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Model Y RWD Charging to 100%
- Thread starter hagpe
- Start date
You can also look at @Baluchi’s good post / update of the degradstion after about 23 months: Model 3 SR+ LFP Battery Range, Degradation, etc Discussion
For the purpose of the charts, 51.5kWh out of 55.4kWh new capacity is about 7% degradation.
I do not have he’s charging habits but from 7% right now from the Factory spec, it would be around 5% in the first year which is quite close with the graphs shown.
LFP cars with 200,000+ km and about two years old are generally at less than 5% loss of indicated range. This is better than other battery types I understand. Particularly considering these are mostly ‘professional’ drivers who likely charge to 100% daily and supercharge often. The km’s travelled or charging habits don’t seem to make much difference, as it’s mostly calendar aging. I believe the LFP batteries are handling use and abuse a little better than other types as expected.
Teslaloggers data show a little bit higher loss than 5% range.
Still to the absolute most extent calendar aging as you say. (Which also is the case for most other Teslas, except the ones covering very long distances each year)
Teslalogger’s average that is noisy from different battery or wheel selection removed and a new line drawn by me.
Still to the absolute most extent calendar aging as you say. (Which also is the case for most other Teslas, except the ones covering very long distances each year)
Teslalogger’s average that is noisy from different battery or wheel selection removed and a new line drawn by me.
That’s such a dicey graph eh, hard to figure out exactly what is going on there. However from a real life example, Model 3 LFP showing 424km indicated range when new, now showing 403km after 230,000km, that would still roughly correlate with the lowest dark ‘smudge’ in that graph - from just over 420 to around 405 now for most cars. (albeit with average mileage much lower at between 20,000 and 60,000km)
The higher ‘smudge’ on that graph could just be bigger battery cars going from 440 - 420 over the same time. Both of these ‘smudges’ indicate less than 5% range loss. The more far flung dots could actually be higher mileage small battery cars - as the bigger battery didn’t come out until later, so that makes more sense from an average mileage perspective. I guess time will tell but I haven’t seen any real life examples of 7% or more indicated range loss on LFP cars on the forums I look at anyway. Fingers crossed!
Having reviewed maybe a hundred or more posts from LFP owners on this site and another, I came to the conclusion that displayed range seemed to only be affected by the age of the car - mileage or charging habits doesn’t seem to affect it - so even a car sitting in a garage and hardly getting used is losing the same displayed range as a car getting used and abused daily and doing ten times as much mileage. I started to wonder if Tesla might just be reducing the displayed range at 100% based on the age of the car. LFP batteries are hard to ‘read’ at the best of times anyway, so maybe this is Teslas workaround? Maybe a crazy theory, but definitely not the worst allegation out there regarding Teslas displayed range lol. Maybe @AAKEE can shed some light on whether this is a credible therory or just complete poppycock.
Yes I agree with that, just wondering if the displayed range at 100% could just be being gradually reduced by Tesla based on the age of the car and no other factors. It’s not like the car is doing a full battery test on itself is it. How does it know the battery degradation? The range is so wildly inaccurate & optimistic anyway there would be plenty of margin for them to reduce range based on a set of pre decided age related milestones and no one is really going to notice.
The displayed range is called "Rated range". This is total battery capacity divided by a hardcoded efficiency value - different for S3XY. It is based in some way to the EPA method of calculating range.
If you look at the energy app, under "since last charge" or after a "current drive"0 and "rated" selected. You will see a straight grey line sloping down from left to right. This straight sloping line is the displayed range at any point in time.
Yes the BMS actually monitors the battery. While the car is asleep with no battery usage it will actually measure an open circuit voltage a few times.
But - yada yada yada yada. Could go on....Basically try to not overthink it. We are not Tesla engineers. One of the traps of incomplete or no knowledge is speculating with little basis for it. With speculation comes incorrect conclusions even myths. Then round and round we go.
Best thing we can do:
Change the displayed range to Battery %. Forget about displayed km. Charge according to Tesla recommendation. There are many Teslas on the road with over 200,000km on the clock with batteries that have only mild degradation. Just drive and charge. Enjoy your Tesla.
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What’s the BMS going to learn from measuring voltage on an LFP pack lol. When you consider that it’s guessing the SOC most of the time, I’m slightly dubious about its ability to magically measure degradation. I still think my theory has merit - until someone with a larger brain and/or better knowledge convinces me otherwise!
That's a good point. I stopped worrying about my battery health with my MY NCA battery after realizing the BMS doesn't accurately measure degradation on it. It's even harder for the LFP BMS. For more details on my NCA thoughts, see: Reducing degradation stress - a tale of three batteries.
It is a valid question and I actually asked the same, and questioned that the BMS might not be able to estinate the capacity that exact.
In a regular Tesla, the BMS estimate a number of kWh to complete the charge
( target SOC - actual SOC) x estimated capacity).
When the charge is complete the real SOC is measured, and if the real SOC is less then the target, the estimated capacity is to low.
If the real SOC is higher than the target the estimated capacity is too high.
With LFP, if the SOC is hard to detect precisely the estimated capacity would be non precise.
I got a message yeaterday from a guy that bought a LFP car to cover daily long trips.
(Hes M3P had lost quite much capacity from very large cycles, so he got a LFP to be able to cover 100-0% daily).
Now he had stranded a couple of km from home with 8 km driven past 0%/0km. I take it as it was a very gentle drive below 0.
The car is charged full 4-5 time a week and was charged full tha day of this drive.
Most probably the BMS has overestimated the capacity by 4.5% - the 8 km drive (perhaps maximum 1-2%) = about 2.5-3.5% overestimation.
The car showed 417 km before the drive of the day.
Thanks for the explanation! I reckon I looked at a few hundred posts with mileage, age and range at 100% on LFP cars. They all pretty much aligned on age only. So either LFP packs are proving very robust or the reduction in displayed range is purely age based.
That’s interesting. In my MY RWD group (LFP) there are people who go below 0% - one guy had a pic of the display actually showing minus 11%! They reckon there’s a good 20 or 30km at least below 0% on MY RWD LFP. (When new at least lol). Maybe the smaller packs have less ‘buffer’ at the bottom.
johnny_cakes
Member
That's interesting indeed. I had thought that the display SoC never goes below 0%, but the trip SoC on arrival estimate does and that's how people are able to determine when they're below 0%.
Strange.
I did drive my car to -2% one time and -1.8% another time, these values was all taken from the BMS via Scan My Tesla.
From my memory the displayed value never went negative but stayed at 0% and 0km.
I did my drives noticing the cell voltage mainly and made sure that these would mot drop too far, this to minimize the risk of getting stranded.
Sorry whoops just found his post again (it was nearly a year ago) and you are correct the display didn’t go below 0%. It was indeed the estimated charge left at destination that was -11%. He did make it to the destination without charging though, so probably went well into the buffer zone. Seen some other posts where people have done 20km on 0% in MY RWD LFP.
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