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Will "short charges" (i.e. 15-20-30 minutes) have a negative affect on battery life?

Discussion in 'Model S: Battery & Charging' started by passion4audio, Nov 12, 2013.

  1. passion4audio

    passion4audio member

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    Will the Tesla batteries exhibit the dreaded "battery memory effect" if the owner puts in short charges?
     
  2. Stoneymonster

    Stoneymonster Active Member

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    Lithium ion batteries don't suffer from a memory effect. The old NiCad and to a lesser extent, NiMH did.
     
  3. strider

    strider Active Member

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    No, but it is a good idea to periodically (every few hundred miles) charge the car fully (90% "standard" charge is fine) and then let the car sit for at least an hour before driving to allow the pack to balance.
     
  4. ACDriveMotor

    ACDriveMotor Member

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    Anything wrong with living in the 70 - 90% zone? I've heard that the big killers from Li-Ion are time at 100% SOC and number of deep discharge cycles. I am trying to figure out whether to live in the 30-50% range most of the time and take it higher when needed or just keep in the 70 - 90% range.
     
  5. bob_p

    bob_p Member

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    The Model S battery pack design is unique because it has over 7000 smaller batteries. The instructions in the owners manual are very simple - leave plugged in whenever possible - don't use the 100% charge very often & only when needed - and avoid allowing the battery to fully discharge.

    There are enough Model S on the road now, some with over 20,000 miles - and some for over a year - and if there were many owners with major problems with battery performance due to charging practices, we probably would be seeing comments showing up on the forums by now.

    Until Tesla changes their official, written, guidance for charging practices (either on the touchscreen display or the owner's manual) - then follow their written recommendations - and don't worry about it...

    Keep it simple...
     
  6. Stoneymonster

    Stoneymonster Active Member

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    Staying in that range (70-90%) is probably so near to optimal you'll never know the difference.
     
  7. TokyoRush

    TokyoRush Member

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    I agree on following the basic Tesla instructions. Keep plugged in when possible and charge to 80%. After 21K miles we have seen no reduction of range at all.

    Jason
     
  8. stopcrazypp

    stopcrazypp Well-Known Member

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    I wouldn't say that's a good idea for long term life. It's just if you are the type to stress over the stated range of your battery, it'll ease your concerns by showing higher numbers.
     
  9. strider

    strider Active Member

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    An out of balance pack will degrade faster than a balanced one as the out of balance cells will be charged higher and/or discharged lower than the rest resulting in faster degradation of those cells which further limits the pack capacity. You can only charge and discharge to the level of the weakest cells.

    We have been keeping data on Roadster packs and by far the biggest factor on degradation is miles driven, period. If you are going to let the car sit for long periods then yes it is best to keep it at 50% but if you're driving it daily the couple hours spent at 90% between when you finish overnight charging and when you drive to work in the morning just doesn't have any noticeable effect.

    My advice to the OP stands.
     
  10. David_Cary

    David_Cary Member

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    While 70-90% is not bad, I don't think it is in dispute that closest to 50% is ideal.

    You can still KISS - If you usually don't drive many miles per day then set the slider to 50% and live at 30-50%. Plug in all the time.

    Some people change oil every 3000 miles. Keeping your SOC down is a similar idea - except that it is free....

    The Model S battery may outlive the car but hopefully it will have a function even if the car is falling apart.
     
  11. mknox

    mknox Well-Known Member

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    During the summer months, I was charging to 70% and returning at the end of each day at about 35 to 40%. I felt playing in this range was probably the easiest on the battery. With the onset of cold weather, and my playing around a bit with Range vs. Standard Mode on the HVAC, I've been charging to 80 or 90% again because the cold weather is using a fair bit more energy. Not exactly "range anxiety", but I do start to notice it when I get down to 20% or so SOC by the end of the day.
     
  12. stopcrazypp

    stopcrazypp Well-Known Member

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    I don't think the damage from regularly charging all cells to 90% is less than leaving it out of balance at 50% or so. Yes, the out of balance cells will be stressed slightly more, but it's still at relatively low SOC (so not overly stressed).
     
  13. brianman

    brianman Burrito Founder

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    These two statements seem to be in conflict. Can someone speak to whether (and under what conditions) balancing will happen at 50% SOC?
     
  14. ACDriveMotor

    ACDriveMotor Member

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    Exactly. This is a better expression of my basic question. I drive ~30 - 60 miles/day most days. I've been standard charging at night. So my battery lives in the 75 - 90 zone. Trying to calculate whether I charge to 50% on weekdays and 90% on weekends (more driving on weekends) is better or worse overall for the battery condition.
     
  15. djp

    djp Roadster 2.0 VIN939

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    Yes, 50% on weekdays and 90% on weekends is better for the pack than keeping it at 90%. You'll have a lower average SOC but still have a chance to balance on weekends.
     
  16. strider

    strider Active Member

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    I agree /w this. But this is only for OCD nerds who want to mess w/ their charge settings every day. If you drive your car every day leave it at 90% and just drive it. If you're going to store it for days/weeks/months put it at 50%. If you want to minimize time at 90% just set your charge timer to start charging later so it finishes closer to when you plan to leave.
     
  17. ACDriveMotor

    ACDriveMotor Member

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    Yes. I've been building confidence towards scheduling a 3AM charge start time. That would cover me and reduce the hours at 90%.

    I would still like more information on balancing. Does that only happen at 90% or above?
     
  18. qwk

    qwk Model S P2681

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    On the Roadster it was 80% and above. I would bet that the Model S is similar.
     
  19. Trnsl8r

    Trnsl8r Blue 85kwh since 12/8/12

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    Related: So if I go on vacation and the car sits for two weeks, what's the ideal percentage?
     
  20. djp

    djp Roadster 2.0 VIN939

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    Keep the car plugged in at a 50% max SOC. This is the closest the Model S comes to a "storage" mode.
     

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