)

No easy way to know without research and people tearing down the cells… or the company producing the cells tells us. Because there is so much nuance in the topic, they aren’t really forthcoming. I believe all CT produced have been NMC in 955 chemistry though possible the most recent have been 973. Tesla has experimented with that chemistry… we don’t know if it is being used currently (practically wouldn’t make a difference). Now the S/X packs are all NCA chemistry (any Tesla with Panasonic batteries are NCA). They vary a tad through the years, but the newest packs (slightly under 100kWh) and the 100 kWh packs are 85/15/5. NCA is a bit more durable than NCM though in real life I wouldn’t expect the difference to be huge. NCM is a bit better thermally and more stable.

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