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Model 3 Towing Hitch? (out of MA)

Discussion in 'TSLA Investor Discussions' started by AndyH, Dec 29, 2018.

  1. AndyH

    AndyH Member

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    Tesla club Sweden wrote about towing hooks. A poll indicates that 65% of buyers want a towing hook and 26% wont buy without one in Sweden. A towing hook is mentioned in the Model 3 manual and Tesla have been testing it as in this picture of one their cars used for testing. It should be coming. Shame that it wasn't available at european launch.
    [​IMG]
     
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  2. bhtooefr

    bhtooefr Member

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    That doesn't solve the problem for Europeans, though.

    Tow ratings in the US are more of a guideline, and exceeding the 0 lb tow rating of a Model 3 here is legal, but you're assuming liability if something goes wrong as a result.

    In the EU, tow ratings carry the force of law, and towing with a car with a 0 kg tow rating can get you pulled over.
     
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  3. SebastianR

    SebastianR Member

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    #3 SebastianR, Dec 29, 2018
    Last edited: Dec 29, 2018
    Weekend OT:

    Hi @AndyH - ja, a trailer hitch will be great. I'm sure we will see one some fine day. And I'm sure that the shorts will scream bloody murder as this will be yet another demand lever for the EU. I'm however also wondering if we will see that on the Model 3 before we see it on the Model S: since the Model S is a hatchback, I don't think the urgency is quite as high, but then again, that's just my opinion...

    Fully agree - however, socially it is more acceptable to keep the kids in the car and the bike in the rain (rather than the other way round if you know what I mean...) /s

    Thanks - yes, I'm familiar with Torklift Central. I also know that TFF (the German Tesla folks) imported a bunch for the Model S incl. getting the right certification / inspections done. When I read about the efforts they went through - to be honest, I rather give that kind of money directly to Tesla :)

    Anhängerkupplung AHK • TFF Forum - Tesla Fahrer & Freunde

    EDIT: There is even more discussion about this topic on TFF and here is a guy that has a "dumb" trailer hitch (i.e. no towing, just as a bike carrier):

    [​IMG]

    Anhängerkupplung und Dachgepäckträger Model S • TFF Forum - Tesla Fahrer & Freunde

    But again, a lot of effort for something I really would like to get from Tesla directly :)

    Anyways, we will see how this develops over the coming months...
     
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  4. KarenRei

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    I know -it's extremely frustrating, and puts us early adopters in the annoying position of having to choose whether to delay our orders for something we don't even know if they'll add, even though it's something very important for us and about the most trivial possible option for Tesla to add. I mean, look at the EcoHitch - it literally is built around just a stamped piece of metal that slots onto already-existing bolts on the Model 3's frame. How much easier could you get than that to produce? Don't want to dedicate the resources to make it yourself? Outsource it; there already are companies that make them. Don't want to "complicate production?" Just flag the vehicles as being tow rated and have the hitches installed by delivery centres or service centres after delivery, and charge enough to pay for the extra labour.

    Not doing this is being pointlessly mean to customers. Right now there are 100-200k people in Europe struggling to decide whether they want to wait for an option that may never come, or sacrifice their vehicle's usability. It's not okay.

    (I also really want air suspension to be able to get extra ground clearance, but at least that has the excuse that it's a relatively complicated thing to engineer. A tow hitch is not. Third party tow packages already exist - they're just not legal here because they're not factory spec)
     
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  5. mongo

    mongo Well-Known Member

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    OT

    Pointlessly mean???

    A car frame built to support itself is not the same structure as a frame designed to support a trailer. Just because you can bolt a piece of metal to a car does not mean the car's frame is designed to support that load, nor the torque placed on the frame by a trailer attached to the ball at some distance from the frame, nor the worst case overloading conditions a driver may subject it to. Neither does it address the change in crash safety due to the additional structure. Further, an add on hitch makes great assumptions about the vehicle electrical system and imposes additional design constraints upon the vehicle to support unknown lighting loads and failure modes.
     
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  6. KarenRei

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    A large portion of these are people who want a hitch (many who very strongly want a hitch) but are choosing to sacrifice usability in order to get their car. That's being pointlessly mean when adding a hitch option is something so trivially easy for Tesla. They could literally just flag the vehicles as tow rated, buy eco hitches and wiring connectors, and have service centres install them, with the profit paying for the extra labour. Not making a hitch option is pointlessly mean to customers.
     
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  7. KarenRei

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    Add-on hitches for the Model 3 already exists. They work just fine. You're not going to be towing a boat with one, but that's not what's being talked about here. The sort of added stress on the rear suspension is akin to having an extra passenger in the back seat.

    Re: your comment about electrical systems, that's what power converters are for trailer light systems (see, for example, the ones made by Hopkins). They have an independent 12V connection and use that to boost the power to the trailer lights. No added current draw to the tail / brake / turn lights' wiring.
     
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  8. KarenRei

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    #8 KarenRei, Dec 29, 2018
    Last edited: Dec 29, 2018
    Would you prefer the word incompetent, then?

    Did you completely ignore the post above? A quarter of Swedish reservation holders polled stated that they wouldn't buy the car at all if it doesn't have a towing hitch, and 2/3rds want to buy it. You'll find the same story across much of Europe. Just because Americans don't generally tow doesn't mean "ignore what's important in Europe and call any European "excessively emotional" for their vehicular needs.
     
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  9. JRP3

    JRP3 Hyperactive Member

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    As I said, a minority. I believe Tesla has always released vehicles without towing capability at first, why would you expect it to be different this time? I want towing on the Model 3 as well but I'm not going to flip out about it.
     
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  10. KarenRei

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    No, a solid majority want to buy it. A quarter won't buy the car at all without it.
     
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  11. mongo

    mongo Well-Known Member

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    OT

    I said nothing about rear suspension issues. Rear axle load is a manageable quantity. Torque on frame and load path are the items that would need addressed to support a trailer.

    There is working as in "hasn't failed yet" and there is working as in "vehicle still meets all performance and longevity standards and will not be adversely affected by trailer". A hitch mounted cargo rack can be a much worse load than a boat. How can you say no one would tow a boat? That is exactly the Pandora's box you open once you add a hitch. Even a small utility trailer, if they load the front first, will exceed the typical tongue weight limits.


    I am well aware of such things having helped designed them. I am also aware that the 3 electrical system does not like the load a mere dash cam presents to the battery due to energy monitoring and self diagnosis. What will happens with a random trailer?
     
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  12. KarenRei

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    #12 KarenRei, Dec 29, 2018
    Last edited: Dec 29, 2018
    In the real world, it's the rear suspension (due to tongue weight), not tensile loads in the frame, that are the limiting factor for towing. Also things like braking and engine/motor power are often limiting, but these aren't going to be a limit for an EV like the Model 3. The frame is virtually never a limiting factor, as the frame has to be strong enough to bear the intense loads that occur in a collision.

    As in "add-on hitch manufacturers would be sued into oblivion if they wrecked cars, yet add-on hitch makers have been around for decades". As in "they're mounted on the same bolts that support the car's rear crush structure, which is designed to bear vastly larger loads than a small trailer will ever impose".

    That's what tow ratings are for. Duh. If you exceed your car's tow rating, the liability is on you.

    Stationary loads on a suspension are almost meaningless compared to the loads the suspension experiences when going over a bump or hole at highway speeds. Loading weight limits are to protect the suspension while the vehicle is in motion, where the forces on the suspension are highest.

    And again, as with all tow hitches - and all aspects of a car in general - if you do things wrong in violation of the manual, and you damage your car as a result, the liability is on you.

    Which is why a converter does not have the power draw of a dash cam. That's the whole point of it. It simply measures if current is flowing, and if it is, it supplies power to the trailer straight from its own 12V connection.
     
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  13. mongo

    mongo Well-Known Member

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    OT

    In the real world, a car designed for minimized weight (maximum efficiency) would not have a rear cross member designed to support a cantilevered torque force. The only force normally on the rear frame is in the vertical. As soon as you bolt on a hitch receiver and place a load on the tongue, you are creating a loading condition that would never occur normally. If I hang a flag pole from the rake fascia of my house and then pull down on the end, what happens?

    Previous cars were not as optimized as a Tesla is. The rear crush structure is made to handle loads in the forward direction (once at magnitude with deformation), not the down, and not in rotation (top fasteners in tension, bottom in compression).

    If people follow tow ratings, then why are people putting hitches on Tesla's that have a zero tow rating?
    Again, I am not saying the suspension is the weak link. The case of hitch cargo carrier is much worse in the dynamic state. If I stick a 10 foot 1-1/2" steel tube in a receiver and then put 300 pounds on the far end, there is <400 pounds on the rear suspension, but it will likely bend something on the car. Torque, not weight.

    And people are apparently already violating the manual, so what is to protect Tesla from them doing it again if there were hitches installed (assuming the frame were built for that)?

    The dash cams were connected with their own 12V feed from the battery, that is what caused the issue. Trailer lights will draw more current than a dash cam...
     
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  14. KarenRei

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    Then the car would not be able to withstand a crash.

    To reiterate: tensile strength in the body is almost never a limiting factor for a vehicle's towing ability as they're so much less - in all axes - than the forces experienced in a crash. The limiting factors for a vehicle in towing are almost always A) the strength of the rear suspension, B) braking capacity, and C) engine / motor power. Look it up. Any site which discusses towing conversions will tell you the exact same thing. The frame / body is almost never a limitation (even when towing very heavy loads); the suspension, brakes, and engine/motor are.

    It's a fictional world where forces in a collision are constrained to a single axis. Furthermore, the tongue weight is so hilariously far from the strength limits on the bolts (many orders of magnitude) and UHSS passenger safety cell that it's silly that we're even having this conversation.

    At their own liability. Duh. And why? Because they need them, which is the whole point of this conversation: people need tow hitches.

    This is nonsensical. If they have their own 12V feed, then you're saying that the 12V lead-acid battery can't support a dash cam. Which is a hilarious notion. A 12V battery is powerful enough to weld with, but not run a dashcam?
     
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  15. MP3Mike

    MP3Mike Well-Known Member

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    There are at least three different rear motors for the Model 3. (IGBT, MOSFET and MOSFET LC) And I think that is just for the LR models, I think there is a different version for the MR model.

    It is possible that they didn't have all the variants available when they started AWD production so they got the P version. But they are likely getting the correct version now. So I wouldn't hold out any hope for software unlocks.
     
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  16. mongo

    mongo Well-Known Member

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    OT

    I have no doubt as to the ability of the motors to pull and stop a load. However, that is not my point. Old cars: overbuild steel with limited engine/ trans/ cooling. Tesla: more optimally design frame with torque happy electric motors. Do we know if Tesla designed the rear cross member to handle the unique loads of a hitch?

    I did not say anything about the bolt not taking the load, I am referring to what the bolts are attaching to. I can attach a flag pole with 1/2 carriage bolts to my house's fascia, and then rip the entire fascia off. However, I can hammer on the fascia all day and only dent it... The fasteners are not the concern.

    The rear structure of a car in a rear end collision is placed primarily into compression. The upper portion of the rear structure in a collision is not pulled toward the crashing vehicle. Also, the rear structure in a collision is made to deform, something you do not want in a hitch attachment.

    Then they should get a car that fits their needs or deal with the compromise, not complain that Tesla didn't give them exactly what they wanted. Or complain that Tesla should have taken the extra time, effort, money, and trade offs to include a hitch (or hitch support structure) and hitch light control electronics originally, or say Tesla is being mean. Relying on people to observe a load limit when they do not observe a load embargo only illustrates that Tesla would need to overbuild the structure if they included towing.

    I did not say the battery cannot drive the lights. The 3 monitors the 12V battery, the 3 charges the battery from the HV pack, the 3 knows how much charge it put in the battery, the 3 throws a fault if the 12V battery drains too quickly. The 3 monitors all loads in the car, so unless you tap into the power port (or Tesla has a hidden auxiliary power tap) the car will sense and throw a fault regarding the unexpected draw. It may be more forgiving when the car is on vs sleeping, but I wouldn't count on it.

    See: Dashcam Install Help
     
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  17. JRP3

    JRP3 Hyperactive Member

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    While true I would be surprised if the car wasn't designed with the intention to have a hitch at some point.

    *Oops, didn't see the mod message.
     
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  18. FrANce

    FrANce Member

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    A hitch is a necessitaty in our household. We already have a Model S and were looking forward to replace the last remaining ICE car with a Model 3. Turns out that we have to keep the ICE (in addition to the two Teslas) for the sole purpose to get rid of garden waste and for the odd transport job.
     
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  19. KarenRei

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    #19 KarenRei, Dec 29, 2018
    Last edited: Dec 29, 2018
    You don't get a NHTSA VSS of 0,38 by having a flimsy frame. Period. End of story.

    You keep missing the point, so often that it's starting to seem deliberate now: there are no "unique loads of a hitch" that are more intense than the loads the frame will experience in a severe collision. On any axis. The forces exerted on a hitch are laughably small by comparison. On all axes.

    "What the bolts are attaching to" is a UHSS safety cell on a vehicle with by far the lowest combined probability of injury that the NHTSA has ever given out. They're the attachment of a critical crush structure to the safety cell.

    Or shear. Depends entirely on the angle of impact. Even when perfectly aligned with the axis of the vehicle, initial force loads then tend to get translated into shear and torque on other elements (something stiffening elements try to resist). Think of crushing an alumium can - what's initially purely compressive force then gets translated into bending and twisting.

    A 1850kg Model 3 in an accident decelerating from 30 m/s to 0m/s in 1/4 second is experiencing an average of 4,2MN force. A 250kg trailer undergoing 1G acceleration or braking is experiencing 1/2000th that force. There's more than three orders of magnitude difference between the two. If we were to analogize the force of a Model 3 in an impact to the weight of a 70kg human standing on the floor, the force of a trailer accelerating or decelerating at 1g would be analogous to the person holding 8 Hershey's Kisses in their hand.

    Towing loads are...
    Not. Remotely. Comparable.
    ... to crash forces. They're completely irrelevant to the structure they're bolted to. Your argument is akin to arguing that a person is going to make the wall of their house collapse because they hung a painting on it.

    Why, great idea! By all means, please point us to the low-cost highly-efficient dual-motor supercharging good-performing AP-capable OTA-updated out-now vehicle that you're picturing as an alternative.

    Yeah, the last thing we need right now is an American (aka, someone from a country where most people don't give a rat's arse about towing) lecturing Europeans about what they do and don't need.

    The nothing, nothing, nothing and nothing - as extensively covered elsewhere. They literally could do nothing more than flag the vehicles as tow rated, buy Eco Hitches and converter-based wiring connectors, and use part of the funds from sales to pay for their installation at the destination (even from third party shops). They certainly can do more than that, but at a bare minimum, the only thing we need from Tesla is simply to give the vehicles a non-zero tow rating.

    Your link does not state what you claim. The problem people in the thread were encountering was the use of cabin 12V sources, which are on wires of limited gauge and virtual-fused. Model 3's DC/DC converter is 2,5kW. Even the 12V socket in the cabin can give 150W, well more than even the most powerful brake light / turn signal kit you could realistically put on a trailer. You think the car is going to cut out if you plug something into the 12V socket?

    ED: Just saw the mod note. Do we have a thread somewhere?
     
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  20. mongo

    mongo Well-Known Member

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    Landing spot for OT debate from Market Action per @AudubonB's proper request. (please update title)

    With help from @MP3Mike who read the manual

    notow.PNG
     
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