Range reduction when towing.

Owner13669

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how much range reduces when I tow with cybertruck, let's say im towing 5000lb.

for a traditional truck, I know when I tow something heavy, my mpg reduces a lot. I think this should be same on cybertruck right?

Do you want to use cybertruck to tow?
how much you tow usually?
An RV company tested this by pulling a large aerodynamic trailer, and a small light one that was not. The fuel mileage was better for the large trailer than the small one.
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An RV company tested this by pulling a large aerodynamic trailer, and a small light one that was not. The fuel mileage was better for the large trailer than the small one.
If you look at No. 46 you will see that there are 6 loads on a vehicle's power source. They vary in relative magnitude depending on driving conditions. Some of them depend on vehicle weight. Some depend on vehicle speed. But drag depends on the square of vehicle speed. So if you drive fast enough eventually drag will become the dominant load. It is not at all surprising that a small trailer could present more drag then a heavier one and therefore, if driven fast enough, deliver poorer mileage.
 

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Here are some loads for a 5000 lb vehicle on flat terrain. The first one represents a CT with no load. Note that regen is on.

5000 lbs Speed 50 to 20 Avg 41.9 mph, 0.0 ± 0.0 %grade , Wh/mi Total: 377.5, Drive: 25.4, Slip: 48.2, Drag: 125.3, Roll: 63.6. Gravity: 0.0, Inertial: 35.7; Regen. On, Brake 22.1

This one is for another 5000 lb vehicle with the same rolling resistance and weight. It represents a towed load. A towed load has no regen so it is off.

5000 lbs Speed 50 to 20 Avg 41.9 mph, 0.0 ± 0.0 %grade , Wh/mi Total: 507.5, Drive: 25.4, Slip: 48.2, Drag: 125.3, Roll: 63.6. Gravity: 0.0, Inertial: 244.9; Regen. Off, Brake 152.1
As passively towed vehicle has no slip loss we need to take that 48.2 Wh/mi off for a total of 459.3 Wh/mi for the towed vehicle. Thus range is reduced to 377.5/(377.5 + 459.3) = 45.1 %


Now doing the same thing for a 4% grade:

5000 lbs Speed 50 to 20 Avg 41.9 mph, 4.0 ± 0.0 %grade , Wh/mi Total: 801.6, Drive: 43.9, Slip: 83.4, Drag: 147.8, Roll: 75.8. Gravity: 336.9, Inertial: 27.7; Regen. On, Brake 12.9

5000 lbs Speed 50 to 20 Avg 41.9 mph, 4.0 ± 0.0 %grade , Wh/mi Total: 877.6, Drive: 43.9, Slip: 83.4, Drag: 147.8, Roll: 75.8. Gravity: 336.9, Inertial: 189.9; Regen. Off, Brake 88.9


Again we take off the slip load this time 83.4 Wh/mi so that the total load for the towed vehicle is 877.6 - 88.9 =788.7 and the range reduction attributable to it is 801.6/(801.6 + 788.7) = 50.4%

So as I said, the reduction in range is about the same, mountains or not.
why is there more drag on the 4% load?
 

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If you look at No. 46 you will see that there are 6 loads on a vehicle's power source. They vary in relative magnitude depending on driving conditions. Some of them depend on vehicle weight. Some depend on vehicle speed. But drag depends on the square of vehicle speed. So if you drive fast enough eventually drag will become the dominant load. It is not at all surprising that a small trailer could present more drag then a heavier one and therefore, if driven fast enough, deliver poorer mileage.
In the article, they were towed at the same speed. Which is interesting. I’m sure at slower speeds, results would vary.
 

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why is there more drag on the 4% load?
Because there was an error in my code. Thanks to you I am aware of it and have fixed it - tentatively. The earlier post has new numbers. They don't change the conclusions.

This kind of feedback represents the forum at its best IMO. I am most grateful.
 

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In the article, they were towed at the same speed. Which is interesting. I’m sure at slower speeds, results would vary.
Yes, they would. Speed isn't the only factor in vehicle load. It gets most of the attention because drag related the energy consumption per mile depends on its square. But it also depends directly on air density, drag coefficient and frontal area. A streamlined trailer (one with low Cd and A) will beat one that isn't even if it is carrying more weight at the same speed.
 

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how much range reduces when I tow with cybertruck, let's say im towing 5000lb.



Do you want to use cybertruck to tow?
how much you tow usually?
"for a traditional truck, I know when I tow something heavy, my mpg reduces a lot. I think this should be same on cybertruck right?"

When we drive an EV we're vigilant about range. When we drive a liquid-fuel vehicle we don't much care, because we can refill at about every major corner. So that makes us think that when an EV pulls a trailer, it's mileage will drop more. But would not the trailer-pull range have a similar decrease with any power source?
 

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"for a traditional truck, I know when I tow something heavy, my mpg reduces a lot. I think this should be same on cybertruck right?"

When we drive an EV we're vigilant about range. When we drive a liquid-fuel vehicle we don't much care, because we can refill at about every major corner. So that makes us think that when an EV pulls a trailer, it's mileage will drop more. But would not the trailer-pull range have a similar decrease with any power source?
I don't think that at all. In fact range should reduce less for CT with the same trailer than it would with a gas F150. The same is true for a diesel vs gas. People try to argue that is because diesel specifc energy is denser but this is wrong.
It takes power to do work, but there are 2 components to power. Force and time.
If we keep time the same and make the f150 have 100 force then double the load it will take 200 force to perform the work. Lets say it takes 100 units of energy to produce 100 force. Therefore 200 takes twice the energy.
For CT it takes 100 units energy to produce 200 force. ( its a more efficient higher torque setup) if we then add the same additional load that doubled the load on the f150 we still only need 200 force to move the load with the same time as the f150. No additional energy is required, all we lost was the CT ability to do the work in half the time before.
What i am saying.... the higher a force that a power plant produces the less additional work affects it. It is the percentage of load increase that matches the percentage of energy increase.
 

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The CT also has a shorter cabin with a more efficient airstream, which means for towing the same brick, the drop in over all (truck plus trailer) air resistance efficiency is more pronounced than the F150.

-Crissa
 

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The CT also has a shorter cabin with a more efficient airstream, which means for towing the same brick, the drop in over all (truck plus trailer) air resistance efficiency is more pronounced than the F150.

-Crissa
So if a trailer adds an additional air load of 10 on a f150 it adds a larger load than 10 on a CT. It doesn't become more of a load just because the tractor is less of a load.
 

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So if a trailer adds an additional air load of 10 on a f150 it adds a larger load than 10 on a CT. It doesn't become more of a load just because the tractor is less of a load.
The drag of a trailer is not a static amount. The drag from the trailer is added minus the wake of the truck.

So if the profile of a CT is .3 and the profile of the trailer is 1. But the F150 is already .4.

So the range loss is going to be related to the difference between the difference in aerodynamics. This will vary some, of course, some trailers will be able to tuck into the truck's slipstream more than others, allowing the truck's leading edge to be more efficient, but for rough-box calculations... This will be true.

The F150 already loses range for being a half-brick.

-Crissa
 

Dids

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The drag of a trailer is not a static amount. The drag from the trailer is added minus the wake of the truck.

So if the profile of a CT is .3 and the profile of the trailer is 1. But the F150 is already .4.

So the range loss is going to be related to the difference between the difference in aerodynamics. This will vary some, of course, some trailers will be able to tuck into the truck's slipstream more than others, allowing the truck's leading edge to be more efficient, but for rough-box calculations... This will be true.

The F150 already loses range for being a half-brick.

-Crissa
Yes I agree that potential interaction between the combination of the truck and the trailer could potentially increase the aero load for CT vs f150. But ignoring that the 1 stays the same. It adds that to both systems and increases energy requirement for both. The question of range reduction is a percentage problem though. A system that is more efficient at converting energy to power does not suddenly become less efficient when load increases than the less efficient system.
 

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The 1 is a maximum for a box. We agree the two trucks use the same energy (aside one motor being more efficient than the other) to push the same air out of the way, right? And the truck itself uses range for some number.

For the Cybertruck, it starts with .3 coefficient of drag. Let's simplify this, and say it uses 3 units of energy to move itself. The Ford has a .4 CD. Therefore it uses 4 units of energy to move itself.

When you add the box's 1.0, that's ten units of energy (given this simplification) needed to pull the trailer. And the existence of the truck might lower the box's number, but we're ignoring that for the moment... So the Ford has to expend 6 additional units of energy, but the Cybertruck has to spend 7.

So the Cybertruck loses more range pulling the big thing that we agree takes more energy to pull.

-Crissa

PS, the Cybertruck will have bigger batteries at a lower cost, so this won't matter. But there will be breathless articles about how much range it loses. Even while the total loss won't be all that bad.
 

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The 1 is a maximum for a box. We agree the two trucks use the same energy (aside one motor being more efficient than the other) to push the same air out of the way, right? And the truck itself uses range for some number.

For the Cybertruck, it starts with .3 coefficient of drag. Let's simplify this, and say it uses 3 units of energy to move itself. The Ford has a .4 CD. Therefore it uses 4 units of energy to move itself.

When you add the box's 1.0, that's ten units of energy (given this simplification) needed to pull the trailer. And the existence of the truck might lower the box's number, but we're ignoring that for the moment... So the Ford has to expend 6 additional units of energy, but the Cybertruck has to spend 7.

So the Cybertruck loses more range pulling the big thing that we agree takes more energy to pull.

-Crissa

PS, the Cybertruck will have bigger batteries at a lower cost, so this won't matter. But there will be breathless articles about how much range it loses. Even while the total loss won't be all that bad.
So you are saying if you artificially set both rigs as a box the more efficient rig has a greater change therefore it is affected more. But what is actually happening is that it was just further to change the efficienct rig as a box.. Since both f150 and CT are the same height and same width the total frontal area has to be the same. The CT slopes that area more effectively and just dropping that and saying now its a box the same as the 150 and because I had to do more to make it a box will not match the real world the .3 CT with additional trailer exposed of say .5 will become .8 and the f150 with .4 add .5 becomes .9
 
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