Rivian off-road struggling?

[CharonPDX]

No such thing as a locking differential in the Rivian setup. The two motors on each axle cannot be physically locked in any way. A "virtual axle" cannot use the power of the wheel's up in the air motor. So that one wheel that is touching the ground, still only has that one electric motors worth of power. No way to double the power in software using the driving power of the other motor that has the wheel in the air.

Each wheel has way more than enough power. Each wheel has almost as much power as the Jeep Gladiator. (208 hp per wheel, compared to the Gladiator's 260-285 depending on engine. With no transmission/differential losses.) You don't need a locking differential when you have 208 horsepower per wheel.

Yes, a heavily-customized-for-offroad vehicle will do better, but the Rivian should be better than basically every other factory offroader.

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[Zybane]

Each wheel has way more than enough power. Each wheel has almost as much power as the Jeep Gladiator. (208 hp per wheel, compared to the Gladiator's 260-285 depending on engine. With no transmission/differential losses.) You don't need a locking differential when you have 208 horsepower per wheel.

Yes, a heavily-customized-for-offroad vehicle will do better, but the Rivian should be better than basically every other factory offroader.

That's not true at all. Slow rock crawling up grades is about torque put down at the tires/wheels. Something like a Diesel Rubicon has not just a little, but WAY MORE wheel torque than the Rivian when the Rubicon is put into 1st gear and 4-low with F/R locked differentials.

If you lift a wheel or two of the Rivian it just gets worse and worse for the Rivian in comparison. Electric motors actually have very little horsepower at slow speed, but 100% of their torque.


Electrical Motor Power, Velocity and Torque Equations

Tinlb = Php 63025 / n

where

Tinlb = torque (in lbf)

Php = horsepower delivered by the electric motor (hp)

n = revolution per minute (rpm)

 

[E.S.]

Um, so why was this thread created considering there is already another full thread dedicated to this very same subject/topic?

@Administrator, can you please merge these two threads?

 

[Autolycus]

If you lift a wheel or two of the Rivian it just gets worse and worse for the Rivian in comparison. Electric motors actually have very little horsepower at slow speed, but 100% of their torque.

While it is literally true that an electric motor has lower horsepower at slow speed than the same motor has at higher speed, I am struggling to understand how that mathematical fact is relevant in any practical context. It is also a mathematical fact with regard to every ICE engine ever made.

 

[Zybane]

While it is literally true that an electric motor has lower horsepower at slow speed than the same motor has at higher speed, I am struggling to understand how that mathematical fact is relevant in any practical context. It is also a mathematical fact with regard to every ICE engine ever made.

Because people keep talking about how much "power" each individual Rivian motor has. WHat's important in low-speed off-roading is Torque. And the mechanical advantage you get from an ICE off-roader can easily surpass the Rivian in that regard.

 

[Zybane]

A new off-road video out:




At 6:40, I've asked him if he could explain more what he means. Almost sounds like he is saying if you go up against a rock, even pressing the accelerator pedal more doesn't give you more power and he says to "adjust your line". Which isn't always possible.

He also has a great mention about the wheels. The stock ones are going to get beat up pretty crazy on trails. And at 7:22, the Rivian once again struggling over a not significant obstacle. You can see the rear spinning due to being in less traction, but once again the front motors stalling (not turning the wheels at all) when presented with a high torque demand situation.


Versus say this video, in which the Tacoma is going over a MUCH harder obstacle AND spinning all the tires to climb at the same time:

 

[Inkedsphynx]

Would help if he'd air down... like... at all.

 

[mini2nut]

Rivian didn’t target the serious off-road market. It’s a premium priced vehicle aimed at the affluent and adventurous crowd who occasionally takes the vehicle off-road to go Overlanding, mountain biking, hiking, etc.

They are not aiming for the Jeep crowd. Think more along the lines of Land Rover buyers who appreciate the comfort and the fact that it can be taken off-road whenever the whim hits.

I think of the R1T as a LR Defender with a practical and utilitarian 4.5’ bed that can still carry sheets 4’ x 8’ sheet plywood or drywall.

 

[SoCal Rob]

A new off-road video out:




At 6:40, I've asked him if he could explain more what he means. Almost sounds like he is saying if you go up against a rock, even pressing the accelerator pedal more doesn't give you more power and he says to "adjust your line". Which isn't always possible.

He also has a great mention about the wheels. The stock ones are going to get beat up pretty crazy on trails. And at 7:22, the Rivian once again struggling over a not significant obstacle. You can see the rear spinning due to being in less traction, but once again the front motors stalling (not turning the wheels at all) when presented with a high torque demand situation.


Versus say this video, in which the Tacoma is going over a MUCH harder obstacle AND spinning all the tires to climb at the same time:

I am glad to see people like Rivian Rex taking their Rivians off-road and documenting it. Before you start getting into the capabilities of the vehicle, he states that this is his Rivian and he’s not a pro driver. This is the only video of his I’ve seen so I don’t know if he’s ever done any off-road driving at all before. If he has a lot of experience off-road then in what? People who aren’t used to modern traction control systems and drive modes which include throttle re-mapping can have a hard time with a vehicle like the Rivian because it behaves so differently compared to what they drive. Beyond that, I think it is natural for people to drive their brand new $80K+ truck more gingerly than they would after they have some literal and figurative mileage on it. I wouldn’t be surprised if he was hesitant to use more throttle in an off-road mode after seeing what the same amount of throttle did when on-road.

Now, sorry for relying on real world examples with our LR3 again, but we have done some serious off-road exploration with it and I think it is close enough to how a Rivian should behave that it is a fair comparison even though the LR3 pales in comparison to the Rivian in virtually all objective measures. Over the 8 years we’ve been off-roading it we have encountered many people in Wranglers, Tacomas, 4Runners, and pick-ups who are amazed to see us calmly ascending, descending, and/or navigating trails they find challenging. There was one time we encountered some side by sides coming up a fairly narrow trail. We pulled as far to the side of the trail as we could so they could pass without losing momentum. Except the first driver pulled up next to us, stopped, and motioned to lower the window. We did and he asked something like, “Did you at least make it to the top before turning around?” and I thought his eyes were going when pop out when my husband told him, “Actually we came up from the other side.” After some discussion about how such a large vehicle could possibly navigate the narrow and super tight switchbacks we’d already cleared, the driver looks at his buddy and says that his wife has one of those and he always thought it might be able to do something off-road but his wife didn’t want him scratching it.

I could go on with examples from the countless adventures we’ve had in it, but please understand that just because something looks like a luxo-barge on itty-bitty tires that doesn’t mean that it can’t do amazing things with the right equipment from the factory and with someone who knows how to use the vehicle as designed and isn’t afraid to use it that way.

I keep saying that the Rivian will do better than our ancient LR3 because when it left the factory our LR3 had 315 lb-ft of torque at 4,000rpm and 300 hp at 5,500rpm to haul around 5,796 pounds of curb weight. I suspect that some of those lb-ft and horses are no longer present after 16 years and 233K+ miles but whatever remains is routed through 2 locking differentials (center + rear) and an open front diff which relies on traction control. All of this is on 18” diameter wheels wearing ~30” diameter tires for about 6” of sidewall.

The Rivian, by comparison, has just under 247 lb-feet of torque for each of the rear wheels (495 combined rear) just under 206 lb-ft for each of the front wheels (413 combined front). The curb weight is around 1,000 pounds more than our LR3 and with the 20” diameter AT wheels in ~34” diameter tires we end up with about 7” of of sidewall.

Even with only 2 diagonally-opposed wheels getting traction, the Rivian will have around 453 lb-ft of torque providing motivation which is nearly a 50% improvement over our LR3 with only a ~17% increase in weight. Obviously with 3 or 4 wheels getting traction the Rivian will only be better and better.

Regarding wheels and choosing a new line… The wheels on his truck are probably about as ill-suited for rocky off-road adventure as the ones on our LR3. Ours do look pretty bad at this point, but we got to see some amazing scenery and some uncommon, and uncommonly beautiful, destinations. Whenever we are on a difficult trail one of us acts as spotter and I feel no shame in saying that there have been times we realized that our initial line wasn’t the best option so we made a slight adjustment and carried on. As a result we have always made it back home safe and sound under our own power. I think that’s better than stubbornly pursuing a bad path.

Sorry for the novel-length post. I just thought a different perspective from someone with experience driving a heavy vehicle off-road with an independent and height-adjustable suspension, and using different driving modes might calm some fears about off-roading.

tl;dr Don’t worry. We’ve adventured far more with far less capability and had a blast doing it!

 

[Zybane]

Even with only 2 diagonally-opposed wheels getting traction, the Rivian will have around 453 lb-ft of torque providing motivation which is nearly a 50% improvement over our LR3 with only a ~17% increase in weight. Obviously with 3 or 4 wheels getting traction the Rivian will only be better and better.

That's not how it works. Direct TQ numbers from the engine/motors are irrelevant. What matters is the wheel TQ that is actually applied to the ground after all gearing multiplication and driveline losses.

Despite common perception, the Rivian low speed TQ numbers at the wheels are actually mediocre/average compared to regular ICE SUV's with transfer cases and well below dedicated off-roader ICE vehicles like the Rubicon Jeeps.

Since there is no mechanical link between any of the Rivians wheels, lifting a wheel is a huge detriment to the Rivian. Lifting two wheels is really bad. You've just halved the vehicles capability when it comes to wheel TQ. This does not happen to an ICE 4x4 with locked differentials.

Now efficiency and speed the Rivian absolutely destroys any ICE off-road vehicle. As an "all around" vehicle the Rivian is the best. As a more off-road geared platform, it's not that special. And Rivian didn't design it as such, as can be seen in the videos and in the known wheel TQ numbers provided by the head assistant Rivian engineer for propulsion.

 

[SoCal Rob]

That's not how it works. Direct TQ numbers from the engine/motors are irrelevant. What matters is the wheel TQ that is actually applied to the ground after all gearing multiplication and driveline losses.

Despite common perception, the Rivian low speed TQ numbers at the wheels are actually mediocre/average compared to regular ICE SUV's with transfer cases and well below dedicated off-roader ICE vehicles like the Rubicon Jeeps.

Now efficiency and speed the Rivian absolutely destroys them. As an "all around" vehicle the Rivian is the best. As a more dedicated off-road platform, it's not that special. And Rivian didn't design it as such, as can be seen in the videos.

Let’s see how it works in real life situations since that’s my whole point. The raw numbers may or may not be meaningful depending upon the design of the whole vehicle and how that vehicle is driven.

Has anyone claimed that the Rivian should be a dedicated off-road platform? If that’s your issue with the Rivian then you may be the only person concerned about it. It’s also a bit of a pivot from what you seemed to be stating.

Most people looking for an adventure vehicle like a Rivian will almost certainly use it for the mundane (Costco, commuting, Home Depot, etc.), the possibly lengthy drive from home to the adventure, and the adventure itself. The Rivian should far exceed most people’s expectations in those 3 cases while a dedicated off-road vehicle would be amazing if it could handle even 2 comfortably and competently.

 

[Zybane]

Let’s see how it works in real life situations since that’s my whole point. The raw numbers may or may not be meaningful depending upon the design of the whole vehicle and how that vehicle is driven.

Has anyone claimed that the Rivian should be a dedicated off-road platform? If that’s your issue with the Rivian then you may be the only person concerned about it. It’s also a bit of a pivot from what you seemed to be stating.

Most people looking for an adventure vehicle like a Rivian will almost certainly use it for the mundane (Costco, commuting, Home Depot, etc.), the possibly lengthy drive from home to the adventure, and the adventure itself. The Rivian should far exceed most people’s expectations in those 3 cases while a dedicated off-road vehicle would be amazing if it could handle even 2 comfortably and competently.

Well in reality I don't care what most people will do with their Rivians. I just want to know its capabilities and limits. I reserved an R1S for my overlanding needs that will have some more difficult off-roading tossed in here and there. But I also reserved back when a "Max Pack" R1S was stated as a real possibility. Now that has basically been taken off the table, the R1S is looking less likely to fill my requirements.

But I'm still buying it!

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