Optimal Speed And Range Pulling A Trailer With A Tesla Model X – Video

OCT 24 2016 BY MARK KANE 16

The topic of optimal speed when hauling a trailer with an electric vehicle can be a little bit tricky because it’s important not only to factor in what is the size and weight of the trailer, but also the route distance/dynamics to be traversed (including elevation), and also which charging options will be available along the way.

Tesla Model X with trailer

Tesla Model X with trailer

Here, Bjørn Nyland shares his insights about the energy consumption of Tesla Model X when hauling a medium-size trailer and gives us a real good look at all the “math” involved in getting the most out of an extended drive with a load in tow.

Bjørn explains many scenarios in the video, but we have also summarized the numbers below as a quick reference.

Consumption, optimal speed and range when pulling a trailer

I discuss consumption with my trailer at different speeds and talk about the optimal speed when traveling between superchargers. I also show some extreme cases where you have to charge very long and what will happen if there are more superchargers on the way.

The base scenario indicates 300-360 Wh per km of energy needed at speeds of 70-90 km/h.

Energy consumption - Tesla Model X with trailer

Energy consumption – Tesla Model X with trailer

But if you need to charge along the route, then it becomes a question of whether it’s better to drive faster (and then charge more) or drive slower (and charge less).

The conclusion is that if the Supercharger will be available after 100 km (62 miles), then it’s a lot better to drive faster:

Energy consumption - Tesla Model X with trailer

Energy consumption – Tesla Model X with trailer

The advantage of driving faster obviously decreases if there will only be conventional DC fast charging/CHAdeMO options available (~40 kW average):

Energy consumption - Tesla Model X with trailer

Energy consumption – Tesla Model X with trailer

Slower charging, such as 16.5 kW isn’t advised. But if it’s the only option, the optimum speed will be lower in order to conserve energy and travel further (but really there not much difference compared to higher speeds – so its more of a driver preference situation).

Energy consumption - Tesla Model X with trailer

Energy consumption – Tesla Model X with trailer

If the route is 200 km (125 miles) there is not much difference between speeds, but higher speeds does still translate to a shorter total time  in total (driving & charging at Supercharger).

Energy consumption - Tesla Model X with trailer

Energy consumption – Tesla Model X with trailer

That said, big changes in elevation on a 200 km leg indicate a sweet spot at 80 km/h (50 mph), on shorter distances 90 km/h (56 mph) will be still better when using Tesla’s Supercharging network:

Energy consumption - Tesla Model X with trailer

Energy consumption – Tesla Model X with trailer

The final insight from Bjørn, that we totally agree with, is to always charge more (5-10%) than will be needed as there can always been unforeseen increases of energy consumption during a long trip.

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16 Comments on "Optimal Speed And Range Pulling A Trailer With A Tesla Model X – Video"

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Nice work

While nice work it clearly shows the need for lightweight and aero EV trailers.
Done right cuts range only 10% in a Tesla at any
speed.
And might even improve range in the not aero Leaf by cleaning up it’s aero drafting style.

Counter intuitive but I think its because the MPH charging rate is so high on the superchargers. It’s also better to run the battery at a lower state of charge since it charges faster than a near full battery. That said I still try to keep 50 miles of margin in case the unexpected happens –like a detour.

Superchargers aside due to limited locations, it is best, electric or ICE motoring, to drive at 55 to 65 mph depending on posted speed limit. Aerodynamic drag affects efficiency, assuming zero wind level surfaces, based on the velocity squared. Unless studies, people will speed always and everywhere no matter the distance. That leads to the average of 3 out 10 gallons of gasoline wasted. For EV’s it
means less miles per k/W hr and higher charging times. Our human bias, the simple calculations that faster means shorter time entities is wrong and leads to more pollution. Do the math to realize that 70 mph+ is not the best option.

Its definitely more energy efficient to drive slower. The rub is that including charging times you are hard pressed to do better than 50 MPH average speed because of the stops. So you find yourself running faster between super charger stops…..and as Bjorn proves it is faster…..assuming you have the superchargers at a short enough interval.

The big news is that there is little measurable difference in total journey time.

I agree with you. I am also surprised that many do not see that. If the difference was say 30 minutes or even 20 minutes I would have listened, but man he is talking about a few minutes here or there. It makes me wonder what are these people like up there in Norway? Do they time the rest room visits too? To see which rest room is best? I think this Bruce Lee look alike should take it easy. Now let me enjoy a few minutes of sun shine here in Cairo Egypt.

The maximum speed limit for anything towing a trailer in NJ is 55mph. Applies even on roads with 65 mph speed limits. It works well for me towing the Seadoo Sparks to the shore with the Leaf as going over 55mph uses too much juice anyway. I do wonder if anyone knows about the 55mph limit when towing, because i see plenty of trailers flying by at 70mph plus. Alot of other states have maximum speed limits when towing too, just google it.

On top of the trailer speed limits, trailer tires (ST rating) are rarely rated for anything more than 65 MPH. Yet I see overloaded camper-trailers doing 75-80 MPH on the interstate all the time. It is crazy.

I appreciate the data, but it would be more useful if there was a wider variation. A low speed of 43 MPH and a high of 56 MPH doesn’t really show much of a range in speed.

I know that some States do limit the speed at which you can pull a trailer… but some don’t. In addition, it would be beneficial to underscore the benefits of driving at a slower speed to maximize range. This article touches on the reality that in some cases, you can get there faster by driving slower, but that would be much more clear if the chart showed speeds in 5 MPH increments from, say, 45 MPH to 75 MPH.

It would also be beneficial to show the difference in pulling a small, medium, and large sized trailer.

I don’t in any way mean to belittle the work Bjørn has put in here. I see it as a good first effort. But I hope someone else will expand on what Bjørn has done.

What it shows is, that at supercharger rate of charging the speed does not affect the total time as much.
While with only 40kW charging rate, you got to think when to drive fast.

+1
Nicely summarized

100km/h missing… (permitted max. speed in Germany if you have the right car and the right “sticker” on the trailer – or does that mean that Tesla doesn’t meet the requirements for that? Or no 100km/h with trailer in his country?).

notting

Unless I missed it somewhere, the missing piece of information is the weight of the trailer. How much did it weigh? That trailer (depending on contents) looks to be less than 1000lbs. My boat on it’s trailer is ~ 3000lbs.

Unless there’s a lot of uphill and downhill travel, and assuming most of the travel is at a steady highway speed, rather than a lot of stop-and-go travel, then the wind resistance of the trailer is going to be a lot more important than the weight.

The rule of thumb is that for a car traveling at 55 MPH, half the car’s energy is spent fighting wind resistance. Pulling a trailer, especially one that’s not streamlined, as the one in the photo above isn’t, it’s going to be a lot worse at highway speed. And since wind resistance increases as the cube of the speed, the impact on an EV’s range is going to become much worse, rapidly, at higher speeds.

For an example of U.S. real-world Model X towing trip, see http://www.edmunds.com/tesla/model-x/2016/long-term-road-test/2016-tesla-model-x-range-and-charging-while-towing-a-trailer.html

Predictably, the Model X sucks while towing in U.S. conditions unless the trip is very short, especially given that many SCs don’t have pull-through spaces yet (Tesla didn’t realize the need for same until after the Model X came out, much as they didn’t realize earlier that all the world isn’t the Bay Area, and that snow clearance would impact SC layout in other climates).