700 mile road trip with R1S Rooftop Tent -- efficiency / range numbers

[Pixelshot]

Hi all - here's the final vid in our Overland Expo 2023 series. This one is all about efficiency on our 700 mile drive with a Rooftop Tent (thanks Joel!). I came up with some pretty interesting conclusions after not just this year (1400 miles round trip) but also incorporating the data from last year's drive over the same route but with a trailer. Turns out that the trailer hit the range really hard - it was a pretty light trailer so I'm guessing it had a lot to do with aero rather than weight. PLUS, we had another R1T driving the same route at the same speed for comparison. No, it's not bulletproof science but the fact that our data calculated out so consistently gives me confidence about the conclusions:

1 - RTT does affect range (but not as much as I thought) - about 8% by this measurement
2 - Speed affects range much more than having a RTT - 26% difference between 75mph and 65mph

All the data is in the vid. Please watch to the end to see the details. Thanks!!

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[LoneStar]

thank you for this detailed info. getting my R1S soon and seriously thinking about putting a RTT on it

 

[Yossarian]

Thanks for posting this.

We're still waiting for our R1S, but when we finally get it, will use it not only to tow our teardrop during the warmer months but also with a Thule cargo box during the winter. I'd think the efficiency hit with the Thule will be similar to what you experienced with the RTT. It's great to have that data point, which of course needs to be factored in along with the additional hit to range of the cold and often windy travel conditions.

 

[Ash]

I appreciate the time you took to share your data. It's very interesting. We're headed to Yosemite next week with a new setup that includes two ebikes mounted on the bed of my R1T and two on the trailer hitch. I'm going to do some testing to see what the range hit is before we leave, with the two bikes sticking up in the wind. I also tend to drive faster, usually setting the cruise control at 79mph on the big open highways. I'm curious to learn how much slower I need to go in order to achieve the same efficiency I get without the bikes sticking up. I know with the bikes only on the hitch, I can make it from San Jose, into Yosemite Valley without charging (just). I usually charge a bit in Groveland anyway, but it will be interesting to see what it's like since the range extending update. Thanks again for sharing. I'm surprised your channel isn't larger by now because you provide thoughtful content. Keep it up.

 

[SingleMalt]

Not that I'm looking for any attention on the post I made in the "Trip Reports / Journals / Logs", but I posted my experiences with a Thule RTT mounted on the bed of my R1T. It might have some useful info per this discussion.

FWIW. - https://www.rivianforums.com/forum/...trip-indiana-texas-new-mexico-and-back.15699/

 

[mikehmb]

Not that I'm looking for any attention on the post I made in the "Trip Reports / Journals / Logs", but I posted my experiences with a Thule RTT mounted on the bed of my R1T. It might have some useful info per this discussion.

FWIW. - https://www.rivianforums.com/forum/...trip-indiana-texas-new-mexico-and-back.15699/

That’s a great write up. Can you post a pic of your truck with the Tepui RTT? It’s about the right size and if it fits over the bed, I’’m in.

 

[Cactus]

Agree that speed affects efficiency and range, but it's the same whether you're in an ICE or EV. If driving in an ICE SUV (Range Rover, for example) with a roof top tent, your range hit (decrease in mpg in ICE vehicle) would essentially be the same as driving a Rivian with a rooftop tent (assuming cross-sectional areas of both vehicles are generally the same-which they are).

Drag equation doesn't change just because you're in an EV. I can't remember the equation exactly, but the force of drag squares as speed increases... OK, I looked it up. Neglecting minor changes in density of air, Drag= velocity^2/2, assuming the areas of the vehicles are the same (or very similar).
This means that going even a little faster creates a LOT more drag (square of velocity divided by 2) and kills mi/kwh and mpg.
We all hate this law of physics because we want to get where we're going faster! LOL.

 

[sillygoose]

The laws of physics don’t change but the ICE is only 40% efficient (60% of the fuel energy lost to heat) so the aerodynamic drag is a much lower percentage of the losses. So while the ICE and EV take an equal hit from the increased drag, the EV takes a bigger hit to range given its high efficiency.

My source for the efficiency numbers: EV vs ICE Efficiency

 

[SingleMalt]

That’s a great write up. Can you post a pic of your truck with the Tepui RTT? It’s about the right size and if it fits over the bed, I’’m in.

Here are the only photos I have currently, for some reason I haven't taken many pics of the truck/tent combo. I will say that the tent fits the bed very well. It's also easy to setup at camp and easy to "tear down" when you're ready to hit the road. It takes no more than 5 - 10 minutes either way.

To install I went out and got some thick bar stock to create my own mounting plates as the holes on the provided plates were just a mite too close together (to me) to allow the bolts to clear the bars completely. I've seen others on the forums that have used the Thule provided mounting plates and they seem to work just fine, although it appears they are a hair less that perpendicular and would rub against the factory (Rivian) cargo crossbars. I don't have any pictures of what I did. BTW, I use an electric hoist to add/remove the tent whenever I use it and I leave the crossbars attached.

All in all, very happy with the Kukenam. I had been looking at them for quite awhile before I purchased. I had been waiting on Rivian's "approved" RTT, but they've never gotten them into the shop. The price I paid for the Thule was far less than the Yakima. I still see them advertised for the price I paid on the Thule site.

Here's the tent deployed and packed on the back of my R1T.

 

[mikehmb]

Here are the only photos I have currently, for some reason I haven't taken many pics of the truck/tent combo. I will say that the tent fits the bed very well. It's also easy to setup at camp and easy to "tear down" when you're ready to hit the road. It takes no more than 5 - 10 minutes either way.

To install I went out and got some thick bar stock to create my own mounting plates as the holes on the provided plates were just a mite too close together (to me) to allow the bolts to clear the bars completely. I've seen others on the forums that have used the Thule provided mounting plates and they seem to work just fine, although it appears they are a hair less that perpendicular and would rub against the factory (Rivian) cargo crossbars. I don't have any pictures of what I did. BTW, I use an electric hoist to add/remove the tent whenever I use it and I leave the crossbars attached.

All in all, very happy with the Kukenam. I had been looking at them for quite awhile before I purchased. I had been waiting on Rivian's "approved" RTT, but they've never gotten them into the shop. The price I paid for the Thule was far less than the Yakima. I still see them advertised for the price I paid on the Thule site.

Here's the tent deployed and packed on the back of my R1T.

These pictures are great, thanks! Particularly fond of the dune image.

Which Tepui version did you go with? And did it mount straight to the Rivian crossbars? (Thule’s site is unhelpful in this regard)

 

[FD234]

What about having AC on/off. How does that impact the range?

 

[SingleMalt]

These pictures are great, thanks! Particularly fond of the dune image.

Which Tepui version did you go with?

https://www.thule.com/en-us/rooftop...tents/thule-tepui-explorer-kukenam-3-_-901301

 

[Pixelshot]

thank you for this detailed info. getting my R1S soon and seriously thinking about putting a RTT on it

I'm going to be trying a couple more tents so I'll let you know how they are.

 

[Pixelshot]

Thanks for posting this.

We're still waiting for our R1S, but when we finally get it, will use it not only to tow our teardrop during the warmer months but also with a Thule cargo box during the winter. I'd think the efficiency hit with the Thule will be similar to what you experienced with the RTT. It's great to have that data point, which of course needs to be factored in along with the additional hit to range of the cold and often windy travel conditions.

Yeah, each little thing adds up (tires, speed, weather, RTT, etc) so it's important to keep an eye on the big picture. But, I find that there is enough battery to handle the little things. The trailer last year was another story, though. It really slowed us down (by adding a lot of charging time).

 

[Pixelshot]

I appreciate the time you took to share your data. It's very interesting. We're headed to Yosemite next week with a new setup that includes two ebikes mounted on the bed of my R1T and two on the trailer hitch. I'm going to do some testing to see what the range hit is before we leave, with the two bikes sticking up in the wind. I also tend to drive faster, usually setting the cruise control at 79mph on the big open highways. I'm curious to learn how much slower I need to go in order to achieve the same efficiency I get without the bikes sticking up. I know with the bikes only on the hitch, I can make it from San Jose, into Yosemite Valley without charging (just). I usually charge a bit in Groveland anyway, but it will be interesting to see what it's like since the range extending update. Thanks again for sharing. I'm surprised your channel isn't larger by now because you provide thoughtful content. Keep it up.

Thanks. (can't argue with the channel size thing! - best way to help BTW is to watch, like and comment on the video itself - and share).

I'll bet you won't see much impact on range. Of course there will be some, but with all of the other factors, like hills and wind, you won't be able to single out that small of a difference in aero. would love to know your results! I do know that the thing that will impact the range the most is speed. When we went from 75 to 65 I saw a big jump in efficiency, maybe 20% or more.

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