Flat towing a Rivian

Discussion in 'Rivian General Discussions' started by CappyJax, Mar 4, 2019.

  1. CappyJax

    CappyJax Well-Known Member

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    I hope Rivian is listening.

    I think they should consider making their vehicles flat towable by RV's. It would be like turning the RV into a hybrid. The Rivian could use power to reduce or eliminate its load on the RV, and maybe even assist in going up hills. Such a feature would allow for towing by just about any other vehicle since the actual load on the towing vehicle would be minimal.

    It could also provide for regenerative breaking going down hills and for stopping the RV. This alone would keep the Rivian batteries fairly well charged.

    These features would make the Rivian the perfect toad.
     
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  2. ACDC

    ACDC Member

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    Great idea and would be an industry first for EVs, but Teslas and the Nissan Leaf can't be flat towed so I'm wondering if there's a reason EVs specifically can't be flat towed.
     
  3. CappyJax

    CappyJax Well-Known Member

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    I think the issue is that they can't be towed with the power off. If you had a system whereby the power remained on, the EV would be driving itself with steering coming from the towing vehicle. I am sure this could easily be done with software. If the RV has a tow capacity of 3,500 pounds, then the Rivian would moderate the power to reduce the load on the RV. This wouldn't take as much energy as driving, and the range of the Rivian under such conditions would probably be double or triple its driving range. The return of energy from regenerative breaking could be substantial since it is slowing both vehicles.
     
  4. EyeOnRivian

    EyeOnRivian Well-Known Member

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    Yes, very innovative idea. I like it. However, this sounds like it would require a significant amount of system integration and of course safety testing. So, if Rivian is listening ;), I personally would rather see them consider it *after* they launch the initial version of their vehicles. Spend the time now refining and testing the reliability of their current options/features for the initial launch.

    RIvian has to be careful to not fall into the trap Tesla did with the Model X by putting in way too many features in the initial version. An admission by Elon himself. He even had a name for it that escapes me at this moment. All those additional bells and whistles drastically delayed the Model X production many times.

    I suspect some feel some of these "additional features" are worth waiting for - they're just too important to not have. I get it, but for me, I would rather have a few less features and a more reliable vehicle get launched in a timely manner than to be strung out over repeated delays. This also typically translates to less vehicle service problems. Plus, it seems a lot of new vehicle features/options for an EV can be added via OTA (over the air) software updates versus having to buy a whole new model year. So we can be enjoying the vehicle now/sooner while we wait for the new feature(s) to become available after sufficient vehicle testing.
     
  5. Kengrigg

    Kengrigg New Member

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    Will this truck be towable? Behind my Motorhome.
     
  6. stank65

    stank65 Well-Known Member

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    Per Rivian twitter, the Rivian will be able to be flat towed. I am going to the NYC event and will be asking them about this.

     
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  7. CappyJax

    CappyJax Well-Known Member

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    Please ask the curb weight of the 180 kWh battery vehicle. I am looking at RVs now, and would hate to get one that doesn’t have enough owing capality.
     
  8. godfodder0901

    godfodder0901 Well-Known Member

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    There is a chart on this site that list the curb weight as 2670kg for all battery options. Doesn't seem 100% correct, but will likely be in the ballpark.
     
  9. CappyJax

    CappyJax Well-Known Member

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    Yea, at roughly 4.5kg per kWh, the different between the 105 and 180 is around 340kg.
     
  10. stank65

    stank65 Well-Known Member

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    Confirmed flat towing from RJ himself at the NY event. He said the four motors will be able to decouple which will allow for the flat tow. It sound like this decoupling ability (which Tesla doesn’t have) will be a key design feature that will help in extending the range of the trucks as well. With the motors being able to decouple, in some instances energy won’t be needed to spin up a pair of the motors and that will be a significant energy savings. Today dual motor model 3s get worse efficiency than single motor because they aren’t capable of decoupling one of the motors.
     
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  11. CappyJax

    CappyJax Well-Known Member

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    So no regenerative braking then. That stinks. You could literally charge the entire battery going through Colorado and using regenerative braking to slow the RV.
     
  12. EyeOnRivian

    EyeOnRivian Well-Known Member

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    @CappyJax - Have some good news about regen during flat tow. I found a recent article (posted yesterday!) stating regen IS possible during flat tow.

    "Many people like to use their motor home or a 5th-wheel to tow a vehicle behind it. Rivian says that the R1T will be capable of charging its batteries while being flat towed behind an RV or another vehicle. This is an innovative idea, but it could and would add an extra burden on the vehicle that is towing it." ​

    Source - TFLTruck: "Now the Rivian R1T Electric Pickup Truck Comes with a Kitchen Sink and Can Be Charged While Being Towed Behind an RV" - May 20th, 2019
     
  13. stank65

    stank65 Well-Known Member

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    Man, this would be great news. Haha you can tell whoever said that doesn’t understand that you use the flat tow vehicle to help you slow down. If done right it shouldn’t be a “burden”.
     
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  14. CappyJax

    CappyJax Well-Known Member

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    That is pretty cool! However, I am now leaning towards building a lightweight, aerodynamic tiny home and pull it with the Rivian. I think I can get over 200 miles of range with the right design.
     
  15. Hmp10

    Hmp10 Well-Known Member

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    The only way that you could recharge the batteries while flat towing is for the wheel motors to be acting as generators. For wheel motors to act as generators, they have to have an external source of energy. In the case of regenerative braking, it's the recovered kinetic energy from scrubbing vehicle speed. In the case of flat towing, it's the pulling force of the tow vehicle against the resistance of the EV's motor spin when acting as a generator. There is no "free energy" that becomes available to store in the batteries from flat towing an EV. In effect, the energy being stored in the towed EV's batteries is coming from the combustion engine in the towing vehicle. The tow vehicle is not just towing the weight of another vehicle whose transmission is put in neutral with its wheels rotating freely. It's towing that weight plus overcoming the resistance of the EV's motors when they're behaving as generators. This most definitely creates an added load on the tow vehicle and in some cases could exceed its tow rating.
     

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