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Optimum Charging/Use Scenario

Discussion in 'Model X' started by vangogh, Jan 23, 2016.

  1. vangogh

    vangogh Member

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    I've looked around the forum and there seems to be a variety of information on charging and use patterns that will result in the best battery life and performance.
    Can anyone describe what the optimum use/charging condition is and how performance is degraded as you move away from this optimum?

    ie...is it best to use/drain to exactly 20% remaining battery life then charge to 80% consistently every cycle
    or vary use and charge between 10 and 30% and 70-90% respectively?
    or drain to near 0% occasionally and/or charge to 100% occasionally (or never)

    Thanks in advance for any information
     
  2. ThosEM

    ThosEM Space Weatherman

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    IMO, all information on this seems anecdotal and all opinions seem to be religious, rather than based on actual controlled studies. But I'd love to see some real data on this, if anyone knows where to find it.
     
  3. TexasEV

    TexasEV Active Member

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    Just keep it plugged in when you can, don't drive it to 0, and don't let it sit at 100%. Other than that, let the battery management system manage the battery, and enjoy the car.
    Remember, a connected Model S is a happy Model S.
     
  4. vangogh

    vangogh Member

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    Good advice @TexasEV....and a connected Model X is a happy Model X as well.....
     
  5. umeshunni

    umeshunni Member

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    If you're keeping it plugged in all the time, isn't it always at 100%?
     
  6. TexasEV

    TexasEV Active Member

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    No because you set the charge limit. This is typically 80%-90%, unless you need a 100% charge for a trip.
     
  7. RossRAllen

    RossRAllen Member

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    I asked my DS the same question. He and the manual suggest not going to 0%, 5% might be a good lower value especially if some energy is unavailable when the battery is very cold. Also, the "daily use" level suggests that consistently charging to about to 80% and using full "trip - 100%" only when needed.

    I also asked the DS about charging rates. I've always heard that slower the better if you can afford the time, but he could not confirm that. Anyway, my HPWC is set for 64A because it's on an 80A circuit.
     
  8. TexasEV

    TexasEV Active Member

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    You didn't hear it from Tesla. Slower is less efficient, and for a battery that can accept supercharging the difference between 20 or 40 or 80A is insignificant.
     
  9. ohmman

    ohmman Maximum Plaid Member

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    The other commonly stated, and I believe logically valid, advice is that when you charge to 100%, plan to hit that charge as soon as you're ready to go. Don't charge it at 7pm, then leave the next morning. Minimize time spent in that upper limit.
     
  10. Cobra Kai

    Cobra Kai Member

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    One of of the you tube videos from the guy in Tampa during his delivery walk-through (Max?) showed the recommended range for daily driving was 50 to 80/90 percent. The charge was set to not go over 90%, unless you are planning a long drive and need that 100% (like ohmman said). I will go along with the comments of keeping it plugged in whenever you can, and stay within that 50-90 range
     
  11. vangogh

    vangogh Member

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    My point exactly..I've heard a lot of "perhaps this/perhaps that"....I'd just like to hear an informed opinion of what would be the best for performance...
     
  12. eloder

    eloder Member

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    There isn't really anything hard and true, with the exception of higher charges aren't as good, long period of time above 90 aren't as good, and long periods of time under 10-20% aren't good. And this wisdom just comes from general LiOn battery chemistry knowledge (why automakers don't allow the entire pack to be used).
     
  13. pvogel

    pvogel Member

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    I deal with Lithium polymer batteries in my hobby where we can be VERY hard on them. Here's what we've learned in 8 years of experimentation in harsh conditions: Don't discharge below 20% on a regular basis, doing so significantly decreases the number of useful cycles. Discharging below 10% is permanent damage. Fortunately, Tesla's software considers something near 10% remaining as 0 and shuts down. DO NOT leave fully charged for more than a few hours. Doing so significantly decreases the number of useful cycles by significantly increasing the internal resistance of the cells. Charging a tesla to 'range mode' takes you to 100%, this is fine if you use it right away, not good to do that on a regular basis unless you are driving long distances that will take it below 80% quickly. For long-term storage with little/no damage or self discharge, keep at 60-80%. This is what the Tesla does when you leave it plugged in all the time, it keeps the battery state of charge in that storage mode, despite the 1%/day drain imposed by the systems that stay on when the car is normally shut down (can still do OTA updates, etc). Keep the batteries from getting too hot or too cold when in use (we often store them in the cold, but they aren't hooked up to anything). Cold increases internal resistance. If the battery is cold, don't ask it to deliver a lot of amps relative to it's capacity. 10-15 X capacity (10-15c) is OK, 30+c when cold is bad for the battery and will reduce total useful cycles. An excessively hot cell also does damage to the electrolytic chemistry. Tesla limits the current from the cells when they are cold and works to warm them up. This is why 'max power' can take a while to be 'ready' when it's cold. Tesla liquid cools the cells to prevent them from getting too hot.

    TL;DR: Don't charge to range mode unless you are going on a road trip within a few hours of reaching 100%, don't discharge below what the software tells you is 10% remaining if you can at all avoid it. Call for roadside assistance before you get to an actual zero if you are too far from available charge.
     
  14. vangogh

    vangogh Member

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    Thanks...Good info
     
  15. proven

    proven Member

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    Anecdotal story #793: Before we got solar panels on our house we were on a flat electric rate. We plugged the S in every time we were in the garage and it charged it back up to 90%--this was fairly frequent as I use my home as my primary office and I don't spend all day at an office with it unplugged.

    Fast forward to getting solar panels and switching over to a TOU rate. Now we have the car set to start charging at 9:15pm. It seems we've lost a few miles since starting that regime while the year before that we hardly lost anything.

    I'm going to keep watching it to see if it continues on that path. If so, it would seem charging it up more frequently would be better for battery life--of course I have no expertise in batteries and it could be other factors.
     
  16. ohmman

    ohmman Maximum Plaid Member

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    Remember that the rated miles displayed are the product of an estimation algorithm. Without reconditioning, the number on your dash can be misleading. Even then, range is tricky to determine - just read the non-classic 7.1 upgrade threads, where they discuss the apparent range increase with the firmware. Without driving the same stretch of highway many times in similar conditions and seeing how far you can truly drive, it's nearly impossible to validate these range display changes.

    I would be surprised if the difference in your charging strategy truly made any difference. Most everything I have read concludes that cycles, which are correlated directly with miles driven, are the main component in battery wear.
     
  17. pvogel

    pvogel Member

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    In normal, non-abusive use, yes, cycles are the main component of wear. But excessive discharge just once easily cuts your available cycles by about 10%. That said, from what I've read in Nick Howe's book, it looks like Tesla SW is doing all it can to prevent excessive discharge.

    The other major destructive force is storing at 100% for an extended period (more than 12 hours). That cuts useful cycle life by about 1% (30 cycles given the rated life of the Tesla battery)

    That said, in my hobby usage I've found that if I baby the battery, it will last far longer than rated cycle expectations.
     
  18. moviemaker2000

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    I have a 2013 S with about 45,000 miles and had been daily charging to 68% for 2 years (based on previous info in an Elon Tweet on battery health). The 90% charge had slipped to 209 miles and 100% down to 229 miles.

    I recently took it in to service for evaluation and they said, "It is possible if you begin charging your vehicle at 90% that in several months ( 6 – 12 ) you may start to regain some of your range. Due to the way you have charged your car and not charging your vehicle the way Tesla recommends you may never have the same range as you did when you first took delivery of your Model S. According to our engineers there is nothing that can be done to bring your range back to where it was and there is no fault with the HV Battery." This was the first I have seen an "official" recommendation to charge at 90% daily. It was my assumption that anything within the 50%-90% slider would be within their recommend range.
     
  19. spleen

    spleen Active Member

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    This doesn't sound correct and doesn't jibe what we know about how lithium chemistry batteries work. It's quite possible that your RANGE ESTIMATION may go back up if you start charging to higher limits (since the estimation software may "relearn" how far the car can go) but I suspect that your actual range is probably showing regular battery degradation and there's been no accelerated degradation from the way that you charge. In that sense, it's true that "there is nothing that can be done to bring your range back to where it was and there is no fault with the HV Battery". Full charge/discharge cycles affect battery life - fractional cycles do not accelerate the degradation.
     

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