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Towing travel trailer with Model Y

Jjrss

Member
Mar 9, 2021
251
164
Tacoma
Lippert is working on a powered chassis with Magna.

The Model Y doesn't have the payload to handle such a monster. I doubt the Cybertruck will have the payload capacity, hopefully it will.
Supposedly the tri-motor Cybertruck will have 14k lb towing capacity.

If a self powering/regen/assist trailer can reduce "actual" load by 25%, that becomes a 17.5k lb trailer, 50% load reduction assist = 21k lb trailer.

Just need the SW for the towing vehicle to predict the best times to tell the trailer when to assist, regen and brake.

Even cooler with putting motors in the axels... self parking/leveling. Unhitch the trailer, it scoots out of the way and backs it in where you tell it to go.
 
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BigTrailer

Member
Mar 18, 2021
70
55
Toronto, Canada
Supposedly the tri-motor Cybertruck will have 14k lb towing capacity.

If a self powering/regen/assist trailer can reduce "actual" load by 25%, that becomes a 17.5k lb trailer, 50% load reduction assist = 21k lb trailer.
Those numbers are always deceiving. You can almost never safely tow to a vehicles maximum capacity, because maximum capacity assumes 10% weight transfer from the trailer.

In other words a 14k trailer transfers 1400lbs to the tow vehicle, and the tow vehicle needs to handle that much payload. Plus its occupants and cargo. For an example, am F150 Limited crew cab can have was little as 1600lbs payload capacity. Even though it advertises 14k capacity with the max tow package. I wouldn't feel safe towing anything more than a 6-7.5k max weight trailer with it.

If you want the trailer to not sway at higher speeds, you generally want to transfer > 12% weight to the tongue.
 
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Jjrss

Member
Mar 9, 2021
251
164
Tacoma
Those numbers are always deceiving. You can almost never safely tow to a vehicles maximum capacity, because maximum capacity assumes 10% weight transfer from the trailer.

In other words a 14k trailer transfers 1400lbs to the tow vehicle, and the tow vehicle needs to handle that much payload. Plus its occupants and cargo. For an example, am F150 Limited crew cab can have was little as 1600lbs payload capacity. Even though it advertises 14k capacity with the max tow package. I wouldn't feel safe towing anything more than a 6-7.5k max weight trailer with it.

If you want the trailer to not sway at higher speeds, you generally want to transfer > 12% weight to the tongue.
Thats where you tie in this tech, but at a bigger multi-axle level:


Essentially, the motor neutralizes the weight to the tongue. While this may increase drag while starting from a complete stop, it would sense forward movement and gradually adjust unit its propelling itself.

More or less smart electric brakes, but using the motors themselves.
 

wackojacko

Member
May 17, 2018
41
20
Toronto
thought I'd add my limited towing with a SR Y. We bought a used tent trailer, 10' box and weighs about 1200lbs. I towed it a good 60KM on the highway and was going about 100 KM, for my American friends that about 40 miles and 60 Miles an hour. My consumption was 220wh/km or 352w/M. I was expecting a little worse, closer to 50% range loss. I think I could easily go 250km of the 393km rated range, which is decent. the shorter trailer for sure helps with range.
 
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BigTrailer

Member
Mar 18, 2021
70
55
Toronto, Canada
Essentially, the motor neutralizes the weight to the tongue. While this may increase drag while starting from a complete stop, it would sense forward movement and gradually adjust unit its

More or less smart electric brakes, but using the motors themselves.
That wouldn't work for a couple of reasons:

They're using torque to cancel weight. When you're talking about 20,000 lb especially going over bumps the amount of torque required to cancel the weight would be logarithmic.

More importantly with multi-axle you'll move the moment to the rearmost axle. That means any axle forward of it is unable to deliver torque to the hinge point. Effectively on more than one axle the other trailer axles cancel out the torque effect.

Finally on such a heavy trailer any powertrain failure on the trailer would mean that the entire trailer would destroy the rear axle of the tow vehicle.

The solution might work on a tiny single axle trailer to a degree. The suspension of the tow vehicle still needs to be adequately reinforced to support the weight in event of failure.

Think the best technology that will have within the next decade or so is something like an Safari Alto trailer. Plenty of room and utility with little weight.
 

Jjrss

Member
Mar 9, 2021
251
164
Tacoma
That wouldn't work for a couple of reasons:

They're using torque to cancel weight. When you're talking about 20,000 lb especially going over bumps the amount of torque required to cancel the weight would be logarithmic.

More importantly with multi-axle you'll move the moment to the rearmost axle. That means any axle forward of it is unable to deliver torque to the hinge point. Effectively on more than one axle the other trailer axles cancel out the torque effect.

Finally on such a heavy trailer any powertrain failure on the trailer would mean that the entire trailer would destroy the rear axle of the tow vehicle.

The solution might work on a tiny single axle trailer to a degree. The suspension of the tow vehicle still needs to be adequately reinforced to support the weight in event of failure.

Think the best technology that will have within the next decade or so is something like an Safari Alto trailer. Plenty of room and utility with little weight.

Or, stick an airbag on the leading axle(s) in 2+ axels trailers that regularly inflates dynamicly in conjuction with the rear axle torque application. Effectively lifting the weight off the tongue.

On emergency/catastrophic drive train loss of the trailer (hopefully exceeding rare), the front airbags inflate, and electric brakes can be used to safely stop, for approriate repair emergency tow vehicle support.

More things that could fail, but so is putting multiple motors and druve-by-wire/sw hardware applications in an EV
 

BigTrailer

Member
Mar 18, 2021
70
55
Toronto, Canada
Or, stick an airbag on the leading axle(s) in 2+ axels trailers that regularly inflates dynamicly in conjuction with the rear axle torque application. Effectively lifting the weight off the tongue.

On emergency/catastrophic drive train loss of the trailer (hopefully exceeding rare), the front airbags inflate, and electric brakes can be used to safely stop, for approriate repair emergency tow vehicle support.

More things that could fail, but so is putting multiple motors and druve-by-wire/sw hardware applications in an EV

Many more reasons why this won't work. Any time you go less than 10% of the total weight of the trailer you're going to create amazing sway. Now you can try overcome this with modulating the motors on the trailer; but I think the forces that will be placed on the hinge will be too strong to overcome. I'd have to sit down and do the math, but honestly I'm too lazy.

Next problem is, if you're using torque to lift the trailer. You've effectively made your dual (or tri) axle trailer a single axle again. Think of a drag-car launching, that's the physics behind removing the hitch weight. I don't think most camping roads can take a 20k axle :D

But maybe we're thinking about this all wrong because we're stuck with the old towing paradigm of unpowered trailers.

There's no reason a trailer couldn't be towed with axles in the front in back, just like a car. Then no weight needs to go to the tow vehicle. Basically it becomes a train instead of a trailer. Add some electronic smarts and you can add steering, and basically its just a "slave" car that follows the commands and maneuvering of the tow vehicle much like its on an electronic set of tracks. If Tesla can make self-driving; surely mimicking a tow vehicles maneuvers to which have access to as they're executed would be a much easier feat.

In reality you wouldn't even need to connect the two cars, they could just follow electronically.

Edit:

Just re-reading, and it looks like their confusion over what hitch weight is. Hitch weight is the amount of downward force that is placed on the rear axle of the car. So a 20k pound trailer transfers about 3000lbs -> 4500lbs of weight to its tow vehicle. The suspension needs to be able to handle that kind of down force. The Model Y can take about 880lbs of total weight (payload) to its suspension. Clearly a trailer of weight would destroy the suspension instantly even if it had the power and braking force to pull and stop said trailer.
 
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Jjrss

Member
Mar 9, 2021
251
164
Tacoma
Many more reasons why this won't work. Any time you go less than 10% of the total weight of the trailer you're going to create amazing sway. Now you can try overcome this with modulating the motors on the trailer; but I think the forces that will be placed on the hinge will be too strong to overcome. I'd have to sit down and do the math, but honestly I'm too lazy.

Next problem is, if you're using torque to lift the trailer. You've effectively made your dual (or tri) axle trailer a single axle again. Think of a drag-car launching, that's the physics behind removing the hitch weight. I don't think most camping roads can take a 20k axle :D

But maybe we're thinking about this all wrong because we're stuck with the old towing paradigm of unpowered trailers.

There's no reason a trailer couldn't be towed with axles in the front in back, just like a car. Then no weight needs to go to the tow vehicle. Basically it becomes a train instead of a trailer. Add the smarts and you can add steering, and basically its just a "slave" car that follows the commands and maneuvering of the tow vehicle much like its on a set of tracks.

In reality you wouldn't even need to connect the two cars, they could just follow electronically.
Yes! The train car vs traditional trvale trailer axle setup is more or less what I was envisioning as well.

Which is exactly how I saw it being able to park itself, unhooked from the tow vehicle.

Once up to speed, the mass inertia wouldn't require much input from the trailers drive train, which, if we're wanting to go further, you'd want to be able to charge the tow vehicle from a potential 200~1,000 kwh trailer battery (depending on how big the trailer frame is).

Hybride H2 fuel cell/battery setup could allow for some pretty cool applications.

And if you move to a Train axle configration, you could also look at independent suspension for forest service road type camping vs glamping trailers that stick to KOA sites and highways.
 

BigTrailer

Member
Mar 18, 2021
70
55
Toronto, Canada
Yes! The train car vs traditional trvale trailer axle setup is more or less what I was envisioning as well.

Which is exactly how I saw it being able to park itself, unhooked from the tow vehicle.

Once up to speed, the mass inertia wouldn't require much input from the trailers drive train, which, if we're wanting to go further, you'd want to be able to charge the tow vehicle from a potential 200~1,000 kwh trailer battery (depending on how big the trailer frame is).

Hybride H2 fuel cell/battery setup could allow for some pretty cool applications.

And if you move to a Train axle configration, you could also look at independent suspension for forest service road type camping vs glamping trailers that stick to KOA sites and highways.
I think you effectively end up with an "autonomous" vehicle that follows you. Maybe to not make the regulators (and public) so afraid of it you put some kind of mock "hitch" in place and if it disconnects the "trailer/train" comes to stop just like current trailers.

Actually I think we just made an electric RV, but instead of the Model Y getting towed you get drive it. And I've seen RV wrecks, honestly I'd rather be in the Tesla from a safety stand-point. No one should be in these RV's while they move down the road!
 

Jjrss

Member
Mar 9, 2021
251
164
Tacoma
I think you effectively end up with an "autonomous" vehicle that follows you. Maybe to not make the regulators (and public) so afraid of it you put some kind of mock "hitch" in place and if it disconnects the "trailer/train" comes to stop just like current trailers.

Actually I think we just made an electric RV, but instead of the Model Y getting towed you get drive it. And I've seen RV wrecks, honestly I'd rather be in the Tesla from a safety stand-point. No one should be in these RV's while they move down the road!

The difference would be, propelling itself at 80+ mph vs "assisting" in getting up to 80+ mph. Getting itself up a hill, and assisting a tow vehicle on hills.

A big drive train difference ;)
 

Araman0

Member
Apr 18, 2018
287
430
Seattle
While the discussion about powered trailers is fascinating, I'd prefer if this thread can stay on-point with the topic of towing with a Model Y. There's a lot of people who have questions, answers, and experiences with different aspects of towing with a Model Y and towing with an EV in general. I strongly recommend creating a new thread for the parallel discussion happening here about the science of powered trailers.
 

Jjrss

Member
Mar 9, 2021
251
164
Tacoma
I'm hoping that the Airstream electric-assist camper (Airstream To Make Electric-Assisted Camper For EVs) becomes a reality. It would be particularly awesome if its battery could be a Powerwall or similar that could be plugged into one's home electrical panel for backup and peak-shaving.
Wish there was more in that article on what they were implementing for the "assist" and any estimates on range extending.
 

hellobye

Member
Apr 14, 2021
55
44
Indiana
I bought this ball mount, and use it positioned upward to give a 2" rise. This is slightly against Tesla's limitation of rising a maximum of .75". But I can't think of a good reason why a 2" rise would cause any problems, and the 2" rise help keep my camper more level (which reduces risks associated with trailer sway).

The ball itself was a 2 5/16", which was what my camper (and possibly most campers?) required.
Increasing the ball mount height in either direction would increase the moment applied to the hitch receiver when starting/stopping. It's probably not a big deal if you're not towing at max load capacity, which most people won't be, but I imagine that's why it's there.

I've towed a lot with my Impreza, but found it incredibly annoying with the 6" rise ball mount that it would wiggle a lot when coming to a stop (flat bed trailer, 1-2 motorcycles), but the OEM hitch design didn't allow any of the "anti rattle" clamps to fit. I ended up using some old free depth gages and using them as shims to reduce the rattle. Given the tight space of the opening, have you guys had any luck with them on the Y?
 

Wabsa

Member
Jan 23, 2021
23
29
Maine
Took the Tesla and RTTC Grizzly out for a shakedown tow. The weather was not great, cold (38F), rain and windy in comparison to my not towing baselines, but here are my takeaways:

The Tesla hitch design sucks. Whoever thought any of this was a good design has obviously never towed anything and should be fired! I have to kneel on the ground behind the car to see what I'm doing!!
As has been widely reported the hitch cover is impossible to remove without tools and causing some damage to it. Clips have been removed, but still not good.
The safety chain hooks are buried and not visible, then the chains, once actually hooked up, contact the rear bumper potentially causing scuffing (I wrapped them to prevent this, but come on Tesla!)
The trailer 7-pin connector is also buried and causes issues if you try to connect a 4-pin to 7-pin adapter as the opening is small, and you can't open the cover flap wide to cleat the retention latch.
Anti rattle brackets will not fit on the hitch

Set Up
Tow vehicle - Model Y AWD LR
Camper - Rustic Trail Teardrop Campers Grizzly ~ 1700lbs as towed - Grizzly Bear | Rustic Trail Teardrop Campers

Test route out and back totaling 50 miles with 28 miles of highway @~65-70mph + 22 miles of backroads @~25-30mph. Minimal elevation change.

Non towing consumption
Northbound = 280wh/mile
Southbound = 246wh/mile

Towing consumption
Northbound = 540wh/mile
Southbound = 460wh/mile

Summary
The car tows effortlessly, installing and removing the tow ball and connecting the electrics and chains is horrible. Consumption increase is basically doubled, but not unmanageable and will meet our needs for our typical trips, but probably not great for super long cross country road trips, I'd probably revert to a tent and B&B's for long trips.
It will be interesting to see the performance over the summer when the weather is warmer, but overall it is a usable solution for towing our small camper
IMG_1132.jpg
 
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Patrick-Ghost

New Member
Apr 20, 2021
4
1
Canada
Just hitched our new Y to our Alto trailer.
Looking forwad to our first camping trip in May.
Dry weight 1750lb
Top up for camping

View attachment 651174
View attachment 651173
Love your yellow Alto! We have an Alto too. I'm trying to find the right ball mount for our MY with enough rise to accommodate the manufacturers recommendation of 17.5" for the Alto. Do you mind telling me what ball mount you got and the rise it has?
 

Tom Spohn

New Member
Jun 28, 2018
3
4
Burien, WA.
Love your yellow Alto! We have an Alto too. I'm trying to find the right ball mount for our MY with enough rise to accommodate the manufacturers recommendation of 17.5" for the Alto. Do you mind telling me what ball mount you got and the rise it has?
I would like to have my logic checked on Hitch Weight for the Model Y. Manual states to have trailer level with the TV, and to have no more than 3/4 inch rise in the ball mount. For trailers that have hitch heights more than about 14 inches these constraints are mutually exclusive. Manual also states that a carrier, for example a bicycle mount, can weigh 160 lbs. I think I understand that this is due to the twisting moment the carrier would exert on the hitch.

I looked at a carrier of about 40inches height that would carry two bikes and, per the manual, assumed I could load a total weight, including the weight of the carrier, of 160 lbs. on it. (Really heavy bikes!) If the hitch can handle 350# at 3/4 inch and 160# at 40 inches simple arithmetic says the 350# limit decreases about 4.8 lbs per inch of rise. So if I install a ball carrier with a 4 inch rise the capacity drops to about 330 lbs. 350- (4.8 X 4).

Does this sound reasonable? Weight change due to height may not be linear or there may be some other engineering variable I forgot to consider.
 

Webeevdrivers

Active Member
Jan 2, 2017
2,279
3,992
Canada
I would like to have my logic checked on Hitch Weight for the Model Y. Manual states to have trailer level with the TV, and to have no more than 3/4 inch rise in the ball mount. For trailers that have hitch heights more than about 14 inches these constraints are mutually exclusive. Manual also states that a carrier, for example a bicycle mount, can weigh 160 lbs. I think I understand that this is due to the twisting moment the carrier would exert on the hitch.

I looked at a carrier of about 40inches height that would carry two bikes and, per the manual, assumed I could load a total weight, including the weight of the carrier, of 160 lbs. on it. (Really heavy bikes!) If the hitch can handle 350# at 3/4 inch and 160# at 40 inches simple arithmetic says the 350# limit decreases about 4.8 lbs per inch of rise. So if I install a ball carrier with a 4 inch rise the capacity drops to about 330 lbs. 350- (4.8 X 4).

Does this sound reasonable? Weight change due to height may not be linear or there may be some other engineering variable I forgot to consider.
In my humble opinion all of this is over engineered anyway. Being 10 percent over on max hitch weight or tow weight is not a concern...in my opinion. In my business I routinely see hitch weights and tow capacities exceeded by as much as double..which is scary...but not unusual.
 
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Araman0

Member
Apr 18, 2018
287
430
Seattle
I would like to have my logic checked on Hitch Weight for the Model Y. Manual states to have trailer level with the TV, and to have no more than 3/4 inch rise in the ball mount. For trailers that have hitch heights more than about 14 inches these constraints are mutually exclusive. Manual also states that a carrier, for example a bicycle mount, can weigh 160 lbs. I think I understand that this is due to the twisting moment the carrier would exert on the hitch.

I looked at a carrier of about 40inches height that would carry two bikes and, per the manual, assumed I could load a total weight, including the weight of the carrier, of 160 lbs. on it. (Really heavy bikes!) If the hitch can handle 350# at 3/4 inch and 160# at 40 inches simple arithmetic says the 350# limit decreases about 4.8 lbs per inch of rise. So if I install a ball carrier with a 4 inch rise the capacity drops to about 330 lbs. 350- (4.8 X 4).

Does this sound reasonable? Weight change due to height may not be linear or there may be some other engineering variable I forgot to consider.
I'm just guessing here, but for the bike mount I don't think the hitch limit decreases by height, but rather by the distance out from behind the hitch. Since the bike's weight is probably centered maybe 1 or 2 feet to the rear of the car / hitch, that distance out from the rear of the car is what produces torque that can multiply the weight of the bikes on the hitch. So in other wards regarding bike hitches, distance up from the hitch is probably not a factor as much as distance out from the back of the car the bikes are positioned.

Also for towing if you have to decide between getting a lower ball mount requiring the trailer to lean forward, or a higher ball mount that keeps the trailer level, it seems that keeping the trailer level is a far better option for stability of trailer. I bought a trailer mount that rises about 2.5 inches but keeps my trailer perfectly level. After almost 1000 miles with the trailer I haven't run into any issues with trailer sway or anything else.
 
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