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Charging Clarification Please

Discussion in 'Model S: Battery & Charging' started by lkuntz, Feb 4, 2017.

  1. lkuntz

    lkuntz Member

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    I have had my 90D for 5 weeks now. I have read many different threads on here about charging percentages and how low to let the battery get, etc., and there seems to be a wide array of opinions. I'd appreciate any clarifications or thoughts, mainly about whether the differences in opinion are actually significant in terms of battery health or whether they are personal preferences.

    Daily Charging Percentage: I have seen 50%, 80%, 90%. I've been doing 80%, but does it really matter, as long as it's not 100%?

    Charging to 100%: I've seen that you should only do this if you will be driving "right away". What timeframe is this? Within 10 minutes? 2 hours? I have done this once to go on a 250 mile trip, but set it to charge the night before. Should I be changing the charge start time to try to anticipate it finishing closer to when I will actually leave?

    Lowest SOC: I've seen not to let the battery get below 10%. I've also seen to arrive at a Supercharger with as little charge as possible. On my one long trip, we didn't make it as far as I had thought we would. We left home with 292 rated miles, but rain, wind, new tires, and inconsistent driving speed (my 19 year old son was driving) all meant we had to pull into an SC at 212 miles with around 6% charge. We charged enough to get to our destination (my son's college) and for me to get back to the SC. On my way home, I charged to 85% and the system said I'd arrive home with 5%. I was able to finagle things to actually get home with 13%. I really didn't want to have to make a second SC stop on the way. So, what's the ideal lowest percentage?

    Range Mode: I've seen some people say to use it on long trips and other people say not to use it. I'm not sure what to think. I forgot to turn it on on the way to the college, but did turn it on on the way back. I'm assuming that contributed to the change in range.

    Preheating: I live in Berkeley, CA, so it doesn't get super cold here very often. For daily driving, I don't think it matters to preheat the car/battery, but is it better for the health of the battery? What about on a full range trip?

    Plugging In: I'm trying to keep the car plugged in all the time at home. There have been a few times when it has gone a day not plugged in. The cable has to go across the path my husband uses to get into the house and it is a minor inconvenience in his wheelchair. My impression is that it's not an issue for shorter periods, but is for longer. I don't expect to need to leave it unplugged for lengthy periods, but how long can it go without damaging the battery?

    Anything else I should know? Thanks!
     
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  2. Hugh Mannity

    Hugh Mannity Mediocre Member

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    Sounds like you are in good shape.

    i.e. stay plugged in as much as you can, no worries if you are unplugged for a few days

    Also charge up to 90% most of the time, the odd charge to 100% is fine if you drive within a few hours after charged to 100 and don't let battery go below 10% much

    Sounds like you are on the path to years of trouble free battery life ;)
     
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  3. TexasEV

    TexasEV Well-Known Member

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    The difference between charging to 80% vs 90% routinely may be statistically significant after several years but it's not meaningful. Don't plan to arrive at under 10%, more because life doesn't always go according to plan than because of battery damage, but if it happens rarely don't sweat it. Some people here really overthink this. Just enjoy the car and let the battery management system manage the battery.
     
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  4. BerTX

    BerTX Active Member

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    [​IMG]
     
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  5. BerTX

    BerTX Active Member

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    Range mode cuts back on power used for non-essential things like climate control and battery temperature control. In your area, it will probably not help nor hurt you very much, but leaving it on full time may not allow the battery to stay at the optimum temperature for longevity. IMHO, best to leave it off unless you have a leg in a trip where you might really need it. Likely your difference in range achieved was due to an elevation change or wind change -- or in this case, a driver change.
     
  6. BerTX

    BerTX Active Member

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    Oops -- re the charging cable on the ground: I and a lot of others have set our charging system up to allow the cord to drop from above by hanging it from the garage ceiling. Maybe you can work out a similar arrangement. Even just loops of rope suspended to allow the cord to pass through will work.
     
  7. lkuntz

    lkuntz Member

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    Thanks. I would really prefer to just enjoy the car and not overthink it, but I was getting a bit concerned with all the different opinions.

    We don't have a garage, unfortunately, so the car is in the driveway and there isn't really an easy way to arrange for a drop down option for the cable.
     
  8. No2DinosaurFuel

    No2DinosaurFuel Active Member

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    80% daily is probably best. It can't be worst than 90%. Unless you need it I say keep it at 80%.

    100% should be rare. Though I think the balancing do kick it at higher soc. The only time I did it is for a trip I know my range can do without charging and that saves time for detouring. Otherwise I just charge 90% the night before and in the morning plug in before I leave to gain a few extra percentage for those longer road trip.

    Arriving as low as possible at a supercharging station might not be good for the newer cars because they start slower. My car starts at a typical 60KW for anything less than 15% soc. Then it ramps up to the full 110KW until 45%. Then it gradually slows. So IMO if you want the fastest charging aIM to arrive with 15% or more.

    Range mode off unless you need it. Like others have said with it on, temperature controls are cut back and can degrade the battery faster like higher temperature during trips. I always keep it off. It doesn't seem to help with range much other than make my climates control a bit worst. I just drive slower if I need more range.

    Plugging is good, but I don't see the need really. Lithium batteries like to be between 30-80% soc. So if you are around that range you are good.
     
  9. TexasEV

    TexasEV Well-Known Member

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    If you don't see the need to plug in, perhaps you haven't seen this from Tesla:
    A connected Model S is a happy Model S
     
  10. Doug_G

    Doug_G Lead Moderator

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    Just do 90%. If you're paranoid do 80% in hot weather. The battery degrades a tiny bit faster if it's at high state-of-charge at high temperatures. (This is why laptop batteries often don't last - fully charging all the time and a very hot processor nearby.)

    100% is only an issue long-term. Leaving it at 100% for a day or two will have no observable impact.
     
  11. No2DinosaurFuel

    No2DinosaurFuel Active Member

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    It says it right there. If it needs to be charged, heated, or cooled. If you never encounter those conditions then unplug away. You will lose a few % overnight so if you are around 80% to begin with no need to worry. Moreover I'm sure if you keep range mode off the bms will kick in when it needs to heat or cool on its own. Again if you know you will have enough charge the night before you are good.
     
  12. JasonA-EV

    JasonA-EV Member

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    That link or pamphlet is from 2013 and no indication that the latest FW needs this. The latest cars handle themselves just fine not being plugged in.

    As for needing to go up past 90% or higher to balance is not true. If you read the cell data the shunts are always working and as I look at my pack sit in the driveway right now (46%, 3.69v/cell) they are all within 3mv.

    They are always actively balancing.
     
  13. TexasEV

    TexasEV Well-Known Member

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    The current version of the owners manual (10/20/2016) still says "The most important way to preserve your battery is to LEAVE THE Model S PLUGGED IN when you are not using it." When the owners manual says something in all caps that suggests to me it's important.
     
  14. JasonA-EV

    JasonA-EV Member

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    I must has skipped over that part, I never saw that before until I REALLY looked for it. So I do stand corrected on that. But on the balancing act.. that is a big no.. The BMS/shunts are working at any level..

    upload_2017-2-5_19-32-7.png
     
  15. ThisIsTrue

    ThisIsTrue Member

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    Is this something "anyone" can see on their car? How?
     
  16. JasonA-EV

    JasonA-EV Member

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    Using something like TMspy or something else like Visible Tesla I think might. There are a number of programs that allow people to see into their cars CANbus data.

    But to be honest, most people don't understand or realize what all the data is. Just want to drive which is perfectly fine! :)
     
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