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Charging Approach

Discussion in 'Model S: Battery & Charging' started by lolachampcar, Dec 8, 2012.

  1. lolachampcar

    lolachampcar Active Member

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    I'm sure this topic has been covered in part in many different threads but it would be nice to have the meat and potatos of those posts in one place.

    What is the best way to approach Model S battery management? I seem to remember from my 4/3rds fat A battery designs many years ago that charge cycles degrade the internal electrodes. That would lead me to believe that charging when close to depleted would lessen the total number of charge cycles for a given number of miles/years driving. That being said, I drive my Zero to the airport and promptly plug it in at the hangar. That's a 22 mile trip on a 60 mile capacity. I then plug it in when I get home as well which adds up to two partial charge cycles per day. Zero's advice is to leave it plugged in whenever possible.

    Does anyone have more up to date technical information regarding how best to manage the pack?
     
  2. steve841

    steve841 Active Member

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    Nothing to offer technically, but Tesla recommends always plugging in when not in use and minimal range charges ...

    Thats my plan, and I am sticking to it!
     
  3. brianman

    brianman Burrito Founder

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    Same. And it's so simple this caveman can do it!
     
  4. Rodolfo Paiz

    Rodolfo Paiz P85 "Plug and Play"

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    Battery charging philosophies are different depending on the chemistry of the batteries. NiCad and NiMH had memory effects, and reducing charge cycles was better. For Li-ion, avoiding the extremes is key: don't empty it out and don't fill it to the tip-top, and it'll live a much longer life. This is what "standard mode" charging does for you. No memory effect, so no problem plugging it in all the time. Also, having the car plugged in allows the car to do some intelligent maintenance on itself like balancing the battery pack. So, basically:

    1. Range charge only if you really need max range.
    2. Storage charge if you're not going to be using the car for two weeks or more.
    3. At all other times, standard charge and plug it in all the time when not using it.
     
  5. jerry33

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

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    Of course, some of those cavemen were probably smarter than we are. We just have the advantage of better education.
     
  6. Robert.Boston

    Robert.Boston Model S VIN P01536

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    Model S does not have a "storage charge" setting, unlike the Roadster.
     
  7. dtich

    dtich #P708

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    wanted to x post this here as it veered into a more general comment about approach to charging... i'm still interested in others thoughts on the matter. i know it seems a bit anal, but the truth is i figure if i've puzzled it out a bit in the beginning and then commit some of these ideas to practice and habit, i'll actually have a concrete effect on my battery life that's worth a couple hours of anality.. to coin a phrase.


    leaving car undriven for 10 days


    (i'd respond to the above in this thread here if speaking to the more general charging plan subject..)
     
  8. dsm363

    dsm363 Roadster + Sig Model S

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    I saw your post about how you plan to charge it. That may gain you a fraction of a percent SOC over time but seems overly complex. Tesla recommends keeping it plugged in at night when you are not driving so that seems the way to go. Once they add 'charge or finish charging at X time' then your car will sit at 90% SOC for a shorter time as well. If you try and hover around 50% and a storm knocks out your power for a long time then you've given yourself less of a buffer to drive around too (one uncommon but possible scenario). I just plug it in every night like my mobile phone and don't worry about it. Much easier.
     
  9. Johan

    Johan Took a TSLA bear test. Came back negative.

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    i-dont-always-charge-my-car-but-when-i-do-its-a-standard-charge.jpg

    :biggrin: In all seriousness I plan to plug in every night and trust Tesla to keep the battery healthy. It wouldn't surprise me though if future firware updates added a kind of long-term storage mode (hidden in the sub menus).
     
  10. dtich

    dtich #P708

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    high-larious. that's what i'm talking about! funny.

    yeah, i know it's over-thinking and nerdily anal now, but just the thinking part.. the doing part is really easy. that was my point. i was eager to hear any real world experience from roadster owners on this...

    the basic plan of plug-in-every-night is a bloody no-brainer. i'm just thinking a little bit beyond to see if a small, easy habit change can perhaps significantly affect batt life in a good way. i still think it can.

    like i said, i'm in socal, so i don't think much about storms and whatnot.. that said, i'm sure for the vast majority of the time my habit will be to simply plug it in every night, as i've done so far, with a couple exceptions.. and that works fine. easy. no complaints. just looking for a little back and forth on the thinking..
     
  11. dhrivnak

    dhrivnak Active Member

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    A large charge stresses a battery more than many small ones. So there is little practical difference in oveall life between 10 charges of 20 miles than one charge of 200 miles. I wish i could give empiric data but the batteries are too new to really know as they have not been around for someone to test 10,000 cycles.
     
  12. 100thMonkey

    100thMonkey Member

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    I read through the warranty the other day and it states that doing anything to try and prolong the batteries life will void the warranty.

    Tesla really wants you to plug the car in at the stable every night and just not think about it.

    It's hard to imagine that the battery pack is so different in the S that applying some basic good habits would hurt the battery but I can imagine a few reasons they have decided to take this extreme approach:
    1. the battery bricking of the Roadster was such a bad PR issue that they really want to make plugging it in regularly part of standard protocol to help make it abundantly clear that leaving it plugged in for prolonged periods explicitely violates the warranty.
    2. Since early adopters can get quite OCD about this kind of stuff, the simple "plug it in every night" approach forces the owner to stop thinking so much about it and just get into a convenient habit... it's low stress and good PR to portray the maintenance as taking very little thought.
    3. having it plugged in assures that the BMS can maintain a constant temperature, which optimizes charging times and performance as well as long term life in hot climates.
    4. having a constant temp during charging and discharging reduces some of the variables that effect range. having a more constant range helps reduce the drivers stress, improving the ownership experience.

    compare this to what has happened in Leafdom:
    Theories about battery life and charging habits have lead to uncertainty about what is best. many owners keep the battery only 50% charged, subverting the standard charge modes, requiring a lot of dinkering around by plugging and unplugging without the convenience of relying on the charging timers or auto shut off. While this might be good for the battery long term it is bad for PR. I've developed such a nuanced charging habit with our Leaf that my wife never knows when it's "ok" to charge it, which really isn't so practical for the masses.

    For me, I'm still a little on the fence about the Tesla charging protocol. I know from driving the Leaf that the 85kW S at a 50% charge will be plenty for most of my driving daily, even my spontaneous trips, even if the pack is cold soaked and thus range limited. I'm pretty certain that keeping the battery cool (ambient is cool here, cooler than the BMS target of the S) and at a 50% charge will significantly extend the batteries life, so leaving it unplugged much of the time is tempting. We just don't get the kind of heat that is an issue for Li-ion batteries in the PNW. I am fine with the notion that I will have to safeguard against letting the battery sit for too long at a low SOC. My track record with Li-ion batteries is very good, basically if you treat them poorly you get a few thousand cycles out of them, treat them well (shallow, mid range cycling, avoiding high temps etc) and you can get tens of thousands of cycles out of them.

    Then again, the thought of just not having to think about it compared to how much I think about it now with the Leaf, my iphone, shaver, and other rechargables is very tempting. Having the threat of voiding the warranty may just be the kind of thing I need to be forced to relax about it all and just enjoy driving the car. Tesla has so many things figured out that it's tempting to think they have a BMS that is truly superior to anything I can come up with on my own.
     
  13. dsm363

    dsm363 Roadster + Sig Model S

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    The Model S only balances the pack after a full standard or range charge I believe so that is one reason to follow what Tesla says. There might be some small benefit to battery pack life by hovering around 50% but think it takes away some of the simplicity of owning an EV. I like the plug it in everytime you hit the garage and not worrying about it but everyone is different.
     
  14. Alpha

    Alpha Member

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    I wish they made some kind of device that you could install on your garage floor, and when you park over it, it would automatically connect a charger from below -- then you could park in your garage every night and not even think about it!
    Would be cool for supercharger stations too. You just pull up in the designated spot, maybe punch a button on the screen, and something "docks" to your car from below and charges it up! Then when you get ready to leave, hit the break and it automatically undocks and quickly recedes into the ground, to stow away flat.
    I wonder if they are planning something like that for the future. Elon's SpaceX can dock to a space station-- surely this would be peanuts in comparison to engineer... and would make charging completely hassle free!
     
  15. Doug_G

    Doug_G Lead Moderator

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    Sure batteries will last longer in storage if they are at 50%, but these batteries are not in storage. They're being used - drawing power from them below 50% is harder on them. So it's not at all apparent that keeping the batteries at a lower SOC is actually good for the health of the pack.
     
  16. montgom626

    montgom626 Active Member

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    I lived in Tacoma-Seattle area for 20 years and now live in Wisconsin. I just smile when you talk about the MS being "cold soaked". ;-)
     
  17. JackA

    JackA Member

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    Alpha; do an Internet search on conductive charging automotive. There are units available however they tend to be make and model specific. Also look at charge on the go. A cool concept using conductive charging from embedded conductors in the road way. I was preparing to file a patent on the idea but in doing the research found that a New Zealand company has the concept in development. Conductive charging is convenient but you do pay an efficiency penalty for the convenience.
     
  18. Alpha

    Alpha Member

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    I think what you meant is "inductive" charging, which I am aware of (my toothbrush charges that way.) It is safer cause there is no chance of short circuiting, but the efficiency can only get up to 80% (maybe 90% best case.) I'm talking about a conductive charger (like the one you plug into the side), but that self docks from the underside and that doesn't have to be lined up correctly or anything. It would be 100% efficient, and I think most of the safety concerns could be addressed through other measures. I haven't heard anyone speak of anything like this before.
     
  19. Johan

    Johan Took a TSLA bear test. Came back negative.

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    Even if you "only" get 1000 full cycles out of the battery before it's significantly degraded (or let's say 2000 half cycles) that's still going to be equivalent (with conservative estimates) to some 200k+ miles of driving (300k+ kilometers) which is quite a lot for any automobile. I would wager it would take most people at least 5 years to drive that ammount, for most a lot more (taxis being the exception) especially since EV's, even Model S, is not a good car for any setting where the car has to be on the road for more than 8 hours per day every day. For most I would assume it would take 7-8+ years to drive 200k miles, and at this point the car as a whole is starting to become worn, outdated and shelf-life (independent of use) starts to become an issue for the battery as well. So there is really no point in having habits that would allow for example 10000 cycles, since you're never going to need 10000 cycles anyway.

    The one thing I guess you could really do to hurt your battery with Tesla's current system is to consistently do range charges.
     
  20. Chas F

    Chas F Model S 60kWh #P6396

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    Very good points Johan. I've seen many threads on this forum where folks focus on details and miss the bigger picture. The same logic can be applied to selection of the appropriate battery size or the usefulness of the battery replacement program, for example.
     

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