Quad Motor Better Than Lockers...?

[zefram47]

The experts teaching me how to off road told me this is the opposite of the right approach. For what it's worth. (And these guys are running purpose built Jeeps--there's no Rivian bias in their approach)

Flooring it to get through an obstacle is the wrong option.

Finding the right path, steering into the problem and placing the tires appropriately, and only applying what you need (throttle wise) is the way to go. Did those vehicles have the right tires and were they aired appropriately?

Bear in mind the Rivians ARE definitely hindered by their total weight. And there are limits (in the case of max angle, break over angle). Do you have a link to that video?

TL;DR, you can't drive an EV the same was as an ICE off-road. Those of us who have owned and wheeled both are having to learn this in realtime so others may learn. In an ICE, you slowly increase throttle until you spin the tires or start moving. If you spin, likely you take a different line and try again.

With the EV off-roaders, to date, if you slowly apply throttle they either go into turtle mode as the inverters or motors overheat due to low stall-torque or you eventually wind up with the throttle to the floor and the vehicle doesn't move and doesn't spin a tire. Again, I've experienced this and have prior ICE 4x4 experience. As in the video I posted, the only thing you can do to get around the stall torque issue is either roll into an obstacle or quickly increase throttle and immediately back off once the vehicle starts moving. But in the event you are trying to get over a rock wall you can't easily roll into the obstacle because the height can easily be too much. Similarly, if you're up against the wall and try to get over then the stall-torque problem rears its head. If you smack the throttle quickly to avoid the overheating / stall-torque problem, now you're deploying 800 hp while you may be tippy on two wheels (been there and done that). It's not safe to deploy power that way in a lot of situations. This is why we need the crawl control mode that just allows all four wheels to spin at a constant speed regardless of the grip at each corner...truly the simulated locker mode we all thought we'd have.

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[zefram47]

You must have accidentally posted a different video from what you're claiming, because the video I just watched showed the Rivian performing EXACTLY how I'd anticipate. And it did exactly what I've experienced (maintain throttle, and it eventually figures it out and moves).

Where is the failure here, exactly?

Try at around 20:15 in the video. Explained in another response, but you have to smack the throttle quickly to get out of some situations and it's pretty uncontrolled when you do since you're deploying so much power very quickly. Also shows being on the floor and the vehicle not moving. It's only spinning the 3 tires at all because it's virtually frictionless on the rollers, but the one wheel with grip does absolutely nothing. The rollers also aren't a good proxy since the vehicle starts sliding towards the edge of the rollers and can inadvertently catch grip when a tire hits the frame of the rollers.

 

[R1Thor]

Try at around 20:15 in the video. Explained in another response, but you have to smack the throttle quickly to get out of some situations and it's pretty uncontrolled when you do since you're deploying so much power very quickly. Also shows being on the floor and the vehicle not moving. It's only spinning the 3 tires at all because it's virtually frictionless on the rollers, but the one wheel with grip does absolutely nothing. The rollers also aren't a good proxy since the vehicle starts sliding towards the edge of the rollers and can inadvertently catch grip when a tire hits the frame of the rollers.

I'm not disagreeing with you, but simply pointing out (I did see that example): that's exactly ONE verily specific (and likely rare to actually encounter in real world) situation, don't you think?

And it was still capable. Even though (admittedly) not an ideal resolution to the hiccup.

But also to everyone's point earlier--this is potentially solve-able with software to handle this situation. However, then the debate goes back to "does it have to?" given the rarity of being found in this EXACTLY singular scenario?


For those of you thinking these vehicles aren't pretty darn incredible and have incredible shortcomings: I want to come wheeling with you I guess I just haven't put myself into the crazy business you all are. I don't think I'd have the nerve, to be honest!

 

[R1Thor]

This is right in most vehicles especially with low gears and crawl control type systems and comes to the crux of the gen1 quad. "Flooring it" is the only option to add more torque when you're stuck on "slow" obstacles due to the torque vectoring in these. It feels unnatural but it's the only option.

Check out this video, he explains it well and even compares similar EV trucks with and without lockers.

I see what you're seeing. And this goes back to why I don't like anecdotes, because my brain isn't reconciling this the same.
During the off-road course I took, we intentionally stopped on an obstacle VERY similar to this one, and the truck had zero issues negotiating resuming (forward).

Which begs the question of is everyone simply looking for all of the weak links and this is all they can come up with? Finding these verily nuanced and intentionally sticky situations.

You guys tell me: are these the 'standard' tests for off-road prowess? Is Rivian not also testing their vehicles on appropriately difficult obstacles?

Does Rivian HAVE to keep up with dedicated, purpose-built off-road vehicles?

Can those dedicated off-road purpose build vehicles ALSO run rally modes? Switch to rock crawling mode? Then switch back to all-terrain, camp for the night, then air back up, merge onto the highway and ride home without a trailer? In all scenarios? If yes to all of the above, then maybe Rivian just isn't well-rounded and there's a better vehicle for your use cases?? ?‍

 

[Blakejakely]

I see what you're seeing. And this goes back to why I don't like anecdotes, because my brain isn't reconciling this the same.
During the off-road course I took, we intentionally stopped on an obstacle VERY similar to this one, and the truck had zero issues negotiating resuming (forward).

Which begs the question of is everyone simply looking for all of the weak links and this is all they can come up with? Finding these verily nuanced and intentionally sticky situations.

You guys tell me: are these the 'standard' tests for off-road prowess? Is Rivian not also testing their vehicles on appropriately difficult obstacles?

Does Rivian HAVE to keep up with dedicated, purpose-built off-road vehicles?

Can those dedicated off-road purpose build vehicles ALSO run rally modes? Switch to rock crawling mode? Then switch back to all-terrain, camp for the night, then air back up, merge onto the highway and ride home without a trailer? In all scenarios? If yes to all of the above, then maybe Rivian just isn't well-rounded and there's a better vehicle for your use cases?? ?‍

They're claiming they're better than purpose built offroaders. Its neither here nor there until they made claims like that. The situations being shown are very common; going up a mountain pass that's been washed out, rocks on inclines where you need to take a specific path, etc. All things I've done in my current gen1 quad. Back to my main argument, they're still super capable, but the torque vectoring like their claim, needs work since you have to give so much throttle to get over obstacles that it becomes uncontrolled, at least in gen1

 

[zefram47]

I'm not disagreeing with you, but simply pointing out (I did see that example): that's exactly ONE verily specific (and likely rare to actually encounter in real world) situation, don't you think?

And it was still capable. Even though (admittedly) not an ideal resolution to the hiccup.

But also to everyone's point earlier--this is potentially solve-able with software to handle this situation. However, then the debate goes back to "does it have to?" given the rarity of being found in this EXACTLY singular scenario?

For those of you thinking these vehicles aren't pretty darn incredible and have incredible shortcomings: I want to come wheeling with you I guess I just haven't put myself into the crazy business you all are. I don't think I'd have the nerve, to be honest!

Do any sort of rock crawling and it's not that uncommon to get in a similar situation. Rivian just hasn't seemed to care about revising the software calibration of the Gen1 QM.

The R1 platform *is* extremely capable, but there are known limitations that owners venturing off-road should be aware of. I bought my R1T because it was the most capable EV out of the box that I could buy at the time and allowed me to swap my EV daily-driver (MINI Cooper SE) and my off-road built 4Runner for a single vehicle. The height-adjustable air suspension even allows it to be more comfortable/practical than my lifted 4Runner was, especially with older parents occasionally riding in it.

 

[Davethadog]

I'm not disagreeing with you, but simply pointing out (I did see that example): that's exactly ONE verily specific (and likely rare to actually encounter in real world) situation, don't you think?

These are pretty common scenarios if you like to take your vehicle off-roading in any kind of capacity other than on fire roads.

 

[White Shadow]

The experts teaching me how to off road told me this is the opposite of the right approach. For what it's worth. (And these guys are running purpose built Jeeps--there's no Rivian bias in their approach)

Flooring it to get through an obstacle is the wrong option.

Finding the right path, steering into the problem and placing the tires appropriately, and only applying what you need (throttle wise) is the way to go. Did those vehicles have the right tires and were they aired appropriately?

Bear in mind the Rivians ARE definitely hindered by their total weight. And there are limits (in the case of max angle, break over angle). Do you have a link to that video?

What I was saying is that Kyle eventually put his foot to the floor in an attempt to get his Rivian moving. He didn't just floor it immediately. He was unable to get his quad motor to send power to the wheels that had traction. Instead, the vehicle acted like a 4wd with open diffs, sending power to the wheels with no traction.

 

[White Shadow]

They're claiming they're better than purpose built offroaders. Its neither here nor there until they made claims like that. The situations being shown are very common; going up a mountain pass that's been washed out, rocks on inclines where you need to take a specific path, etc. All things I've done in my current gen1 quad. Back to my main argument, they're still super capable, but the torque vectoring like their claim, needs work since you have to give so much throttle to get over obstacles that it becomes uncontrolled, at least in gen1

From everything I've seen, Rivian is not better than a purpose built offroad vehicle. They aren't even as good as a purpose built offroad vehicle. Hell, they aren't even in the same class as something like a Wrangler or a Bronco. For me, if a Rivian is as good as a 4Runner or Grand Cherokee offroad, then that's good enough for me. That's really the class that Rivian competes with anyway.

 

[R1Thor]

These are pretty common scenarios if you like to take your vehicle off-roading in any kind of capacity other than on fire roads.

You must have missed the part where I HAVE had my R1T offroad, on both a 101 and 201 level course (taught by experts). I am absolutely familiar with what this vehicle can do on terrain I couldn't have even imagined navigating--over terrain including terrain I would've had a difficult time HIKING over.

I earnestly DO NOT think that a scenario where you lose ALL BUT ONE specific tire's traction is improbable, and further, based on conversations I've had with the very same experts, if you're putting yourself in a situation where you'll likely be down to having only one tire with traction left... I'd recommend you get some training, mate.

 

[usulio]

This is right in most vehicles especially with low gears and crawl control type systems and comes to the crux of the gen1 quad. "Flooring it" is the only option to add more torque when you're stuck on "slow" obstacles due to the torque vectoring in these. It feels unnatural but it's the only option.

Check out this video, he explains it well and even compares similar EV trucks with and without lockers.

Funny how the video is supposed to show how important lockers are, but the Rivian just walks up the obstacle way easier than the others including the F-150 with a locked rear diff.

I'm totally sold on the theoretical value of lockers, but finding a difficult crawl situation for Rivian may be easier said than done.

Edit: I think you really need a low-traction situation to cause problems, not just off-camber or wheels in the air. The other Out of Spec video where the quad struggles was using road tires at road PSI, which is just silly.

 

[DuoRivians]

In my current quad R1T, while I’ve had to “gun” it more than I wanted to generate momentum, I haven’t come across any obstacle or slow crawl situation where the current quads couldn’t handle it.

The obstacles that I didn’t try were limited by the truck’s approach, breakover, departure angles before any traction issues.

I’m sure the new quads are even more capable, fine tuned

 

[Glembi2]

…

I'm totally sold on the theoretical value of lockers, but finding a difficult crawl situation for Rivian may be easier said than done.

Edit: I think you really need a low-traction situation to cause problems, not just off-camber or wheels in the air. The other Out of Spec video where the quad struggles was using road tires at road PSI, which is just silly.

I was hoping those videos would substantiate my belief that lockers are superior to quad motors to the point that QMs would not move while only those with lockers or limited slip diffs would be drivable. The only thing those videos clearly showed was one needed to quickly depress the go pedal to get the truck to move.

yes, the sudden lurch and need to immediately stop is an issue but that does not equate to the binary conclusion that QMs won’t navigate ___[insert term] terrain.

Those videos make me respect my QM than I did before. For most of us, this point is theoretical. I’ll likely never be at the edge of the capabilities of the truck where a truck with lockers would be drivable while the QM would not. Rather, I have to believe that the crappy surface would quickly overcome the ability of trucks with lockers as well.

 

[Dark-Fx]

In my current quad R1T, while I’ve had to “gun” it more than I wanted to generate momentum, I haven’t come across any obstacle or slow crawl situation where the current quads couldn’t handle it.

Rivian really could/should be redirecting the requested torque in these situations, but IMO in rock crawl it's pretty safe to give it a lot more pedal because crawl does limit how much acceleration the already spinning wheels get, which you can see in Kyle's video above at 23:05. A traditional open diff vehicle in this situation is going to spin the fuck out of those loose tires without the brakes acting as anti-slip to redirect the torque.

 

[OneForTheRoad]

I read this debate in the other thread a while back and it does seem like there are very real situations where the QM falters. My question for people here: which of the various solutions proposed would be best? Physical lockers would be great, but is it even possible, let alone practical, with a QM set up? Or would a digital locker set up from a crawl control keeping all wheels spinning the same be good enough? What about a low range gear like someone said Stellantis is doing? Do any of these even solve the issues of low stall torque and motor overheating?

Essentially, if you were designing the top of the range Rivian, what would be your order of changes to make it better in the most practical way?

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