R1T vs. R1S in snow?

[R.I.P.]

I missed the part where we were talking about locked diffs. I see there was a quick mention of it above, but last I'd checked, this entire thread was regarding snow performance--you don't want locked diffs for snow. Did we switch to rock crawling when I wasn't looking?

Did you also miss the part about me talking about my experiences, driving my vehicle(s) in snow and ice?

If I were to claim to know better than you what is in your right front pocket at this moment I would have similar credibility to your insistence that you know my experiences in my vehicles better than I do. You seem offended that my experience does not line up with what you feel is the science. I have no issue with the science. I am just telling you that in my experience, it is not working the way you say it should when it comes to the QM.

I will note, that there are a growing group of us, some of which you can find on you tube that have QMs, drive QMs test QMs, and are all saying that they are not working well in many situations where we expected them to.

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[R1Thor]

Did you also miss the part about me talking about my experiences, driving my vehicle(s) in snow and ice?

If I were to claim to know better than you what is in your right front pocket at this moment I would have similar credibility to your insistence that you know my experiences in my vehicles better than I do. You seem offended that my experience does not line up with what you feel is the science. I have no issue with the science. I am just telling you that in my experience, it is not working the way you say it should when it comes to the QM.

I will note, that there are a growing group of us, some of which you can find on you tube that have QMs, drive QMs test QMs, and are all saying that they are not working well in many situations where we expected them to.

Anecdote ≠ data.

Objective truth has nothing to do with one persons experience or your personal bearing witness to whatever you claim. Do you have any idea how many people insist they've seen UFOs? Ben abducted by aliens? I guess we should believe them in a blind?

Show me EVIDENCE.

Scream louder all you want, man. I've already laid the foundation for being ready to be proven wrong. But you've still offered literally zero, tangible, repeatable, scientific evidence. Go get me some data, with some controlled data, that's repeatable. That's all we ask. That's all!

 

[R.I.P.]

wow

ok then

we will just leave that right there.....

 

[Z00mBye]

RIP - I wanted to thank you for the information shared in these posts. Very helpful. I'm in Colorado, drive to the mountains regularly, and waiting to lock in. I've been waffling about QM v DM. This is great information. Appreciate it. ?

So DM for u ?

 

[Nine_One_Six_R1S]

I think it's absolutely possible.

There's nuance to it. Because it's VERILY difficult to overcome slippery friction. You want static friction between your contact patch and the ground. So, being able to intentionally adjust for your rolling friction to achieve (or in the case of slippage, RE-acquire) static friction is incredibly powerful. In *theory* the QM could do this with software control and put EXACTLY the power needed to EXACTLY the right place at EXACTLY the right time.

In practice, the reason R.I.P. seems so credible is because we don't know that that's the case here. I still would love to see a DM go head to head with a QM with professional drivers on a closed course.

Or even better, can we get a set of trucks to these guys??? https://www.youtube.com/channel/UCJfliGgEFUBDyqTuNzGbH4A

I recall I saw a video on YT of a R1T on rollers. Getting stuck when on 3 rollers with the guy slowly increasing throttle. And then getting out by mashing the throttle. So the stall was experienced differently depending on the throttle response.

Personally, I have experienced what was shown in the video. Stuck on steep hill with bad traction (loose sand/rock mix). Stall initially with modulation of the throttle. And then different (i.e no stall) response by mashing the throttle and getting out of trouble.

 

[runningdenver]

So DM for u ?

yes, I think so. I was leaning to the max pack, and need better snow performance, so this helped.

It's a little annoying that Rivian put the 'premium' touches - yellow calipers, accents etc on the QM, when you could argue that the DM max pack is the most 'premium' based on cost. At least give us a MAX logo !

 

[R1Thor]

I recall I saw a video on YT of a R1T on rollers. Getting stuck when on 3 rollers with the guy slowly increasing throttle. And then getting out by mashing the throttle. So the stall was experienced differently depending on the throttle response.

Personally, I have experienced what was shown in the video. Stuck on steep hill with bad traction (loose sand/rock mix). Stall initially with modulation of the throttle. And then different (i.e no stall) response by mashing the throttle and getting out of trouble.

I wonder if the 'stall' isn't a function of the motors failing in any meaningful way, so much as the software trying to 'determine' what to do next to compensate...? Time will tell (especially if software improvements are made!)

 

[Z00mBye]

yes, I think so. I was leaning to the max pack, and need better snow performance, so this helped.

It's a little annoying that Rivian put the 'premium' touches - yellow calipers, accents etc on the QM, when you could argue that the DM max pack is the most 'premium' based on cost. At least give us a MAX logo !

Could not agree more !!!

 

[usofrob]

I don't have a Rivian yet (I continue my DM/QM waffling), but based on what I hear from others on here, it seems like the R1T may have relatively low stall torque compared to it's peak torque. Is there any way to test that? And/or it is heat limited as you slowly add more throttle, e.g. effectively low stall torque. This would be overcome by mashing the throttle to get the SW to drive high power first while it's cool.

All indications are that the DM motors have a much better cooling system, and maybe don't suffer as much heat limited torque stall. And if the DM's differential allows the motor to spin one wheel, then it's not stall torque anymore, and can provide the full power (* 59%).

FYI: The DM individual motors are each rated for 350 hp, but when they're both running together, it's less total. You can see this in the EPA information. But, I suspect the QM is like that as well.

As far as the differential having 'better' properties than two independent motors, I suspect the major difference is that the differential essentially responds quicker. 100 times a second isn't actually that fast. It's probably the sampling rate. To actually determine slip, you'd have to see multiple data points in a row, then calculate slip and hit the brakes.

Furthermore, the point about lateral stability in very slippery conditions is that the side that has traction doesn't get the power thus it doesn't slide sideways. Maybe the opposite wheel braking to get power to the grippy tire is just softer than the QM implementation. Although, the wheel braking would also have the same sampling delay as in the QM.

As I saw all of this, it really makes me wonder if the Achilles heal of the QM for very slow speed grip is that it has relatively low stall torque that also over heats the motors that don't cool quickly. Maybe if they just put a disc clutch in between the motor and the wheel, they could spin the motor and modulate the power application per wheel to get past stall torque. AND that digital sampling and response still isn't as responsive as mechanical connections.

Does anyone have some good videos on electric motor stall torque? I've seen some explanations in the past related to the high power needed at 0 RPM, but I'm a bit rusty.

 

[jmtreetop]

I recall I saw a video on YT of a R1T on rollers. Getting stuck when on 3 rollers with the guy slowly increasing throttle. And then getting out by mashing the throttle. So the stall was experienced differently depending on the throttle response.

Personally, I have experienced what was shown in the video. Stuck on steep hill with bad traction (loose sand/rock mix). Stall initially with modulation of the throttle. And then different (i.e no stall) response by mashing the throttle and getting out of trouble.

Here is a good example

 

[Nine_One_Six_R1S]

Does anyone have some good videos on electric motor stall torque? I've seen some explanations in the past related to the high power needed at 0 RPM, but I'm a bit rusty.

I have not seen the TFL one yet but that video seems like that is a more realistic Off road scenario (uphill with low traction)

Here is another one

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