omgwtfbyobbq
Active Member
Are there any other measurements to confirm it's reporting rated range as a function of battery pack capacity alone?
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TeslaFi - Battery Degradation Reports (upload your data)
- Thread starter remlemasi
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You can check out this thread by @wk057 . Relevant excerpt:
"These are the exact numbers pulled from the Tesla firmware. Rated miles are static Wh/mi. They do not change with driving style or anything else besides the configuration of the car as noted above. The car simply takes the estimated usable energy remaining as reported by the BMS, divides by the appropriate static number above, and displays the value."
(This is from a thread about X and S but I see no reason why it wouldn't be the same in the 3)
omgwtfbyobbq
Active Member
In that case, it should be the same in the 3. At the same time, if it's reporting the usable energy reported by the BMS instead of averaging it and adjusting it for battery balance, battery temperature, and so on, it's likely not going to be accurate to use to compare capacity over short time periods.
An exception would be if someone can control for battery balance, temperature, and whatever else effects the capacity reported by the BMS. So if I charge to full, cycle it shallowly a couple times to help balance it at higher voltages, charge to full again (ideally on 120V to also give it time to balance), and leave it in my climate controlled garage for 12 hours before taking a measurement, that should give me a good idea of cycle and age related capacity fade because I'm controlling for things that can change the energy capacity reported by the BMS. If my measurements aren't controlled, then they're less likely to be accurate, especially over short timer periods.
I agree that these current reports aren't going to be too accurate. Just a bit of a novelty to see how we all compare and what may be affecting the reading.
The report does allow you to select "Completed Charges Greater Or Equal To", so if you have range charges (say over 95%, or only 100%) over a longer period of time you may actually be able to see true battery degradation.
I'll probably do my first 100% charge this weekend, so it will be interesting to see if that has an affect.
No software or BMS updates around that time. The only thing significant was it was near 100F for a couple of days there.
I’ve charged to 100% twice since the drop, with no change in max range.
Ulmo
Active Member
Are you sure about that part? I thought deep swings caused stress. I am not a chemist!
It's not charging to 100% (or draining to relatively low SoC) that's bad. It's extended periods at or near 100% or very low %. The general advice is to set max charge to 90% (or 80%, or whatever meets your needs) most of the time, but you shouldn't fear charging to 100 as needed. Just try to time it so you finish that charge shortly before you are ready to hit the road.
Don’t take the range numbers as if they were holy writ. They may change around with version changes, battery temp and myriad other happenings. My S75 originally was supposed to be 249 miles. It never showed more than 247, and now 238 at 100%. However I often drive 4-5 miles before the reading starts dropping. A trip of 190 miles I make routinely still ends showing the same miles left as when the car was new. You only need to worry if the car suddenly starts dropping serious miles as that may indicate a battery problem.
The Teslafi battery report provides some extrapolated estimate of 100% capacity for each charge, even if you didn't charge to 100%.
Whether that extrapolation is accurate is unclear, hence the report allows you to exclude, say, any charges completed below 80% (or whatever threshold you choose.)
insaneoctane
Well-Known Member
For non-Teslafi folks using the API, does anyone know which attributes you would use to calculate this battery degradation?
Although I do not use TeslaFi, I have noticed my battery degraded about 1-2 miles (correlates to about 0.33-0.66% loss). I noticed this whenever I Supercharge to 80%. Normally at 248 miles, it's now showing 246 or 247 miles at 80%. This is at about 500 miles for Model 3 Performance, and some fun launches. Avg. lifetime Wh/mi is low 300s.
Stretch2727
Engineer and Car Nut
I am recently seeing only 203 miles with a 70% charge. 290 Mile equivalent 100% charge range. I think it occurred after a recent software update. I am on 2018.36.2. I am going to deep cycle the battery one time to see what happens. Anyone see something similar as it very quickly lost 20 miles range:-(. It was not slow degradation. One day charging to 219 miles, the next only 202 with my daily charge limit. Same for about a week now.
Stretch2727
Engineer and Car Nut
You are seeing approx what I am seeing. A step function degradation to the low 290's range.
Quick Update:
Did a 100% charge that showed 307 miles range. Shortly after a 80% showed 308 blip on the graph before settling back to 306. Then the latest software update 2018.36.2 brought it down to 301.
Stretch2727
Engineer and Car Nut
Thanks, this makes me think it is just the software (2018.36.2).
I did a deep cycle from 20% to 100% and the stated range is now 300 miles, close to what you are seeing. I will relax for now and try not to look at it too much
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