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What makes a Model S weigh so much?

Discussion in 'Model S: Interior & Exterior' started by nickt, Jan 4, 2013.

  1. nickt

    nickt Member

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    The car drives like a dream. It's gorgeous. It's possibly the best-designed American car ever. But what the heck makes a Model S weigh over 4,600 lbs? A Mercedes S550 weighs less than this. Even a Chevy Equinox SUV weighs about 1,000 lbs less.

    I've been talking to a friend who works in the battery group at Tesla. His guess is the batteries weigh between 1,500 and 2,000 lbs. Fine. Where is the rest of the weight? The whole frame is aluminum, which is lighter than the steel typically used in gas-powered cars. There's no engine, transmission, driveshaft, exhaust, firewall, radiator, or other heavy components. There's the motor and the inverter, but I'd have to think they weigh less than 300 lbs each, given the size I've seen in the Tesla store.

    Any guesses or calculations?
     
  2. dsm363

    dsm363 Roadster + Sig Model S

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    I thought the battery pack weighed around 1,000 lbs.

    The Audi A8 weighs 5,700-6,000lbs for reference.
    2013 Audi A8 Specs
     
  3. AnOutsider

    AnOutsider S532 # XS27

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    The A7 is closer in body size as well, and it's 4,167-5,456 lbs. so somewhat closer.
    2013 Audi A7 Specs
     
  4. nickt

    nickt Member

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    It's a minor nit, but the curb weight for the A8 is between ~4,400 - 4,800 lbs. I think you were looking at gross weight, which includes passengers & cargo.
     
  5. MikeK

    MikeK R#129, TSLA shareholder

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    It is a physically large car, and therefore has a lot of material in it. The batteries are heavy. It has a lot of sound deadening material installed, which is heavy.
     
  6. nickt

    nickt Member

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    In poking around on the net, it looks like the Roadster battery pack (56 KWh) weighs about 1,000 lbs. So it'd make sense that the Model S is between 1500 and 2000 lbs.
     
  7. unclfuzzy

    unclfuzzy Member

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    Even though it doesn't seem like it when I'm trying to squeeze my big a$$ through the drivers door, this car is huge! Plus there's the weight of all those secret hidden but not yet activated features like sonar, 360 degree cameras, motors to fold the mirrors, etc.
     
  8. dsm363

    dsm363 Roadster + Sig Model S

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    Thanks. I was looking at the wrong line and even comparing the wrong car I guess. Even Audi's aluminum car is heavy though but as AnOutsider pointed out, it's larger as well.
     
  9. richkae

    richkae VIN587

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    The equinox is 3777 pounds and is 187.7 inches long, 72.5 wide, and 66.3 high
    The Model S is 4647 pounds and 196 inches long, 77.3 wide and 56.5 high

    So the weight difference is 870 pounds. If the battery in the Model S is 1500 pounds, then it would be 630 pounds lighter than the Equinox. If you took out 500 pounds of drivetrain out of the equinox, it would still be 130 pounds lighter. That seems reasonable considering the Model S is a longer larger car made out of aluminum.

    Don't forget when you compare the weight of an ICE car to the Model S, that those ICE cars have empty gas tanks.
    15-20 gallons of gas is 125 - 165 pounds.
     
  10. TEG

    TEG TMC Moderator

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    Model S was designed to be one of the safest cars on the road too.
    So, I think there is extra material here and there for intrusion protection, extra crumple zones, and such.
    They could probably have made it lighter if they weren't trying to make it so safe.
     
  11. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Don't forget that motor -- that's going to weigh several hundred pounds too... (ever pick up a 5 HP motor? :) start multiplying!)
     
  12. jkirkebo

    jkirkebo Model S P85+ VIN 14420 EU

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    The Roadster has 6831 cells. The Model S 85kWh has ~7000 cells of higher energy density. So the battery weights should be pretty even, maybe 1100 lbs tops for the Model S battery.
     
  13. SuperCoug

    SuperCoug Model S Res #7734

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    :biggrin:
     
  14. derekt75

    derekt75 Member

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    On the tour, the guide admitted to not really knowing the answers, but she thought that the battery weighed about 1200 - 1500 lbs. Someone asked about the frame, and she was rather hesitant to guess since she didn't know but when pressed she took a guess at 700 lbs. [After online research, that might be a decent guess, since the aluminum frame of an old A8 weighs about 600 lbs.] I'm not sure why none of us bothered to ask where the other 3000 lbs. came from as I'm as curious as the OP. I read that the Roadster motor weighs 115 lbs, so maybe 300 lbs. for the Model S inverter and motor? That still leaves a lot of weight unaccounted for. I guess everything just adds up. Glass, wheels, brakes, seats, dash, etc I guess all have noticeable weight.
     
  15. richkae

    richkae VIN587

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    The cells in the Roadster battery are only about 68% of the weight. ( 6831 cells at 45g = 677 lbs out of 990 pounds ) So there is 313 pounds of non-cell weight.
    The surface area of the Model S battery is about triple that of the Roadster battery box. 90 square feet versus 30 square feet.
    Roadster battery box is approx 37" x 23" x 22" and the Model S is approx 60" x 96" x 6" ( guesses ).
    The long rectangular shape means that there are longer runs for cabling and cooling fluid. Longer runs for cooling fluid means more cooling fluid.
    The rectangular box that is 3x the surface area of the squarish box could significantly increase the 313 pounds of non-cell weight.
     
  16. captain_zap

    captain_zap Electron tamer

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    I think the Model S battery box is steel for underbody damage protection and protection of the batteries. After crunching mine hard on a steep driveway a couple times, and not seeing a scratch, I think it's true. That's a lot of steel.
     
  17. Omer

    Omer Member

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  18. brianman

    brianman Burrito Founder

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    Getting the charging duration so wrong makes me less confident in that number.
     
  19. Brian H

    Brian H Banned

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    Yes, and much of that is boron steel. And the case of the battery is steel.
     
  20. VolkerP

    VolkerP EU Model S P-37

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    Weight optimizing a car design takes a lot of time. You have to re-run all the crash test, driving dynamics, and NVH computer simulations. Given the tight schedule to bring Model S into production, Tesla might have pulled a line and stayed on the safe side of crash worthiness etc.

    I expect refinements in Model S 2.0 that will sum up to a complete new level of driving experience. Shedding weight is a major benefit to just everything, acceleration, tire noise, handling, energy consumption...
     

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