I suspect the electric motors will - in practical terms - tow vastly more than gas or diesel trucks.

and they will get the energy back going downhill.

It will ultimately be limited by it's cooling, as all Teslas have been. Can it manage long, steep grades while towing? Downhill, ICE motors can be driven by the wheels to preserve both fuel and brakes.

If regenerative braking is good enough technology for trains, it ought to be good enough of a technology for a light truck.

https://en.m.wikipedia.org/wiki/Dynamic_braking

Note that trains are a very different scenario due to not being battery powered.

Many (most?) trains dump excess charge into the grid, meaning that it has no limitations on brake power nor capacity.

Battery-powered vehicles have to protect their battery, limiting brake power to keep the battery cool, and brake duration as it cannot overcharge the battery.

To compete with a train, a battery powered vehicle would need to implement rheostatic braking (i.e. brake resistors).

Of course, conventional engine braking is not worth comparing to any of this, but I thought it was important to emphasize that trains ≠ cars.

Of course there are many differences between a train and a car.

But the technology is exactly the same: apply an electrical load to a motor/generator and it will generate a braking force. The source of the load doesn’t really make a difference as long as it meets implementation requirements.

(Perhaps maybe the most ironic way they could dump excess electricity could be by running the onboard air compressor — literally the same thing an ICE vehicle does to dump energy when engine braking: compressing air.)

My point is that the technology is definitely a good fit for braking large loads.

Of course, except that normal cars have no component to dissipate the load. The battery is the only way, and it has significant limitations.

A resonable auxillary air compressor won't make a difference. With a heavy trailer going down hill, you'd need to at least dissipate tens of kilowatts, maybe even touching triple digits if you also need to slow down.

Nowhere to dissipate the power → no regenerative braking.

There’s probably a few things this truck has that normal cars don’t have.

The air compressor comment was an illustrative tougue-in-cheek comparison, not a serious suggestion.

Imagine the amount of power needed to run an air compressor with a displacement in the 5-6 liter range. That’s exactly the amount of power we’re talking about. Because that’s literally what an engine-braking truck is doing, it’s driving its engine as an air compressor.

Your “tens of thousands of watts” estimate is probably just about right. And that’s not anywhere outside the realm of doable. That’s probably well within the abilities of regenerative system in the drivetrain this vehicle will have, but even if we assume it isn’t, a 10kw resistive load is a $100-$200 part, off the shelf.

My PHEV minivan (Chrysler Pacifica) does close to 100 kW of regen in hard braking. I imagine the Cybertruck could easily double that, probably a lot more.

Peak dissipation is not particularly interesting in this context.

That current is charging the battery—not dissipation. I have no idea what kind of energy the friction brakes dissipate (that's not reported on the dash like regen braking is).

From the perspective of braking a motor, charging a battery is just a way to dissipate energy. A bad one at that, considering that there must be ample room for charge, and the charge rate must be limited.

Sports cars dissipate several hundred kilowatts in their friction brakes (for reference, the Porsche Taycan which can almost do with only regen braking can regen ~270kW). A hard-braking truck will exceed this significantly, but of course distributed over many more brake discs.

However, for the trailer scenario, I assume that if you go up a certain slope using N kilowatt of propulsion to maintain a stable speed, you'd need somewhere in the ballpack of N/2 killowatt of braking power when going down during the full duration (unlike hard braking, which is only for a few seconds).

I'm not following some of your logic (especially the "bad one" part). Unless you start your journey downhill (which does apply to some people, I realize), you should always have room in the battery to store whatever energy you're dissipating—you had to get the energy to accelerate in the first place from somewhere, after all.

Also, peak braking performance is much different than effective regen potential, since you shouldn't need to do hard braking very often.

> I'm not following some of your logic

There are 3 things that limit regenerative braking in its braking capacity at normal speeds:

1. Battery capacity, as you mention. Mostly a concern if you started high, as you mention.

2. Battery charge rate (thermal and lifetime concerns), as you're within or exceeding fast-charge charging rates. Especially important as the battery is likely already operating hot from pulling the load uphill. To give an idea of battery wear, note that a Tesla Model S only allows you to fast-charge a fixed amount on a given battery before you are permanently locked out to not further deteriorate the battery.

3. Charge capacity from the motor controller, which limits total regenerative braking capacity.

The first two are unique to batteries, and become an issue with continuous regenerative braking (such as a long downhill slope with a heavy trailer). Number 2 is likely to be the biggest issue.

Optimal regenerative braking sinks take whatever you throw at them: Either a brake resistor for rheostatic braking, or a connection to the grid which from the perspective of the vehicle is an approximated load of infinite size. Rheostatic braking is only limited by cooling of the brake resistor, which can both operate much hotter than a battery and is much easier to cool.

So why do cars not have brake resistors? Because normal vehicles do not have problems with excessive regenerative braking. Even going downhill, their weight is unlikely to cause severe battery load (although it may fully charge). However, gravity is a bitch when your total weight exceeds 10 tons.

> Also, peak braking performance is much different than effective regen potential, since you shouldn't need to do hard braking very often.

Exactly. The reason I mentioned this is that you noted peak brake numbers, which have no meaning in relation to continuous load capacity, which is much, much lower.

Engine braking with ICE is practical, but is pretty much pointless to compare with regenerative braking capabilities of an electric motor.

Not only does regenerative braking recharge the battery, it is possible to apply entirely arbitrary reverse torque should need be, where an ICE has a pretty fixed resistance.

>where an ICE has a pretty fixed resistance.

That's what the gearbox is for

Apart from inertia on initial clutch-in, there are diminishing returns from increasing the gear ratio when it comes to compression losses.

It's not very useful on gas engines but it is for diesel

Towing capacity tends to be limited by braking/stability, not power.

It would need a compressed air brake system for the trailer, wouldn't it?

Not at this size. Electronic brakes are king when you’re sub-fifth-wheel.

As far as I know, at these trailor weights you have to seperatly brake the trailer itself, which you use compressed air connected to the trailer at the moment. I would guess unless you can brake the trailer electrically as well you would still need it. not sure how many traileros with electric brakes there are.

With the exception of rental trailers and boat trailers electric brakes are literally the standard until you get into trailers big enough that any vehicle you'd tow them with will have air brakes. Electric drum brakes are literally the standard. For the sizes of trailers a truck like this would be expected to tow you would have to go out of your way to find a trailer that does not use electric brakes (once again, boat and rental excepted).

Which is my point, in order to pull "near infinite loads" you most likely reach trailers that require air brakes. e.G. my Range Rover is allowed to tow up to 6.5 tons with the air brake system installed (which it isn't anymore because I never ever need it). And at these loads, the towing vehicle's brakes are much less relevant than the trailer ones.

When he said "near infinite loads" I was thinking more like the Toyota space shuttle stunt which is just something for the internet cheerleaders to jerk off to and doesn't actually say anything about the vehicle's real world performance.

Nobody is realistically thinking this truck can pull more than ~15-20k (and even then it would be a short distance and no hills type of trip because of cooling limitations) with the acceleration/braking distance/handling we expect in this day and age for vehicles towing things on public roads.

The single motor version is 7,500 lbs - almost exactly the same as a Dodge Dakota.

The Tri-motor is 14k lbs, a 2019 F150 is 13,200 lbs. https://www.ford.com/trucks/f150/2019/features/capability/f1...

I stand by my comment, this thing falls between a dodge dakota and a ram 1500.

"The towing capacity of the 2019 Ford F-150 ranges from 5,000 lbs. to 13,200 lbs., depending on how the vehicle is configured.*"

There is exactly one model of F150 that can tow 13,200. The other 47 models [1] mostly tow between 8-10,000 pounds.

[1] - https://www.ford.com/trucks/f150/models/f150-xl/

There’s exactly one model of cybertruck that tows 14k lbs. what’s your point?

My point is it outperforms the top-end F150, just like Elon promised it would, while also beating a Porsche 911 in a drag race. Just like Elon promised it would.

I haven’t done enough research on F-150 but I would guess it outperforms a more expensive F-150 at each of the 3 price points offered.

And that’s before accounting for maintenance and fuel savings.