Model X Travel Trailer Consumption Analysis

[idoco]

it doesn’t seem to recognize when you are in Tow Mode and factor in the additional drag.

Agree with everything you said except ^^.

If you put a destination in the trip planner and toggle between trailer mode on and off you'll see a different estimate for energy usage and expected range. Trailer mode will reduce range estimate compared to trailer mode off.

What I'm still trying to figure out is if the estimate with trailer mode on is fixed or based on recent consumption. For the most part I find the estimate "adequate". But I wouldn't necessarily trust it blindly for a very long stretch between SC's where the SOC near the end would be < 15%.

As an aside...for longer legs where SOC at the end is predicted to be below 15% I start out a bit slower than the speed limit. After 15-30 miles I'll look at my energy usage. If lower than ideal (ideal for me being 475-500 wH/mile) I'll speed up. Higher than ideal I'll slow down. This basically ends up being a proxy for real time evaluation of winds, elevation, and temperature effects on energy usage.

 

[ohmman]

Agree with everything you said except ^^.

If you put a destination in the trip planner and toggle between trailer mode on and off you'll see a different estimate for energy usage and expected range. Trailer mode will reduce range estimate compared to trailer mode off.

What I'm still trying to figure out is if the estimate with trailer mode on is fixed or based on recent consumption. For the most part I find the estimate "adequate". But I wouldn't necessarily trust it blindly for a very long stretch between SC's where the SOC near the end would be < 15%.

As an aside...for longer legs where SOC at the end is predicted to be below 15% I start out a bit slower than the speed limit. After 15-30 miles I'll look at my energy usage. If lower than ideal (ideal for me being 475-500 wH/mile) I'll speed up. Higher than ideal I'll slow down. This basically ends up being a proxy for real time evaluation of winds, elevation, and temperature effects on energy usage.

I believe it's a fixed differential. It's never nearly enough for my camper. My guess is that your Bowlus has an efficiency more in line with whatever fixed parameter they use for tow mode. I can be certain that the trip planner estimate isn't nearly enough for my camper. It would surprise me tremendously if it were somehow dynamic.

 

[aesculus]

Tesla should hire @aesculus to work on that project. He could implement all kinds of fantastic improvements in the car nav! And also improve the Tesla app.

Geeze @ohmman , you should have thought of that years ago.

 

[AltoGrayhound]

Bonjour from Quebec, with my Garyhound X100D and Alto F1743.
I haven been on the forum for a while but I have new infos. This summer we travelled around 3000mi in different condition rain, front wind and sometimes good back wind. Instead of calculating each trip with weather variation I made an average for the summer of 624wh/mi with average temperature of 75F( I am in Canada!!). As some of you might remember, I was talking to add a nose to fill the gap between the Alto and the TX. See picture below. With this box prototype made of coroplast I gain 16% at 523wh/mi we did over 1000mi with this "nose". With those good numbers I decided to build a permanent one.
I am in discussion with Safari-Condo the manufacturer of Alto and a local small welding company. My next step will be the tail drag. I will do a coroplast prototype inspired by the tail system that we see on trucking trailers. I taught to include a bike rack eventually in the "tail box" After that I will work on side and under the Alto where there is a lot elements that can make turbulence. I hope to work with Safari Condo to manufacture something aesthetic. Thank you to all of you for the input via this group. As some have said, we need to work on aerodynamic to get EV accepted. There is always a lot of surprise and questions in camp sites around the capacity of towing.

Another interesting model might come to market from France. Look for "Tipoon" on internet. They will have a very low drag being as low as a jeep as you will see on the advertising. This type is very promising. The only potential problem is the slide out system. There is frequently water leaking with those.

 

[ecarfan]

This summer we travelled around 3000mi in different condition rain, front wind and sometimes good back wind. Instead of calculating each trip with weather variation I made an average for the summer of 624wh/mi with average temperature of 75F... With this box prototype made of coroplast I gain 16% at 523wh/mi we did over 1000mi with this "nose".

Bonjour from your fellow Model X / Alto F1743 owner in California. Thank you very much for your post. I am impressed by your hard work and the results. So do I understand you correctly that during your summer travels you averaged 624Wh/mi with “no nose” and 523Wh/mi with the “nose”?

What speed do you tow at on the open highway?

 

[AltoGrayhound]

Bonjour from your fellow Model X / Alto F1743 owner in California. Thank you very much for your post. I am impressed by your hard work and the results. So do I understand you correctly that during your summer travels you averaged 624Wh/mi with “no nose” and 523Wh/mi with the “nose”?

What speed do you tow at on the open highway?

Bonjour ecarfan 55MPH maximum on the cruise control most of the time, so even in the hills.

 

[ecarfan]

Bonjour ecarfan 55MPH maximum on the cruise control most of the time, so even in the hills.

Okay, thank you. I am surprised that at 55mph you averaged 624Wh/mi with your Alto F1743. I just returned from a 2,520 mile roundtrip from California to New Mexico and back towing my Alto F1743. For the entire trip my average was 525Wh/mi. I estimate that over 90% of that mileage was at 55mph, the remainder was at 60mph or below 55mph. My route included a lot of long flat stretches of road as well as elevation changes of thousands of feet in a single day.

So my towing energy usage at 55mph is essentially the same as what you get when using your “nose” on your Alto, and without your “nose” you have much higher energy usage than I do. That is puzzling.

By the way: I have the 15” wheels with Michelin tires. I assume you have the 13” wheels with Goodyear tires? But I doubt that makes much difference. I’m just trying to think of any differences between our trailers.

What is your tongue weight? I keep mine between 250 - 290 lbs.

What size wheels on your Model X? I have the 20” wheels.

 

[ecarfan]

If you put a destination in the trip planner and toggle between trailer mode on and off you'll see a different estimate for energy usage and expected range. Trailer mode will reduce range estimate compared to trailer mode off.

Thank you, I was not aware of that!

When I am towing and viewing the trip energy graph my experience is that the car navigation always underestimates my actual energy usage by at least 10% by the end of the route. So I don’t rely on it. I use the EV Trip Optimizer app.

 

[AltoGrayhound]

Okay, thank you. I am surprised that at 55mph you averaged 624Wh/mi with your Alto F1743. I just returned from a 2,520 mile roundtrip from California to New Mexico and back towing my Alto F1743. For the entire trip my average was 525Wh/mi. I estimate that over 90% of that mileage was at 55mph, the remainder was at 60mph or below 55mph. My route included a lot of long flat stretches of road as well as elevation changes of thousands of feet in a single day.

So my towing energy usage at 55mph is essentially the same as what you get when using your “nose” on your Alto, and without your “nose” you have much higher energy usage than I do. That is puzzling.

By the way: I have the 15” wheels with Michelin tires. I assume you have the 13” wheels with Goodyear tires? But I doubt that makes much difference. I’m just trying to think of any differences between our trailers.

What is your tongue weight? I keep mine between 250 - 290 lbs.

What size wheels on your Model X? I have the 20” wheels.

Bonjour ecarfan, I did better score on some trips but it is the average of the summer( including heavy rain times). I have effectively 13" tires on Alto and 20" on Grayhound.

My first guess is the temperature here compare to south of USA.
The other facxtor could be the size of the trips. This summer the longest we did is in May is 665 mi without the box with temperature 68-75F and had an average of 572wh/mi. Doing small trips is usually on smaller roads with more stop-start.

In September we did a trip of 200mi with temperature of 50 to 66F and got an average of 515wh/mi.
Last week-end we went for a small trip of 375mi with a lot of hills but with temperature around 48-50F. We came back to our 624wh/km.

We are going to Florida in January, we will get much more difficult condition when we strat in Quebec with the snow and cold temperature.

In my condition, I still think that the average gain of 16% is worth the investment. I will let you know when I get pricing and finalize discussion with Daniel Nadeau the owner of Safari-Condo.

 

[AltoGrayhound]

Okay, thank you. I am surprised that at 55mph you averaged 624Wh/mi with your Alto F1743. I just returned from a 2,520 mile roundtrip from California to New Mexico and back towing my Alto F1743. For the entire trip my average was 525Wh/mi. I estimate that over 90% of that mileage was at 55mph, the remainder was at 60mph or below 55mph. My route included a lot of long flat stretches of road as well as elevation changes of thousands of feet in a single day.

So my towing energy usage at 55mph is essentially the same as what you get when using your “nose” on your Alto, and without your “nose” you have much higher energy usage than I do. That is puzzling.

By the way: I have the 15” wheels with Michelin tires. I assume you have the 13” wheels with Goodyear tires? But I doubt that makes much difference. I’m just trying to think of any differences between our trailers.

What is your tongue weight? I keep mine between 250 - 290 lbs.

What size wheels on your Model X? I have the 20” wheels.

No tongue weight available. How do you weight it?

 

[ohmman]

No tongue weight available. How do you weight it?

A couple of ways. You can use a tongue scale such as this one: https://www.amazon.com/Sherline-LM-2000-Trailer-Tongue/dp/B007REK28M or you can use a lever and a bathroom scale something like this: Measuring trailer tongue weight with a bathroom scale.

I believe @ecarfan has a receiver that also has a scale built in, so he can spot check tongue weight at any time. Not sure about the calibration needs of such a device, but he can probably answer that.

 

[ecarfan]

My first guess is the temperature here compare to south of USA.

During my recent trip from California to New Mexico, temperatures ranged from 50F to 75F. Much of the time I was at 5,000 to 7,000 ft, so it’s not as warm as you might think.

No tongue weight available. How do you weight it?

The tongue weight likely has little effect on towing energy usage, but I was trying to think of possible differences between your towing setup and mine. See this Google search page how to measure trailer tongue weight - Google Search

I think this is a good article on measuring tongue weight Determining Trailer Tongue Weight | etrailer.com

I use this Weigh Safe Ball Mounts | etrailer.com . I have adjusted my tongue weight to be about 260 - 280 lbs. More information at Towing with a Tesla

IMPORTANT: incorrect tongue weight can can result in serious accidents! Quote: “If you don’t have enough weight on the trailer tongue, the trailer may be prone to swaying from side to side, making it difficult to control. Conversely, if you have too much weight exerted on the hitch ball, the force could overload the rear tires of the tow vehicle and push the rear end of the vehicle around. This could also negatively affect handling – you might not be able to go around corners and curves properly, and your vehicle may not stop quickly enough when you press the brake pedal.”
Tongue Weight Is Key To Safe Towing - GMC Life

I urge you to measure your tongue weight, for your safety and for the safety of the millions of drivers who share the road with you. Watch these videos:

 

[ecarfan]

I believe @ecarfan has a receiver that also has a scale built in, so he can spot check tongue weight at any time. Not sure about the calibration needs of such a device, but he can probably answer that.

When I first started towing I checked my Weigh Safe hitch reading against a conventional tongue weight scale and they were reasonably close. The Weigh Safe scale cannot be read to within +/- 20 lbs or so because the markings are in 100 lb increments and the indicator needle doesn’t quite reach the markings; a remarkably poor design. But it still provides a useful dynamic measure of tongue weight, in my opinion.

This photo is taken from the side opposite where the tongue weight indicator is located.

 

[ecarfan]

You can use a tongue scale such as this one: https://www.amazon.com/Sherline-LM-2000-Trailer-Tongue/dp/B007REK28M

I like that scale because it’s compact, the scale markings are in 50 lb increments, and the indicator needle touches the scale markings, so it’s easy to read.

As far as calibration goes, the issue is similar to tire pressure gauges: different gauges give different readings for the same tire. So it’s best to use more than one tongue weight scale and see if you can get two different scales to provide you with similar values.

An additional complication is that if the car and trailer are not level the tongue weight reading will change, in my experience. I live in a hilly area and my driveway is sloped. It’s hard for me to find a level spot to measure my tongue weight.

 

[ecarfan]

To get back to energy usage while towing...

My next step will be the tail drag. I will do a coroplast prototype inspired by the tail system that we see on trucking trailers.

If you modify the rear of your Alto, I am wondering how you are going to deal with the rear lights (taillight, brake lights, turn signs) being obscured? Anything that extends the length of the trailer body is going to block the view of those lights.

The rear end aerodynamic modifications I have seen on semi trucks are designed so that the rear lights can still be seen; the modification is made above the rear lights. Like this:

However, the Alto trailer lights are placed high up where the roof curves down to form the rear wall. Here’s a photo of my Alto on the day I picked it up at the dealer.

How are you going to modify the rear of the trailer and keep the taillights visible? Also, the trailer license plate has to be visible.

In my opinion, the placement of the taillights on the Alto is far from optimal. They are much too high. And because they are LED and therefore directional, they are not as bright as they could be because they are angled upwards. I added two additional taillights down low and pointing straight backwards, as shown in this photo.

 

[Yinn]

I like that scale because it’s compact, the scale markings are in 50 lb increments, and the indicator needle touches the scale markings, so it’s easy to read.

As far as calibration goes, the issue is similar to tire pressure gauges: different gauges give different readings for the same tire. So it’s best to use more than one tongue weight scale and see if you can get two different scales to provide you with similar values.

An additional complication is that if the car and trailer are not level the tongue weight reading will change, in my experience. I live in a hilly area and my driveway is sloped. It’s hard for me to find a level spot to measure my tongue weight.

I have the weigh safe universal ball on a .75" riser and completely agree. It's a good ballpark gauge, but not specific in any manner. Even the calibration method for the universal ball says to adjust by backing it off until the needle no longer drops...not very scientific there.

To get back to energy usage while towing...I

I squeaked out 142 miles on a MX 75D on a single while towing. Range mode on, Chill Mode on. 20" wheels with Minor elevation changes. Mix of highway up to 70mph and local. Averaged speeds of ~45mph.

Starting Charge: 100%

Leg 1: Empty 5x8 trailer, ~1500lbs dry weight, cloudly ~70F - 52 mi
Leg 2: Filled 5x8 trailer, ~2300lbs loaded, slight rain ~66F - 55 mi
Leg 3: Empty 5x8 trailer, ~1500lbs dry weight, rainy ~66F - 34.9 mi

Ending Charge: 5%

My observation is that towing on 20" wheels during mixed usage is getting me comparable efficiency as normal driving on 22" wheels. I averaged about 460wh/mi on that tow. On 22's without a trailer, I was frequently around 415wh/mi-450wh/mi. A lot of that may also be attributed to my personal driving style. For comparison, on 20's w/o a trailer I average ~330wh/mi.

 

[ecarfan]

@Yinn thanks for your post. What is the height of your 5x8 trailer? That will give us the frontal area, which has a major impact on towing energy usage. If it’s a utility trailer I assume it’s only 3 or 4 ft high. So that is not comparable to a travel trailer (camper) which is usually at least 8 ft high and can be 10 ft or more for the big ones.

I also average 330Wh/mi for my X with 20” wheels when not towing.

 

[Yinn]

@Yinn thanks for your post. What is the height of your 5x8 trailer? That will give us the frontal area, which has a major impact on towing energy usage. If it’s a utility trailer I assume it’s only 3 or 4 ft high. So that is not comparable to a travel trailer (camper) which is usually at least 8 ft high and can be 10 ft or more for the big ones.

I also average 330Wh/mi for my X with 20” wheels when not towing.

It’s an enclosed cargo trailer, it’s approximately 84” in height. Still not as high as a full travel but closer to one than a standard utility.

 

[Evoforce]

It’s an enclosed cargo trailer, it’s approximately 84” in height. Still not as high as a full travel but closer to one than a standard utility.

View attachment 342282

I've got a cargo trailer myself that is soon to go 2500 miles loaded across country. Mine is a 6x12!

 

[ecarfan]

Thanks for the data. So the frontal area of your trailer is 5,040 sq in. That is great that you average 420Wh/mi towing it. The frontal area of my travel trailer is 8,256. Of course that is only one factor among many that effects energy usage, but it is an important measure.

It’s an enclosed cargo trailer, it’s approximately 84” in height. Still not as high as a full travel but closer to one than a standard utility.

View attachment 342282