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

[Candleflame]

Is it possible that they are somehow software nerfed to behave like a "used" pack?

no.
You can read out the "new" pack via canbus as i have done above. The BMS for the Model 3 also is attached to the pack (as opposed I think the S/X in the car?). No need to let it get reads and not discharge the pack to <20% for 1 month etc.

ie:

 

[Candleflame]

Where do you think Tesla gets these packs from?

afaik its pretty much all but confirmed that Tesla has the same problem as anyone else and individual modules are not replaceable due to the BMS being unable to balance anything which has more than >20mV of imbalance routinely at high SOC. So unless the new module matches the degradation pretty much by <0.5% thats not possible. And even then - if the new modules is newer or older than the other ones it may degrade at a different rate.
Apparently they genuinly just throw the damaged pack away and it gets recycled.

The refurbished packs are battery packs which are damaged but the individual modules are working ok. I.e. if a customer needs pack replacement because the BMS died or the outside of the pack is damaged, or the car got totaled, or the masterfuse is broken and needs replacing etc. Those packs go back home and get fixed/refurbished.

At least that is what I have read.

 

[AAKEE]

Same here 57% on the MYLR dual motor (Australia May 2023 build) equates to about 300km estimated range. I drive daily and total about 300km/week and charge about 3x week to 57% - only because I don't need more and the estimated range is a nice round number and easy to see if it changes over time. I could charge to 40% and still be comfortable with available range

I am interested in your views about Jeff Dahn's recommendations a few years ago to charge to 70% SOC

I think I already has written about that.

Long story short - If Jeff Dahn has the knowledge it seems, his statement is not made on the reduce the degradation of the battery (calendar aging mainly).

It is most probably he’s view on the best compromise between range and degradation.

From science we know that going above 57-58% true SOC (think 55% displayed) increases the calendar aging, and we need not to go very much above 60% to see a double calendar aging.

There is so much ”evidence” that it would be very unwise to dismiss the evidence.

 

[Quickst]

What is the temperature of a scheduled departure "preconditioned battery"

 

[AAKEE]

What is the temperature of a scheduled departure "preconditioned battery"

In my case with my M3P it did mostly not heat the battery if the car hasnt been out and been cold soaked.

Even if the setting was used, the battery was only heated if it was cold outside and the battery was cold enough.

Charging with the WC at maximum power (11kW) heated the battery more than the preconditioning only.

The heat in the battery can be used by the heat pump down to the battery reaching 11-12C

 

[Quickst]

cold soaked.

Are there any battery health issues if I start to drive with a cold battery. For me "cold " = zero Celsius (Australia). Another way of asking that : does preconditioning help battery health with battery temperatures of zero Celsius

 

[AAKEE]

Are there any battery health issues if I start to drive with a cold battery. For me "cold " = zero Celsius (Australia). Another way of asking that : does preconditioning help battery health with battery temperatures of zero Celsius

No, not directly.

The car heats a sub zero Celcius battery very quickly ubtil it is a few degress om the warm side.

In theory a warmer battery is better but the cyclic aging is anyway small.

You can either start the heater for the cabin before the drive or planning a departure to get the precinditioning. It do not warm the battery if it os not cold.

 

[KenC]

Same here 57% on the MYLR dual motor (Australia May 2023 build) equates to about 300km estimated range. I drive daily and total about 300km/week and charge about 3x week to 57% - only because I don't need more and the estimated range is a nice round number and easy to see if it changes over time. I could charge to 40% and still be comfortable with available range

I am interested in your views about Jeff Dahn's recommendations a few years ago to charge to 70% SOC

Saw this on twitter not long ago, so I screenshotted it. There was long video, which I did not watch, but this is what someone said Jeff said. Not sure if your 70% is what is being referred to here.

 

[Quickst]

Not sure if your 70% is what is being referred to here

Ill have to datamine some info. There have been a lot of comments around his "70%" . Some speculate that the Li-Ion cells are at neutral chemistry at 70% . Above 70% there is greater Li plating and below 70% anode or cathode issues (can't remember what). @AAKEE has real world data which I respect, whereas something like the above really is for the lab environment. I'll go with the real world data.

 

[AAKEE]

View attachment 954782
Saw this on twitter not long ago, so I screenshotted it. There was long video, which I did not watch, but this is what someone said Jeff said. Not sure if your 70% is what is being referred to here.

Nahh.

Rule of thumb = 0.1V = 10%.
4.2V = 100%
4.1V = 90%
4.0V = 80%
3.9V = 70%
Etc. Etc.

The worst degradation for NCA is often found to be at around 80%.

Internal resistance increases faster with high SOC but above 80% it’s much faster.
(Mostly affects available power and possible charging speed and not range directly, as the losses for this is already incorporated in the calendar aging test results).

In general, there is a myth about how bad it is for batteries at 100%.
Also, the myth’s luring people to think 80-90% is the best SOC.

This is Real Tesla model S cells taken from a 6 months old car.

 

[Quickst]

Rule of thumb = 0.1V = 10%.

Obviously not for LFP.

........

Also what you are saying is even though 30% SOC is better than 50% SOC, the difference is smaller than the effect of calendar aging?

 

[AAKEE]

Obviously not for LFP.

........

Also what you are saying is even though 30% SOC is better than 50% SOC, the difference is smaller than the effect of calendar aging?

30% better than 50% is the calendar aging thing.

Look at NCA for example (most used chemistry in Teslas until now.

 

[RichAZ/CapeCod]

And I thought I was being a good do-bee by keeping my MY LW AWD at 80% SoC...

 

[AAKEE]

And I thought I was being a good do-bee by keeping my MY LW AWD at 80% SoC...

Thats very common.

Remember, keeping 80 or 90% will not kill the battery, only degrade it a little faster than low SOC.
If you are happy with how Tesla is thinking ( "degradation is a normal thing, and does not matter") just keep uysing 80%. No Problems.
But if you really did use 80% becuase you tried to reduce degradation, then a lower SOC is a good option.

 

[Quickst]

Look at NCA for example (

Would be also interesting to see data for the same cells after 5 years

 

[AAKEE]

Would be also interesting to see data for the same cells after 5 years

There is data for 3 years at least.

The researchers are widely agreeing that calendar aging is reducing its rate by the square root of time formula.

The reason for this is that the loss for calendar aging is build up of solid electrolyte interphase (SEI) which in turn act as a procection for further SEI build up. The rate decreases with time.

What we get in one year takes furter three (total of four) to double.

What we get in four years takes furter twelve (total of 16) to double.

We can forecast it quite well in other words.

 

[3sr+buyer]

afaik its pretty much all but confirmed that Tesla has the same problem as anyone else and individual modules are not replaceable due to the BMS being unable to balance anything which has more than >20mV of imbalance routinely at high SOC.

Maybe not everyone else... LG/GM BMS in the Chevrolet Bolt seemed to tolerate unbalanced cells while treating the pack capacity like that of the worst cell.

 

[Quickst]

There is data for 3 years at least.

And the data and calendar ageing formula for LFP is similar?

Is 100% indicated by the BMS for LFP or NCA the actual 100% for the battery?

 

[AAKEE]

And the data and calendar ageing formula for LFP is similar?

Yup.

All research results is from cells at least a couple of years age. Getting the hand on, testing for 1 year and writing and getting the report approced takes about two years in total. In some cases more, if the test protocoll takes more time.

But we can see that LFP in the RWD Teslas seem to degrade about as much as the other chemistries and about as much as expected from the test result we have.
All lithium ion chemistries behave about the same. And a specific chemisty will probably continue to behave about the same even if its tweaked and the total degradation might be slightly lower.

The reason that we can see about the same, maybe slighty less degradation on RWD cars with LFP is because they degrade as usual or about as usual from calednar aging. If they did not, we would se almost non degradation at all, as the cyclic degradation is very low with modern LFP's.

Is 100% indicated by the BMS for LFP or NCA the actual 100% for the battery?

Yes, Tesla use 4.20V/cell as 100%, which is the branch standard. Its possible to charge more, to 4.3 och 4.4V (like 125% os so) but the life will be short so the branch standard is set where the batteries doesn't break from use within the approved SOC range.

For the LFP I'm rather sure that the maximum voltage Tesla set is the same as the max allowed voltage from the cell manufacturer. There simply is no reason to reduce it and use a top buffer. They can stand a lot of full 100-0% cycles and they can stand 100% about as well as the other chemistries can. We also have learned that 100% is not much worse than 80%, and in some cases even worse than 80%, so there really is no reason to not use the full 100% as the cars 100% (no top buffer).

 

[DownshiftDre]

Its heating up in Vegas now 110F (43C). Having access to service mode has given me inside peek at battery temps and octovalve modes.

45C battery temps are normal during usage.

I do not notice any active battery cooling whatsoever through the use of the heat pump. It just circulates coolant passively and hopes temp will eventually go down. Maybe I am not catchinh it during driving?

Even when I plug in inside a hot garage the battery just remains with 45C coolant circulating with 45C battery. No heat pump engaged to actively pull heat out of battery coolant loop. In the morning you are lucky if the battery eventually got to the same temp as hot 35C garage.

The only active battery cooling I have seen is with Track Mode. Heat pump will engage and Battery coolant loop will route through the chiller and cool the battery coolant to 23C.

Anybody have any insight to the Model 3/Y battery cooling logic? My Chevrolet Volt had a very aggressive battery cooling logic trying to keep battery less than 30C as soon as plugged in or driving. Of course smaller battery…