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But if that is all you have, you still need:
safety chains,
a hitch,
a standalone brake controller (sits on the drivers side floor and physically pushes on the brake pedal when it senses deceleration),
a setup with lights to mimic the brake lights and turn signals of the RV (usually sits on rear trunk),
a baseplate (piece bolted to the Tesla that the hitch attaches to, which I think would be non-trivial for the Tesla because the attach points are usually in the grill),
and the way to run the coolant pump.

The "baby elephant" mode would only need the safety chains (legal reasons).

Even if it is not practical to charge the Tesla from the RV while driving, the Tesla would still get maximum range, as it would not be doing any fast starts or high speed driving. You might have to still charge it at a Supercharger every few hours, but that would be the same as any long trip.

This really would be a good market for Tesla - it is getting harder and harder for RV owners to get cars to flat tow. A favorite used to be the Honda CRV, but that can no longer be used because they went to a constant velocity transmission.
 
But if that is all you have, you still need:
safety chains,
a hitch,
a standalone brake controller (sits on the drivers side floor and physically pushes on the brake pedal when it senses deceleration),
a setup with lights to mimic the brake lights and turn signals of the RV (usually sits on rear trunk),
a baseplate (piece bolted to the Tesla that the hitch attaches to, which I think would be non-trivial for the Tesla because the attach points are usually in the grill),
and the way to run the coolant pump.

The "baby elephant" mode would only need the safety chains (legal reasons).

Even if it is not practical to charge the Tesla from the RV while driving, the Tesla would still get maximum range, as it would not be doing any fast starts or high speed driving. You might have to still charge it at a Supercharger every few hours, but that would be the same as any long trip.

This really would be a good market for Tesla - it is getting harder and harder for RV owners to get cars to flat tow. A favorite used to be the Honda CRV, but that can no longer be used because they went to a constant velocity transmission.

The brake controller and lights can also both be done with software. As a matter of fact, the brake lights should just work since they are always triggered by deceleration. The attachment for the hitch is the only physical part.
 

JeffK

Well-Known Member
Apr 27, 2016
6,997
6,932
Indianapolis
I'm not super sharp on induction motors, mind giving a quick explanation on this?
AC induction motors don't have permanent magnets and to generate electricity you need a coil of metal rotating in a magnetic field.
Therefore, what he's saying is that because an AC induction motor does not have permanent magnets the only way to generate electricity from the spinning motor is if you provide the coils in the motor just enough charge to allow them to act as an electromagnet providing a magnetic field for the rotating coils.

Here's a video about it from another thread:

 

Frank99

April 2018 Model 3 LR RWD, EAP, FSD
Apr 7, 2016
402
554
Arizona
Exactly.
You can take the starter motor from your car, and spin it by hand, and generate electricity. That's because it uses permanent magnets, and spinning it causes the loops of wire in the motor to rotate in the magnetic field.

Tesla could enable a "trickle charge" mode if the car was being towed by an RV. It would use exactly the same approach as regen mode, and could generate as much power to charge the battery as you wanted. But, you'd be requiring the RV motor to generate more power, and would be an inefficient way to do so. It'd be a lot more effective to cover the roof of the RV in solar panels....

A really cool (but really niche) approach would be to hook the Tesla Regen capability into the braking system when being towed, and use the Tesla to slow the RV by charging the Tesla's battery. When the Tesla battery was full, you'd have to switch back to using normal brakes, though. A lot of complication for a few owners for such a small company; but I'm sure that someone will do it 20 years from now when they're searching for features to add to their electric cars to differentiate them.

Technically, there really isn't a reason that I know of that a Tesla couldn't be towed. The motor rotor will be spinning - but the only thing that might wear there would be the bearings, and they'd be under such a slight load that the wear would be much less than if you drove the same number of miles that you towed. The Gearbox will be spinning, but with no clutches the oil pump should be spinning also and keeping everything lubricated - again at much lower load than driving. The oil in the gearbox is unlikely to need cooling at the load levels seen in this application. None of the batteries, electronics, or motor windings will be dissipating power, so none will need cooling. Everything else (driveshafts, etc) don't know the difference between towing and driving, so shouldn't have an issue.

/frank
 

Zoomit

Active Member
Sep 1, 2015
2,306
4,554
SoCal
A lot of complication for a few owners for such a small company; but I'm sure that someone will do it 20 years from now when they're searching for features to add to their electric cars to differentiate them.
Agreed. There are a lot of possibilities with a towed BEV to turn the combined vehicles into a through-the-ground hybrid. With a braking signal from the RV tow vehicle, as provided from it's brake controller or even just brake light circuit, the BEV could assist with braking by recuperating energy every time the driver brakes. The BEV could be turned on and provide a minor propulsion force dependent on grade. When going down a hill it would coast. On level ground it might add say 5 kW. Going uphill it could increase to maybe 30 kW to help the RV slightly.

As long as the BEV has that brake signal input, I think this could all be done with "just software." It might have 2 modes, one for max assist and one to ensure a full battery at the destination. You could set the modes from a phone app, but the BEV would need to know the destination to ensure the battery was full for that mode.
 

Frank99

April 2018 Model 3 LR RWD, EAP, FSD
Apr 7, 2016
402
554
Arizona
but the BEV would need to know the destination to ensure the battery was full for that mode.

That's exactly the kind of detail that someone will add in 20 years - integration of the navigation system (where am I going?), terrain database (what kind of hills am I going to run into today), BEV state of charge (Do I want to get there with the car fully charged, or am I arriving home at 10 PM and it'd be better to use the charge to improve RV mileage, and charge the car with cheap electricity in the garage), etc. A lot of juicy details to dig into and implement, but it's really too early to consider that now.
 

Zoomit

Active Member
Sep 1, 2015
2,306
4,554
SoCal
That's exactly the kind of detail that someone will add in 20 years - integration of the navigation system (where am I going?), terrain database (what kind of hills am I going to run into today), BEV state of charge (Do I want to get there with the car fully charged, or am I arriving home at 10 PM and it'd be better to use the charge to improve RV mileage, and charge the car with cheap electricity in the garage), etc. A lot of juicy details to dig into and implement, but it's really too early to consider that now.
I don't understand why this would take 20 years to implement. All of this is already done onboard the Model S/X. The Tesla app would "just" need to be updated to interface with the car's navigation system. I don't think there are any significant technical roadblocks; however, the user market is pretty limited so I don't see Tesla devoting the resources to creating this functionality anytime in the next few years.
 

Frank99

April 2018 Model 3 LR RWD, EAP, FSD
Apr 7, 2016
402
554
Arizona
There's absolutely nothing keeping this from being implemented today - except for the software engineering man-years of effort required to define it, specify it, program it, test it, validate it, and make sure it's rock-solid before shipping it out in production. I'm pretty sure Tesla has higher priority items at the moment.
 
There's definitely a market for flat-tow-able vehicles, but it's a very, very small percentage of the market. Tesla most likely will not be willing to spend the engineering time to make it happen.

There are 3rd-party solutions to make other vehicles flat-tow-able. But to make a Tesla the "be-all-it-can-be" tow-able vehicle, it really needs software updates. Because you would want features like:
  • Use regenerative braking as a "trailer brake" to help slow down the main vehicles, while also recharging the battery instead of wasting the braking energy. This is usually accomplished via mechanical linkage, but could be done by detecting wheel slippage and acceleration rates while in a "trailering" mode.
  • "Wireless" activation of brake lights and turn signals. Use the autopilot's front-facing camera to activate the Tesla's lights when it detects the brake & signal lights activating on the tow vehicle. No additional wiring required.
I just can't see it being worth the engineering hours, but I'd love to see it. You would see every single motorhome towing a Tesla behind it, because it would make 0 sense to use any other vehicle as the dinghy.
 
I still claim you shouldn't even need a hitch, and I don't think it makes sense to try to help use the Tesla to push or brake the RV.
It should be a relatively easy software addition to the autopilot capability to follow the RV at a set distance (1/2 a car length?), mimicking the RV's tail light and turn signal pattern just by using the cameras. You should not need a brake line wire, a hitch, nothing more than safety chains (and even those would only be necessary if they were a legal requirement).
The car would be driving itself, truly autonomous. It would probably get great range figures, as it would be being "driven" very conservatively and would be drafting the RV. The fact that it is operating as normal just means that the RV would need to make stops near a Supercharger on trips of more than 200 miles or so a day. For myself, I'm picturing having lunch in the RV as the Tesla recharges. Most campgrounds used by big RVs have 50 amp service to charge overnight.
Doing it this way (not actually towing) means that a small motorhome with not much towing capability could still use a Tesla as the "towed" car.

Issues:
You would probably have to get in and drive the Tesla out of the way if you had to back the RV up.
You would want to protect the Tesla from anything being thrown up by the RV (but this is already an issue with RV's towing anything.

I think it is a larger market than most people think. There are an awful lot of Class A and Class C motorhomes out there that would love an easy-to-flat-tow Tesla, and that market is only going to grow as the baby boomers retire.

I think this would make a great new feature for opening up a new market for Teslas, where most of the new functionality would be using already existing autopilot capabilities.

And do I hope that the above sentence triggers a search algorithm? Yes I do.
 
I like that idea UncleMoose. Especially the simplicity since you don't have to connect or disconnect the dinghy. But you would have to worry about the car running out of battery during long trips, possibly requiring supercharger stops along the way.

I think the towed version that charges itself whenever the brake is applied would be more desirable. The car could be charged & ready to go upon arrival.
 

_Guy_

New Member
Nov 20, 2016
1
0
Texas
I am a motorhome owner and have towed various vehicles for the past 12 years. When I heard about the upcoming Tesla 3, I gave them my $1K deposit in case I am done with that lifestyle and need a self-driving vehicle in a couple of years. It only occurred to me recently to look into whether the Tesla 3 could be a tow vehicle, and this forum came up in my search. I am very pleased that this subject is being actively discussed, and wish Tesla to know that my decision on whether to actually purchase the Tesla 3 when my place in the queue is reached may depend entirely on whether I will be able to tow it behind my motorhome.

Being able to charge the vehicle while it is being towed or 'baby-elephanted' by whatever means would be a huge plus, as I am more of a 'boondocker' and rarely frequent RV parks with power pedestals, and I also prefer remote locations that are typically far from charging stations.

I appreciate the opportunity to have shared my thoughts on this forum.

Guy
 

israndy

Supercharger Hunter
Mar 31, 2016
5,209
6,128
Alameda, CA
If it had to be a trailer [...] the car can "park" itself in the trailer you do not need room for a person to enter/exit the car.

I wrote elsewhere about wishing to tow a Tesla or just Summoning the car when I need it and in a day or so it just shows up, joining us on our trip and then parking itself while we travel away. Now that the car is soon to be in my hands I wonder what I will do the first few years. If I plan to full time and the M3 cannot be towed (still not sure why considering it can coast down hills) I will have to put it on a trailer. I am considering getting a box that I can put it in as it will be a new paint job, why not protect it.

Will the car be able to put itself into or onto a trailer with the summon mode? I keep seeing videos of people trying to stuff their MS into a garage only big enough for the car and it balks and going forward. I imagine that would only be made worse by putting a ramp between the car and it's destination. Once it's in an enclosed trailer I won't be able to chain down the front, will chaining down the back be enough?

Should I post this to a less model specific thread?

-Randy
 

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