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Model 3 SR+ LFP Battery Range, Degradation, etc Discussion
- Thread starter Baluchi
- Start date
Teslogger.de doesn’t have age, only km. So the cars could be losing range based purely on age, but it appears as a cluster around certain km’s because that’s just the km’s of most cars of that age. Hopefully that makes sense. Basically that data doesn’t prove much without battery age data, plus there are two battery sizes on that graph, which muddies the waters considerably.
Here's a chart I put together from data on TeslaFi comparing displayed range vs age of five Model 3 RWD with 60 kWh LFP batteries. I only selected cars that connected to TeslaFi within the first ~300 miles, and I attempted to normalize age by adding an extrapolated days since delivery to the date connected to TeslaFi, which only resulted in adding 2-6 days for each car. For example, if a car was connected to TeslaFi on Jan 10 with 100 miles and it drove an average of 30 miles per day after connecting, I would do (100 - 14 (estimated mileage on delivery))/30 = 2.9, and then subtract that from the date they connected to TeslaFi and assume the car was delivered on Jan 7. I also showed the miles / month each car drove in the legend (as you can see, no difference between driving 400 mi/mo and 1700). Will try to add more cars later, but it's somewhat tedious and takes at least 5 minutes to add a car when I find a good candidate.
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Yeah, I’m a little worried about that too. 5.5% degradation after 2 years doesn’t sound so bad, but 10% after 4 years or 14% after 6 years wouldn’t be very good IMO. Most of them only have a very slight bend and are very close to linear except for car 8. Not sure why that one is so different than all the others.
I just hope degradation plateaus before displayed range reaches 250 miles (~8.5% degradation), because I feel like dropping below 250 would hurt more psychologically.
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Really nice charts! Can I suggest a couple enhancements?
1. Color code the lines by miles/month using some sort of hot-cold gradient. Would be harder to tell cars apart, but would make it easier to tell which lines have more miles than others.
2. Add an average line to the chart. Should make the gradual shallowing of the curve more visible.
I imagine that we'll see the curve get pretty flat around the 245 mile range mark, or around 10% capacity loss, you can already see that the curve is bending.
Doesn't appear to be much correlation between miles driven per month and degradation (the lines for the least driven and most driven car are perfectly on top of each other at month 5), but here it is. I'll see if I can dig into the data a bit more and find any correlations that push some higher vs lower.
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10 month vs 20 month: 4 mi
0 month vs 10 month: 9 mi
Academic models approximate calendar degradation as proportional to sqrt(t) with t as age of cell.
sqrt(2) = 1.41
sqrt(2) - sqrt(1) = 0.41 (20 montbs vs 10 months)
9 mi * 0.41 = 3.69. 4 mi degradation observed.
Limited data here but consistent with theory
It appears to be 10 miles in first 12 months, so 10 miles * sqrt(Years) is likely first guess at calendar degradation. 20 miles in 4 years. 40 miles in 16 years.
Well it’s only troubling if displayed range reflects the cars’ actual degradation lol. We could just be watching Tesla’s master plan (of pre programmed range reduction based on age only) unfold before our very eyes! ;-)
Great graph thank you. I hope one day we will have enough data to draw some accurate conclusions. I am not surprised to see a bit of variation as the range seems to bounce around a bit based on recent (short term) charging habits - like when people don’t charge to 100% for ages, or leave it a low SOC for a while - then once they resume the 100% once a week habit the range seems to bounce back.
Added more cars, average lifetime temperature reported by the cars, country of manufacture, and gave the cars that seem to have the least degradation long dashed lines and the cars that seem to have the most degradation dotted lines.
Temperature doesn't seem to have much correlation with degradation, except for car 17 from Bavaria with an average temp of 48F, which does seem to have the least degradation. However, car 8 is located in Quebec, Canada and it seemingly has the worst degradation, or possibly just a really poorly calibrated BMS. And car 2 is in Arizona and has less degradation than average despite the highest average temperature.
I do notice a possible minor trend in country of manufacture. All of the cars built in China stay above the average line most of the time, apart from a few temporary dips. I wonder if that's simply due to the battery cells being older when US cars are built because they had to be shipped across the ocean first.
Temperature doesn't seem to have much correlation with degradation, except for car 17 from Bavaria with an average temp of 48F, which does seem to have the least degradation. However, car 8 is located in Quebec, Canada and it seemingly has the worst degradation, or possibly just a really poorly calibrated BMS. And car 2 is in Arizona and has less degradation than average despite the highest average temperature.
I do notice a possible minor trend in country of manufacture. All of the cars built in China stay above the average line most of the time, apart from a few temporary dips. I wonder if that's simply due to the battery cells being older when US cars are built because they had to be shipped across the ocean first.
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The range displayed at 100% is probably just an arbitrary number it doesn't reflect anything, whether it be 440klm or 420klm.
Its how far you have driven when it reaches 0% that is relevant and I think NEDC, WLTP, EPA give the manufacturers a lot of room to play with truth on displayed range.
The remaining range at the top of the main screen is the rated range based on the estimate of remaining kWh stored in the battery. I.e. remaining kWh multiplied by the rated km/kWh or rated miles/kWh. The multiplier does not vary by how efficiently or inefficiently you drive, unlike the estimated remaining range on one of the energy screens or the guess-o-meter distance-to-empty on other EVs or some ICEVs. It is best to treat it like a high resolution "fuel gauge".
In the US, the US EPA rating is used for the multiplier. It looks like the US EPA rating is used for this purpose in other countries, since the WLTP, NEDC, etc. ratings seem to be more optimistic (too optimistic). Lead-footed posters here say that the US EPA rating is too optimistic for them as well, though it is attainable with non-lead-footed driving.
Yes, Tesla use the EPA range as the displayed range at the battery all over the world.
Hopefully this graph levels out at some point. Although 2.5% coming off the original displayed range each year is not the end of the world for me. It might be the end of the solid resale value we’ve currently got in my country though. (One year old MY RWD LFP cars are selling only a few thousand below the price of a new one at the moment)
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