Rivian towing efficiency

[Groover]

Long Rivian towing test

Bottom line, the Rivian range was reduced by 62% when towing a Mustang on a car hauler.

The route was from Detroit to LA so it was plenty long but other than that not a whole lot details.

62% range reduction sounds like much more than would expect if I were towing the rig with my F150 but as a Tesla owner I expected towing to hit an EV harder than an ICE powered one for several reasons.

1) Most EVs have great aerodynamics to extend their range so they will be affected more by a not very aerodynamic trailer than the average pickups already on the road.

2) EVs benefit from regeneration during stopping but in most cases the regen is sized to handle the base vehicle weight. Extra weight may have required the use of mechanical braking more frequently resulting in lost energy. Batteries don't absorb energy as well as they provide it so their is limit to how strong the regen circuit can be. Also, the regen circuit is different from the drive circuit so putting in a stronger regen circuit would add cost and weight to the vehicle.

3) Electric circuits lose efficiency according to the square of the amount of power being pushed through them so there may have been a major efficiency drop from the higher currents.

Anyway, this is just one piece of data and the results will be different for every trailer. I am impressed that they found enough chargers to let them make the trip so this proves that it can be done. And more charging stations are being built every day. The photos show that tow vehicles are not accommodated well. That will become more important as EVs become more prevalent.

I would love to see a similar test replicated by an ICE powered truck to compare the losses. Some graphs on drivetrain efficiency vs power to the ground for various drivetrains would be interesting too.

[Groover]

Reisender wrote:

time2roll wrote:

Groover wrote:
62% range reduction sounds like much more than would expect if I were towing the rig with my F150 but as a Tesla owner I expected towing to hit an EV harder than an ICE powered one for several reasons..

Is that what it said? I see this:


"which evidently resulted in a 62% degradation of the battery after just 118 miles of travel."

If 62% got you 118 miles I would expect the remaining 38% to get me another 45 miles.
118 + 45 = 163 miles total range. Range not towing is 300 so the real range dropped by 45% or slightly less than half was lost.

I recommend the not yet available 400 mile range RT1 if you plan to tow something large for a significant distance.

I saw that too but wasn't sure if I was reading that right. That is closer to what our friends see towing a teardrop with their model Y. They lose about 40 to 45 percent of the the cars range. But they definitely are not travelling 73 mph average either though. Mavbe 90 to 95 kilometres an hour. Speeds are slower here.

It is confusing but I think that the article referred to two different test reports. One said the the battery used 62% or its charge (battery degredation?) in 118 miles with no other description of the test. The second report tells us that they had a Mustang on a car hauler and pulled it well over 1,000 miles and observed 62% reduction in range.

The article is not well written and having the same percentage referred to in both tests adds to the confusion.

[JRscooby]

Am I getting the numbers about right? Comparing ICE that gets 10 MPG while towing, unhook the trailer and mileage jumps to 16.2?

[time2roll]

Really good for 73 MPH. I would like to see a range test at 73 MPH to get a baseline.
Head wind? Up hill? My EV will seem to use a bit more going up even 500' in 50 miles... get it all back going back down.

[blt2ski]

45% drop is on par with the ICE version's I've had, how much I'm are towing, terrain etc.

Aerodynamics as noted, drag from tire type and style, road bed.......

Using one of BenK's comments, re bicycles, a human notice 1-2 ounces of wt removed from a moving part, take 2 lbs from a nonmoving part like the frame to notice. using same ratio, I put 4 new tires on truck, 10-15 lbs heavier than old ones, yes inch in diam more, but lost 3-4 mpg. those 40 lbs of tire add, times 30 equals 1200 lbs of wt added to truck in a non moving fashion. ABout how much mpg I lose with that much wt in the bed.

my non engineering background says things will be similar % loss of range etc, be it an electric rig, gas, diesel, alcohol etc for power use towing or carrying x number of lbs of wt. The real issue, is comparing amp hrs of battery use to kilowatts of energy in fuel or equal comparison.

Marty

[stsmark]

I was thinking the same thing, Time. The wording of the quote is deceptive.

[Reisender]

time2roll wrote:

Groover wrote:
62% range reduction sounds like much more than would expect if I were towing the rig with my F150 but as a Tesla owner I expected towing to hit an EV harder than an ICE powered one for several reasons..

Is that what it said? I see this:


"which evidently resulted in a 62% degradation of the battery after just 118 miles of travel."

If 62% got you 118 miles I would expect the remaining 38% to get me another 45 miles.
118 + 45 = 163 miles total range. Range not towing is 300 so the real range dropped by 45% or slightly less than half was lost.

I recommend the not yet available 400 mile range RT1 if you plan to tow something large for a significant distance.

I saw that too but wasn't sure if I was reading that right. That is closer to what our friends see towing a teardrop with their model Y. They lose about 40 to 45 percent of the the cars range. But they definitely are not travelling 73 mph average either though. Mavbe 90 to 95 kilometres an hour. Speeds are slower here.

[time2roll]

Groover wrote:
62% range reduction sounds like much more than would expect if I were towing the rig with my F150 but as a Tesla owner I expected towing to hit an EV harder than an ICE powered one for several reasons..

Is that what it said? I see this:


"which evidently resulted in a 62% degradation of the battery after just 118 miles of travel."

If 62% got you 118 miles I would expect the remaining 38% to get me another 45 miles.
118 + 45 = 163 miles total range. Range not towing is 300 so the real range dropped by 45% or slightly less than half was lost.

I recommend the not yet available 400 mile range RT1 if you plan to tow something large for a significant distance.

[rjstractor]

I read the test also, and it affirms the towing results I've seen from tests of various Tesla models- moderate towing cuts an EVs range to somewhere between a half and a third of its solo range. A prospective EV owner who wants to do serious towing should think in terms of KWh per mile, not advertised range. The Rivian towing a modest size load consumed power at about 1 KWh per mile, a huge increase in power consumption compared with its EPA estimated range figures which pencil out to about .43 KWh per mile. Towing a high wall travel trailer I imagine would increase the consumption to 1.25-1.5 KWh per mile, cutting the truck's range to under 100 miles. I look forward to seeing a tow test with something like a high profile bumper pull toy hauler, which would be within the Rivian's tow rating, but takes a lot more power to move it down the highway than a car on a flatbed trailer. The main issue with EVs in a towing application is not performance or power, it's range. It's going to take a battery in the 500 KWh range to enable an EV to tow a significant load long distances between charges.

[NamMedevac_70]

I will stay with my 3 gassers as I spend a lot of time in remote areas and small rural towns where gas is easy to obtain.

[Groover]

pianotuna wrote:
Grover,

I think it may be the square of the voltage--not "power".

Example

120 x 120 = 14,400

100 x 100 = 10,000

10,000 / 14,400 = 69%

So a 31% drop in wattage.

.
The voltage of a lithium ion battery is essentially fixed for any given vehicle. Since power is volts times amps and voltage is fixed the amps vary with power. So the I squared R losses do apply.

[Reisender]

IdaD wrote:
Given the weight and profile of that trailer, the efficiency took a much bigger dive than I'd expect out of a traditional truck on a similar trip. Especially a diesel truck.

Agreed on the diesel. But remember, this is a half ton truck. I’m not sure how common a diesel is in half tons nowadays. (Really no idea).

I know with our gas GMC 3/4 ton pulling a 7000 poundish trailer we were looking for a gas station after about 220 kilometres or so and getting panicky at 275. And that was in Saskatchewan. Course that was 20 years ago. I’m sure it’s better now.

[wildtoad]

I think more and more tests are needed with EV’s to get live usage numbers. Impact of towing on flat ground or hilly. Impact of 90 degree weather and running AC. Impact of freezing and running heater. I’m not sure comparing a EV to an ICE based vehicle is actually that helpful. We have 100 plus years of data, personal experiences, and can fill up a near empty fuel tank in 10+\- minutes just about anywhere. We know what to expect if we run out. For me knowing how far I can realistically expect to go before I have to stop, and for how long (recharge time) is fairly important to know when planning a trip.

[IdaD]

Given the weight and profile of that trailer, the efficiency took a much bigger dive than I'd expect out of a traditional truck on a similar trip. Especially a diesel truck.

[pianotuna]

Grover,

I think it may be the square of the voltage--not "power".

Example

120 x 120 = 14,400

100 x 100 = 10,000

10,000 / 14,400 = 69%

So a 31% drop in wattage.

[Reisender]

Interesting. Thanks for posting.