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Charge time from 80% to 100%

Discussion in 'Model S: Battery & Charging' started by DevFonzy, Jun 9, 2017.

  1. DevFonzy

    DevFonzy Member

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    I'm about to take my brand new MS 75D on a road trip this weekend. I have not charged it to 100% yet. How long will it take to charge from 80% to 100%? I ask because I don't want to leave it at 100% too long. I will be charging at home (40 amps) where I get 30 mph when charging up to 80%.

    Thanks
     
  2. David99

    David99 Active Member

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    It will charge normal speed up to 90% or maybe a little higher, then it gradually slows down and the last 2% take the longest. I would allow about 2 hours before you leave. That should be plenty. Don't worry about being at 100% for a while. It's not good to keep at 100% for longer, but you don't have to worry about a few hours here and thre.
     
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  3. brucet999

    brucet999 Active Member

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    Do you really need a full charge to get where you are going? For most trips, all one needs is enough to get to the next SuperCharger. I have only fully charged my S70 once, when the nearest SuperCharger was 226 miles from my start point.
     
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  4. DevFonzy

    DevFonzy Member

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    There is a SC on the way. Doing a round trip and starting at 100% will let me skip the SC on the way there and have a buffer. I'm new to this and range anxiety is real. Not to mention I'll be traveling with two three year olds and a wife who hasn't drank the Tesla kool aid.
     
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  5. TexasEV

    TexasEV Well-Known Member

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    It doesn't matter if you "need" it or not. When you start a trip from home it's best to start at 100%. There's no reason not to. It will shorten your time at your first supercharger stop.
     
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  6. David99

    David99 Active Member

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    You also always start a road trip with 100% no matter what. At home you can charge without wasting any time before you start the trip and you start with the most amount of energy with you.

    From there on the rule on road trips is:

    If you stop only to charge and wait for it to finish, then only charge as much as you need to get to the next Supercharger or your destination. Charging more will only add time without benefit.

    When the car is waiting for you, always charge as high as you can. If you sleep in a hotel, go to a restaurant, do some shopping or take a longer break, always keep charging while having the slider set to 100%. This makes the best out of the time in terms of energy.
     
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  7. Piney999

    Piney999 Member

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    start with 99% and stop at the SC on your way there for Coffee and bathroom break. I find it hard to ever pass a SC no matter my SOC. Make up an excuse and stuff 5 minutes of electrons in the car. You will feel better about everything in the end.
     
  8. andrewket

    andrewket Well-Known Member

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    Stopping at a SpC with a high SOC when you don't need it is a waste of time. If you need to stop for a bio-break OK plug in for a few, but otherwise..
     
  9. ShockOnT

    ShockOnT Quickish

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    The charge rate on a home charger is the same at any battery level, so next time you charge at home take a note of battery percentage and how long it took to reach target percentage (eg. 43% to 60% took X hours). That will give you a 'time per percent' on your home setup that you can use to calculate your 80 to 100% time.

    Also some tips if you're a new owner:
    • It's OK to leave your battery at 100%, just not every day
    • Leaving home with 100% saves time on road trips
    • Supercharging to 100% is crazy unless you really need to. My 75D supercharges 20-40% in 10 min, or 80-100% in 40 min.
    • If a supercharger is on the route, it's not always best to skip it. Spend 10 minutes to stretch your legs, have a pee, get a coffee. You'll be amazed how much juice you'll pick up without feeling like you've waited at all.
    • Staying somewhere with good charging makes things so much easier. While you're checking in and unpacking the car gets enough juice for you drive around town, then while you're sleep it gets back to 100% for tomorrow's journey.
    • Plan your trips carefully to make it look to your wife like EVs don't require carefully planning :)
     
  10. brucet999

    brucet999 Active Member

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    No, it is not best to charge to 100% before you start unless you need that extra charge to reach your destination. Charging to 100% stresses the battery, which is why Tesla recommends charging to 90% most of the time.
    And starting with a full charge will not necessarily save time at the first supercharger. Arriving at a lower SOC results in a faster initial charge rate that tends to shorten the time needed to reach sufficient charge to reach the next SC.
     
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  11. TexasEV

    TexasEV Well-Known Member

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    I disagree on both counts:

    "Most of the time" is just that-- it does not include trips. There is no significant impact on the battery from an occasional 100% charge. The problem is leaving the battery at 100%, especially in heat, not charging to 100% and then driving. If you're that concerned about another potential 1 or 2 mile range loss after many years, you may have bought too small a battery. I have only lost 4% range in 4 years of my S60, well within what everyone reports, and I have charged to 100% two to three times a month, but it's always just before I drive, I don't leave it there overnight.

    Yes there is an initial faster charge rate at a lower SOC, but regardless if you start with more miles you'll get to your target faster than if you start with less miles. Are you saying it takes less time to charge from 20 to 90% than it does from 30 to 90%? It's just not mathematically possible.
     
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  12. brucet999

    brucet999 Active Member

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    To get to the next charger you only need to add 120 to 150 miles, so the end SOC need not be the same, only the amount added. 20% to 80% will take less time than 30% to 90%.
     
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  13. FlatSix911

    FlatSix911 918 Hybrid

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  14. TexasEV

    TexasEV Well-Known Member

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    We're all well aware of the graph you posted, FlatSix911. It's not relevant to the discussion.

    Whatever state of charge you're aiming for, starting at a higher state of charge gets you there quicker. If you do only need 80% SOC to get to your destination or the next supercharger, fine. Say you drive from home starting at 100% and end up at 30%. You will supercharge to 80% faster than if you started from home with 90% and ended up at 20%. You're saying it's faster to use the lower end if the battery. I'm saying with smaller batteries that's often not an option, especially outside of California where there's a supercharger around every corner, and we usually need to charge to 80 or 90 or even 100%. Starting the trip with a full battery helps, period.
     
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  15. tnt1971

    tnt1971 Member

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    I usually budget an extra half hour beyond what would be a normal charge rate (for me it is 10% per hour). It usually finishes 15 minutes early.
     
  16. FlatSix911

    FlatSix911 918 Hybrid

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    Actually, it is relevant if you want to optimize your charging time when you arrive at a Supercharger ... :cool:
     
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  17. David99

    David99 Active Member

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    That's where your mistake is. You don't have to charge a certain amount on top of what you have left in the battery but you have to charge to a certain level. If you arrive at the first Supercharger and you now need to charge to 80% to reach the next one, it makes a difference in time whether you arrived at 40% or at 20%. Thus charging to 100% when you start your trip at home will always save you time at the first Supercharger.
     
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