Tesla sets charge limit to 90%

[AAKEE]

They actually do that too. It's the standard charge when they deliver vehicles. At least mine was @ 90%... hence this thread.

The set charging level and the actual SOC seem to vary.
I did get mine with 97%, but they knew I had a 1000km drive home.

I only bought one Tesla but from what Ive seen in forum, much lower SOC seems to be the standard.

The set level when getting the car should not be taken as a instruction how to charge…

The Charging instruction is under 90%
which includes all selectable numbers between 50 and 90%. If reading it by the word, it should be below 90%, but I guess 90 is about as OK as 89%.

For storage of spare battery packs, Tesla recommends 15-50%

 

[thefisch]

@AAKEE

So, in my situation, I drive about 25 miles a day. For the best results, I plan to charge to 50-55%. Would you recommend charging everyday even though my SOC at the end of the day is around 40-45% or should I charge every 3-4 days when my SOC is down to 20%? Also, I will plan to schedule my charging to happen closer to leaving home in the AM when I do go to hook up. Thanks for the info!
Chad

Most weekdays we drive between 5 and 25 miles depending on errands. FWIW we charge daily M-F to 55% using the scheduled departure option for the morning commute (we don't have time of use rates). We have the WC and charge at 48A even if it is only a 15 minute charge.

At first, we went a couple of weeks without regularly charging and found ourselves always talking about whether or not we needed to plug in before the next day. Since we switched to (almost) daily charging, we have one less thing to think about and use the app to make adjustments if the need arises.

On the weekends, we don't always leave at the same time so we'll get down to 20-30% depending on what we are doing and then charge before Monday morning.

 

[jcanoe]

They actually do that too. It's the standard charge when they deliver vehicles. At least mine was @ 90%... hence this thread.

Home Charging - Frequently Asked Questions

Learn more about how to charge a Tesla at home, including home charger installation costs, equipment options and how long it takes to fully charge a Tesla battery.

www.tesla.com

Tesla delivered my 2020 LRMY to my home with 30% SOC.

 

[Iron]

Tesla delivered my 2020 LRMY to my home with 30% SOC.

Maybe someone dropped the ball cause that's almost at the other end of the spectrum. I picked up from the SC. A line of cars were all on the chargers and all were charged to 90.

 

[jcanoe]

Maybe someone dropped the ball cause that's almost at the other end of the spectrum. I picked up from the SC. A line of cars were all on the chargers and all were charged to 90.

Also 30% when I picked up my Model Y after Tesla Service had the vehicle for 10 days to make repairs to the compressor.

 

[Iron]

Also 30% when I picked up my Model Y after Tesla Service had the vehicle for 10 days to make repairs to the compressor.

Okay point taken, but your SC sucks. Lol

 

[jcanoe]

Okay point taken, but your SC sucks. Lol

I returned the Model S loaner with 30% SOC.

 

[johnny_cakes]

They actually do that too. It's the standard charge when they deliver vehicles. At least mine was @ 90%... hence this thread.

Home Charging - Frequently Asked Questions

Learn more about how to charge a Tesla at home, including home charger installation costs, equipment options and how long it takes to fully charge a Tesla battery.

www.tesla.com

In the FAQ you linked to, Tesla says to set your daily limit "up to approximately 90%". I can understand why many people interpret this 90% as gospel, but the recommendation is 90% or below. They also don't say 90% is best for battery health.

Note also on this screenshot where Tesla recommends "to maximize battery longevity, only charge to the level needed".

 

[AAKEE]

Maybe someone dropped the ball cause that's almost at the other end of the spectrum. I picked up from the SC. A line of cars were all on the chargers and all were charged to 90.

This is not relevant to the best charging stategy anyway. Its more of superstition than science

My car was delivered with 97%, thats an odd number so even numbers is dangerous?

 

[Art84]

Thank you both for the replies. I will plan to charge daily then. Last question, I have the ability to charge at 48A. Is there any advantage/detriment to charging at a slower rate, say 32A?

I saw somewhere on this forum research about that. The conclusion is that charging at around 30A level is the most energy efficient because of less energy loss on cable heat and resistance. It has nothing to do with battery health though. Just a slightly less loss of energy during the charging.

 

[AAKEE]

I saw somewhere on this forum research about that. The conclusion is that charging at around 30A level is the most energy efficient because of less energy loss on cable heat and resistance. It has nothing to do with battery health though. Just a slightly less loss of energy during the charging.

I am a bit sceptical to that.

What has been tested earlier is that the higher charge power on AC the less losses.

The car uses 200-220W by being awake, as it is when charging. A slower charge will use more energy for keeping the car awake

200W is 5% of a 4kW charging power but only 1.8% when maxing the 11kW.

 

[Rocky_H]

What has been tested earlier is that the higher charge power on AC the less losses.

I remember seeing some tables on that from years ago, and it wasn't open-ended like that. It wasn't always more efficient with higher and higher power. There was some kind of small efficiency peak in the middle somewhere. I wouldn't try to name a specific amp number here on the forum, though, because I think that sweet spot peak moves some with the different generations of chargers.

 

[Art84]

@AAKEE
Here: Most efficient charging level | Tesla Motors Club

 

[DayTrippin]

If this is related to the wall charger cable being of inadequate gauge with too much resistance at higher amperage level, then maybe an aftermarket one would be more efficient if better wire.

For example I have a 40 amp EVSE with a Tesla adaptor and it never feels warm to the touch. Whereas my Tesla wall charger cable is definitely feeling warmer when charging at 40 or 48 amps. Might even be more significant on a hot day.

 

[DB288]

Right from the horse's mouth. It's also consistent with all the research reports that @AAKEE 's been posting. Thanks for sharing this. Hopefully this dispels the "Tesla recommends charging to 90% daily for best battery health" myth.

replacing the 90% myth with the 55% myth

you really believe all this armchair science?

until one actually sits in a lab and tries to design experiments that answer difficult question (and do it for years) can one appreciate the complexity of these questions…

the cars are deployed in hugely varying environments (minnesota versus key west) and used in hugely different ways by different people …and the cell is connected to a complex computer controlled electronic system…

there probably is not one answer (55%) or there may not even be a best answer that applies to most people…

the 90% recommendation is probably not optimal but it’s not crazy to assume that it is a best guess from pretty knowledgeable at what practically works for most people (conspiracy theories aside)

 

[AAKEE]

replacing the 90% myth with the 55% myth

you really believe all this armchair science?

Its not armchair science.

Its real science from a lot of scientists.
Its a lot of consistent research reports

until one actually sits in a lab and tries to design experiments that answer difficult question (and do it for years) can one appreciate the complexity of these questions…

Its already done that way, see what I wrote above.

the cars are deployed in hugely varying environments (minnesota versus key west) and used in hugely different ways by different people …and the cell is connected to a complex computer controlled electronic system…

The environment have been researched also, so the impact of heat or cold is known.

A complex computer (a.k.a BMS) can not stop calendar aging or hinder cyclic aging.
These things will happen regardless of a BMS.

there probably is not one answer (55%) or there may not even be a best answer that applies to most people…

I agree. What charging habit that that is beat for an individual wont always be the same.
But the for batteries it is known facts and not a variable.

the 90% recommendation is probably not optimal but it’s not crazy to assume that it is a best guess from pretty knowledgeable at what practically works for most people (conspiracy theories aside)

There is no 90% recommendation.

Tesla says under 90%. Which includes all charging settings between 50 and 90% (or 89% if we read it as written).

The research data is actually very much in line with what we see in real Teslas.
Amoung the people here on TMC we have people using low SOC and we see the low degradation in these cars. Same for a Swedish forum, a lot of people that have started using low SOC and we se the same in those cars.
Among the high SOC-cars we se the usual double degradation.

I see the low degradation as well

Degradation (calendar aging and cyclic aging) is foreseeable, its not coincidental.

As I wrote before, I could probably calculate your teslas degradation and not hit very far.

 

[DayTrippin]

I early on read a lot of what @AAKEE posted and adopted what would work in my situation. My MS LR that was older than the Plaid I replaced it with, and had more miles, had 3 times less degradation while being driving in a similar environment. That car was maintained at higher charge levels and more SC use. I limited both as much as I could and maintained a very low average SoC.

I have no plans to ever sell the Plaid unless Tesla finally puts back in something equivalent or better then the USS they removed and hobble the car. As a result, based on how slow Tesla can correct these things, I could be driving the Plaid for a long, long, time so I plan to do what I can to minimize degradation. Even more since I am on 21's and get less range to start. WIth the 19's and my LR, I almost always had range to spare unlike my MY LR which always seemed to be looking for a supercharge when on a trip.

@AAKEE I greatly appreciate all you have posted on this topic! It has been very useful and it is a similar approach I take to my phones and notebooks. My wife charged her iPhone to 100% every day and she has lost 30% of her battery in 2 years. I use my phone a lot more but keep it charged, but more frequent small charges, in the 40-80% range and still have 100% of my battery after 16 months of owning the phone. My MacBook Pro after more than a year is kept at 50% when plugged in (thank you AlDente Pro) and I am still at 100% with it.

There is a lot of data out there and I appreciate you pulling it together to make it easier for people to understand it her on the Tesla forum. For some, they won't care. I just hate wasting resources. Even if I don't keep my car forever, it means it will likely last longer for the next person and ultimately be better for the environment if we don't have to recycle as many batteries.

Keeping my average SoC around 50%, charging just before leaving to higher if needed, small charging cycles more frequently rather than one big one, have keep the degradation low on 3 of my cars so far. I am in a very hot environment with summer temps often over 100F (38C) which is very hard on the batteries to begin with.

 

[AAKEE]

This is a research/test which used actual Model S 18650, from a Tesla that was used for 6 months since new. Report from 2017. so maybe a 2015 or 2016.
I have had this report for a while but if I remember it right, I havent used this as reference before.
Remember, this is not a question of finding one specific report showing something, it is the sum of reading more than 100 research reports, and disregarding a few of them. The rest, still more than hundred, builds the case.

8650 lithium-ion battery cells (Panasonic) for the aging study. The typical nominal capacity of a cell is 3.03 Ah with a voltage operation window from 2.5 V to 4.2 V. The cells tested were taken from a Tesla model S electric vehicle, which was used for 6 months.

Note, that the calendar aging is highest at about 80%, a thing I have been writing about for quite long time.
Also note that 50% and below have significantly lower calendar aging.

For warm climates, it will be a considerable difference having the cells at 55% or below.
These numbers match the other reserach quite well, I calculated that the step1 and step2 cyclic aging must have taken about half a year, so these numbers is for month 6-12 in the cars age.

Tesla Model S18650 test

This is the cyclic test of the same cells, confirms that the degradation per cycle for full cycle (100-0%) is in pair with virtually all the other research.

As this test only had four datapoints for calendar aging 20-50-80-100, it will hide the true form of the graph.
Using this graph that do not hide the step that is caused by the central graphite peak as it use 16 SOC points we easily can se that it is benifical to stay below 55% - Actually, reading that report show us that the real step is at 57-58% on a new NCA cell. Tesla hides 2% SOC on model 3/Y at 55%(part of the buffer is hidden there) så charging to 55% keep us on the right side of 57-58%

 

[johnny_cakes]

This is a research/test which used actual Model S 18650, from a Tesla that was used for 6 months since new. Report from 2017. so maybe a 2015 or 2016.
I have had this report for a while but if I remember it right, I havent used this as reference before.
Remember, this is not a question of finding one specific report showing something, it is the sum of reading more than 100 research reports, and disregarding a few of them. The rest, still more than hundred, builds the case.




Note, that the calendar aging is highest at about 80%, a thing I have been writing about for quite long time.
Also note that 50% and below have significantly lower calendar aging.

For warm climates, it will be a considerable difference having the cells at 55% or below.
These numbers match the other reserach quite well, I calculated that the step1 and step2 cyclic aging must have taken about half a year, so these numbers is for month 6-12 in the cars age.
View attachment 934226
Tesla Model S18650 test

This is the cyclic test of the same cells, confirms that the degradation per cycle for full cycle (100-0%) is in pair with virtually all the other research.
View attachment 934228

As this test only had four datapoints for calendar aging 20-50-80-100, it will hide the true form of the graph.
Using this graph that do not hide the step that is caused by the central graphite peak as it use 16 SOC points we easily can se that it is benifical to stay below 55% - Actually, reading that report show us that the real step is at 57-58% on a new NCA cell. Tesla hides 2% SOC on model 3/Y at 55%(part of the buffer is hidden there) så charging to 55% keep us on the right side of 57-58%
View attachment 934233

It's pretty convincing, thanks @AAKEE. I have yet to see any evidence that refutes your claim.

 

[johnny_cakes]

replacing the 90% myth with the 55% myth

you really believe all this armchair science?

until one actually sits in a lab and tries to design experiments that answer difficult question (and do it for years) can one appreciate the complexity of these questions…

the cars are deployed in hugely varying environments (minnesota versus key west) and used in hugely different ways by different people …and the cell is connected to a complex computer controlled electronic system…

there probably is not one answer (55%) or there may not even be a best answer that applies to most people…

the 90% recommendation is probably not optimal but it’s not crazy to assume that it is a best guess from pretty knowledgeable at what practically works for most people (conspiracy theories aside)

I like to keep an open mind, but I'll follow the data and science. So far I have seen lots of scientific evidence advocating for the low SoC strategy to minimize degradation, while I haven't seen any evidence against it (at least not for battery degradation). But I agree that it's not for everyone.