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RV trailer with 80kWh battery and motors

Discussion in 'Cars and Transportation' started by ecarfan, Aug 24, 2018.

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  1. ecarfan

    ecarfan Well-Known Member

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    See Dethleffs puts a new spin on towing with an electric camping trailer that nearly drives itself

    I haven’t found much information about this trailer other than the minimal amount that is in that English language article (there are number of German articles about it as well). It appears that concept is that there are two 40kW motors (powered by an 80kWh battery pack in the floor of the trailer!) to drive the trailer wheels so that the trailer can be towed by small cars with small engines that wouldn’t have enough torque to tow a trailer of that size. Of course the Model X has more than enough torque to handle that trailer, which looks to be about 15 ft and 2,000 lbs.

    The question that comes to mind is, will those two motors in the trailer result in a greater range when towing with an X? I would say the effect would be minimal, since the primary factor reducing X range is the aerodynamic range of the trailer. But those two trailer motors might have some modest positive effect on X range when towing.

    The article offers almost no technical details about the trailer. It has solar panels on the roof but their capacity is not specified. There is nothing about what the trailer battery charge rate is. I doubt that the trailer solar panels could charge up the battery in a day if it was very low.

    Still, an interesting concept, and I’d like to know more and would like to see interior photos.
     
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  2. ecarfan

    ecarfan Well-Known Member

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    Correction: with an 80kWh battery pack, that trailer may well weigh more like 3,000 lbs.
     
  3. bob_p

    bob_p Active Member

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    This could be an interesting idea...

    How much will motors on the trailer help to reduce the effective load on the towing vehicle?

    The battery pack (and associated hardware) and motors will add weight/mass to the trailer - which could be more than 1500 pounds. Is the benefit enough to make up for this increased weight?

    The article mentions the possibility of having smaller vehicles tow the trailer - if the trailer weighs more than the towing vehicle, even with motors and brakes in the trailer, will that pose safety problems while driving and braking?

    If a Tesla battery pack was used, could it provide additional battery power to the towing vehicle, also helping to increase range? [This would require support by Tesla.]

    Having a low center of gravity has clear benefits for the Model X. What would be the impact of having a trailer also with a low center of gravity? Would it be positive or negative?

    With an 80-100 KWh battery pack, the trailer shouldn't have any need for propane and could go all electric for appliances and heating.

    And when the battery pack is fully charged, you'd be able to exist "off the grid" for a long time...

    Could be an interesting idea...
     
  4. ecarfan

    ecarfan Well-Known Member

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    #4 ecarfan, Aug 25, 2018
    Last edited: Aug 25, 2018
    Here is a quote from the article that I believe is an exaggeration:
    ”Cutting the tow weight means that even a small vehicle with limited towing capacity can pull the E.Home Coco to camp. It also means that an electric car won't experience the devastating range cut that it would otherwise experience when towing a big, heavy trailer.”
    —————————————————————————————————————-

    The writer seems to not be factoring in how aerodynamic drag effects energy usage. Can the two trailer motors completely negate the increased drag? I would like to see data on that, as well as data on how much energy is drawn from the trailer battery to power the trailer motors at highway speeds.

    And then there is the issue of recharging the trailer battery. My guess is the manufacturer is assuming that is done at the campground.

    I really want to see real life data on how this trailer performs. But my impression is that the manufacturer has just shown the trailer publicly for the first time and it has yet to go on sale.
     
  5. ecarfan

    ecarfan Well-Known Member

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    Good point. I don’t know the trailer weight yet. But with that enormous battery it could approach the weight of a small tow vehicle. A weight distribution hitch would certainly be required.
     
  6. ecarfan

    ecarfan Well-Known Member

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    In my opinion it would be positive in terms of handling. My Alto trailer has the fresh/grey/black tanks below the floor next to the axle to keep the trailer CG as low as possible.
     
  7. mspohr

    mspohr Active Member

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  8. aesculus

    aesculus Still Trying to Figure This All Out

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    It would seem this would best be applied for going up grades. I would probably not engage it in the flats and of course you want the regen to take effect downgrade but that means you have to have a place to put the energy so some careful charging might be in order prior to descents.

    It sounds like they are going to spend 2019 playing with the concept and figuring out what makes the most sense.
     
  9. mspohr

    mspohr Active Member

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    It will take a fair amount of fine tuning to avoid problems. Interesting concept, though.
     
  10. BerTX

    BerTX Supporting Member

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    #10 BerTX, Aug 25, 2018
    Last edited: Aug 25, 2018
    I suspect the trailer pictured is the current non-powered one. Dubious that they could get that trailer plus 1200 pounds of battery plus drive assembly in at under the max weight for a single axle.

    Edit: no, that is the concept. I'm still skeptical.
     
  11. mspohr

    mspohr Active Member

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    I agree that adding 500 kg of battery to a 1000 kg trailer would add significant weight. Motors probably add another 100 kg.
    Might cause problems for a single axle trailer... I assume they will test this and may have to go to a double axle to handle the weight.
     
  12. BerTX

    BerTX Supporting Member

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    People usually need to load other gear into the trailer, too, and most manufacturers leave enough axle load capacity to allow for this.
     
  13. mspohr

    mspohr Active Member

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    That's why trailers have a Gross Vehicle Weight rating to account for the extra stuff.
    In researching this, it looks like using a large diameter single axle can handle up to 8000 pounds GVWR
     
  14. BerTX

    BerTX Supporting Member

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    True, and they built their own axle assembly. They would need special tires to handle the weight, but no doubt those are available.
     
  15. mspohr

    mspohr Active Member

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    It will be interesting to watch the progress of this project.
     
  16. ohmman

    ohmman Maximum Plaid Member

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    This is interesting, indeed. In my towing trips, many people have said things like "too bad the trailer doesn't have a battery with which you can charge the car." But this obviously is a better solution if properly implemented.

    They either have to solve, or have already solved issues of sway. One thing that tension on the hitch provides is stability during sway conditions. If the propulsion system on the trailer loosens up that connection too much, it could provide a dangerous instability risk. But I'm guessing there are sensors, and the torque vectoring at the trailer wheels will allow it to help counter sway.

    Being able to also run the camper's convenience features (microwave, HVAC, AC outlets) while off-grid would be a huge benefit. 80kWh is a sizable reserve.
     
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  17. mspohr

    mspohr Active Member

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    An active system, if it is designed properly, has the potential to greatly improve the stability of the trailer.
    I'm thinking of the traction control and active stability systems of my Tesla. I've found that it is very difficult to get the car to slip and lose traction, even on snow and ice. Only one time did the car slip when I was on I-80 going around a curve at 75 MPH on a wet road. I felt the rear end slip and at the same time heard a tone and a message flashed on the screen that the stability control was active. The car corrected itself within a second and everything was stable again.
     
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  18. ohmman

    ohmman Maximum Plaid Member

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    Agreed. I wasn’t criticizing the concept at all, just noting that it is one factor they have to engineer. And as you mention, the outcome could quite reasonably be an upgrade in trailering safety.

    Yet another thing they’ll have to solve is how to do regen in concert with a standard brake controller. I’m guessing that’s not nearly as complicated an issue but it’s certainly important.
     
  19. ecarfan

    ecarfan Well-Known Member

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  20. ecarfan

    ecarfan Well-Known Member

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    A trailer of that size is typically much heavier than 1000kg even when unladen. And wouldn’t an 80kWh battery weigh more than 500kg?

    I just discovered this thread, thanks to @ohmman. I started a thread about this Dethleffs concept trailer two days ago at A camper trailer with dual electric motors and an 80kWh battery

    I put my thread in a Model X forum since only the X has a factory towing option and was curious to hear from others their thoughts regarding if such a trailer could significantly increase range when towing.

    Here is a quote from the article that I believe is an exaggeration:
    ”Cutting the tow weight means that even a small vehicle with limited towing capacity can pull the E.Home Coco to camp. It also means that an electric car won't experience the devastating range cut that it would otherwise experience when towing a big, heavy trailer.”
    —————————————————————————————————————-

    The writer seems to not be factoring in how aerodynamic drag effects energy usage. Can the two trailer motors completely negate the increased drag? I would like to see data on that, as well as data on how much energy is drawn from the trailer battery to power the trailer motors at highway speeds.

    And then there is the issue of recharging the trailer battery. My guess is the manufacturer is assuming that is done at the campground.

    I really want to see real life data on how this trailer performs. But my impression is that the manufacturer has just shown the trailer publicly for the first time and it has yet to go on sale.
     

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