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Use Scheduled Departure to Have Less Time at High SOC?

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I've been using Scheduled Departure so that the car will spend somewhat less time at a lower SOC, but I'm over-optimizing things.

For example ...

Let's say that I typically drive 50 miles in a day on average, and I charge to 80% each night. I charge at 25 MPH.

If I use Scheduled Charging and start at midnight (when off-peak begins), and leave at 9 AM, the car will be done charging at 2 AM and sit at 80% for seven hours (2 AM to 9 AM). If I use Scheduled Departure, it will be at 80% for very little time (presuming I leave at 9 AM).

Over five years, this means the car will sit at 80% an extra 12,775 hours (7 * 365 * 5).

The problem is that occasionally I drive a lot in one day, so I have to adjust things so that it won't start charging before midnight. I think I'll just change to have charging always start at midnight. Thoughts?
 
Playing around with this. Lately I’ve only been charging to 65% for local driving and don’t charge every night as we don’t run errands every day.

I charge to higher SOC if we’ve got a big trip planned the next day.
 
I've been using Scheduled Departure so that the car will spend somewhat less time at a lower SOC, but I'm over-optimizing things.

For example ...

Let's say that I typically drive 50 miles in a day on average, and I charge to 80% each night. I charge at 25 MPH.

If I use Scheduled Charging and start at midnight (when off-peak begins), and leave at 9 AM, the car will be done charging at 2 AM and sit at 80% for seven hours (2 AM to 9 AM). If I use Scheduled Departure, it will be at 80% for very little time (presuming I leave at 9 AM).

Over five years, this means the car will sit at 80% an extra 12,775 hours (7 * 365 * 5).

The problem is that occasionally I drive a lot in one day, so I have to adjust things so that it won't start charging before midnight. I think I'll just change to have charging always start at midnight. Thoughts?
 
Is there any valid battery science that can inform this discussion or do we just muddle along digesting anecdotal voodoo which is so prevalent sometimes on these forums?
A lot.

I have written tons about calendar aging.

I use scheduled charging to minimize the time at ”high” SOC.
I usually charge to 55%, commencing at 0330 so the charging is finished around 0530-0600 and I leave around 0630.
I arrive with 20-35% home after work depending on the time if the year/consumption.

Below a chart of calendar aging for different chemistries. NCA is the normal Long Range chemistry. (There is Teslas with NMC and LFP as well).
Calendar aging degrades the battery much more than driving/ cycles for most people during the first five years or so.
Picture from This research report but the researchers are all having similar results so there is no doubt about that high SOC increase the degradation.
1C391DB9-44F7-435A-B161-98A83344CB26.jpeg


Calendar aging reduces with time.
-To double the first years calendar aging it will need another three years.
-To double the first four years(above) there will be needed another 12 yrs.
 
OK, AAKEE, so it looks like I will lose about 10 miles in my first year. So I can realistically hope to lose another 10 miles in the next 3 years, for a total loss of 20 miles after 4 years. At that point my projected range at 100% SOC would be 233 miles. Then I would lose another 20 miles over the next 12 years, so my range would be down to 213 miles. That’s if I don’t abuse the batteries with high and low SOC’s. Are we agreed?
 
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OK, AAKEE, so it looks like I will lose about 10 miles in my first year. So I can realistically hope to lose another 10 miles in the next 3 years, for a total loss of 20 miles after 4 years. At that point my projected range at 100% SOC would be 233 miles. Then I would lose another 20 miles over the next 12 years, so my range would be down to 213 miles. That’s if I don’t abuse the batteries with high and low SOC’s. Are we agreed?

Yes, we agree with a few exceptions :)

The graph shows calendar aging only, but cyclic aging is low. Probably less than 1% per year for most people.

Low SOC do not cause any increased wear, either for calendar aging or for cyclic aging.
Lithium batteries is safe with very low degradation down to 0% true SOC.
Tesla show 0% when the true SOC is around 4.5% so you are safe even below 0%.

The low SOC damage is a forum truth ( = not true).
Usually the next post will argue that ”Tesla say that….” but Tesla do not say that. So there is some other forum truths about what Tesla say about low SOC.

How much you loose the first year depends on the average SOC and the cycles ( how big and how high up they are).

Low average SOC is good
Avoid high ambient temp if possible.
Avoid having the car parked with high SOC during high ambient temps.
Small cycles is good, two small is much better than one big.

This said, just following Teslas simple advices (Teslas real advice from the manual, again, not the forum truths ;)) will be enough to save the battery.
This probably will not get you the least degradation so all in this post is about minimizing degradation for people that like to do that.

I did bot loose any range during the first 40K km/ 25K miles. This as the range indication do not always follow true degradation. Recently it started to drop, after a software upgrade. Now it seems like it show slightly less than the real capacity.

I had a full charge this tuesday and had 490km range on screen, thats 17km loss from the first 1 1/2 year and 45K km / 28K miles.
14190F45-694A-4042-89A1-CFD1F9138289.jpeg

The real capacity is probsbly around 78.5-79 kWh according to my calcs so the real on screen range should be about 496 km.
 
Recently it started to drop, after a software upgrade. Now it seems like it show slightly less than the real capacity.
I don’t understand why the fleet average is so noisy in this plot. Seems like it is from one other vehicle? I assume TeslaFi tells you how many matches there are to your criteria.

I agree: Seems to me your most likely capacity is probably currently closer to 495rkm.
 
I don’t understand why the fleet average is so noisy in this plot. Seems like it is from one other vehicle? I assume TeslaFi tells you how many matches there are to your criteria.

On each datapoint I can see the number of other cars. My car have been floating around the longest driven of the cars so somtimes there is only 1 car that have reached the same miles on the odo.

Not a high number of M3P 2021 that use teslafi:
At 30K there is around 18 cars.
At 41K km theres 4 cars in total.
 
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On each datapoint I can see the number of other cars. My car have been floating around the longest driven of the cars so somtimes there is only 1 car that have reached the same miles on the odo.

Not a high number of M3P 2021 that use teslafi:
At 30K there is around 18 cars.
At 41K km theres 4 cars in total.
Ah ok that makes sense. I am surprised it is still so noisy below 10k km, but it is better, but I guess in the end there is a limited number of participants.
 
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How are you measuring battery degradation over time? Simply using the stated vehicle range on the screen based on SOC of 100% would not be an accurate metric. Seems to me you would need to actually drive the car from 100% to 0% SOC and see how far it goes and perform this test repeatedly at various time intervals for accuracy.
 
So should I wait until I'm close to 0% before charging?
That's not strictly necessary. I believe that it's more a question of convenience and what suits you. To allow it to drop down towards "0%" is ok as @AAKEE says but make sure your 12V battery is healthy! Personally, I would not do that.

Without becoming too granular, as an example, I follow @AAKEE's suggested guidelines for battery care (M3 LR AWD). I leave the car anywhere between 15-30% SoC when not used/stored and normally charge it to ~40-50% depending on intended use. I only charge it above that for a road trip of more than150 Km (<1/month). My car is 9 months "old" and the average SoC since the dawn of time is ~40%. Keeping to this rhythm isn't laborious for me and I'll see after the first year how the battery is doing!
 
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How are you measuring battery degradation over time? Simply using the stated vehicle range on the screen based on SOC of 100% would not be an accurate metric. Seems to me you would need to actually drive the car from 100% to 0% SOC and see how far it goes and perform this test repeatedly at various time intervals for accuracy.
Probably the best way would to do what you describe. However that's maybe not always too convenient and possibly dangerous for the car. Bear in mind also that the "0" value the car shows does not include the bottom buffer of 4.5% ie, a 74.5 kW battery would still hold about 3.3 kWh of capacity when showing 0% on the screen.

Other methods use estimations or calculations based on data the BMS holds. One example would be simply to keep a note of your Max Rated Range (MRR) over time (sometimes KM are used instead of time). See this link for an example: Degradation . One other example would be to install SMT and a dongle, to extract and plot data from the car such as Nominal Full Pack (NFP) against time which is possibly more reliable that MRR. Nevertheless, not everyone agrees on the best way to measure degradation.

One thing is clear though, different cars and owners live in different climates and have different habits for driving and charging and sometimes it seems that some batteries hold up better than others (for whatever reason) - you can find claims of "no degradation after 2 years "within these forums. Whilst low degradation is seen, "0" degradation seems unlikely (my opinion).

Look up @AAKEE and @AlanSubie4Life who have posted a lot of helpful comments on this subject.
 
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Simply using the stated vehicle range on the screen based on SOC of 100% would not be an accurate metric. Seems to me you would need to actually drive the car from 100% to 0% SOC and see how far it goes and perform this test repeatedly at various time intervals for accuracy.
It is the best metric possible. Of course what matters is how much energy you can get out on a drive (trip meter), but this value is well correlated with the vehicle range indicator.

Of course it is an estimate, but it’s not bad. If it says you have lost 10%, you can be reasonably assured you have lost between 12% and 6%, so it’s very close indeed to the correct value.

In any case nothing wrong with driving all the way down to close to 0 on the trip meter and seeing what you get, extrapolated(should be 95.5% of the capacity approximately). Might not work well with LFP though, which seem to pose estimation challenges.

You can see the accuracy of the estimate by measuring the rated mile use and comparing to the trip meter. And remember the estimate re-assesses after parking so you may see a rebound or a loss of range after parking.
 
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