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Please correct my views on Model S charging if wrong.

Discussion in 'Model S: Battery & Charging' started by darker123, Oct 14, 2016.

  1. darker123

    darker123 Member

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    Hi to all I'm a recent owner of Model S 75D. Due to me livinyg in an apartment building and having absolutely no charging facility (yes even 120v) I'm forced to top off my car once a week. I do not any weekly work commutes it is a weekend car.
    I been reading this forum a lot prior to my purchase and very familiar with terminology that you shouldn't change a car past 90% and "plugged tesla is a happy tesla."
    Due to charging situation I keep my tesla with: Range Mode ON, Power Saver ON, Always connected OFF. Smart preconditioning off. With 50F-60F outside I loose 0 Rated Miles per 24hr the car sits.

    I believe that people got a concept wrong when it comes to chargin. When I got to supercharger once a week I do charge it up to 250miles out of 259.. Which is close to 97%
    However what most people do realize it is harmful for battery to sit at that charge, it is not harmful if it is immediately driven off like in my case. By the time I get back home I have 223miles left which is below 90%
    I honestly believe that daily battery cycling that majority people are doing are more harmful than 1 a week charge at supercharger.
    When it comes to battery lifespan the more cycles you put on it, the higher the degradation. Therefore less cycles = less degradation even if they are above and immediately driven off 90%

    So people in a know correct my views if I'm wrong...
     
  2. habanero69

    habanero69 I Dont Need Cialis. I Drive an EV.

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    I'm not a battery expert, but pretty informed. Your logic is basically fine. However, you will probably be met with others on the far sides of the argument. Some don't give a crap and do what they want, while others are hard fast on doing the 90%, etc., etc.

    What sucks is that you have zero at home charge capability. I would not have done that even though I have a large, relatively lightly used SC 3 miles from my house. I commend your patience and ability to enjoy your car even in spite of that challenge.
     
  3. jelloslug

    jelloslug Member

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    Tesla will tell you to charge to 90%. The real thing that can damage the battery is leaving it at a very low state of charge (below 5%) for extended periods of time. Personally, I don't think you are doing anything very detrimental to the battery.
     
  4. Boourns

    Boourns Member

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    Also not an expert, but my understanding is mostly the same. It's bad to leave the car sitting at very high or very low states of charge. If it sits between 90 and 10, I wouldn't worry about it.
     
  5. Boatguy

    Boatguy Member

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    OK, you're wrong. If you read the literature, you'll find that a battery cycle is one complete discharge/charge cycle. Reading further you'll find that 2 cycles that discharge to 50%, and then back to 100% equals 1 full discharge/charge cycle.

    So there is no difference between discharging and charging 10% each day of the week, and your practice of discharging 70% each week, and then charging back up. From a battery perspective it's the same number of cycles.

    In practice, your car will have less cycles because you're not driving it very much, thus not discharging and charging very much.

    Enjoy your new car!
     
    • Like x 1
  6. OlavA

    OlavA Member

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    The 90% charge marker kicks in a battery charge balancing algorithm so the frequent charges allows the car to distribute the chaging amoungst the thousands of cells and packs.

    There's a great thread that articulates the concepts very clearly regarding the charging sequence.
     
  7. Saghost

    Saghost Active Member

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    Without being more specific about the daily cycling, it's hard to tell if you're right.

    If the daily cycling people are going from 80-90% every day, you're probably right.

    If they're going from 70-80 or 60-70%, you're probably wrong.

    Anything that takes the battery near either end is harder on the battery, especially over 90% and under 10% (remember that the point the displays call 0% is actually more like 5% of the nameplate capacity - the car won't let you use that last bit for safety.)

    I don't think what you're doing is particularly bad for the car - it's only the comparison attempt that trips me up.
     
  8. abasile

    abasile Independent Software Eng.

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    While your situation would not be cause for any real concern and it sounds like you're able to make this arrangement work, I do have one comment to add.

    With Li-ion batteries, not all charge cycles are equal. Shallower cycling of a battery, i.e., between 30% and 80%, generally helps to extend its lifetime compared to, say, cycles between 5% and 95%. The net result is less battery capacity loss over the long haul. So one should expect that more frequent, shallower charging at home would be a bit more ideal. If I were in your situation, I'd consider stopping each weekly charge at 90% rather than closer to full, but only if this works for you, and I wouldn't stress over it. Overall, Tesla batteries have proven to hold up quite well over time.
     
  9. WannabeOwner

    WannabeOwner Member

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    There's another thread on here somewhere about a Taxi that was charged to 100% every day (although, presumably, then immediately driven) and lost (from memory) 6% of charge after 200,000 miles. Dunno how low the charge got during each day, but I presume "quite low" as it must have done quite a lot miles each day.

    So I reckon your strategy is fine, and even if not the difference in loss-of-charge after a couple of years between optimal and slightly sub-optimal is probably not going to be something you can measure.
     
  10. Hash Browns

    Hash Browns Member

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    The original poster is correct that time spent at 100% state of charge is a driver for battery degradation. Consuming energy right after charging to 100% is better for degradation than leaving the car sitting at 100%.

    However, recommend you give further consideration to your choice to leave the car in Range Mode.

    The Model S owners manual says: "To automatically limit the amount of power that the climate control system uses to maintain the temperature of the battery and cabin area, touch Controls > Driving > Range Mode > On"

    This can be interpreted to mean that Range Mode sets a higher average battery temperature threshold before battery cooling engages, which would allow more energy to be used to push the car down the road. However, if used all the time it could mean the battery spends more time at higher temperatures, which is as much a driver of battery degradation as state of charge. In fact, this interpretation is partly how Range Mode operated in the Roadster.

    I'd encourage you to use Range Mode only when it's really needed, and do as much further investigation into a home charging solution as you can. It's a drag to refuel once a week, and of course, there is much discussion over the topic of local Supercharging.
     
  11. WannabeOwner

    WannabeOwner Member

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    Range Mode makes my ears ring, so I only use it on journeys where range is critical,m and I turn it off the moment I am sure I have enough power to reach my destination (unless I want to arrive with maximum energy to save some recharge time). The saving provided by Range mode is pretty small
     
  12. Ashkenaz

    Ashkenaz Member

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    How does it make your ears ring?
     
  13. Ashkenaz

    Ashkenaz Member

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    So range mode is bad for car? How does that affect battery heat? I thought that was cabin temp control.
     
  14. davewill

    davewill Member

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    I think your approach may be better than only charging to 90%, and therefore having the car go to a lower SOC. I also would value my convenience in having more range available over other considerations, anyway. Of course, I would also be looking to move somewhere that I could have at home charging ASAP!
     
  15. Saghost

    Saghost Active Member

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    Range mode changes a bunch of parameters. It does reduce the power available for cabin heat and cooling.

    It also allows the battery to run at higher temperatures (to waste less energy cooling the battery,) and causes the car to heat the battery less in the cold, among other things.
     
  16. rhumbliner

    rhumbliner Member

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    This is the article you're referring to: Tales from a Tesla Model S at 200k miles
     
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  17. bob_p

    bob_p Member

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    Note that Tesla advertises the supercharging network is for "free long distance travel".

    Doing local charging - up to 90% or higher takes considerably longer than the long distance charging that may only need 80% charge (or less) to get to the next charger or destination.

    If there is any contention for a supercharger, it's better to stay at 90% or less, and let someone else have the charger. It takes much longer to get that extra 7% of charge - time someone else could be using the charger.

    Anyone considering purchase of a Tesla should also look for local charging options other than using a supercharger. Especially as the number of Tesla cars increases significantly when the Model 3 goes into production, it seems very likely Tesla will do something about owners using superchargers for local charging.
     
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  18. WannabeOwner

    WannabeOwner Member

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    Range Mode (on a D) uses Torque Sleep. I don't know the ins-and-outs of that, but I would normally be using Range Mode on a long highway journey at a constant 70 MPH and my understanding is that Range Mode uses the smaller front motor, which is more efficient at that speed, and that's the whine that I hear. Its most noticeable when i turn range mode off and my ears are instantly relieved, I tend not to notice it when I start out, but i become aware of it during the journey. That said, I don't think my wife has ever commented on it, so maybe it doesn't bother everyone.
     
  19. Acrono

    Acrono Member

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    I'm in a similar situation as you: no home charging because I live in an apartment complex that has absolutely zero wiring in the parking garage (not even NEMA 5-15), but I live less than a mile away from a supercharger. I charge once every 4 to 5 days, and I use my car daily for a short commute to the office (no chargers there either). The one difference is that I set my charge limit to 85% and have never dropped below 25%.
     

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