charge everyday or once in 3 days

[AlanSubie4Life]

because there is no data on Tesla batteries

* except for a fitted model based on data from Tesla batteries which has good predictive value.

Science!

 

[AAKEE]

There is in fact little support in science for most of what people have to say about Tesla batteries because there is no data on Tesla batteries. People are making statements based on general facts that are applicable to Lithium batteries, often based on laboratory tests. To my knowledge there is little real world data, and the Tesla Battery Management system not been factored in.

This is why we have thousands of posts - because there is in fact no definitive answers.

-There is data from actual Tesla batteries taken out of tesla cars - both model S and 3.
-These data follows the other research tests quite close with similar/same cells. From this we know that we can use the data from the other tests as well.
-A BMS can not stop calendar or cyclic aging. It can not decide what charge level that is set or how big the cycles are - it can merely sit there and watch things happen. I bet a BMS would like to cool the battery some hot days at the parking - but it is not allowed to.
A BMS is there to try to get a lot of cells work fine togheter. In the best case scenario the cells are well matched and in balance - in that case they all are happy and feel like the single cells in the research reports. In other cases, out of balance or badly matched, they feel worse than the single cells in the research tests.
Any hour at a given SOC and temperature will cause the calendar aging that it does - with or without a BMS.
Any cycle will cause the cyclic aging it does for that C-rate, DoD and temperature.

We definitely have answers. The Science knows how the batteries are affected from both cyclic and calendar aging.

Many posts comes from spreading the myths - of course no one that does knows these are myths.

 

[AAKEE]

This is a Test of actual Tesla model S cells, taken from a 6 month old car:
ShieldSquare Captcha

Here’s cyclic tests with actual Tesla model 3 cells:
http://kth.diva-portal.org/smash/get/diva2:1755178/FULLTEXT01.pdf

Another model 3 cyclic + calendar aging test:
https://research.chalmers.se/publication/535926/file/535926_Fulltext.pdf

2170 NCA cells of a non disclosed brand (most probably Panasonic 2170 NCA from a model 3):
https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/batt.202100046

 

[Darmie]

2170 NCA cells of a non disclosed brand (most probably Panasonic 2170 NCA from a model 3):
https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/batt.202100046

Looking at the other reports now. This really debunks keeping the cells at 100% worse than 80%. What is your take on that?

 

[father_of_6]

Looking at the other reports now. This really debunks keeping the cells at 100% worse than 80%. What is your take on that?

It says "Cells at 100 % SoC have better capacity retention than cells stored at 80 or 90 % SoC but develop micro-short circuits when exposed to T≥40 °C."

So it seems like degradation isn't the reason for not storing it at 100%.

 

[AAKEE]

Looking at the other reports now. This really debunks keeping the cells at 100% worse than 80%. What is your take on that?

I have written my view on it a lot of times here.
I usually do not recommend using those examples to as how we should think about calendar aging. Not all research show 80% worse than 100%, only some of them.
Several shows that 80% is about the same as 100%.

A good way to think is that high SOC ( ~70 to 100%) cause about the same calendar aging unless in very hot days when 100% is worse than 80%.

I normally use these examples when people are ”good damned sure” that ”80% is the ideal SOC and 100% is very very very bad”.


Most research reports with high resulotion at different SOC show at least signs of that 100% might be less bad than 80%.

Probably already posted in this thread but as the report you refered to does not disclose the cell brand (albeit many things points to tesla cells or at least Panasonic NCA).

This is model S cells taken from a car.

This is Panasonic NCR18650, more or less the same as the cells above:

The takeaway from this is not to start having the car at 100% every day.
High SOC causes a higher increase in internal resistance so Performance wise it is a bad thing.
The takaway is that there is no imminent danger to the cells if we need to leave them at 100% over night or something like that.

It is still recommended to stay below the step step in the curve as much as possible (while still not breaking the back to always be there).

Baby the battery at 80%
Leaving the battery at 100% will break it.
Dont drive it below 20% as it is bad for the battery

 

[J Neptune]

I don’t have a schedule method. Sometimes I let it run down to 20%, other times I plug in when at 60%. It’s more of where do I need to go tomorrow.

I have never dropped below 10% though.

 

[howardnj]

This. I plug in every day no matter what the state of charge is

So do I! My Y charges to 85% every night except when leaving for Florida when it charges to 90%
My temperature is set for 70* and its nice to get into a warm car at 6AM every morning especially on cold NJ mornings.

 

[heavync]

I don’t have a schedule method. Sometimes I let it run down to 20%, other times I plug in when at 60%. It’s more of where do I need to go tomorrow.

I have never dropped below 10

So do I! My Y charges to 85% every night except when leaving for Florida when it charges to 90%
My temperature is set for 70* and its nice to get into a warm car at 6AM every morning especially on cold NJ mornings.

Out of curiosity why don’t you charge to 100% when going to Florida?

 

[Marc Connery]

Somewhere on TMC I saw a recent study with cyclical degradation being slightly improved with a of 55% driven to 35% on the 2170 cells Some new data from research on Tesla model 3 cells

For myself I charge up to 70% which safely keeps me in my occasional 100 mile days but allows me to top off to 80% at my first stop which has a free charger

2023 MYLR Grey

 

[howardnj]

I don't need to. I have a list of almost 60 charge stations between NJ and Florida. After leaving home we started taking the Ferry from Cape May, NJ to Lewes, Delaware. There is a charge station in Cape May 124 miles from home so I charge there. Next is Exmore ,Va.
I usually stop to charge, eat, and pee about every 150 miles.

 

[johnnycnote]

So do I! My Y charges to 85% every night except when leaving for Florida when it charges to 90%
My temperature is set for 70* and its nice to get into a warm car at 6AM every morning especially on cold NJ mornings.

Hello there fellow Jersian! I go to 90% and 100% when I know I'll be spending the whole day on the road