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Charging question

Discussion in 'Model S' started by Grisik, Mar 26, 2015.

  1. Grisik

    Grisik Member

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    Had my S85 for a week now. When I was setting up the charge schedule it shows charge limit of daily and trips. Is there any reason I should not charge the car to 100%? I am charging at night while I sleep.
     
  2. LucM

    LucM Member

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    Yes, it is not healthy to charge the battery to 100% very often. If you are going on a long trip and need the miles, then by all means. Just don't let it sit at 100% for a long time before you use the car. Otherwise, charge it to 80%, that seems to be the consensus.
     
  3. mknox

    mknox Well-Known Member

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    If you regularly charge to less than 90%, you may appear to lose range when you go back and do a 90 or 100% charge. I think the jury is still out as to why, but some leading theories are that the cells in the battery back get out of balance and/or the car needs to "see" several high to low state of charge cycles to properly calibrate itself.
     
  4. TexasEV

    TexasEV Active Member

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    I think 90% is more common, that's the top end of the daily range on the charging screen.
     
  5. CHG-ON

    CHG-ON Still in love after all these miles

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    I have a question: I understand the concept of battery balancing. But I have no idea what I am supposed to do, or allow the car to do, in order to get them balanced. Is it as simple as leaving her plugged in? I charge to 80% almost always and usually leave her plugged in unless I happen to forget.

    Thanks!
     
  6. mike-415

    mike-415 Member

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    Does Tesla have an official recommendation?
     
  7. mknox

    mknox Well-Known Member

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    Nope, not as far as I know. I've asked my Service Center about this and their response is to just use the car and not worry about it (I'm paraphrasing a bit). They did do a battery diagnostic and simply told me my battery is "fine". In my case, everything is working fine except that I lost about 27 Rated Miles of range at 90% after a summer of charging to 70% daily.

    There is lots of speculation and anecdotal evidence of how balancing and deep discharge/charge cycles work here on the forums, but to your specific question of an official Tesla recommendation, the answer seems to be "no".
     
  8. caddieo

    caddieo Member

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    Frequent or constant charging to 100% shortens battery life. Figure out your average daily mileage, add a buffer (say 80 miles or so) and set your slider limit accordingly. In my case, my average daily mileage is 40 (+/- 10) and my slider limit is set to 155-160, the amps to 20 and charging start to 0015 hrs. If it looks like the next day will have some longer drives, then I just adjust the limit slider accordingly before saying good night to the car and maybe up the amps if needed.
     
  9. RAW84

    RAW84 Member

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    When I took delivery, my delivery specialist told me I should only charge to around 90%, and to only charge to 100% when I knew I was going on a trip. Now given the track record Tesla has of different Service Centers telling people different things, I would not count that as an "official" stance, however they did put "daily" and "trip" on the screen where you set the charge limit, I think it holds some weight that they don't recommend you charging to 100% regularly
     
  10. JimmyAZ

    JimmyAZ Member

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    There is circuitry built into the lipo packs, and complete cell, that balances them automatically. I use lipos for radio controlled planes and we have the same circuits built into ours. If I have a 3-cell lipo that is charging, one cell may reach let's say 85% at the same time the other two are at 80%. The balancing circuit will drain the high battery until it's balanced with the other two. As charging continues, the balancer will drain from each pack as needed to keep the series in balance with each other until they're all completely charged.

    One of my balancers has LEDs that light up for each cell that is being balanced. It's very interesting to watch. Quite a lot goes into these cells to 'safely' bring them to peak charges.

    I hope that explanation helps. And no, I definitely haven't seen inside the Tesla packs, but lipo technology should be the same across the industry for the same chemistry.
     
  11. CHG-ON

    CHG-ON Still in love after all these miles

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    Thanks! Awesome explanation. So I will just the car do its own thing and not worry about it. Heck, it's warranteed for 8 years.

     

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