I'm confused by the question-reponse-thanks about how often one should balance the pack. No recommendations from Tesla that one should do it at all (if anything, conflicting advice from them to not max charge unless needed). Folks seem to do it to see what absolute max they can squeeze out of the battery, to try to determine whether it appears they've had capacity degradation, etc. Not to help the battery itself.
So unless one wants a few extra miles for a dicey trip, isn't the real answer "don't bother/not needed"? I meant it's not like max charging is good for/helps/is recommended for the battery, right? (Even if it's okay as long as it's not left at 100%.) Have I missed somewhere here (or elsewhere) where someone provided a scientific explanation of why it's best for the battery to balance it regularly?
Sorry, a lot of interesting stuff in this thread, but some of it makes my eyes glaze over, so I may have missed something.
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Beyond a general impression that Tesla's made changes since the Roadster, there are references to storage mode in what Jerry quoted, and your question about CAC, that contribute to my thought that I can't just read Roadster threads and apply it all to my car. Throw in Supercharging and battery pack revisions, and the impression the battery management systems aren't quite the same, and it really seems like . . . well, not apples and oranges, but maybe oranges and tangerines. ;-)
People periodically quote non-Tesla Lithium Ion battery reports and recommendations, and others point out that Tesla's batteries and/or management system make report X or recommendation Y not apply to the Model S. I know that's not Roadster versus Model S, that's Model S versus non-Tesla/non-car (sometimes). But it also contributes to my impression that I can't just read things about something other than the Model S and apply it to my Model S.
But I can see why it seems like folks are reinventing the wheel (er, battery) from where you sit.
(I can barely keep up with Model S threads; I can't imagine also trying to keep up with Roadster ones, sorry! ;-) )
For me, Balancing is regularally, as I range charge often. In my opinion, i'd say Monthly with Lithium.
Having a balanced pack is important for longevity as well. In a out of balance pack, the lower voltage cells are getting cycled deeper then the higher voltage cells, causing them to go to a lower state of charge.
I have found this website, which explains it fairly well. Would like to copy and paste it here, but it's better to link and give them credit.
http://mpoweruk.com/balancing.htm
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I have a real hard time with the 209 after 20,000 miles. My model S is a 40 pack with 6000 miles and about 8 months old. I have a kwh/miles of 300. I drove the S to 9 miles then went for a full charge. I lost 1 mile in rated charge from 129 rated to 128. I live in southern CA with the car in the garage, so temp is not a factor, nor are my driving habits since 300 ave kwh/per mile. The problem as I see it is that Tesla is MUTE on the subject. My service center talks about the weather, driving habits. Tesla pulled my records and stated no problems. They would not give me a degraded rate that they would state would be a problem. Maybe when I can't back out of the garage. UNHAPPY Tesla owner. Fred
If you have a hard time believing me, can always watch my youtube video showing my range going up. This one doesn't show the 209, but it shows the 208. https://www.youtube.com/watch?v=d0NQpqjEJRw
And you can always call the desk at Highland Park service center where we were watching it tick up to 209
As for only loosing 1 mile after driving 9 miles, seems without doing a full depth discharge and a max 100% charge (which your unable to do), The car is having some trouble calculating the total energy capacity of the pack.
I have also seen little impact of driving style to rated range. No matter how many Wh/Mile I consume, my car is always calculating rated based on 300Wh/Mile (I believe it was 290 on firmware 4.5 for me). Right now, as of yesterday, I hit 340Wh/Mile. made absolutely no difference.
Now, their are 3 calculations, car only shows 2. a nice application is Visual Tesla, written by one of the board members here. It will show you the Ideal Mileage, the Rated Mileage, and then the Estimated Mileage. Now, it is the ESTIMATED miles that is based on your actual driving habits. To give you a example, it is -8*F right now. At a 90% charge, my car is reporting 155 Rated Miles, 180 Ideal, but my Estimated, based on my Wh/Mile, is 88.7 (that is, if I continue to consume the same per mile as I did on my last charge. This number varies wildly, and can only be seen by the Visual Tesla app, not on the car or via the Tesla phone app)
Back to your comments (I get off track easily), you have not lost range, the car needs to recalculate the battery capacity.
The only way I can think of that will allow one of the software limited 40's to balance and help the car recalculate the capacity, is to drain it low, to say 5-10 miles rated, then charge at the slowest pace, which would be a 120v outlet, at 5amps. This will take a very very long time, so I'd say do that when you wont be needing the car for a few days (Vacation) or charge it at 12amp 120v up to it's allowed capacity. Thats all I can think of if the service center wont temporally unlock it to let it balance.
If you call Tesla phone support, and request a Engineer looks at your car logs, they can log into your vehicle, and see what the actual capacity loss of your pack is in a %. If you do have loss, it will most likely be in a fraction of a percent. 0.001%, something very low. When they checked mine when I "thought" I was having problems after the firmware 5.6 update (I was having problems, the firmware caused my vampire losses to more then double, 5.8 fixed that), they said my potential loss was about 0.008%, almost not calculable
What I'd like to see is a option on the charge screen, that we could select that would force battery balancing at any charge %. I'd like to see it lock the car out from being driven until complete (shouldn't take more then a half hour with a lithium pack) so i'd be like the firmware updates do.
