Hell's Gate in my R1T

[BeanEW]

Don't be too hard on yourself... the line was perfect!

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[BillArnett]

... One thing I read about electric motors is that when a wheel comes off the ground it spools up fast regardless of the amount of current going to it. Where I see this being a problem is when it makes contact back with the ground. I watched or read some early rivian videos or articles that said getting the motors to work right in zero traction situations is very hard.

I'm envisioning a different way to thinking about the accelerator pedal. Usually we think of it as controlling the amount of force applied to the wheels. Perhaps in very low speed rock crawling situations it should instead by a simple speed control: push down, the wheels spin faster; each wheel's controller applies the amount of torque to achieve the desired rotation rate. The goal is simply to make all 4 wheels spin at the same rate. It doesn't have to be perfect. It would be OK for there to be a few milliseconds of lag and a few rpms of difference between the wheels.

 

[BillArnett]

Nice work! It is an intimidating obstacle (also dropping down the entrance to get to the start of the climb takes some commitment). Here's a view from the bottom giving a different perspective. My 4runner was on 35" tires with front and rear lockers, as well as lower axle and transfer case gears.

Very nice. I don't think I could have done it that slowly with the R1T.

 

[BillArnett]

I definitely had the truck go into turtle mode while trying to climb the rock wall I mentioned. Something overheated for sure. Let it sit for a minute or two and it cooled down enough to keep going...

Is that what it means when it says "Performance limited"?? I've had that a couple of times and always assumed it was some sort of traction control nanny-ism. "Oh, no! your wheels are spinning! I'm going to shut you down."

But if it really is overheating, then the warning message should say so.

 

[BillArnett]

Traction control systems will always be reactive. By the time they realize they don't have traction or need to apply more/less power, it's to late...

Well, that depends on how fast the reaction is. Maybe Rivian needs a faster computer?

 

[HaveBlue]

That zero rpm stall really complicates crawling for electric motors. They just don't do well applying metered power smoothly and end up with to much or too little.

I ordered a dual motor which will have less of an issue with that and will be investigating locking differentials. Which is to say I worked with ARB engineering to sort out applications and test products but I don't see how to engineer an air locker for a differential inside a planetary housing. I haven't seen it personally though so there might be a way depending on the case. Otherwise an automatic type if internals can fit.

 

[dleepnw]

I definitely had the truck go into turtle mode while trying to climb the rock wall I mentioned. Something overheated for sure. Let it sit for a minute or two and it cooled down enough to keep going. Lowering gearing would certainly help, but it also adds weight and complexity.

We'll see though. Mercedes is supposedly adding a low range to their upcoming EV G-wagon, possibly lockers and portal axles too. The G has always been a ridiculously capable off-roader that almost never goes off pavement because of how expensive they are.

i think existing G wagons already have portal axles, no? Rivian should build the low range gearbox as an option for hard core off-roaders.

 

[tosehee]

I use the term "lockers" loosely in this context to mean "software lockers" ie "better individual motor controls". I was actually pleasantly surprised how well the current software works in most cases. There's a lot of unnecessary wheel slip but mostly I was able to get thru the obstacles anyway. But there were a couple of times when it just gave up and said "Performance limited" and I had to back down (no easy feat on "Tip Over Challenge" :-(

Quad is only *potentially* better than mechanical lockers. Compare my video on Hell's Gate last year with my Jeep (no chirps, no slipping, just a nervous wife behind the camera

Your wife is not nervous... My wife won't even let me try here..

 

[HaveBlue]

The motors are already geared 10:1. They aren't direct drive 1:1

 

[BillArnett]

I see the idea of wheel slip being bad thrown around a lot. When in reality, excessive wheel slip is the reaper of death. Leads to a lot of lateral vehicle movement. No wheel slip provides confidence and sure-footedness.

Well, mostly. But sometimes lateral movement is helpful. You'll find lots of videos of Jeeps spinning all 4 for a few seconds with some lateral movement until just the right spot is found and traction resumes. Done carefully this is a useful technique.

...We see a software version of an electronic locker on the Hummer EV that targets tight wheel speed thresholds between opposite-side tires. This creates an additional issue. One tire might be on a lower mu surface (gravel), the other tire may be bumped up against a bolder. This creates an issue where the computer does not know which wheel speed to set as the reference point.

So let the accelerator pedal be the reference!

... It is no secret that the cooling system for the inverters on the Quad motors is undersized for high-performance applications. Also, it appears that sometimes a single motor just does not appear to be up to the task of pulling the entire vehicle over a larger bolder. (this is likely a combination of motor capability and tire grip) We will get a better idea of these two issues once the new update is released. It is supposed to list motor temp. Then all we need to read is the current demand of each motor and repeat Hell's Gate to see if there is truly a hardware limit.

What is this new update you're referring to? Do you have any more details?

... gives me hope that Rivian may be able to tune the system over time. But as stated above, if it's hardware, not much can be fixed then. I bought my R1S for its capability today. I do not expect them to end up with a vehicle that is identical to a mechanical locker. If I wanted the best vehicle for offroading alone, I would have built out a jeep, bronco, or custom job. Instead, I bought the R1S because it can get me through the Rubicon trail if needed, beat almost any car off the line at a stop light, and is comfortable on road trips.

Despite my carping, I'm pretty happy with my R1T for exactly the reasons you state. We'll see if the Cybertruck is any better. No doubt it will have a different set of trade-offs.

Do you really think a Rivian could get thru the Rubicon with no damage? Prior to my experience in Moab this year I would have said "definitely not". Now I'm on the fence. Do you know of anyone who has tried?

 

[BillArnett]

I don't remember where I read or watched one of the Rivian guys talking about, but it seem that the problem that you get stuck when two diagonal wheels are in the air and the two with traction does nothings is inverter heating related
...
What makes me feel more confident that this is the case is that if you release the throttle let if cool down for a bit, and then floor it, it can have a burst of torque that get you out, since tires will slip and start to spin and will allow you to have the full torque on each wheel, and as long as you keep moving you will be fine

Unfortunately this isn't something that can't be solved by software

thanks. That backs up my intuition that to make it up Hell's Gate I had to not stop.

 

[WSea]

Well, mostly. But sometimes lateral movement is helpful. You'll find lots of videos of Jeeps spinning all 4 for a few seconds with some lateral movement until just the right spot is found and traction resumes. Done carefully this is a useful technique.



So let the accelerator pedal be the reference!



What is this new update you're referring to? Do you have any more details?



Despite my carping, I'm pretty happy with my R1T for exactly the reasons you state. We'll see if the Cybertruck is any better. No doubt it will have a different set of trade-offs.

Do you really think a Rivian could get thru the Rubicon with no damage? Prior to my experience in Moab this year I would have said "definitely not". Now I'm on the fence. Do you know of anyone who has tried?

The Rivian R1S Becomes First Production EV to Tackle the Rubicon Trail (roadandtrack.com)

 

[Ralph]

Wouldn't it be cheaper and easier to beef up the cooling system?

I wouldn't have any idea if "beefing up the cooling system" would be easier or cheaper.

I have to assume that Rivian engineers went to the trouble to file this patent for a reason. Perhaps just to document what became a dead end. They may indeed have different/better, more practical solutions up their sleeve.

Or not.....

In any case, I for one am glad that Rivian takes the problem seriously enough to investigate solutions. The competition surely is doing so. And although less than 1 percent would actually need or use a solution, marketing capability is a very real thing.

Oh, and let me be clear: I'd not being doing Hell's Gate or many of the other routes there in any case. Kudo's to all that do so! But as we have seen in other videos, and perhaps personally, there are lots of other situations that a solution to this problem would useful.

 

[zefram47]

Is that what it means when it says "Performance limited"?? I've had that a couple of times and always assumed it was some sort of traction control nanny-ism. "Oh, no! your wheels are spinning! I'm going to shut you down."

But if it really is overheating, then the warning message should say so.

It's an icon on the lower left of the dash that looks like a turtle...orange, IIRC. I think they use that icon for several things, but some component overheating is one of them I think.

 

[pntbllarea51]

Well, mostly. But sometimes lateral movement is helpful. You'll find lots of videos of Jeeps spinning all 4 for a few seconds with some lateral movement until just the right spot is found and traction resumes. Done carefully this is a useful technique.



So let the accelerator pedal be the reference!



What is this new update you're referring to? Do you have any more details?



Despite my carping, I'm pretty happy with my R1T for exactly the reasons you state. We'll see if the Cybertruck is any better. No doubt it will have a different set of trade-offs.

Do you really think a Rivian could get thru the Rubicon with no damage? Prior to my experience in Moab this year I would have said "definitely not". Now I'm on the fence. Do you know of anyone who has tried?

I won’t attach the article with Rivian completely the Rubicon with a basically stock vehicle since someone above me has already.

but you can find info on the upcoming software update here.

https://rivian.software/2023-38/

Currently it’s only an internal release.

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