Tesla packaged trailer upgrade kit

firsttruck

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Adding a motor to a trailer is simply unsafe. Here's why:

A trailer can become unstable if there is too little tongue weight on the trucks hitch. You can mitigate this dangerous situation by applying the trailers brakes if the driver is clear headed enough to do this, and do quickly enough. Applying only the trailer brakes will transfer weight from the trailer to the trucks hitch, temporarily applying the needed tongue weight to stabilize the truck and trailer.

If you add a motor to the trailer, with the thought of "pushing" or even providing a neutral drag affect, it will un-weight the hitch and create the dangerous scenario described above.
This would not be done with a simple on/off switch. There would be a control interface between the Semi & trailer where everything is coordinated.

In the future trailers probably come standard with a lot of sensors and cameras (inside & outside) too. All monitored by Semi and truck headquarters.
 

Crissa

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I'm not sold on adding power to the trailer wheels. I don't see the advantage. Maybe adding a battery pack to the trailer would be helpful to extend range, but power and or regen are not short supply with the CT
One, a motor is added rolling resistance.

Two, your regen is limited by your traction and your battery.

Three, if your battery is larger, you can handle more regen.

Four, your point about the hitch pull-weight stands: You still need more drag from the trailer when stopping to retain control. Which means you can't use all that regen available in the truck, it's capped by the trailer stopping power.

-Crissa
 

Gvardaman

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Well, since Tesla is battery-constrained at the moment, I think the OP‘s kit might nor have them.
Here’s what I am thinking. Please forgive me ifs some or all of these have been posted, I admit I red the first few posts and then wrote this.
solar roof, for sure
specs for a hardwired connection
specs for a wireless connection
specs for weight distribution
Possibly a camera package that could also integrate
And if/when possible, a battery pack or specs to make one
For the solar roof integration with or without a battery, you would need an interface that would filter the energy and convert it to a voltage the CT wants or store it for use in trailer amenities.
Likewise, a standard for how power can be taken from the CT when camped, to allow the drain to be managed with calculated distance to a charger/supercharger.
An additional connection that could be attached to the vault HVAC vents to feed the trailer would be nice.
ideally, a trailer would have a massive battery pack that could even be plugged in to a charger to carry a nice range extension along and an umbilical to feed to CT the high voltage while driving.

having a single motor which would be decoupled while towing, would be nice to connect
for <5 mph remote driving for parking, storage or camp placement..
 

OneLapper

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One, a motor is added rolling resistance.

Two, your regen is limited by your traction and your battery.

Three, if your battery is larger, you can handle more regen.

Four, your point about the hitch pull-weight stands: You still need more drag from the trailer when stopping to retain control. Which means you can't use all that regen available in the truck, it's capped by the trailer stopping power.

-Crissa
There would be some regen that could be recovered from the trailer when and if the trailer brakes need to be applied. Certainly not enough to justify hub motors on the trailer.

But, having a trailer with hub motors would be awesome if you could use them to move the trailer around the yard or parking lot!
 

firsttruck

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but power and or regen are not short supply with the CT
All heavy trailers have brakes for a reason. They do get used. Some have to be replaced in less than 50,000 miles. Also from a physics standpoint it is very difficult to design brakes for tow vehicles (Cybertruck, Tesla Semi, Ford F-250, Mack Truck) to do all the braking for the tow vehicle + trailer in all situations. Also it is not just the brake mechanisms. You have tire traction issues too. The braking on tires on the tractor are not always enough. When going down a mountian steep grade, even if the battery pack has room for a charge, the Cybertruck/Semi regen probably can not handle the regen charge rate that would be generated by trying to brake for the extra weight of the trailer.

The point is if motor cost & battery costs are low enough it might be worth it to put one on the trailer to get some of the energy back, extend life of trailer brakes, and reduce battery drain on towing vehicle, instead of just letting braking energy escape as heat.

This is all doable. The question is do the economics justify doing it. 10 years ago it would not have. Today, using scarce & costly lithium nickel probably not.
But if might make economic sense today using LFP batteries & solar panels on roof if you reduce need for more scarce & costly lithium nickel on Cybertruck & Semi.

Does it make economic sense to have 800 miles and up range battery on Semi when it is not needed most of the time? Or should trailer that need the range supply some of the motive power.
 
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firsttruck

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But, having a trailer with hub motors would be awesome if you could use them to move the trailer around the yard or parking lot!
Should be easy. Just need a two wheel dolly for the 5th wheel end of the trailer and a controller on the trailer or separate controller.
 

FutureBoy

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There would be some regen that could be recovered from the trailer when and if the trailer brakes need to be applied. Certainly not enough to justify hub motors on the trailer.

But, having a trailer with hub motors would be awesome if you could use them to move the trailer around the yard or parking lot!
So have a joystick controller that can be attached at the hitch that will allow you to “drive” the trailer around at very low speed.... That would be a killer feature.

The lift at the hitch would need a little larger wheel that is on a shopping cart wheel pivot but that should be simple.
 

Crissa

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There would be some regen that could be recovered from the trailer when and if the trailer brakes need to be applied. Certainly not enough to justify hub motors on the trailer.
The trailer brakes would have to be applied every time regen activated to maintain drag on the hitch for safety. That's alot of energy just thrown away as heat.

The added benefit of turning every trailer into a walking tractor would just be icing on the cake. Think of the narrow spaces you could shove it in. Or even be able to put it into space hitch-first, optimizing position for door access, umbilicals, or sun.

-Crissa
 
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Tinker71

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Ajdelange is right that for regen, the motor needs to be of appropriate wattage.

But I don't think it's as big of an ask as he seems to. He's making it sound impossible when it's actually quite simple... You just have to make sure draw and regen never exceed the battery's rating, and it has a limit how much regen it can take. But you can dump that to a radiant resistor or just use more brake. That's not rocket science.

-Crissa
I try to hypermile when ever possible. I avoid complete stops, anticipate stop lights etc. Heck when towing I even turn off the AC up steep grades and turn it back on going down. In a hard braking application you would waste a lot of the regen because the single drive motor assuming 20 HP max would only be able to take 14000 watts but as you said the other brakes would take over.
I think Elon already said Cybertruck would in realtime sense some towing load characteristics. The Cybertruck will already know if it is traveling on level surface or up/down hill. Based on increased torque needed to accelerate, regen when braking Cybertruck & trailer, increased power usage needed for steady cruise with trailer vs none, up/down hill power needs the Cybertruck would have a lot of info
Adding a motor to a trailer is simply unsafe. Here's why:

A trailer can become unstable if there is too little tongue weight on the trucks hitch. You can mitigate this dangerous situation by applying the trailers brakes if the driver is clear headed enough to do this, and do quickly enough. Applying only the trailer brakes will transfer weight from the trailer to the trucks hitch, temporarily applying the needed tongue weight to stabilize the truck and trailer.

If you add a motor to the trailer, with the thought of "pushing" or even providing a neutral drag affect, it will un-weight the hitch and create the dangerous scenario described above.
That is precisely why the motor needs to be smallish..... in my example I used a 20 HP motor, but you would never apply that much power accelerating, that size is for capturing regen. You take your on board battery size and spread that capacity over your trip time. For ease of math you have a 50 KWhr usable battery and divide by say a 5 hr trip. You would task 10,000 watts to offset friction. That is about it.
 

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