Minimising battery degradation

[GeorgeSymonds]

It’s worth noting that 2021.32.5 had a change to the displayed range to better represent real world conditions. What that really means is anybodies guess but I’ve noticed 100% is varying more than it used to (I’ve not charged to 100%, just seen what the car thought i5 would be by moving the slider)

 

[MrBadger]

VanillaAir - how did you go about resetting your CAC?

Tesla remote diagnostics took it upon themselves to do in response to a query I had about displayed range.

~1500 miles after our CAC reset, our (blue) range estimate is settling back on the (green) fleet average

 

[Nick77]

Why does the charge port open automatically when you go into the charging section on the official app.

That's annoying. I only want to check the charge limit and what the 100% gives. It closed when you back out of it but still.

 

[MrBadger]

Something odd going on with that part of the app and/or widget - not got to the bottom of it yet. I think there may be a difference if car is awake or not. When I hit charge button first thing in morning after car been on scheduled charge, it tries to close charge port with cable still plugged in - it fails thankfully. But if I do it some time after, it doesn’t appear to. Possibly as by that time the car is awake.

 

[GoodKarma]

~1500 miles after our CAC reset, our (blue) range estimate is settling back on the (green) fleet average

View attachment 722488

Thanks for the update. My blue line is way below the fleet average.. Model 3 LR AWD 2021

 

[Duke846]

Whatever you do to try and minimise battery degradation it wont impact on the resale in a few years time because whoever buys the car from you will not be able to obtain conclusive proof your efforts have resulted in a longer predicted battery life - so its unlikely the value of your car will be any different to anybody else's car.

I wouldn't give the battery a second thought - you have 8 years Tesla guarantee on it for a start, The battery is monitored and maintained by the BMS and thermally Tesla are well ahead of the field in looking after the batteries. I would also ignore the predicted range of the car as its just a prediction based on an algorithm from the BMS and its impossible to predict because there are so many variables.

I think too many people are obsessed with range, the overall life of the battery and become almost neurotic over what is --- just a car, - charge it, drive it, enjoy it. None of us know how long the useable life is but I'm confident 20 years will be easily achieved - and in 20 years there will be chargers available as freely as there are petrol stations now so it will matter not if your range has dropped to 200 miles - and i suspect battery reconditioners and battery swap specialists will be abundant within just a few more years anyway - and swapped at a reasonable cost.

Tesla does pre inspection on used Tesla’s for 200$ they will give you a battery health. I would say eventually people will figure this out.

 

[Irata]

Tesla does pre inspection on used Tesla’s for 200$ they will give you a battery health. I would say eventually people will figure this out.

What does the report say in it? How is battery health represented?

For example, If it just said "battery healthy", that doesn't enable two healthy cars to be compared. And healthy could be a very wide margin.

 

[Duke846]

What does the report say in it? How is battery health represented?

For example, If it just said "battery healthy", that doesn't enable two healthy cars to be compared. And healthy could be a very wide margin.

In AH.
compairs it to the similar vehicles.

 

[MrBadger]

In AH.

How do they know the Ah? Thats determined by the BMS which is estimating the CAC - a figure that can be reset to any number. So its an estimated number rather than an actual value and the estimated number can be thrown out by all sorts of reasons? What does that give for $200 that current range value wouldn't give?

 

[Duke846]

How do they know the aA? Thats determined by the BMS which is estimating the CAC - a figure that can be reset to any number. So its an estimated number rather than an actual value and the estimated number can be thrown out by all sorts of reasons? What does that give for $200 that current range value wouldn't

 

[metroplex]

No, thats not right!

Its easy to draw the wrong conclusions when only reading one research report.
The results are very depending on which cycling schedule that is chosen.

From a lot of research reports we can be sure that these things are facts:
- Calendar aging might degrade the battery as much or more as cyclic aging. Most cars is used a few ours per day, during most of the rest of the day the battery is aged by time.
- The lower the SOC, the lower the calendar aging is. No exceptions as long as not below 0% SOC on the battery meter.
- Lower temps is god for calendar aging. When the battery is in use, 20-25C is goo
- The smaller the cycle( depth of discharge) the lower the degradation is.
- The lower the cycle is( ie the charging target) the lower the degradation is.

So, charge every day, not each other.
Use as low charging target as possible. Charge to 50% and arrive with 30% is better than charging to 60 or 70% and arrive with 40 or 50%.
Set the charge to start so the charging is done a relatively short time before starting to drive. If done so, the battery is at a lower SOC for most of the day.

I have a ‘21 M3P( Freemont, pana 82kWh).
I charge to 55-57% daily, use about 20-25% each day commuting to work. Charging is set( 11kW) to commence so it is ready about 1 hour before I go for work.
After 9 months and 23000km I still have full range om the battery meter and teslafi shows the same. The Nominal Full Pack value( via Scan my Tesla) is the same as when the car was new. Of course there should be a slight degradation but it is not seen by the BMS yet.
I have read, and have at least 30 research reports. A lot of reading, but this information sum up the things valid for Teslas/panasonic NCA cells:
How to preserve the battery

My plan seem to work:
View attachment 710746

Degradation from time( “calendar aging”) on panasonic NCA:
(Lesson learned: keep SOC low, and if possible battery from high temps during long time. High SOC together with high temps is not the best).

View attachment 710747

The difference between deep and shallow cycling. Lessons learned: shallow cycles at low SOC is better.
View attachment 710749View attachment 710750

How has this worked out over the past few years? Any updates to the degradation report?

 

[AAKEE]

How has this worked out over the past few years? Any updates to the degradation report?

Theres no changes to the theories / research reports. Same things is valid.

My car still has very little degradation, last full charge was two weeks ago showed 495km range.
60K km / 37K miles.
Today’s NFP is 78.8kWh. My car topped 82.0 remaining and 81.6 Nominal full.
Knowing that most M3P starts at 80-81, 78.8 is a quite good result.

[Edit]The full rated range shown is not correct. Latest version of Scan My Tesla has a bug in the calculation so the full rated range value decreases when SOC decreases. It shows the same (495km) at 100% SOC but goes down when SOC goes down. Before, it showed the same independent of SOC.[End edit]


My car has about 1/3 of the average degradation at the same ODO.
In fact, as the daily value of other cars i 4-8 or so, the average would drop considerably if my car wasnt dragging the average up.

So, for what it is worth I’d say that the low SOC stategy tactocs work very well to keep degradation low.

I have a little help with a cold climate, but when comparing between Swedish and other cars, fpr example USA model 3’s here on TMC, there is not a very big difference in general between Swedish ans US modeö 3’s.
Other People using the low SOC strategy see similar low degradation as I do.

 

[AAKEE]

Last full charge, march 6:th

495 km out pf 507 after 2 1/4 years and 60k Km is well above average.

 

[JIBYC]

Theres no changes to the theories / research reports. Same things is valid.

My car still has very little degradation, last full charge was two weeks ago showed 495km range.
60K km / 37K miles.
Today’s NFP is 78.8kWh. My car topped 82.0 remaining and 81.6 Nominal full.
Knowing that most M3P starts at 80-81, 78.8 is a quite good result.
View attachment 921929
[Edit]The full rated range shown is not correct. Latest version of Scan My Tesla has a bug in the calculation so the full rated range value decreases when SOC decreases. It shows the same (495km) at 100% SOC but goes down when SOC goes down. Before, it showed the same independent of SOC.[End edit]


My car has about 1/3 of the average degradation at the same ODO.
In fact, as the daily value of other cars i 4-8 or so, the average would drop considerably if my car wasnt dragging the average up.
View attachment 921932

So, for what it is worth I’d say that the low SOC stategy tactocs work very well to keep degradation low.

I have a little help with a cold climate, but when comparing between Swedish and other cars, fpr example USA model 3’s here on TMC, there is not a very big difference in general between Swedish ans US modeö 3’s.
Other People using the low SOC strategy see similar low degradation as I do.

It's a shame you lose out on peak power at lower SOCs, not much between a LR and a P below 50%.

 

[AAKEE]

It's a shame you lose out on peak power at lower SOCs, not much between a LR and a P below 50%.

Thats true.

Charging with high power and late before the drive helps by keeping the battery warm, reducing the difference.

So, if needing maximum power at any given moment low SOC might not be an option.
Charging late reduces time at high SOC and also keeps the battery warm = best power.

If the battery often i left at high SOC for long time, the internal resistance will
Increase more than if the SOC was low.
As the battery is the limiting factor for a M3P, the low SOC will Preserve the battery and keep the internal resistance low.
In the end, a M3P that ised the low SOC strategy will gove more power ( when charged to the same SOC).