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Optimal charging if you don't drive a lot

Discussion in 'Model S: Battery & Charging' started by Oz88, Jan 17, 2015.

  1. Oz88

    Oz88 New Member

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    Jan 17, 2015
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    Location:
    Hong Kong
    I live in the city and take public transportation to work, so M-F I am only driving it a few miles each day after work. On the weekends it gets more. It seems silly to charge it each day if I am only driving 5-10 miles but the Owners Manual says to charge after each use. Any thoughts? Obviously I don't want to harm the battery if I can help it.
     
  2. invisik

    invisik Member

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    Location:
    Minneapolis
    I'd set your charging limit to 50% and schedule it to charge once a day. Other things happen while charging behind the scenes, so it's still good to charge and keeps the car happy.

    -m
     
  3. Alysashley79

    Alysashley79 Member

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    Seattle, WA
    unless they changed something in 6.1...it doesn't turn on to charge every day even if you have the scheduler set. It waits until the battery loses x% before it turns on again. (I believe 2.5%) and if you have a scheduled charge it won't turn on again until the next scheduled charge after dropping below x%.

    Tesla has gone on record by saying a happy tesla is a plugged in tesla. So if recommend leaving it plugged in when not in use...and only charge up to what you use.
     
  4. invisik

    invisik Member

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    Fair enough... if not enough charge has been used for it to recharge it, then let it do it when it needs to.. I agree, as long as it's plugged in and scheduled, let it do what it wants. :)

    -m
     
  5. Oz88

    Oz88 New Member

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    Location:
    Hong Kong
    Thanks for your comments. What is not clear to me is how having a scheduled charge helps me. If I set it at 50% and drive 10 miles that day and plug it in hat night, won't it simply re-charge back up to 50%--charging back up what I use--and then automatically stop charging? If so what is the benefit of a scheduled charge (I don't have off peak rates where I live).

    Also, can someone explain how in my circumstances it benefits the battery to only charge up to 50%, as opposed to 70% or 90%?
     
  6. Panu

    Panu Member

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    My understanding is that scheduled charging is important if you charge it close to full because it is not good for the battery to keep it full. If you charge it to 50% I think that could be done immediately.

    The lower the battery is charged the longer it will live. Using the battery to near 0% is also harmful I believe.
     
  7. Firewired

    Firewired Member

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    San Antonio, Texas
    Worst is to remain at 100% charge for long periods, particularly when warm. That leads to a higher risk of parasitic loss within the battery.
     
  8. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    When not in use, 50% is where the smallest amount of degradation occurs. When driving more degradation occurs when the SOC is below 50%. However, there is less difference between 90% and 50% than between 100% and 90%.

    The timer helps because you are at the lower charge level for longer during any 24 hour period. Example:

    Charge to 210, dDrive 50 in the morning, sit nine hours at 160, then drive 50 in the evening sit until 02:00 at 110, is better than sitting from when the charge finishes in the evening to the next morning at 210. Charging during the wee hours also helps your neighbourhood transformer and charges on base load which is often wind and nuclear rather than coal and NG.
     
  9. gglockner

    gglockner Member

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    I'm an IE, not an EE, but after reading a bit about the issue, I decided to charge our 85 to 70% during the winter and 60% during the summer. I don't bother with scheduled charges during the winter, but I'm a good citizen and charge at night during the summer. I charge to a greater level if I have a longer trip planned, of course. HTH.
     
  10. simonog

    simonog Member

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    United Kingdom
    Scheduled charging is most useful if you have a supply agreement for your power which has differential rates depending on time of day. Cheaper night time power (where the definition of night varies by supplier) is common.

    If you have such a scheme, use scheduled charging.

    Otherwise plugging in and letting your car trickle itself when it wants to is wisest. The software is really good and as long as you keep the battery between about 20% and 80 to 90% the degradation of the battery due to chemistry should be minimal.

    There is no downside to leaving the car plugged in!

    It is recommended only to charge to above 90% when you are going to need the range our next outing. Try to minimise the time the car sits at full or very low charge so perfection if you need a full charge is to drive away very soon after it completes.
     

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