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Model 3 SR+ LFP Battery Range, Degradation, etc Discussion
- Thread starter Baluchi
- Start date
That since charge metric only counts energy used while the car is in drive, not while it's in park, so if you want to use it to measure battery capacity, you optimally need to do it all in one drive.
Had a lot of driving to do yesterday, so I did a little test to see how much range I could get and how many kWh I could pull out of the battery. Unfortunately, it wasn't a perfect test, because it took about 14 hours from the time I unplugged, including 5 drives, 54 minutes of idling (car in park, but not yet sleeping), and 7 hours 42 minutes of sleeping (Sentry and Cabin Overheat off). Here's the stats:
53.5 * (97 / (97 - 0.4)) + 1.82 = 55.54 kWh
So the total amount, including the buffer, should be:
55.54 / .955 = 58.16 kWh
If full when new design capacity is 60.5 kWh, then I guess I have 96.1% of design capacity remaining, or about 3.9% degradation. If someone were basing degradation off of displayed miles remaining vs when new, they might assume 265/273 for 2.9% degradation. But I think current RWDs won't display any range above 273, even if the battery has more capacity, and if we assume the cutoff for displaying 273 is 60.0 kWh, then everything would line up... 273 * (58.16 / 60.0) = 264.6 or 265, which is what my car shows.
But to throw one last wrench into things, my Ingenext module reports current full nominal as 58.6 kWh, not 58.16 kWh like I calculated, so not sure why that doesn't line up. If the capacity is really 58.6 kWh and I just didn't get an accurate reading due to not doing it all in one drive, maybe 273 miles displayed actually equates to >=60.5 kWh, because 273 * (58.6 / 60.5) comes out within 0.1 of my displayed range.
Overall, pretty happy to see that you can actually match the EPA range in the real world, even without dipping into the buffer. Driving was 25% backroad driving at 50-60 mph with a few stoplights, and 75% interstate driving at 65-75 mph where possible, but there were 4 or 5 5-15 minute traffic slowdowns. Overall average for the whole day was 49.4 mph, including waiting at stoplights and the traffic slowdowns.
- Car delivery date: Dec 10, 2022
- Current displayed miles at 100%: 265 (264.53 according to TeslaFi)
- Displayed kWh used: 53.5 kWh (I recorded everything as soon as displayed kWh used since charge changed from 53 to 54)
- Displayed distance driven: 259 miles
- Displayed efficiency: 207 Wh/mi
- Displayed battery remaining at end: 8 miles / 3% / 1.82 kWh (182 Wh/mi * 10 miles projected from energy app)
- Displayed percent used in park (from energy app): 0.4%
53.5 * (97 / (97 - 0.4)) + 1.82 = 55.54 kWh
So the total amount, including the buffer, should be:
55.54 / .955 = 58.16 kWh
If full when new design capacity is 60.5 kWh, then I guess I have 96.1% of design capacity remaining, or about 3.9% degradation. If someone were basing degradation off of displayed miles remaining vs when new, they might assume 265/273 for 2.9% degradation. But I think current RWDs won't display any range above 273, even if the battery has more capacity, and if we assume the cutoff for displaying 273 is 60.0 kWh, then everything would line up... 273 * (58.16 / 60.0) = 264.6 or 265, which is what my car shows.
But to throw one last wrench into things, my Ingenext module reports current full nominal as 58.6 kWh, not 58.16 kWh like I calculated, so not sure why that doesn't line up. If the capacity is really 58.6 kWh and I just didn't get an accurate reading due to not doing it all in one drive, maybe 273 miles displayed actually equates to >=60.5 kWh, because 273 * (58.6 / 60.5) comes out within 0.1 of my displayed range.
Overall, pretty happy to see that you can actually match the EPA range in the real world, even without dipping into the buffer. Driving was 25% backroad driving at 50-60 mph with a few stoplights, and 75% interstate driving at 65-75 mph where possible, but there were 4 or 5 5-15 minute traffic slowdowns. Overall average for the whole day was 49.4 mph, including waiting at stoplights and the traffic slowdowns.
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If you don’t charge to 100% often enough the BMS will increase the buffer and that number will drop. Charge it to 100% a few times and it might increase. Or maybe it’s just normal degradation, either way I wouldn’t worry about it.
Mine regularly moves based on my charging habits, which are irregular. I try and stick to 100% charge every week but it isn’t always possible.
Took delivery of M3 RWD in October and I had a 2019 M3 SR+ previously. I know a lot of people has been talking about this. And for the average person driving 20k a year, charging to 100% on LFP is probably the best practice for cell balancing and BMS estimate. But my situation is a bit different from average. I drive 12k KM every month (approx 7.5k miles) does any one know what’s the best charging practice for my situation? Right now I charge to full once every 5 days or so. Charge to 90 or 85 on other days.
Also I got pretty lucky with the car. When I first took delivery and took it to a supercharger it took 30 minutes just to calibrate I called Tesla when it was calibrating (cause it took like for ever) they told me that the battery has an extra 500w of capacity compared to other new cars
7.5k miles a month and you charge to full every 5th day? I'm sure I'm not reading this right.
AlanSubie4Life
Efficiency Obsessed Member
Basically the same as for anyone else - keep the time-averaged charge level as low as possible, preferably below 60% for as much time as possible (a little higher than 55% is ok for LFPs).
It looks like you are driving approximately 400 km or 250 miles per day on average. If you are getting approximately the EPA-rated efficiency and range (which is used for the rated remaining range display at the top of the screen), then you are using over 90% of the battery capacity every day.
So it looks like it is not realistic to charge to <= 70% to try to reduce time spent at high state of charge to prolong battery life. However, it matters less for LFP batteries than NCA/NCM batteries, and if you set your charging to finish just before you leave, the time spent at > 70% will not actually be that great, since you will presumably drive it down below 70% relatively early in the day.
Yea you are reading it right. So basically change to 85 charge to 90 charge to 95 charge to 90 charge to 100 something like that.
Yea I use over 90% of the battery every day. I try to dcfc before the battery hits the 30% mark. I’m guessing I should keep doing what I’m doing and schedule the charge to end just at the time before leaving and continue to charge 80 or 90 and charge full once in a while for cell balancing.
That’s right. Mine dropped to 428km originally 438 after not charging to full five or six times in a row. But after one charge to 100 it goes back to 438 it’s just the bms trying to protect battery.
Do you actually need to use fast charging to make it home after a day of driving, if you start with 100%?
Just charge it to 100% every day and don’t worry about it. Trying to keep it below 70% or whatever in your case is pointless - that is intended for longer term storage or if you don’t drive the car much. In my case I leave it below 70% during the week as it stands mostly in the basement and I charge it to 100% on a Friday or Saturday for the weekend. In your case I wouldn’t overthink it at all and it won’t make much difference to battery longevity.
If I start at 100% maybe not but the soc would be super low. Around 5% or lower barely making home.
If you fairly reliably use 95% in a day, it may be more convenient to start at 100% and drive most days without having to use fast charging, assuming that fast charging is readily available in case you take side trips or have more than typical consumption on occasional days. Note that fast charging is generally faster at lower states of charge.
70,000 mile (112,650 km) update for my Sep 2021 SR+ LFP. I missed the 65K mile update because I've been adding miles so quickly. The car is now 2 years 3 months old and was originally rated at 253 miles on a full charge. The Tessie app shows a battery capacity of 51.2 kWh (down 6.3% from my original Oct 2021 post of 54.6 kWh), and a max range of 237 miles (down 6.3% from my original range of 253 miles, and down one mile since my 60,000 mile update). I've had Tessie since my first day or two or ownership, so this data shows the entire life of the car.
According to the car's screen, I'm averaging 210 Wh/mi over the life of the car (down from 211 at the 60,000 mile update). In cold winter weather I can expect 240+ Wh/mi when it's below 30f, and in ideal temps (75-85f) I routinely manage under 200 Wh/mi on my 100 mile round-trip commute. Assuming I could tap into the current 51.2 kWh battery at my lifetime average 210 Wh/mi efficiency, that gives me a real-world range of 243.8 miles.
My charging is mostly Level 2 from a Grizzl-E delivering 24 amps on a 40 amp circuit in my garage. I charge almost every day/night due to a long commute, typically to about 75% a few times per week and a 100% once or twice a week. I fast charge about twice per week on average, but these aren't usually deep charges.
Driving the same distance in my old Ford Focus would've cost $6,622 in gasoline. To a large degree, my car is sun-powered since installing solar at my home. If I'd kept my 2012 Ford Focus (37mpg), I would've used 1,892 gallons of gas to travel these 70,008 miles. At about 19 pounds of CO2 per gallon, that would've been 35,950 pounds of CO2. Prior to getting solar, my carbon emissions were about 35% of what I would've released in my efficient little Focus. But now that I have solar, that number is much lower, and it's pushing the car's lifetime average down every day.
Notably, in 70,000 miles I've only had one real issue with the car. It was early on when my on-board charger broke (I could only DCFC until it got replaced). That's it, which I think is pretty impressive for a brand that doesn't have the best reputation for quality.
I'll try to post another update at 75,000 miles.
According to the car's screen, I'm averaging 210 Wh/mi over the life of the car (down from 211 at the 60,000 mile update). In cold winter weather I can expect 240+ Wh/mi when it's below 30f, and in ideal temps (75-85f) I routinely manage under 200 Wh/mi on my 100 mile round-trip commute. Assuming I could tap into the current 51.2 kWh battery at my lifetime average 210 Wh/mi efficiency, that gives me a real-world range of 243.8 miles.
My charging is mostly Level 2 from a Grizzl-E delivering 24 amps on a 40 amp circuit in my garage. I charge almost every day/night due to a long commute, typically to about 75% a few times per week and a 100% once or twice a week. I fast charge about twice per week on average, but these aren't usually deep charges.
Driving the same distance in my old Ford Focus would've cost $6,622 in gasoline. To a large degree, my car is sun-powered since installing solar at my home. If I'd kept my 2012 Ford Focus (37mpg), I would've used 1,892 gallons of gas to travel these 70,008 miles. At about 19 pounds of CO2 per gallon, that would've been 35,950 pounds of CO2. Prior to getting solar, my carbon emissions were about 35% of what I would've released in my efficient little Focus. But now that I have solar, that number is much lower, and it's pushing the car's lifetime average down every day.
Notably, in 70,000 miles I've only had one real issue with the car. It was early on when my on-board charger broke (I could only DCFC until it got replaced). That's it, which I think is pretty impressive for a brand that doesn't have the best reputation for quality.
I'll try to post another update at 75,000 miles.
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