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Driving up to Big Bear or any mountain...additional energy required to gain elevation

Discussion in 'Model 3: Battery & Charging' started by MikeR55, Dec 17, 2019.

  1. MikeR55

    MikeR55 Member

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    Seeing as there are so many LA people on here- has anyone done the drive up the 210 to the 330 to Big Bear? Wondering how much loss of battery that takes to go fro basically zero to 7000 feet in 45 minutes up the mountain.

    Deciding on SR+ or AWD - and I make that trip from Sherman Oaks often. Although I try to avoid in the winter so not sure I need the AWD
     
  2. SageBrush

    SageBrush 2020: Drain the Sewer

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    Car: 1800 kg
    Climb: 3200 meters
    g = 9.8

    So 1800 * 3200 * 9.8 joules = 15.7 kWh for the climb
    Add 15.7 to the kWh needed for the distance travelled
     
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  3. CharleyBC

    CharleyBC Active Member

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    Sacramento here. We've gone up 50 and 80 (no "the" in the north end of the state) to Lake Tahoe, which is a similar elevation gain. You absolutely pay for it in range. You're lifting a two-ton object 7000 feet. That ain't free.

    But the cool part is the return trip. When we come down 80 toward Sac, we watch the charge in our battery increase as we go along. I forget the exact numbers now, but we see the battery go up like 10 or 20 miles, even as we are covering distance. In short, bringing that two-ton object back down 7000 feet converts a lot of potential energy to electricity!
     
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  4. SageBrush

    SageBrush 2020: Drain the Sewer

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    I live at the base of a 7,000 foot mountain. My up and down trip worked out to 65% regen. Amazing
     
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  5. MikeR55

    MikeR55 Member

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    So how much in miles would that eat up? (For those of us who are comedy writers who got C- in math)

    Would an sr+ make a 107 mile trip with the last 45 minutes up a twisty cold mountain? And how much range would I have left?
     
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  6. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    The math is correct but the inputs are wrong:

    3700 pounds * 7000ft * 9.81m/s^2 in kWh - Wolfram|Alpha

    3200 meters is not 7000 feet is the main error. Anyway it's about 10kWh for an SR+.

    The minimum is 9.8kWh assuming a single 150 pound passenger. Realistically due to inefficiency it will be a bit more, let's say 11kWh.

    11kWh/209Wh/rmi = 53 rated miles.

    This is approximate. If you carry 600 extra pounds of people and stuff adjust accordingly!

    Whether you make it depends on conditions. Personally, I'd start with 100% charge and have a place to charge when you get to the top (but be careful about charging too high when you're up there since you will get a lot of regen on the way down and you don't want to burn up your brakes - I'd leave at least a 50 rated mile buffer from 100%).
     
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  7. SageBrush

    SageBrush 2020: Drain the Sewer

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    Do you mean rated miles ?

    The SR+ is about 225 Wh/mile while the AWD is about 250 Wh/mile

    15.7/0.225 = 70 miles for the SR+
    15.7/0.250 = 63 miles in the AWD

    Comedy is the salve of my life. I owe you
     
  8. SageBrush

    SageBrush 2020: Drain the Sewer

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    Oops -- right you are.
    More like 2366 meters
     
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  9. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    Closer to 209Wh/rmi for discharge.
     
  10. holmgang

    holmgang Active Member

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    Depends on the air-speed velocity of an unladen Tesla
     
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  11. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    You can try using ABRP to model this drive, BTW.

    You'll probably make it, but it depends. Personally I'd buy all the range I could get. Small advantage with AWD is that you might be able to avoid putting on chains in some conditions, though extreme caution is advised.

    A Better Routeplanner

    (Select the alt route on this link obviously.)
     
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  12. CharleyBC

    CharleyBC Active Member

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    What do you mean? An African or a European Tesla?
     
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  13. Jimbydude

    Jimbydude Member

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  14. CharleyBC

    CharleyBC Active Member

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    Which part? Tahoe or the SoCal spurious "the"?
     
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  15. MikeR55

    MikeR55 Member

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    Very cool! This link helps a lot. Seems like I do not need an AWD save $9,000 if possible
     
  16. SageBrush

    SageBrush 2020: Drain the Sewer

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    ABRP is a really excellent tool, but keep in mind that it cannot take road or weather conditions into account. If you have a way to take on extra charge en-route if needed then by all means shave it close, otherwise buy some insurance in the form of a larger battery.

    Also keep in mind that Li-x batteries from Tesla can lose up 3-4% of range the first year and then 1-2% a year thereafter
     
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  17. MikeR55

    MikeR55 Member

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    Yeah especially when the first 60 min of the trip is 90 degrees and the last 60 is around 20 degrees.
     
  18. SageBrush

    SageBrush 2020: Drain the Sewer

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    Now you are thinking like an EV driver :)
    Add to your calc non-dry roads and headwinds
     
  19. MikeR55

    MikeR55 Member

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    Is there really a difference between all-wheel drive and not all wheel drive going up and down a mountain on dry weather conditions? In terms of handling?
     
  20. KenC

    KenC Active Member

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    No, not really.
     
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