Confusion on keeping the charge limit at 100% and charge fully once per week

[sgreadly]

Hi all,

I need some advice on the wording in the Tesla app (not on how to charge as this has been answered in other threads).

I've got a 2021 Model 3, Standard Range Plus, which has an LFP battery based on Control > Software > Additional Info. My charging limit bar is a 0 - 100 where you can change it to whatever limit you need. I set it to 80%. If it helps, I travel ~200km/day, consuming half my battery capacity, it dropps from 80% to 20% daily.

I was told to never charge it to 100% unless I'm doing long distance travels where I'd need the whole battery. Instead, to charge it to 80%, which I've done, and I understand the reasoning. All good there.

The confusion..

Few months back, the Tesla app says to maintain battery health, keep the charge limit at 100% and charge fully once per week.

The wording is confusing to me..

"To maintain battery health, keep the charge limit at 100% and charge fully once per week".

Here's another example too,

This doesn't make sense, as it contradicts itself.

• If I keep the limit at 100% it'll charge to 100% every time.
• Otherwise, to do what the app wants me to, I'd have to manually set it to 80% 6 days a week, and manually to 100% the 7th day, which again contradicts what the app is asking me to do (i.e., keep the charge limit at 100%).

In other words, it's impossible to keep the charge limit at 100% and charge fully once per week. It's either/or, not both.

Is it just me? Or is what they're trying to say worded incorrectly? Or did I misunderstand it?

 

[AAKEE]

Does it actually allow you to choose *any* limit? My M3LR (NCA battery) has a minimum of 50%.

I think its still 50% for LFP’s as well.

 

[Skryll]

I know LFP can be charged to 100% regularly. What would be the guideline when storing the vehicle when not moving it, is charging to 100% a good idea even if parked in the blazing sun for a few weeks, or is that different from regular use?

 

[father_of_6]

I know LFP can be charged to 100% regularly. What would be the guideline when storing the vehicle when not moving it, is charging to 100% a good idea even if parked in the blazing sun for a few weeks, or is that different from regular use?

Any battery *can* be charged to 100% regularly, but at what cost to battery health - that's the question.

My understanding is that it's also not healthy for an LFP battery... however the BMS can't correctly calculate SoC / range / health unless it hits 100%. This is because only at 100% do the cells provide a change in voltage that the BMS needs to see.

Here's a post that concurs:

Even for LFP charging to 100% is never good for the battery - because in the end it is still a Lithium ion battery. Tesla only recommends charging to 100% because the BMS only accurately predicts SOC and therefore range, when the voltage is maximum.

 

[E90alex]

I know LFP can be charged to 100% regularly. What would be the guideline when storing the vehicle when not moving it, is charging to 100% a good idea even if parked in the blazing sun for a few weeks, or is that different from regular use?

I would leave it at 50% or less before parking for long periods. If plugged in, set the limit to 50%. If not plugged in make sure you have enough battery so it won’t be completely dead after the storage period accounting for phantom drain etc.

Then charge back to 100% right before you need to use it.

 

[3sr+buyer]

I know LFP can be charged to 100% regularly. What would be the guideline when storing the vehicle when not moving it, is charging to 100% a good idea even if parked in the blazing sun for a few weeks, or is that different from regular use?

While LFP batteries are likely to have less degradation generally, high states of charge are likely to increase degradation, though perhaps less noticeably than with NCA batteries.

Long term parking is best done with the car plugged in with the charge target set to the lowest possible (50% for Teslas). Upon returning to an LFP battery car that has been parked for a long period of time, charge it up to 100% just before driving off to ensure that the BMS has not lost the true state of charge (the voltage curve is very flat from ~20% to 99% state of charge).

If you cannot leave it plugged in, you need to check the rate of parking drain and leave it with enough state of charge so that it does not go below 0% (or below enough to drive to when it can be charged) while parked.

 

[Olle]

I know LFP can be charged to 100% regularly. What would be the guideline when storing the vehicle when not moving it, is charging to 100% a good idea even if parked in the blazing sun for a few weeks, or is that different from regular use?

In the blazing for weeks is probably the most damaging way to store any kind of car at least in hot climates. If may use battery to stay cool. Once depleted, the battery will bake and degrade fast. Not necessarily good to start w 100% soc either if the sun heats it to just under the the cooling target and strays in high soc. Better to park in the shade and not have to worry about it.

 

[lipcio]

Most people forget that SOC drop from for example 100% to 80% while driving and charging overnight back to 100% is not a full charge cycle. You would have to do it 5x (5 days) to complete one full battery cycle.

 

[AAKEE]

In the blazing for weeks is probably the most damaging way to store any kind of car at least in hot climates. If may use battery to stay cool. Once depleted, the battery will bake and degrade fast. Not necessarily good to start w 100% soc either if the sun heats it to just under the the cooling target and strays in high soc. Better to park in the shade and not have to worry about it.

At low SOC heat wear much less so if ”depleted” (which do not mean completely but at safe 0% or above) the battery is safe.

 

[AAKEE]

Most people forget that SOC drop from for example 100% to 80% while driving and charging overnight back to 100% is not a full charge cycle. You would have to do it 5x (5 days) to complete one full battery cycle.

And LFP, if we are talking LFP, they degrade very very little, even from large cycles so we more or less can disregard the cyclic aging anyway.

 

[Wdisty]

It is horrible wording. As a professional design engineer this would in someway suggest leaving at 100 but having to manually stop at 80-90 somehow balances the cells better and that by "hard" setting to anything below that may limit the full battery cells potential or 'equilibrium '. Someone at Tesla really needs to remove this or better explain because it's a bad warning if that serious to leave at 100. Many things I have been surprised about the Tesla with bad programming. It's still amazing yes, but when you understand design and programming in detail, there are many misses and shouldn't be.

 

[Woody5575]

I used to think that after nearly 45 years of working with computer technology in every field from design to sales, support, implementation, training and management, that I have a pretty good understanding of how things work. Then I got a Tesla and discovered that it a whole new world when you add a different technology into the mix. I realized that im pretty much clueless about electricity and batteries. It was devastating to my ego!

 

[AAKEE]

It is horrible wording. As a professional design engineer this would in someway suggest leaving at 100 but having to manually stop at 80-90 somehow balances the cells better and that by "hard" setting to anything below that may limit the full battery cells potential or 'equilibrium '.

I do not really get what you mean (not native english and no reference to whom you answer.

The cells are not easier to balance at 80-90 than at 100%.
The voltage curve for LFP are really föat and even if reading the samw voltage the SOC can differ.

Someone at Tesla really needs to remove this or better explain because it's a bad warning if that serious to leave at 100.

Leaving cells at 100% is not serious. Thats more a myth than anything else.

Cars without LFP get a warning (suggestion) on the display after 3 consecutive charges to 100%.

This is because Teslas idea is to charge to 80% or less for daily driving (it was “below 90% until recently).
High SOC and large cycles wear more so it is quite natural to suggest not charging to 100% every day for these cars.

 

[SageBrush]

I live in a 4 season climate. We own a chevy Bolt and lease a Model Y. Both are parked outside. Both have charge limits set to ~ 80%, and it is rare for SoC to drop below 25%. If it does, we do not let the car sit at that SoC. In the cold winter and hot summer the Bolt is plugged in whenever it comes home because it has inferior pack thermal protection compared to the Tesla

For trips we top off the Tesla to ~ 95% the morning of the trip. Very easy with the phone App. I choose 95% SoC because we live in foothills and the first 10-ish miles from home are downhill.

 

[PianoAl]

It is horrible wording. As a professional design engineer this would in someway suggest leaving at 100 but having to manually stop at 80-90 somehow balances the cells better and that by "hard" setting to anything below that may limit the full battery cells potential or 'equilibrium '.

Let's suggest some better wording. In writing these, I can understand the difficultly in providing information that's appropriate for different driving needs (e.g. someone who drives sixty miles every day versus someone who drive less than sixty miles in a week).

To allow your Tesla to better estimate remaining range, charge to 100% at least once per week, depending on your driving needs. Consult your owners manual for more information.

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Charging your Tesla to 100% once every six charging cycles will allow it to better estimate remaining range and will not damage the battery.

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Based on your usage over the last week, Tesla recommends charging to 100% today.

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Your Tesla's LFP battery can tolerate frequent charging to 100%, but charging to lower levels may improve it's lifetime. For more information, consult your user's manual.

 

[Wdisty]

Right,,so Tesla should let me figure out what is best and if I am going to leave it charging and do not need 100%, they should not put a warning,/seemingly strict recommendation to leave at 100. I want to put to 80/85/or 90 so I don't have to set a reminder to turn it off if it was set to 100. Basically I take design recommendations serious so I don't really want to leave at 100 to remember to cut it off,,,but is it really a problem to set it at 80 and I'll remember to , once a week, move to 100

 

[Wdisty]

Let's suggest some better wording. In writing these, I can understand the difficultly in providing information that's appropriate for different driving needs (e.g. someone who drives sixty miles every day versus someone who drive less than sixty miles in a week).

To allow your Tesla to better estimate remaining range, charge to 100% at least once per week, depending on your driving needs. Consult your owners manual for more information.

------------

Charging your Tesla to 100% once every six charging cycles will allow it to better estimate remaining range and will not damage the battery.

------------

Based on your usage over the last week, Tesla recommends charging to 100% today.

------------

Your Tesla's LFP battery can tolerate frequent charging to 100%, but charging to lower levels may improve it's lifetime. For more information, consult your user's manual.

What is should say I am gathering is , "please remember to set back to 100 to fully charge once per week."