We don't know if the battery health test in the service menu works correctly on this model. Kyle Conner did it on his Model 3 a while back, got weird results, and when he reached out to a contact at Tesla, they told him there was a bug in that test with certain models. Makes me wonder if it's outdated code that hasn't been maintained and is no longer used by Tesla anymore.
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Model 3 SR+ LFP Battery Range, Degradation, etc Discussion
- Thread starter Baluchi
- Start date
We don't know if the battery health test in the service menu works correctly on this model. Kyle Conner did it on his Model 3 a while back, got weird results, and when he reached out to a contact at Tesla, they told him there was a bug in that test with certain models. Makes me wonder if it's outdated code that hasn't been maintained and is no longer used by Tesla anymore.
Oh wow ok so we basically have no idea about the true degradation of these packs lol - we’ll just have to use the estimated range at 100% SOC…. (which thus far is unproven to be an accurate reflection of actual SOH)
Maybe we need some people to just drive their cars from 100% down to 0% and calculate the capacity from the w/ml
Oh wow ok so we basically have no idea about the true degradation of these packs lol - we’ll just have to use the estimated range at 100% SOC…. (which thus far is unproven to be an accurate reflection of actual SOH)
Maybe we need some people to just drive their cars from 100% down to 0% and calculate the capacity from the w/ml
We know how batteries degrade, both from cycles and Calendar aging. Its prefictable and drops like @mariod had most probably comes from BMS having been off and correcting or going South on the calibration.
(The other option is a battery problem, but I guess it statistically happens selldom.)
Im not clear if @mariods is a LR RWD or a AWD, but five years in with toronto climates would degrade the battery around 10% for calendar aging only. The driven miles would add a little to this, but not much.
If it is a AWD, the 100% range would be around 460km from 499km (there some 2% loss hidden before the range starts to drop).
If it is a RWD, I dont know the numbers in my head, but then the calendar aging still has costed 10%, so the capacity is at 70 kWh (out of 77.8) or so, minus a little for the miles driven.
AlanSubie4Life
Efficiency Obsessed Member
Is it unproven? Seems pretty good to me.
I and others have done this. It’s usually within a % or so. Depends on the accuracy of the BMS estimate, which is usually quite good! If in doubt about the estimate, just meter it!
Just checking you think it’s been proven for LFP cars and you and others have driven to 0% and calculated back in LFP cars?
AlanSubie4Life
Efficiency Obsessed Member
Unless the BMS is confused because of insufficient charging to 100% in LFP, it’ll work the same way. But I have not done this for an LFP.
Feel free to meter this and go through the energy screen steps in an LFP. It’s easy enough to do and I can explain how via private discussion ( or public if you want).
Does not have to be a full discharge to demonstrate the method though of course to really check you do have to do all the way to near 0%.
Yes it has.
I know of one LFP car, about one year old (somewhere around 50K km) that did drive until it stopped and there was just a little less under the 0% on the screen compared to the 4.5% buffer it should have had. More of a slight temporary difference than anything wrong.
After this he got Scan My Tesla, and I just checked and it seems that the energy from 100-0% which he drives more or less avery working day is the correct number compared to the nominal full pack and buffer numbers. (He always use all the battery 100-0% so the dynamic buffer is at the 4.5% minimum.)
As he only had the energy graph before SMT he knows that calc very welll and states that the energy graph and the SMT nominal full pack is showing the exact same thing.
He is not using the car even close to the average owner, using 100-0% all the time, but for him the BMS seem to keep a good track of the capacity.
100-0% meaning down to the buffer, not the true 0%? Most drivers might not be that precise with their consumption.
100-0% displayed daily.
Once until the car stopped (true 0%).
The energy numbers seem to match ok.
I love this bloke’s commitment to the cause lol.
That great that the numbers are matching up thus far. (Although to be fair I could probably guess anyone’s range loss based purely on the age of their car at the moment - there’s very little variation on LFP cars)
I guess we’ll be able draw some more relaible conclusions about how LFP is holding up after a few more people do this type of thing and really test it out. I will disregard that battery test I saw showing 12% capacity loss as possibly unreliable. (The car was showing 5.5% range loss)
Does anyone happen to know what indicated range a MY RWD LFP started out with? (19inch wheels, Shanghai built - non BYD battery)
I figure I might as well look at my own car now that’s nearly a year old. RWD MY LFP might end up as the most common Tesla globally at some point perhaps.
AlanSubie4Life
Efficiency Obsessed Member
Very likely to be unreliable, since the metering doesn’t count any use while parked. The test has to be done carefully to make sure all the energy is counted.
Without knowing more specifics it is hard to say anything more.
This guy commutes very long every day.
He has a M3P ’21 that he used, needing 90-95 to 10% each day, and the capacity was decreasing faster than he liked so he did get this RWD with LFP.
I think basically he use 100-0% for commuting each day, adjusting the speed in the end to make it reach back home.
He once had it stop after ”only” 2% below 0% dislayed, otherwise it seem good.
I think the NFP is 59.0-59.5 or so, and he uses up 56-57kWh on the rounddtrip with 2.66 as buffer.
I think it will be possible to check the SOC behaviour around 0% after a drive to be able to judge if the BMS estimate is good (as the voltage slope is better around 0-5% true SOC then in the middle SOC range.).
I will try get him to check this, I think we will get the answer soon.
He also talked about maybe driving another test until it stops, with the support of Scan My Tesla.
For now we do not have anything pointing at the BMS not being able to judge the capacity well.
Id say for the holding up thing, we know that the latest LFP can do litterally thousands of full cycles.
Miles/cycles will not be a problem.
Teslaloggers graph show about 5% loss of range the first 50K km. In reality we are talking calendar aging for the very most part, but this is about the expected. Its slightly less than for example model 3LR.
So I would say that we more or less know how they will hold up. The ”only” question was if the BMS was able to measure/ track the capacity close to the real number…which it at least seem to do wuite well.
It is possible that the BMS has trouble tracking the true capacity with LFP, which could explain the apparent “pre determined “ degradation.
It looks more and more like the LFP is a set and forget type battery. Just leave it at 100% and enjoy the car!
It looks more and more like the LFP is a set and forget type battery. Just leave it at 100% and enjoy the car!
I charge my M3 LFP to 100% weekly or so, on an L1 charger at 10amps. Current max displayed range is 419 km (437 new in March 2022) with 48k kms. Yesterday, i drove to a local 50kw DCFC and arrived with 98% SOC and since the L1 doesn't provide enough current to calibrate, I like to do a calibration charge every few months . Theoretically, this should mean that the battery would require ~1.2 to ~1.4kw to fully recharge but the DCFC actually provided 2.9kw yet the displayed full range didn't change...
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Not enough current to calibrate? What makes you say that? My understanding was that ‘calibration’ is happening right at the end of the charge when it’s sitting at 100% but still drawing a tiny current for like 30 mins or so. (My actual car says 100%, but the app says 99% for ages and draws super low current before hitting 100%)
Calibration is a strange world, its cell balancing really.
That’s awesome. I hope he’s happier with the degradation of the LFP over time. Definitely an interesting case to follow.
I’ve always thought there might be a bit of a market (like this guy) for RWD Long Range Teslas. Biggest battery possible with the most efficient drive train. Would make sense to make such a car LFP though so it can be constantly charged to 100%. Not sure if there are bigger LFP batteries out there that fit at the moment.
Yeah that’s what I am thinking it’s doing in my head - topping up all the cells to an even level. It’s a nice feeling knowing they’re all balanced lol.
It’s going to be fascinating eh - when these cars are ten years old - what range are they getting, what are they worth etc. Even if they’re still at 70%, if the other mechanicals are holding up, they should have decent value as a used car.
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