Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health

[AAKEE]

Would NCA batteries benefit from occasional charging to 100% to keep the BMS in sync? I.e. similar to the once per week 100% charging for LFP batteries, but less frequent (perhaps once per month)?

No.

That is only valid for LFP, that has such a flat voltage curve that the BMS has a hard time judging the exact SOC.
Charging to 100% give the BMS a fixed point.

NCA gas a steeper voltage curve so there is no risk that the BMS looses track of the SOC.

 

[Candleflame]

Would NCA batteries benefit from occasional charging to 100% to keep the BMS in sync? I.e. similar to the once per week 100% charging for LFP batteries, but less frequent (perhaps once per month)?

i dont think charging to 100% is ever of benefit. 90% is enough. (and 100% is also not harmful if you need the range)

 

[AAKEE]

I have started to spike my max limit up once a month for a few days to ensure my BMS has the best idea of useable capacity for those long road trips where I need it.

For practical reason:s the displayed range and navigation function might benefit from that, but the real possible usable range does not change.

I also can see the joy of having a higher capacity and lower number on degradation.


I did a 100-0% drive in the end of the summer, could use 75.15 kWh until 0% (actually 0.27% SOC according to BMS/SMT, which started to climb slightly after arrival).
3.5 buffer plus another 0.3kWh useable left.

The BMS had the NFP at about 76.5 kWh if I rememberbit right ( that about 3% off downwards to the about 79kWh that the 100-0% drive showed.
The BMS is back (by itself) to around 79kWh since some time.

 

[3sr+buyer]

No.

That is only valid for LFP, that has such a flat voltage curve that the BMS has a hard time judging the exact SOC.
Charging to 100% give the BMS a fixed point.

NCA gas a steeper voltage curve so there is no risk that the BMS looses track of the SOC.

But then how does the BMS lose track of the capacity on NCA batteries?

 

[AAKEE]

But then how does the BMS lose track of the capacity on NCA batteries?

You need to separare SOC and capacity.

The BMS doesnt loose track of the capacity in LFP, it loose track of the SOC.
If you cannot measure the SOC very precise you can charge to 100%, the you get a fix point.

To estimate the capacity the BMS would prefere to measure it from 100-0% often.
As the BMS does not get that chance too often the BMS calculats the capacity by measuring the energy between different SOC.
If the car use up 40 kWh between 70% and 20% true SOC, thats half the capacity at 40 kWh. Then full capacity would be 80 kWh.
To measure the exact SOC the car must be sleeping so the battery is disconnected and the BMS can measure the open circuit voltage.

 

[Macb00kemdanno]

I'm not an expert like many of you battery wizzes in here, but I was able to reclaim some range from my 2021 SR+ which has 24,000 miles on it (originally rated at 263 miles). The estimated range had dropped to as low as 231 miles in the past month or two. However, I was able to reclaim a good portion of that range.

I typically charge to 90 percent, drive until I get to about 25 percent, then plug it in. Rinse and repeat. However, two weeks ago, I decided to run it until it got down to 15 percent, then charged it up to 100 percent, and then immediately took off on a long drive. I then recharged it to my usual 90 percent and drove it back down to about 18 percent, then charged it back up to 100 percent again. After doing that, my max range increased from 231 miles to 242.7 miles.

I’ll keep my 90% max charge rate for the next month or so, then do the occasional 100% charges to see if I can reclaim some more mileage. But I like what I’m seeing so far. The battery degradation also ticked down from 9.1 percent to 9.0 percent.

 

[mlkirch77]

what happens if I charge in the 90% range all the time

 

[GtiMart]

Depends what battery chemistry your car has. The worse that can happen is that you slightly accelerate the degradation or your battery, nothing more.

 

[johnnycnote]

Don't worry about it. If it applies to the batt type your have, by the time you notice the additional batt degradation you'll prob be in a new car anyway

 

[Sklith]

90% is fine. I don't personally do it since I never need that much range. I do 80%.

 

[xmodem240]

I typically do 80% in the summer, 85% in the winter to make up for the heating usage.

2021 M3P

 

[M3_Performante]

Just picked up my first Tesla last Monday and loving it !!!

But, kinda disappointed to see a range of 244 miles at 90% charge on a car that was advertised from Tesla @ 299 mile range

I have a 2020 M3P with 25,988 miles

Just curious if this is about typical for the year and milage and see what others are getting at 90% charge?

let us know your year, model and 90% range so we can compare

 

[TesslaBull]

I'm not an expert like many of you battery wizzes in here, but I was able to reclaim some range from my 2021 SR+ which has 24,000 miles on it (originally rated at 263 miles). The estimated range had dropped to as low as 231 miles in the past month or two. However, I was able to reclaim a good portion of that range.

I typically charge to 90 percent, drive until I get to about 25 percent, then plug it in. Rinse and repeat. However, two weeks ago, I decided to run it until it got down to 15 percent, then charged it up to 100 percent, and then immediately took off on a long drive. I then recharged it to my usual 90 percent and drove it back down to about 18 percent, then charged it back up to 100 percent again. After doing that, my max range increased from 231 miles to 242.7 miles.

I’ll keep my 90% max charge rate for the next month or so, then do the occasional 100% charges to see if I can reclaim some more mileage. But I like what I’m seeing so far. The battery degradation also ticked down from 9.1 percent to 9.0 percent.
View attachment 900080

I'm not the master authority on batteries around here, but here's my take. I don't think the actual capacity of a battery can change from one day to the next. Your battery is exactly the same as it was a day or two, or a week or two ago. You have reset or recalibrated your computer to perhaps more accurately reflect the capacity of your battery. But the battery itself did not magically change.

Also, from what I have seen, keeping your maximum daily charge level to 55% or lower will result in the lowest possible degradation over time, if that charge level is enough to provide for your daily commute.

 

[AAKEE]

Just picked up my first Tesla last Monday and loving it !!!

But, kinda disappointed to see a range of 244 miles at 90% charge on a car that was advertised from Tesla @ 299 mile range

I have a 2020 M3P with 25,988 miles

Just curious if this is about typical for the year and milage and see what others are getting at 90% charge?

let us know your year, model and 90% range so we can compare

Its expected to ”loose” about 10% or so after three years. The OSO reading is not very important in this case, as the nost of the loss comes from ”time”.

299 miles -10% loss is about 270 miles (there is some part of the loss ”hidden” but we can disregard that for this discussion).

244 / 0.9 = you have 271 miles at 100% charge. Completely normal and expected.

Here is a graph of logged data for M3P (2018-2020):
(Km / 1.609 = miles)

It is graded in km, and time would be a better choise but in general its common to use miles/km instead of time.
Your car has few miles for a three year car - will show more / mile due to this.

 

[KenC]

Its expected to ”loose” about 10% or so after three years. The OSO reading is not very important in this case, as the nost of the loss comes from ”time”.

299 miles -10% loss is about 270 miles (there is some part of the loss ”hidden” but we can disregard that for this discussion).

244 / 0.9 = you have 271 miles at 100% charge. Completely normal and expected.

Here is a graph of logged data for M3P (2018-2020):
(Km / 1.609 = miles)

It is graded in km, and time would be a better choise but in general its common to use miles/km instead of time.
Your car has few miles for a three year car - will show more / mile due to this.
View attachment 908334

Ha, degradation rate looks worse when the graph is that vertical! In fact, they should let you see it with the scale starting at Zero, just to remind you it's only a fraction. For example, in the above chart, since it only shows 500km down to 340km, the drop is 3x as dramatic, compared to if the scale went down to Zerokm.

Anyhow, the OP seems to be at the lowish end of the normal distribution. Given his mileage 26000 and 270miles, converted to km, would put him around the spot I highlighted on the chart.

 

[PianoAl]

The info on the improvements in HW4 is a reminder that by the time our batteries degrade very much, we'll all be Jonesing for new and improved cars. It made me realize that it's not only range than might improve.

However, I still can't bring myself to charge Tessie to 100% and let her sit for a week or two. I keep her around 80%, and take her to 100% only before taking her for a drive.

Before we got her and before I edgakated myself about the reason for Tesla's advice, I had really looked forward to just changing her to 100% without complicated procedures. Still happy though.

 

[AAKEE]

Anyhow, the OP seems to be at the lowish end of the normal distribution. Given his mileage 26000 and 270miles, converted to km, would put him around the spot I highlighted on the chart.

Is your chart M3 Performance or LR?
At Teslalogger.de there is a difference in the average line between LR and P.
At about 42000km it is 470 km vs 462km.
Not much but it could reflect that Performance cars use higher power and more often, as high battery power/load also causes degradation.
I would guess the slightly low side on @M3_Performante’s car is due to lower miles than average compared to the age of the car. Maybe also that it used high SOC in a warm climate.

View attachment 908427

 

[nurusz]

Can someone summarize this long thread
in something useful?!

 

[AAKEE]

Can someone summarize this long thread
in something useful?!

1. The battery will survive the car in many cases (~10-15 years) by just following the very few tips/rules Tesla gives.
2. Read 1 again and make sure you understand it. Dont worry too much.
————————
Artificial pause
————————

3. If you follow the Tesla simple rules, like only use max 90% charge for daily use this will not result in the minimum degradation.
4. It is possible to reduce the degradation by about 50% (without any big sacrifice) by applying the known facts from research:
- Use low SOC when possible. Below 55% cut the degradation from time in half.
- Charging late, like in the morning before the drive instead of when arriving in the evening before reduce the time at higher SOC.
-Do not charge more than you need (including a margin for range anxiety).
- Charge often - the smaller each cycle the smaller the degradation from cycles.

5. Low SOC is NOT dangerous. Below 20% is safe and do not cause increased wear. It actually reduce the calendar aging.
100% SOC is not as bad as the forum myth says. You do not need to drive asap. The degradation is about the same at 100% as at 80-90%. Sometimes slightly more, sometime slightly less.
90-100% increase the cyclic aging, this is the main reason to stay below 90% for daily driving.
High ambient temperature increase the cyclic aging. The combination of high SOC and high temperature causes more degradation by time. Avoid leaving the car with high SOC very warm days.

 

[KenC]

Is your chart M3 Performance or LR?
At Teslalogger.de there is a difference in the average line between LR and P.
At about 42000km it is 470 km vs 462km.
Not much but it could reflect that Performance cars use higher power and more often, as high battery power/load also causes degradation.
I would guess the slightly low side on @M3_Performante’s car is due to lower miles than average compared to the age of the car. Maybe also that it used high SOC in a warm climate.

It's the P chart.