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527 Posts
Discussion Starter · #1 ·
I've posted fairly often regarding range and towing, and why I believe I need the Max battery pack to be able to successfully tow even my smaller teardrop over longer distances. There is still not a huge amount of data available regarding power consumption and range for Rivian towing, and most of what I've seen is based on towing larger, bulky loads. Their consumption figures are not encouraging, with most at or even below 1.0 mi/kWh. There is a Youtube video of a family towing a 30' Airstream with an R1T that was encouraging however. The figures they posted were in the 1.3 m/kWh range.

I recently had a on-line dialog on another website with someone towing a teardrop that is similar in design to mine, though quite a bit longer, wider, higher and heavier. Their tow vehicle is a Tesla Model Y, and they report consumption averaging 370 watts per kilometer. If I'm doing the conversion properly, that would be about 592 watts/mile and would in turn mean a theoretical max range with a Rivian LR Large pack of 228 miles. Using 80/15 charge/discharge parameters brings effective range down quite a bit, but still to a very respectable 150 miles.

Am I making a mistake in my calculations? As importantly, am I making a mistake using the Tesla as the basis for things? I'd think that the larger and heavier Rivian, regardless of whether it was the R1T or R1S, would better the Model Y, or at least be no worse. With my teardrop being smaller and 1,000 lbs lighter than the one towed by the Model Y, I'd also think that at the least, using the Tesla figures would be very conservative.

The bottom line for me is that if I could get those numbers towing my [email protected] 320 with a Rivian LR Large pack, I'd gladly forgo the wait (which could be indefinite) for the Max to become available.

527 Posts
Discussion Starter · #13 ·

My family and I just finished a trip from Kalispell, MT to Jasper, AB with our R1T. We had 5 bikes over the bed and we were pulling a 27' Keystone Passport camper. The overall trip was 1300 miles and speed (wind resistance) was the largest factor. Case in point - the longest leg without charging was 132 miles and 6700' of elevation gain. I was able to squeak out 1.16 mi/kwh through very conservative driving.

In preparation for the trip I did a lot of tow testing with a variety of trailers at various highway speeds. I found that on a 62 mile loop with roughly 680 feet of elevation gain I saw the following efficiencies:
1. R1T in conserve - 2.69mi/kwh @ 51mph avg*
2. R1T in towing w/ flatbed trailer weighed down to ~5000# - 1.48mi/kwh @ 45mph avg*
3. R1T in towing w/ Keystone camper (approx 5500#) - .92mi/kwh @ 48mph avg*
4. R1T in towing w/ empty cargo (probably 3500#) - 1.06mi/kwh @ 47mph avg*

As is noted all over on the Internet wind resistance is the largest consideration as drag increases (if nothing else changes) as a function of the square of your speed. This is why trains are so efficient. Once they get their load up to speed the energy required to keep it moving is less.

The final tow test that I did pre-trip was to drive a 126mi route with 4400' of elevation gain (and loss) as an out and back. I got the following results:
1. 1.11mi/kwh @ 44mph avg - Cruise Control set at 55mph*
2. 1.15mi/kwh @ 44mph avg - "hypermiling" by speeding up going down hills and slowing down going back up hills**

This gave me the confidence that I could make an appreciable improvement in my efficiency by constant throttle rather than constant speed.

592wh/mi is equivalent to 1.7mi/kwh. I achieved this efficiency with a motorcycle on a hitch rack and pulling a lightweight (1500#?) trailer with a raft on it for ~140 miles. My average speed was 46mph (but this likely included loading and unloading the raft, so actual driving speed was much higher).

If you are okay with driving slowly (targetting 55mph give or take) I think 1.7 mi/kwh may be achievable depending on the cross section of the teardrop. If it's a shorter teardrop this seems within reach. If it's taller you will certainly see better numbers than I saw on our trip (up to 1.2 mi/kwh) but may not get to the full 1.7.

I hope this helps. If you have more specific questions let me know. I would love to pull more trailers on my course to get additional data. I am trying to line up an airstream so I can compare it apples to apples against my Keystone at the same speeds. I'd really like to understand if their shape makes that much difference...

*These tests were done using the 22" Rivian wheels and Scorpion Zero tires
**This result came with new 20" American Racing wheels and Scorpion AT tires AND 5 bikes over the bed of the truck.

Thanks much @ipadl - the info is welcome and helpful.
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