TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker and becoming a Supporting Member. For more info: Support TMC

Ok to routinely charge from 45-50% SOC to 57% SOC

Discussion in 'Model S: Battery & Charging' started by mmanner, Jun 19, 2017.

  1. SageBrush

    SageBrush 2018: Drain the Sewer

    Joined:
    May 7, 2015
    Messages:
    7,523
    Location:
    New Mexico
    Sure ... but that was not really the point @David99 was making. Charge SoC is only one variable in the battery degradation story. To continue your analogy for physicians, consider cholesterol: as a single agent it cannot be shown to have much atherogenic effect unless the person also consumes a high saturated fat diet. Since your wider context cannot be assumed for others (in fact, one is on pretty firm ground in presuming the reverse,) your experience cannot be extrapolated to others with much confidence.
     
  2. TexasEV

    TexasEV Well-Known Member

    Joined:
    Jun 5, 2013
    Messages:
    7,512
    Location:
    Austin, TX
    I'm not saying my experience should be extrapolated to others. I'm saying no one has shown data that routine charging to 50% has a meaningful difference in Model S range after a few years compared to 90%. If someone has that data, please provide it. By meaningful I mean more than a few miles. If a few miles after many years is going to make a difference for someone then they bought the wrong battery size.
     
    • Like x 1
  3. mal_tsla

    mal_tsla Member

    Joined:
    Sep 29, 2016
    Messages:
    571
    Location:
    Austin, TX
    Tesla actually explains why 90% is magic:

    "There is a huge difference in cycle life between a 4.2V/cell charge (defined by the manufacturers as “fully charged”) and a 4.15V/cell charge. 4.15 volts represents a charge of about 95 percent. For this reduction of initial capacity (5 percent), the batteries last a whole lot longer. Unfortunately, further reduction of charge has a much smaller benefit on cycle life. Understanding this tradeoff, Tesla Motors has decided to limit the maximum charge of its cells to 4.15 volts, taking an initial 5 percent range hit to maximize lifetime of the pack."
     
  4. Mediocrates

    Mediocrates Member

    Joined:
    Apr 16, 2017
    Messages:
    274
    Location:
    San Diego, CA
    I would recommend not using that category of analogy. It will confuse those who have knowledge of how the lipoprotein system (what you probably meant by "cholesterol") interacts with diet and atherosclerosis.
     
  5. David99

    David99 Active Member

    Joined:
    Jan 31, 2014
    Messages:
    4,142
    Location:
    Brea, Orange County
    There is plenty of data from many studies and all of them show that charging to 50% is better for battery life and charging to 90%. I'm not sure why you say there would not be any data. It's one of the most consistent finding of any study exploring the life of Lithium batteries.

    As for a few miles make no difference, that's beside the point. A small difference is still a difference and gets bigger the longer the car is used. The oldest cars are just 4 years old. If there is no disadvantage charging to only 50% why would you recommend charging to 90% knowing well that it does degrade the battery faster.
     
    • Like x 2
  6. TexasEV

    TexasEV Well-Known Member

    Joined:
    Jun 5, 2013
    Messages:
    7,512
    Location:
    Austin, TX
    You're still using words like "better" and "degrade the battery faster" without quantifying it and without any evidence of practical impact on a Tesla's range, which is all anyone cares about when discussing this. People read this and become obsessed with caring for the battery and making life difficult with keeping a lower state of charge thinking it's necessary to protect their investment. Again, no one has shown any data that such behavior WITH A TESLA is doing anything other than treating themselves.

    If, for example, the car would lose 1% more range in ten years by routinely charging to 90% than 50%, yes the lower rate is "better" but that would have absolutely no practical effect on how the car can be used then (if the original owner even still has it). Is that worth owners obsessing over?
     
    • Like x 1
  7. Rocky_H

    Rocky_H Active Member

    Joined:
    Feb 19, 2015
    Messages:
    3,220
    Location:
    Boise, ID
    But you don't need to treat people like children who can't think for themselves either. If they really only drive 10 or 20 miles a day most days, then they're not hurting or inconveniencing themselves if they set it to 60% or whatever most of the time. It's very much like running the UMC at 40A or HPWC at 80A. Some people want to do that because it's officially rated for that, so it should be able to handle it, and tell people they should just do that and not obsess about it. Others say that they really have no need for the car to finish charging in 2 hours instead of 3 hours overnight, so there's no benefit to them running at full power, and they would rather save that little bit of stress on the equipment and maybe extend the life of it a little bit.
     
    • Like x 1
  8. SageBrush

    SageBrush 2018: Drain the Sewer

    Joined:
    May 7, 2015
    Messages:
    7,523
    Location:
    New Mexico
    I cannot remember where I saw the data, but a group of Tesla owners have been monitoring their range loss over time. The range seems to be as low as a couple percent over 4 years and as much as 10%.

    Since a priori an owner cannot probably guess with much confidence where they will fall on the curve, I understand the inclination to take practical steps to retard battery aging. I agree with you that a Tesla owner does not have to go crazy and lose sleep over the battery, and the car should be allowed to fulfill the tasks asked of it, but simple measures to protect the battery are a good investment.
     
    • Like x 1
  9. BGuz

    BGuz Member

    Joined:
    Jun 3, 2017
    Messages:
    18
    Location:
    91752
    Thanks for this info!
     
  10. SageBrush

    SageBrush 2018: Drain the Sewer

    Joined:
    May 7, 2015
    Messages:
    7,523
    Location:
    New Mexico
    I'm under the impression that every manufacturer recommends car storage at 50% SoC. This is not because storage is harder on the battery than daily use; it means that absent a good reason to charge higher, 50% is advised.
     
  11. David99

    David99 Active Member

    Joined:
    Jan 31, 2014
    Messages:
    4,142
    Location:
    Brea, Orange County
    No one is obsessed. The original questions was, is it OK to only charge to 50 or 60. And yes that's perfectly fine if you only drive a small amount of miles. There is no obsession nor making life difficult as you say. If I only need 10 miles for a day there is absolutely no point recommending to charge to 90%.

    Give people a little more credit. They can understand the facts and make their own decisions. I'm actually always recommending to charge to 100% on road trips whenever the time allows because the use of the car is more important than the tiny tiny amount of degradation that a high SoC causes in a short time. When it comes to what you do on a daily basis we are talking about a lot of time at a given SoC and it's fair to say, yes only charge as much as you need. That's all. No need to dramatize into one direction or the other.
     
    • Like x 2
  12. mmanner

    mmanner Member

    Joined:
    Feb 28, 2017
    Messages:
    21
    Location:
    Nashville
    The discussion of ideal SOC is interesting, and was triggered by my reference to routinely charging to a 57% level for SOC given my short distance routine use (I note that at that level, I still have about 2.5 times the total range I had with my LEAF!!!). The question that I was more interested in, that has I think been answered too, was whether there is any harm in plugging in daily when the amount of discharge for that day was only 2 or 3%. In other words, is it ok to charge each day that very small amount. I think the answer is yes, but if a couple of you could direct your replies to that specific case I would appreciate the advice.
    Thanks,
    Mark
     
  13. TexasEV

    TexasEV Well-Known Member

    Joined:
    Jun 5, 2013
    Messages:
    7,512
    Location:
    Austin, TX
    • Helpful x 1
  14. David99

    David99 Active Member

    Joined:
    Jan 31, 2014
    Messages:
    4,142
    Location:
    Brea, Orange County
    A well renown battery expert and Tesla consultant Jeff Dahn said that in terms of degradation it makes almost no difference whether you make many shallow cycles on the battery or less but deeper ones provided the total energy charged and discharged is the same. So it makes no difference to the battery if you charge only every few days or every day.

    Just to give you an idea how much degradation to expect: based on hundreds of Tesla owners providing data the degradation is really small on Tesla's batteries. I have 117k miles in 3 years and about 7% lost capacity. It went down from 271 to 249 miles range. I totally agree with TexasEV that a few percent are virtually meaningless considering it will not affect your daily driving at all. But we should also be fair and realize that battery degradation is not only lost range it is also lost efficiency (higher internal resistance in the cells) and it has slowed down my Supercharge rate by about 5-10% compared to when it was new. So there are other effects.
     
  15. SageBrush

    SageBrush 2018: Drain the Sewer

    Joined:
    May 7, 2015
    Messages:
    7,523
    Location:
    New Mexico
    I don't know the source data and methods for this particular statement from Dahn, but in prior articles I have read of his testing methods the temperature is tightly controlled. That is not case for current model Teslas.
     
  16. ReddyLeaf

    ReddyLeaf Member

    Joined:
    Mar 19, 2014
    Messages:
    854
    Location:
    Pasco, WA
    mmanner, I still have my Leaf and use it for all daily and in-town driving. The 70D sits at 50% SOC, plugged into 120V, anxiously awaiting its' next out-of-town experience. All that's required is to start charging a day before leaving. Superchargers in all directions are less than 140 mi. I don't worry about %SOC since the car is mostly "in storage mode." When traveling, I change the limit and charge to 80% mostly, but to 100% whenever it's warranted (overnight hotel or winter travel). Yes, I've received the dreaded "are you sure you want to charge to 100%" message. In less than two years I will have more miles on the 70D than 6 yo 2011 Leaf. My rated range is just 1 mi less than new.
     
    • Like x 2
  17. mmanner

    mmanner Member

    Joined:
    Feb 28, 2017
    Messages:
    21
    Location:
    Nashville
    My daughter has my Leaf now, in Los Alamos, a perfect spot for it since the area is somewhat geographically constrained. A great car to run around town in. I actually miss driving the Leaf here in Nashville. It is the perfect size for a city, and is really quick. However, I really love driving the Tesla, so I am not complaining.
     

Share This Page

  • About Us

    Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.
  • Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


    SUPPORT TMC