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New to Tesla: Distance added per hour of Destination Charge - kW, MPH, Amps, etc

Discussion in 'Model S' started by PickledRamps, Sep 22, 2019.

  1. PickledRamps

    PickledRamps Member

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    I am seeking to make the transition to EV, and planning to order a Model S within a few weeks. I have read many of the threads on this forum which have been an invaluable source to learn about charging.

    I am specifically interested in charging at vacation destinations where I may spend extend periods of time, and where a Supercharger would not be realistic, so please assume no access to Supercharger in this scenario. I will likely have easiest access to Tesla Destination Chargers (16kW) and ChargePoint (6 kW).

    As I understand it kW determines the flow, and can be calculated by..
    Volt x Amp = Watts

    At home my electrician says my Tesla wall charger will..
    1) 240 V x 60 Amp = 14.4 kW

    Tesla Destination Level 2 chargers
    2) 208 V x 80 Amp = 16.6 kW (listed on Tesla Site)

    ChargePoint
    3) Not sure, but listed as = 6 kW

    In two of the scenarios above the onboard charger, which is 48 Amp / 11.5 kW, is the limiting factor. I have confirmed with Tesla that no upgrade is available (at least as a factory order).

    My real question is how do I translate the kW to miles added per hour. I have read things on this forum such as "you can charge at 208 V * 48 A = 10 kW, or about 30 miles per hour of charging". Is there some simple conversion that I am missing that allows my to make this leap from 10 kW to 30 mph of charge, or in the examples above the 11.5 k limited by car or 6kW by ChargePoint to miles added per hour.

    Thank you
     
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  2. ucmndd

    ucmndd Well-Known Member

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    There's a basic chart here:

    Wall Connector

    But I'd encourage you to try and think beyond "miles added per hour" as it's a goofy measure that has way too many variables to be useful. A better way to look at it is to keep things in kilowatts and kilowatt-hours.

    For example, a 10kw charger will add 10 kilowatt-hours to your battery in 1 hour. Thus, to fully charge a 100 kwh battery from empty to 100% will take ~10 hours.

    Also, a minor correction on your home charger above - Your Wall Connector, even though it's on a 60 amp circuit, will only provide 48 amps of current (80% of the circuit breaker rating, per electrical code). 240 x 48 = 11.5kw.

    Also, consider that just about any Level 2 charger will provide you with an adequate charge overnight - even that 6kw ChargePoint.

    Welcome to EV driving - you'll love it!
     
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  3. M3BlueGeorgia

    M3BlueGeorgia Active Member

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    MPH is a pretty good measure of charging speed and something a lot of people can get their heads around.
     
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  4. PickledRamps

    PickledRamps Member

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    Thank you for your response, and the useful chart link. Yes, I think I understand that I will be limited 11.5kW, if for no other reason than the on-board charger. And I have no concerns in scenarios where I have access to a Level 2 charger and lots of time such as overnight stays.

    I am really just interested to know how long I need to stay on a given charger to be able to reach either home or a Supercharger if my battery is low. Meaning how long will it take me to add the 100-150- miles.

    Many thanks.
     
  5. TIppy

    TIppy Active Member

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    #5 TIppy, Sep 22, 2019
    Last edited: Sep 22, 2019

    The miles added per kwh is based on the epa wh / mile rating for the car. It varies depending on which model you are considering. For example, my car, a performance long range with 19" wheels, is rated at 324 wh / mile. I have a 240 volt, 40 amp connection that I use to charge my car. That's 9600 watts, so in one hour I add 9600 watt-hrs, or 9.6 kwh. 9600 wh divided by 324 wh / mile gives 29.6 miles per hour of charging. This is, of course, if you drive an epa combined highway / city loop. YMMV depending on if your driving style gets you close to 324 wh / mile.

    This takes into account losses incurred while charging.
     
    • Informative x 1
  6. TIppy

    TIppy Active Member

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    #6 TIppy, Sep 22, 2019
    Last edited: Sep 22, 2019
    150 miles times 324 wh per mile is 48,600 wh, or 48.6 kwh. If you are charging at 11.5 kw, you get 48.6 kwh divided by 11.5 kw is 4.2 hours. But like I said earlier, it depends on how you are driving. 90 mph is going to deplete the battery faster than if you drive 70. After you've had the car awhile, you'll get a better handle on your average wh per mile for your driving style.
     
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  7. tcoombes

    tcoombes Supporting Member

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    I have a 40 amp circuit and charge at 32 amps. I set the charging screen on the car or on my app to charge to 80% of capacity and begin charging at midnight when electrical rates are lowest. I get about 25 miles per hour of charging so by 5am I have charged 125 miles which covers my local driving needs very nicely. I try to find a good balance between charge timing and practices that minimize battery degradation (charge at lower amperage and only to 80% unless more mileage capacity is needed for a particular trip.)
     
  8. TIppy

    TIppy Active Member

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    This may be of interest to you. Musk says charging to 80% is only slightly better than 90%.
    In this graph 1000 cycles is equal to 300,000 miles. You can see that after 100,000 miles there is very little difference in degradation for anything less than charging to 100%.

    TeslaCharging.png
     
  9. Simon21

    Simon21 Member

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    Just keep it simple. 3 miles per kw. 10kw charger will give you 30 miles per hour
     
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  10. pschubert61

    pschubert61 Member

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    If you need 150 miles which will likely get you to a supercharger then:
    110v 4 miles /hr
    220v 18-24 m/hr
    Level2 charger 28 m/hr
    Tesla wall charger (destination charger)
    36-42m/hr depending on amps.
    So overnight full battery unless it’s a 110 A charger.
    I do look for Tesla destination chargers and call ahead to see if I can reserve.
     
  11. ucmndd

    ucmndd Well-Known Member

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    This is a rather confusing list.

    120v, not 110.
    240v, not 220. Assume you’re speaking about the mobile connector here?
    A “level 2” charger is generally defined as any 208/240v EVSE and can range quite a bit above this depending on amperage.
    A Tesla Wall Connector IS a level 2 charger.
     
  12. PickledRamps

    PickledRamps Member

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    This is all very helpful. The idea of thinking about it as adding kWh to the battery and then understanding how many Wh per mile one uses makes sense. I suppose I will understand this number based on my driving style when I have the car for awhile, but I can't know for sure yet and am hoping to get an estimate. I have seen graphs and tables that attempt to do so, but I am not sure how applicable it is to the current Model S Long Range with 19" wheels which is what I intend to order.

    I am interested in this car more for the diving than for the fuel savings (that is also important but not the primary thing). I am in the northeast so will frequently use A/C or heat. I will likely drive 80+ mi/hr routinely, and often in very cold temperatures. Anyone have a good source on what I can expect for Wh per mile of driving with that information.
     
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  13. dannycamps

    dannycamps Member

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    The way I always look at it is:
    120v Level 1: ~3-4 miles per hour
    240v Level 2 16A (3.3kw / 20A circuit): ~11-12 miles per hour
    240v Level 2 32A (6.6kw / 40A circuit): ~24-25 miles per hour

    From there it's relatively simple math. A pre-raven 100D (rated at 335 miles) would take approximately 13.4 hours to charge from empty to full or 6 hours to add 150 miles.

    One thing to note about EVs is that you are almost always never going to go from empty to full. Most charging will be partial charges (e.g. topping up).
     
  14. TIppy

    TIppy Active Member

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    #14 TIppy, Sep 23, 2019
    Last edited: Sep 23, 2019
    The epa says 304 wh per mile for that car. People report a loss of as much as 40 % of their range in cold weather, but that car has a range of 375 miles. There are things you can do to lessen the impact of cold weather on range.

    Here's a plot of range vs speed for an earlier Model S that had a range of 265 miles. If you multiply the data from the yellow curve by 375 / 265, or 1.41, that should give you the range of the long range model s vs speed.
    [​IMG]
    The car has a trip planner that will do most of these calculations for you.
     
  15. TIppy

    TIppy Active Member

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    #15 TIppy, Sep 23, 2019
    Last edited: Sep 23, 2019
    This link has plots of actual gathered data. It's pre-raven, so the ranges would have to be multiplied by 1.15. Likewise, the power would have to be divided by 1.15

    Range vs Speed vs Temperature from 805 Teslas

    These numbers are based on kwh delivered by the battery, which doesn't include charging losses of about 10 %. The 304 wh per mile the epa quotes includes the charging losses. That is, it's the energy your power meter would register.

    If you look at 80 mph for the temperature range of greater than 68F to less than 32F, the range varies from 300 miles to about 240 miles. So you would lose about 20% of your range. Again, you should multiply these ranges by 1.15 for the long range model s.
     
  16. BPeter

    BPeter Member

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    FYI the older cars had larger onboard chargers, at least as an option. My late 2018 P100D has a 72A charger, so if AC charging speed is important to you you could look at buying an older one. You could also attempt to ask your local service center(s) to see if they'd be willing to upgrade the onboard charger post-delivery. The 72A charger should still fit in any new car, they just don't offer it anymore for some reason.
     
  17. beyerch

    beyerch New Member

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    If this chart is accurate, there is something wrong with my car. A 70 mile trip @ 60-65 MPH used over half of my charge. (Was charged to 205 miles, drove 70.8 miles and range remaining was 98 miles......

    P85D in "range mode", etc. Just started making some longer road trips and greatly disappointed in accuracy of range rating vs. actual miles.
     
  18. dannycamps

    dannycamps Member

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    The three biggest factors that affect range are ambient temperature, speed, and terrain. In colder temps (which in a Tesla now seems to be anything under 50F), it takes significantly more energy to move the car due to battery heating, cabin heating, and reduced regen. Terrain factors in as well. If you drove your 70.8 miles up hill, you will expend more energy. Finally, speed kills range but 60-65 MPH should be fine.

    What was your average wh/mile number while driving (this is the amount of energy needed to move the car)? The baseline in my experience seems to be around 290 where the car will come closest to the EPA range. If a lot higher than 300, the range will be reduced.
     
  19. henderrj

    henderrj Member

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    So, am I correct in hearing that there is no higher amperage on board charger available now? I have dual 40 amp chargers in my model s now, 80 amp charging, 19.2 kilowatt, better than 60 miles an hour. I would not be happy with half that speed! So, really, I can't get more/faster charging in the new cars?
     
  20. dannycamps

    dannycamps Member

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    Not at home. Obviously none of this matters at a supercharger where the Raven S/X can pull a theoretical 200kW and the 3/Y(?) can pull 250kW.
     

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