Model X Travel Trailer Consumption Analysis

[bob_p]

While this is mentioned in several threads, it's difficult to collect enough information to predict how much range we'd likely get with the various trailers.

Whether it's a spreadsheet or just a separate thread - would be helpful to have this information in one place, standardized enough so X owners considering a travel trailer purchase could estimate the range with each of the trailer options.

Based on what's been posted so far, it appears the Road Chief gets the best range (at a relatively high cost), though there are other ultralight trailers (like the Alto) which might get similar range. Clearly the heavier trailers and those with less aerodynamic shapes will consume more energy.

 

[ecarfan]

Whether it's a spreadsheet or just a separate thread - would be helpful to have this information in one place, standardized enough so X owners considering a travel trailer purchase could estimate the range with each of the trailer options.

I am pleased that you have volunteered to take on this task.

This thread is the best place for people to post their towing energy usage data, and there have been many such posts for a variety of trailer models.

My rule of thumb is for a level road with no rain or headlined, assume a minimum of 50% increased energy usage at 55mph, and it can be higher. Prolonged uphill stretches, rain, headwinds can double my energy usage compared to when not towing.

Highly recommend the EV Trip Optimizer app. Set your vehicle configuration in the app to “High Profile”, set your wheel size, set Payload to weight of trailer plus what’s in the car, set Power Factor to 30 (will require some experimenting to find the right setting for your particular trailer), set Max Speed to what you tow at (55 for me), set 90% Range value in miles for your battery (mine is set to 265), then plan a trip and compare your actual usage to what the app predicted. Adjust settings as needed. It’s an excellent app.

 

[AndreyATC]

Just a thought,
If everyone with their RVs provide average WHM for entire round trip, this could give us a high level view of what to expect from given trailer.
Then we should be able to build some simple data spreadsheet per type of trailer
We can include some other pieces of info, like wheels and Model X type, etc

@ohmman already compiled some data, which is a good start. See below:

 

[Yinn]

I am pleased that you have volunteered to take on this task.

You Sir, must be in executive management.

 

[bob_p]

We're missing a few key items - such as performance or non-performance, and 20" or 22" wheels, both of which impact energy consumption. Though with the X, the difference between these configurations isn't as significant as with the S.

349.5 Wh/mi would result in around 286 miles at 55 MPH with a 100 KWhr battery pack, which probably means this was a performance X, with 22" wheels.

A non-performance X will get about 2% better range - which would reduce the Bowlus energy Wh/mi to 465.5, and increase the rated range to 214 miles (or 172 miles keeping the battery pack between 10-90%), for an X 100D with 20" tires.

It's surprising the Alto, which has a shorter roofline performs poorer than the 22' Airstream Sport, which is over twice the weight...

Are there any other ultralight travel trailers that are being towed by a Model X?

Lance has a couple of lightweight models.

 

[Yinn]

We're missing a few key items - such as performance or non-performance, and 20" or 22" wheels, both of which impact energy consumption. Though with the X, the difference between these configurations isn't as significant as with the S.

349.5 Wh/mi would result in around 286 miles at 55 MPH with a 100 KWhr battery pack, which probably means this was a performance X, with 22" wheels.

A non-performance X will get about 2% better range - which would reduce the Bowlus energy Wh/mi to 465.5, and increase the rated range to 214 miles (or 172 miles keeping the battery pack between 10-90%), for an X 100D with 20" tires.

It's surprising the Alto, which has a shorter roofline performs poorer than the 22' Airstream Sport, which is over twice the weight...

Are there any other ultralight travel trailers that are being towed by a Model X?

Lance has a couple of lightweight models.

I was also expecting a bigger % impact with 20's to 22's and didn't notice it. W/o a trailer I get about 8% reduction. With a trailer, it actually didn't seem to have a noticeable impact. I wonder if this is because as a proportion of weight, friction (ground & air) it's just simply a smaller fraction of what the trailer ends up adding.

 

[aesculus]

We're missing a few key items - such as performance or non-performance, and 20" or 22" wheels, both of which impact energy consumption. Though with the X, the difference between these configurations isn't as significant as with the S.

At the bottom of this tutorial I have started to assemble some EVTO settings guidelines for various trailers. If others would like to send me their settings for power factor and car profile I can add it to the table.

Towing with EVTO | Digital Auto Guides

As @ecarfan points out there are a number of settings that need to be experimented with but once you get it tuned it should be fairly accurate. One thing to watch out for is situations where there is a lot of up and down elevation over shorter (ie 50 miles or less) distances. You may have to bump the power factor up a bit in those cases (ie continued mountain driving). Long steedly climbs and descents are fine. It just these up and downs that give the model (and car) fits.

 

[aesculus]

I was also expecting a bigger % impact with 20's to 22's and didn't notice it. W/o a trailer I get about 8% reduction. With a trailer, it actually didn't seem to have a noticeable impact. I wonder if this is because as a proportion of weight, friction (ground & air) it's just simply a smaller fraction of what the trailer ends up adding.

Was your speed the same? That has a huge impact. And yes the proportion will not be the same, but the energy loss would be, so it could be masked by all the other factors that are contributing to the overall consumption number. It might go from being 8% for the unladen situation at 75 mph to only 1-2% with the trailer at a lower speed.

 

[Yinn]

Was your speed the same? That has a huge impact. And yes the proportion will not be the same, but the energy loss would be, so it could be masked by all the other factors that are contributing to the overall consumption number. It might go from being 8% for the unladen situation at 75 mph to only 1-2% with the trailer at a lower speed.

I think that’s exactly right. The speeds were about the same. But where I may have been expecting a percentage loss might’ve actually been a set factor loss (30wh/mi) which in trailer mode is a shrug and ends up being hidden by the 200wh/mi drag of the trailer.

 

[ecarfan]

It's surprising the Alto, which has a shorter roofline performs poorer than the 22' Airstream Sport, which is over twice the weight...
Are there any other ultralight travel trailers that are being towed by a Model X?

Not surprising to me. When towing on a level road at a steady speed, the weight of the trailer is almost inconsequential compared to the shape of the trailer when analyzing what are the contributing factors to increased energy usage. The heavily radiused edges of the Airstream result in a significant reduction in drag compared to the same size trailer with square edges.The Alto has a nicely sloped front end along the short axis but the sidewalls are vertical from the base to the roofline; no radiused corners.

The Model X has so much torque that you needn’t concern yourself much with the trailer weight; the car can handle it up to Teslas recommended tow weight* and tongue weight. If you are trying to reduce energy usage, concern yourself with the shape of the trailer.


*Though keep in mind that based on @ohmman’s experience, the Bosal hitch is not suitable if you are going to use weight distribution bars when towing; he switched to a DrawTite and is happy with it. I do not use weight distribution bars when towing with the stock Bosal hitch and so far have had no issues with the hitch loosening or with trailer sway with my Alto (if I was getting any sway that would indicate a need for weight distribution bars). But the X outweighs the Alto by more than 2:1 even when the trailer is fully loaded and that helps keep the trailer stable. That said, I have yet to tow in a really strong crosswind (30+mph).

 

[ecarfan]

At the bottom of this tutorial I have started to assemble some EVTO settings guidelines for various trailers. If others would like to send me their settings for power factor and car profile I can add it to the table.
Towing with EVTO | Digital Auto Guides

You can add the Safari Condo Alto F1743 for a Power Factor of 30 and Model X High Profile. I will continue to use EVTO for my future towing trips and let you know if 30 is the right number or not.

The Alto R1723/1713 models appear to use more energy than my F1743 but I don’t know anyone towing them who uses EVTO so don’t know what an appropriate Power Factor would be.

 

[aesculus]

You can add the Safari Condo Alto F1743 for a Power Factor of 30 and Model X High Profile.

Done. Thanks for that.

 

[ohmman]

Here are the results of a relatively flat stretch northbound on I-5 at 60mph. I was following a semi with TACC following distance set at 6. It is only slightly higher than I was consuming at 52mph “in the open”.

 

[ecarfan]

When you were behind a semi with TACC at 6, I would estimate your following distance at about 60 - 65 ft. Does that sound right?

What was your Wh/mi at 52mph when not following a semi?

It would be an interesting experiment to follow semis at various TACC settings to see the effect on your Wh/mi. Though personally I never have TACC on less than 7 so I won’t be doing that experiment.

 

[ohmman]

When you were behind a semi with TACC at 6, I would estimate your following distance at about 60 - 65 ft. Does that sound right?

What was your Wh/mi at 52mph when not following a semi?

It would be an interesting experiment to follow semis at various TACC settings to see the effect on your Wh/mi. Though personally I never have TACC on less than 7 so I won’t be doing that experiment.

The distance varied. It may have been that I had TACC set to 60, and the semi was fluctuating between 59 and 61, but I would say that I never felt as close as 60 feet. Minimum was maybe 100 feet.

I was consuming ~550-560Wh/mi at 52. The Vacaville-Corning stretch is a long one for our rig, which is why I typically start slow. But so long as I can stay under 600Wh/mi average, I know I’ll arrive with plenty to spare. The problem is that much of that stretch is two lanes, and going 52 on a road where the passenger vehicle speed limit is 70 (and cars are going 80) feels obtrusive. This is one stretch I feel more comfortable tagging along behind a semi.

 

[bob_p]

We've narrowed our choices to a Bowlus Road Chief or Airstream Sport 22FB.

Using the OP's energy consumption numbers at 55 MPH, assuming we start with 100% charge after overnight charging and charge only to 90% at superchargers in mid-trip, I'm estimating that a 400 mile trip in the Airstream would take about 9 hours (driving + charging) and about 8.5 hours in a Road Chief.

The Airstream costs less than half of the entry level Road Chief and about 1/4 the cost of the Limited Edition Road Chief.

We like the "off the grid" benefits of the Limited Edition, though it appears we may be able to add that to an Airstream with aftermarket solar panels (mounted on the roof) and LiOn batteries.

Onboard storage seems better with the Airstream, with the large storage area underneath the bed and a larger closet, plus more overhead storage.

With the Road Chiefs you get a cellular booster and with the Limited Edition you get a WiFI repeater/cellular router for a private WiFi network. Those are both after market items that can be added to an Airstream.

The Road Chief has a polished design, with a number of clever features - the Airstream isn't quite as polished, though has a number of more practical features - like the double sink, separate shower, convection microwave, TV/stereo, …

Assuming a typical long road trip drive is 400 miles - if the travel time is around a half hour longer with the less energy efficient Airstream, and we can add the features we like in the Limited Edition Road Chief to a much less expensive Airstream, it's hard to justify the extra cost (especially for the Limited Edition).

Or, are we missing something in this analysis???

 

[AndreyATC]

@bob_p, thank you for your analysis
I'm curious to see how you determined the difference of 1/2 hour between the two, it's only 6%?
Either i'm applying my math incorrectly (not really good at) or the difference between consumption of Bowlus and Airstream is so small, that it yields only small percent gain?
475whm vs 575whm is much higher difference

Thank you

 

[bob_p]

400 miles of driving at 55 MPH is around 7 hours and 15-20 minutes - let's use 7.25 hours to keep it simple.

I'm estimating the Airstream will need about 1.75 hours of charging to reach the destination (and have at least a 10% charge) vs. 1.25 hours of charging for the Bowlus - in both cases, 2 charging stops would be required.

This is a crude estimate, that will be different IRL based on spacing of the superchargers. And driving/charging times will be different if the spacing allows us to drive faster on some segments with enough charge to reach the next supercharger or destination.

For comparison, our S 100D or X 100D (without a trailer) should cover the same 400 mile trip using only a single charging stop - and do it in about 6 hours (driving + charging).

Again, these are very crude projections - if we were planning an actual trip, would likely use one of the trip planner tools or build a spreadsheet with the specific superchargers & destinations and come up with a better estimate.

 

[ecarfan]

We've narrowed our choices to a Bowlus Road Chief or Airstream Sport 22FB.

Bob, I think your analysis is reasonable, though I suggest focusing less on the relatively small differences in energy usage and travel time and more on the features and styles of your two choices (assuming the large price difference is not a major factor for you). One major feature difference is bed size: if you are a large/tall person that Airstream may not work for you. The Bowlus has a much roomier sleeping area. If you like a lot of window area the Airstream seems the clear winner to me, and the interior design is very clean and modern. On the other hand, the shape of the Bowlus is damn sexy and the quality appears to be very high. It has more of a retro look and a traditional feel to the interior.

I went through a similar trailer analysis almost two years ago, though I was considering slightly smaller trailers that would fit into smaller campsites and be easier to manuveur. I ended up with a 17 ft ultralight Safari Condo Alto F1743 (1,740 lbs empty) that included a queen size sleeping area, table for two, shower, toilet, sink, stove, fridge, microwave. I then more than doubled my investment in the trailer by adding a variety of factory options plus a very high capacity solar/battery system installed by a third party. That brought my total cost to a bit more than a base Airstream 22FB. Airstreams are expensive...except when compared to a Bowlus.

By the way, Safari Condo offers a 21 ft version of the model I own, which means you get a true king size bed, table for 4, bigger fridge/freezer, and more storage yet weighs just 2,365 lbs. See Caravanes (Alto) – SÉRIE F21 – 2114 | Safari Condo . About the same as the base Bowlus, and less than the Airstream.

Good luck with your choice and I look forward to reading about your towing adventures!

 

[ecarfan]

Regarding energy consumption while towing, here are some numbers for my Alto F1743:

San Mateo CA to Petaluma CA: 475Wh/mi, max speed 55mph, average speed somewhat less because of surface streets going through San Francisco, temp 55 to 90F, no wind

Petaluma CA to Hendy Woods State Park: 495Wh/mi, max speed 55, average speed slightly less, temp 90, no wind

I was pretty pleased with those numbers. Charged once in Petaluma. Great Supercharger for a trailer with the pull through stalls. Yes, I block one of the stalls while charging but I monitored the number of empty/available stalls and it was never less than 4 and usually 5 or more (20 stalls in total). I was surprised it was that busy midday during the week. And there were 3 or 4 Model 3’s there all the time.