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Model 3 Performance Battery Degradation One Month (Story)
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Eno Deb
Active Member
These are literal quotes copied from a statement Jerome Guilen made in 2014 regarding the range estimator in the early Model S cars:
A Senior Tesla Executive's Comforting Answer to Concerns Re: "Loss of Range" | Tesla
gzerninplatz
Member
Well...maybe the Model 3 is a new problem for them in this area...but it is rather disconcerting to see that answer played back 4 years later...
So, it's a Battle of The Tesla Technicians . . . . . The "senior" technician I spoke with insisted that Rated Range does not take into account driving habits/history, at all. He pointed to the Energy app and told me that's where I should go, if I wanted to see how recent driving habits were affecting my range (the 5/15/30 miles history options). He also pointed out that the Rated Range indication on the Energy Chart is there specifically so you can compare your range based on the past 5/15/30 miles of driving habits, to the rated range which is a constant and not based on driving habits.
Sorta the Wild West out there, with these technicians it seems. I wish they'd just be educated consistently on what it really is, so owners wouldn't have to spend time getting at the truth. . . .
Assuming I've actually lost some capacity, which I probably have sitting at 6,500 miles driven, a 70% charge gives me right around 210 miles. I use around 35 miles a day for commute/errands. That leaves *plenty* for unexpected events. Not really sure I need to go to 90% for much more unexpectedness. If I can live with the more inaccurate range estimate, and still have plenty for unexpected emergencies, and I can eke out some more life/extended capacity on the battery long term, I'm not seeing any downsides to a consistent 70% charging regime.
Bottom line, when you start with 310 miles range, and after the expected 5% degradation, 70% SOC gives you plenty of "emergency" range. As I'm sure you know, a lot of the mid/lower battery capacity S's get around 250 brand new (see, eg, a 75), which after a year and 5% degradation brings that to 238-ish, which at 90% SOC is 215, give or take. The 60kw S's are of course even lower than this. So, at 70% SOC, my 3 has as much "emergency" range as a similarly aged mid/lower capacity Model S charged to 90%. I think I'm good at 70%.
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I feel the same way since all my local drives usually are in the same range as what you describe. I still follow the advice of the tech I spoke with and so far I like the results. I quit charging daily to 70% on a scheduled charge but I still plug in at the end of the day so I can preheat the car on line power if needed or if I decide I need more range the next day I can start the charge from the app. When I plug in, I just stop the charge right away since I took it off a scheduled charge. When my range gets below 100 miles, I will start a charge after the 10pm TOU rate for that evening and let it charge back up to 70%. That shows a range of 216-217 miles just like it did when the car was new. I know the issue is software and I am fine with that but I do like to see the range display an extrapolated 310ish and it does consistently since I have been following that routine. I also started turning off my Bluetooth on my phone when I'm home since I think it was constantly waking or keeping the car somewhat awake while moving about my home as I could see it connect and disconnect depending where in the house I had the phone. I have got in the habit now of just turning it back on when I go out to the car to leave which isn't much different than remembering to grab the key fob of any other car since I don't use Bluetooth for any other device while I'm at home. So far so good.
Many service techs don't know as much about the car as you think they might-- almost as bad as the salespeople. Just because someone is trained to run diagnostics and replace defective parts doesn't mean he would necessarily know how the displayed range is calculated.
I'm tempted to try this (keeping it plugged in every night, but just not activating charging until it goes below 100 miles), but I'm concerned about my tendency to forget non-routine crucial stuff like remembering on those particular days to actually charge it up. Like with the new Dashcam feature - where you have to actually turn the camera off every. single. time. you get out of the car - invariably, I forget to do this one time, and it corrupts the usb drive, and I have to re-do the thumb drive on a computer. What a hassle, renders it in all practicality useless for me long term, until this is fixed.
The problem is me, I know - I do better with establishing a regular routine (like charging every single night), than trying to remember when I need to charge, and then invariably forgetting one time (not often, but occasionally forgetting), and leaving me with severely diminished range, where it's likely to occur, under Murphy's law, exactly on the one unusual day I really do need 200-plus miles range.
I guess the one saving grace is you do plug it in every night, but you just don't set it to charge always, so that routine of at least still plugging it in might help prompt me to consider whether it needs to be charged that night. . . . . .
VLTWGGN
Member
Yeah, as of this last weekend I noticed a significant "degradation" in the rated range. An 84% charge gets me 239mi of rate range...well short of the 260 I was expecting (about 9% drop). I'll keep monitoring it, but the car only has 2500mi and is about 3mo old. If it gets any worse I'll have a word with my SC.
Just got back from SC. They did a diagnostic check on the battery and indicated all was fine. The customer service guy indicated the technician's viewpoint was the lower implied range when charged was due to my driving habits and that if I drove more conservatively, my range would increase. I didn't argue with him, although everything points to this being inaccurate.
I'm going to continue charging to 90% to see if the imputed range improves.
I'm going to continue charging to 90% to see if the imputed range improves.
gzerninplatz
Member
Funny - the suggestion in the last line in the recent message from Tesla Executive Care, re Service being able to do "a kind of recalibration", is unknown to Service here in Portland. And that recommendation isn't in the original Jerome Guillen version of the message...so either it is so new that local folks don't know about it, or it is imaginary...
Tesla's battery expert, Jeff Dahn, disagrees with your assertion that smaller, more frequent charges are better than fewer larger charges. He basically said that charging from 70 to 80 five times has the same wear effect as charging from 30 to 80 once. It is the number of cycles x energy that matters. In fact, he recommends keeping the battery at 70 SOC or less for maximum battery life.
The Techs are not battery experts in the same way that chemical engineers are. If you want to know what Tesla's battery expert says, google "Jeff Dahn tesla Battery" tons of results..
phigment
Member
Lots of info here: Jeff Dahn's recommendation on long term battery preservation
and here: Charging strategy for battery longevity
Generally googling "Jeff Dahn Tesla" yields tons of results.
Keep in mind, many of the comments are just posters opinion. Jeff says total charge amount is what matters, not number of cycles. I don't have the exact article handy, as there are so many of them.
L
Let me also add I am not suggesting DEEP discharge has no consequence. It does, But 80 down to 30 and then back to 80 is fine from what I have read, and is equal to 5 10Kwh discharges and recharges.
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