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Flat Towing

I have emailed Tesla asking if the model S is flat towable. The response I got said no, as the gearbosx is only lubricated when the car is ON.
I did a bit of research and found out that the Model S has a Borgwarner gearbox, that is mechanically lubricated. In other words, so long as it is rotating, it is lubricating. The only thing that would keep it from being flat towed is the Park Pawl, which can be electrically overridden.

The reason I want to be able to flat tow, is because I have a diesl pusher motorhome and would like to take my primary car with me. Yes I know, I could trailer, but you try showing up at a camp ground with a 40' RV and a 20' car hauler trailer. 90% of all camp ground(especially National parks) cannot accomadate that combo. Most RV'ers flat tow and then park their car sideways in front of their RV or park in the overflow area. Also, if the Model S could be towed, then I could charge it with my Diesel Generator. It puts out 220V @ 45Amps. Enough to charge.

So, I ask an Engineer from Tesla to weigh in on the subject. Do you say it isn't flat towable to avoid warranty issues, like toyota with their the FJC(yes I flat tow my 6MT) or id you guys really forget to think of all the potential RV customers who would love an all E car. If it is just to avoid warranty, then I could careless and would reserve one and when I get it, make it tow ready like my FJC
6MT FJC towable

Best Regards
-AL

I have been curious about this too. If the car can be put in neutral while not in drive or reverse and the car can be pushed then it should be fine.... however I don't know if this is possible. Anybody with an S put it in neutral yet and seen if it rolls down a hill on it's own 8-O

Is it possible that there is no way to turn of regen?

@SwiCago | NOVEMBER 7, 2012: The only thing that would keep it from being flat towed is the Park Pawl, which can be electrically overridden.

Oh, is there a Park Pawl in the Model S? I was assuming that it didn't have one, because when you put it in park, it engages the emergency brake. I thought the Model S was more like a manual shift car, rather than an automatic as far as "park" is concerned.

@Sudre_
Honestly I could careless about regen, when Towing and I am sure Tesla has a way to allow the customer to select or they could add the option with Software. If I flat tow with an RV, I would not want regen...it would cause to much drag. Recharging at campsite or with an umbilical cord from my diesel generator would be smarter and more efficient.

@Alex K
From what I read about the BorgWarner gear box, it is an E-ParkPawl, but who knows, it might be a different configuration for the model S...hence asking for an Engineers input.

Again, would be nice for an engineer from Tesla to weigh in on the subject...An Electric motor not engaged with the battery, will neither take or produce power. It is in a state of free rotation and since the drive gear is mechanically lubricated, I can't see how anything could be damaged. The only thing that keeps the car from rolling away is the ParkPawl and possible the engaging of the brakes.
I saw a chassis floor model of the S and I was able to freely move it back and forth. So I am very interested in flat towing this car. Others may not be, because it is a pricey car...but again I could careless about that. I'd flat tow a Ferrari if it was possible LOL

For what it's worth - your thinking makes perfect sense. We are fellow RV'ers and the "S" would be the perfect car for towing - charging could be done at the campground or via a generator. I would love to see an RV pull into a campground with a Model S behind it - it would create quite a stir:-)

SwiCargo;
That's "couldn't care less".
The only "cost" of flat towing in gear would be the spinning up and down of the motor mass and drive. I.e., inertial effects. As you say, no "generator drag".

@Brian H
You're right, my bad...old force of habit. At least I spelled brakes right LOL

But you understand what I am asking Tesla.
Hopefully we'll hear directly from them on this. This is the only reason why I have not signed yet. I will not buy an EV that I cannot tow.

More problematic for Model S towing is that there is nothing to attach the towing cable. Every part in the front is designed to withstand push but not pull. If you attach towing cable to bumper you end up towing that bumper instead the full car.

I think same applies with Model S used as towing vehicle, only in the rear.

Only way I can think of that could work is with "tow bar" system that lifts the front wheels off the ground and uses them as towing point. Not necessarily very healthy for the car though.

Not sure you want to pull it with the front end raised. Too easy to drag the rear, since the car is so long and low.

@Timo

Flat towing means all four on ground with a tow bar, not tow dolly.
You would never tow a car behind an RV with just cable. What is to prevent it from smashing into the RV, when it stops.

To make a car flat towable, requires modification to the front. This is generally a mounting bracket that is attached to the frame and then a tow bar is attached to that mounting bracket. The brackets are usually made and installed, so that they do not look like S#%t. Safety chains/cables are added in case of break away. And depending on skill of the installer, you would either add lights with magnets or tap into vehicle lights. Same for brake control. Either a device is added or the vehicle brakes are tapped into.

In my first post, I posted a link to my tow setup for my FJC..there you can see what flat towing is. I installed the entire system and the RV has full control over the FJCs lights and brake systems.

An EV would be an ideal tow car for many RV'ers. You could charge while towing or at camp grounds. I see no reason why the Model S can't be towed. But that is why I am here, to hear from an Engineer.

Frame is aluminum and supporting beams are deep in the car interior. It just isn't designed for that kind of use. There is nothing close to front that you could use as mounting point, or that is my understanding of the reasons why Model S can't be flat towed.

Also if you refer to regen by "recharging while towed", then reason is that that causes strain to car structure. AFAIK car can't be charged while it is moving.

It's also kinda heavy high-end car. I don't think you see many high-end MB:s or Jaguars towed by RV:s either. It is meant to be driven, not to be towed.

@Timo,

I don't buy that. Any car can be modified to be towable. Brackets could extend out from under the front and be attached directly to the frame, I have seen that before! But that is besides the point.

I never said anything about regen. Big RVs have diesel generators that can push a lot of current. More then what the Tesla needs. If I was told that in theory it could be flat towed, I'd add a charge receptacle to the front. Charge with my generator while towing or just charge at the campground when I would arrive.

Now to your other point. "I don't think you see many high-end MB:s or Jaguars towed by RV:s either" Trust me, more RV'ers woruld if the transmissions of those cars would allow it. You cannot flat tow an Automatic trans car, unless you can disconnect the drive line. And sometimes you cannot tow a manual transmission if it doesn't have a t-case(4 wheel drive cars) that you can disengage.
You never want the trans to rotate while towing. If you cannot disocnnect the drive line, you risk damage. That is why you don't see many high end cars being towed. But trust me, there are lots of expensive RVs ($500k+) on the road and if those folks could, they'd tow a BMW instead of a Honda. Heck, I looked into the Lotus Evora, but unfortunately it won't work.

The Model S is different. It doesn't have a transmission. It just has a single gearbox that is lubricated mechanically. And I know there is interest, because others already replied and there are other forums discussing EVs as tow'd vehicles...

So if you are not a Tesla Engineer or are not an RV'er interested in towing, your opinions in this thread are useless. It doesn't help to shoot down a topic that has not meaning for you. Sorry, but that had to be said.

SwiCago, as far as Timo shooting you down... you already posted, "I have emailed Tesla asking if the model S is flat towable. The response I got said no...."

Tesla has replied to you. So anything in this thread is just going to be user opinions.

When I mentioned the regen I did not mean anything about dragging the car around to charge it. I meant that Tesla said the car would have to be ON for it to be flat towed. If the car is on the regen is on.... unless you can completely turn it off. I know people own cars and they could respond to that. Do you know if it is possible to turn off regen completely? If the car is not on then it is in park.

I think car automatically turns regen off when battery is full (you can't charge a car that is already full), so that is possible with software. I think also that gearbox is locked when car is at park so that would prevent towing, but I think that that too can be turned off by software.

Maybe Tesla answer is more a case of "how it is designed", more than "what can be done". Model S is not designed to be towed. In order to flat tow it you need to change a lot about the car, especially the usable tow points for the tow bars are deep inside the car, so that would require quite a bit modification.

If you are ready to void the warranty you can buy Model S and modify it to be towed, but I would not recommend it. As SwiCago says any car can be modified to be flat towed, it is only matter of can it be done with reasonable amount of work and time (and money). I think you would need to stretch the concept of "reasonable" if you modify Model S to be flat towed.

Here are some design features i would like to see in later versions released.

I would like to see a gear selection added - "Towing" as there are a number of legitimate reasons you would flat tow your Tesla as the original poster pointed out.

how i envision it working is like this, using an array of accelerometers to switch on charging, the car would harvest energy from the tow ONLY when going down hill or when decelerating so as not to tax the efficiency of the towing vehicle. this would have an added advantage of drag reducing the amount of breaking needed as your towing vehicle picks up speed going down an incline.

this means that no matter what charge condition the car was in when hooked up it would in all likelihood be fully charged when you and your RV get to your destination and this is pure convenience

just one whacky idea eh :)

The flat-towing problem appears to be structural. There seems to be no attachment points forward which would not dis-assemble the car. Not good. Perhaps a dolly/"truck" under the front wheels would serve.

The tow manual does show attachment points for pulling the car onto a truck.

Would they be safe for flat towing? Possible, but dubious.

I have seen the raw chassis in person. The tow bar attachment points would be where the current bumper is mounted. It would be a bracket that is either welded on the bumper(permanent) or bolted between the bumper and frame(reversible). The attachment points would have to come through the dummy grill on the front. The grill could easily be replaced when reversing the setup, and covers could be made to hide the tow points.
I also got my hand on the schematics and there actually is a cooling pump for the gearbox (Borgwarner lied). The pumps are software enabled through relays. These pumps would either have to turned on via software or by means of jumping the relays in order to prevent any mechanical damage. All relays and fuses responsible to prevent damage to the drive train are in fuse box #1.
It is do-able, most likely not via software as Tesla probably doesn't want to be liable. So most likely it would have to be jumper overrides. Not your typical DIY, but doable with proper knowledge. I did a similar setup for my FJC, so who knows, maybe I will jump in and get on the waiting list.
Now the next thing to find out is if I can charge the Tesla, while off, but in motion ;) Charge via RV's generator


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