Model 3 SR+ LFP Battery Range, Degradation, etc Discussion

[DuncanM]

Any info on calendar degradation for LFPs? Tessie (see sig) will not be driven much.

This post might provide some info:

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

Sounds like the car battery must be cycled one time. I'd do this only if absolutely necessary, and in particular if you're at very low SOC. It's going to discharge to low single digits, then charge up to 100% or something. I would guess less than 24hrs, but who knows until someone does it...

teslamotorsclub.com

 

[AAKEE]

Any info on calendar degradation for LFPs? Tessie (see sig) will not be driven much.

Well, there is a lot of info in the research.

For now, I havent seen any new data indicating a very big difference to the calendar aging.

There was one report from 2017 that showed the same calendar aging at both 50 and 100% SOC for normal temperatures.

Except that one, most of them show about the same calendar aging as the picture in the post linked to above.

We could expect that, maybe, the latest LFPs has lower calendar aging than we see in the picture. That it would be completely gone is not probable, not that it is very much smaller either. Time will tell.

I haven't read very much about LFP, as I have a Performance with NCA and LFP also is quite new in Teslas. Many research reports do also cover LFP’s as well so searching for and reading about NCA (and sometimes NMC) will give info about LFP.

 

[USBSeawolf2000]

Nominal Full Pack (NFP) is 55.0 kWh

I charged it to 100% overnight and this morning I got 253 miles. Car has 1,700 miles on ODO.

Replying myself 12 months and 13,700 miles later. Nominal Full Pack (NFP) is down to 52.4 kWh. ~4.7% degradation.

Energy Buffer (EB) is at 2.38 kWh, if I recall it was 2.5 kWh reserved before.

Tomorrow after work, my SOC will be down to 6% (if no errand) and I will be starting the battery health test. It should have 100% in the following morning and I will check the NFP and EB again.

 

[AlanSubie4Life]

Replying myself 12 months and 13,700 miles later. Nominal Full Pack (NFP) is down to 52.4 kWh. ~4.7% degradation.

Energy Buffer (EB) is at 2.38 kWh, if I recall it was 2.5 kWh reserved before.

Tomorrow after work, my SOC will be down to 6% (if no errand) and I will be starting the battery health test. It should have 100% in the following morning and I will check the NFP and EB again.

And ~242 miles when charged to 100%? (52.4kWh/54.7kWh*253rmi = 242rmi). Based on the post I wrote down to keep myself sane a while back.

Yep, energy buffer is always 4.5%, except when it isn't, for LFP. So right on target.

 

[USBSeawolf2000]

And ~242 miles when charged to 100%? (52.4kWh/54.7kWh*253rmi = 242rmi). Based on the post I wrote down to keep myself sane a while back.

Yep, energy buffer is always 4.5%, except when it isn't, for LFP. So right on target.

the last full charge said 243 but SMT app said 241 so you are right in the middle .

 

[inigoml]

My experience this past weekend with my 55kWh M3 SR+. My car usually has a range of 411km, NFP 52.4 and 2.4 buffer.

During a small trip around Madrid I depleted battery till 6%. I left for one night at this level. Next day I started charging at 11kW.
Just when starting charging I realize full range has dropped to 402km. Plugged SMT and NFP has also fallen to 51.2kWh.

So, when finishing charge I was looking at was happened.. at 99% NFP started rising up. Charge speed kept at 11kW until almost the end. So it's controlled by voltage and not by SOC level. NFP rised 0.2kWh under what Nomimal Remaining was showing. So, when Nomimal Remaining reached 52.6kWh, NFP scaled up to 52.4kWh that is what I previously had. This changes happened while loading. No need to wait for two hours. Just in the regular charging session. Session ended when voltage reached 392V, as usual (only managed to reach 402V when DC charging at SuC V3, not V2).

So, in my understanding, we could go with regular 20-80, 20-50, 20-90 or whatever. BMS drifting can be recovered just by loading up to 100% once a week or two weeks before start running same way we do with NCA batteries.

 

[USBSeawolf2000]

Went to the service menu this morning and looked at the battery screen. It said my battery health is 100%.

I am sure it will drop after I perform the actual test tonight.

 

[TSLM3CAN]

My M3 RWD : 30,000 kms (18,461miles) in 8.5 months . Range dropeed to 427km ( 265 miles). Daily overnight L2 charging to 100%. Used supercharger only once.

 

[PianoAl]

Here's a hypothetical to help me understand how the BMS calibration works.

Tessie (see sig) seems to lose about .5% of SOC a day sitting in the garage. Right now she's at 81%. Let's say she doesn't get driven for four weeks (28 days). Her SOC drops to 67%.

At that point, would the BMS be pretty well calibrated? Would it be reasonable to drive her without charging to 100%?

 

[USBSeawolf2000]

Here's a hypothetical to help me understand how the BMS calibration works.

Tessie (see sig) seems to lose about .5% of SOC a day sitting in the garage. Right now she's at 81%. Let's say she doesn't get driven for four weeks (28 days). Her SOC drops to 67%.

At that point, would the BMS be pretty well calibrated? Would it be reasonable to drive her without charging to 100%?

The Energy screen now has the number of miles lost while parked so the car has the ability to count the idle energy loss. I think that can be used to calculate expected SOC from NFP.

 

[USBSeawolf2000]

Starting the battery Health at 4.3% SOC. Pack voltage says 340V and cells average 3.2V. Doesn’t that indicate 20% SOC based on the graph I have seen?

If the 4.5% buffer is taken account, 8.8% should be below 3.1V at cell level.

 

[AAKEE]

Starting the battery Health at 4.3% SOC. Pack voltage says 340V and cells average 3.2V. Doesn’t that indicate 20% SOC based on the graph I have seen?

If the 4.5% buffer is taken account, 8.8% should be below 3.1V at cell level.

Your ”True SOC” is 8.7%.
[Nominal remaining / nominal full pack] or 4.5% buffer plus 4.35% displayed SOC = 8.8%.

LFP’s have a very flat voltage curve.
Are you thinking about a voltage curve from a regular lithium ion battery?

LFP voltages is so flat that even the BMS have a hard time being sure about the SOC from the cell voltage.

If you look at a discharge curve from a LFP you will see that it is close to 3.2 V/cell (between 3.3 and 3.2) in almost the whole range.
SOC cannot directly be seen on the most voltage curves as they most often show the Amphs delivered. The final part where the Voltage drops rapidly might seem like perhaps 10% SOC but it is not. If it looks like 10%, then it is probably 5%.

SOC is energy wise, calculated by [amphs x voltage]. as the voltage drops, each milliamphere will be worth less energy.

 

[USBSeawolf2000]

The link of the graph in my previous post is of LFP. It shows 3.2V at 20% SOC.

Are you thinking about a voltage curve from a regular lithium ion battery?

 

[USBSeawolf2000]

Update on the battery Health Test. I was able to unlock the Gateway to start the test but nothing happened. It said all the criteria met and “Starting Test” and there was a 900 seconds. I waited and nothing happened.

I tried charging the battery to 7% which then turned green from orange. Hard rest and nothing worked.

I could have left it overnight but I need to use the car to I exited the service menu and charged it manually.

This morning it showed 243 miles with NFP at 52.5 kWh.

 

[AAKEE]

The link of the graph in my previous post is of LFP. It shows 3.2V at 20% SOC.

Ohh, missed that link. Too early in the morning, I think.

That research report is from 2015.
The LiFePo4 has developed quite much so that voltage curve is not representative for a modern LFP cell.

 

[Ther0ck]

Update on the battery Health Test. I was able to unlock the Gateway to start the test but nothing happened. It said all the criteria met and “Starting Test” and there was a 900 seconds. I waited and nothing happened.

I tried charging the battery to 7% which then turned green from orange. Hard rest and nothing worked.

I could have left it overnight but I need to use the car to I exited the service menu and charged it manually.

This morning it showed 243 miles with NFP at 52.5 kWh.

NFP is an LFP, right ?

I've read somewhere you have to be at 50% to start the test. But don't quote me on this. I might be wrong.

 

[USBSeawolf2000]

NFP is an LFP, right ?

I've read somewhere you have to be at 50% to start the test. But don't quote me on this. I might be wrong.

NFP is Nominal Full Pack in kWh which is usable energy when fully charged.

Test needs SOC to be below 50% and I was well below.

I did upgrade to 2022.36.6 from 2022.36.5. Wonder if it is a bug in .6.

 

[DuncanM]

NFP is Nominal Full Pack in kWh which is usable energy when fully charged.

Test needs SOC to be below 50% and I was well below.

I did upgrade to 2022.36.6 from 2022.36.5. Wonder if it is a bug in .6.

I suspect you just need to be a bit more patient. The test will take a minimum of ~10 hours as it needs to fully drain the battery and then L2 charge it back to 100% SOC again.

 

[AAKEE]

NFP is Nominal Full Pack in kWh which is usable energy when fully charged.

To minimize the risk for confusion:

NFP is the whole capacity, not only ”usable” (includes the buffer).
It is also Nominal, a calculated value.
In the perfect world Nominal Full Pack and Nominal remaining is the same when the battery is fully charged.

 

[Ther0ck]

NFP is Nominal Full Pack in kWh which is usable energy when fully charged.

Test needs SOC to be below 50% and I was well below.

I did upgrade to 2022.36.6 from 2022.36.5. Wonder if it is a bug in .6.

The way you said it you had an NFP lol.