Snow Mode?

[JGard18]

taller gearing? man, that'll be a real achievement for the dev team to change via OTA update

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[Dark-Fx]

This is more a factor of not allowing any wheels to lock under regen. In my 4x4 I can brake more confidently in 4WD than in 2WD partially because the inertia in the drivetrain helps prevent lockup under light braking. I even use the gears a ton to engine brake without using the friction brakes, more akin to regen. The concern with regen in the snow is that if it doesn't properly sense lockup like ABS and friction brakes then you can get very undesirable handling characteristics. I very much still want regen in the snow though...as I said, similar to engine braking, but we also need that capability to make all the wheels turn at nearly the same rate (virtual lockers) to make it more effective.

Rivian's regen at low speeds is kinda weird on loose dirt roads. I imagine the feeling is going to translate the same to snow covered roads. It feels like it entirely kills regen briefly. We only had somewhat slick/icy roads once since I've had the Rivian, and I don't remember it acting that way then, but I'm sure it's no different. It definitely errs on the side of not locking the wheels up. If the roads are slick you're going to be on the physical brake pedal anyway most likely because of that if you're exceeding the limits of available braking power.

 

[MountainBikeDude]

So, reached out to the The Guy on this subject.

I asked if Rivian was working on a "Snow Mode" and if it would potentially work in the ability to reduce regen and thus reduce the likelihood of sliding while descending on icy/compact snow?

I was told "snow mode" wasn't necessarily the naming, but the winter feature would meet a similar objective

Didn't really want to push for more information as I appreciate the openness with some of their lead people, also, nice to leave some things as a surprise!

 

[moosehead]

taller gearing? man, that'll be a real achievement for the dev team to change via OTA update

Would it? Isn't it electronically controlled by ECU to each motor? Say, quasi similar to a tow mode having slightly higher RPM shift points per "gear" starting at the lowest.

 

[JGard18]

Would it? Isn't it electronically controlled by ECU to each motor? Say, quasi similar to a tow mode having slightly higher RPM shift points per "gear" starting at the lowest.

I don't think you understand what "gears" are? There's a single reduction gear from motor to driveshaft, that's all it is.

 

[godfodder0901]

Would it? Isn't it electronically controlled by ECU to each motor? Say, quasi similar to a tow mode having slightly higher RPM shift points per "gear" starting at the lowest.

I don't think you understand what "gears" are? There's a single reduction gear from motor to driveshaft, that's all it is.

And in that scenario, the gear ratio doesn't change, only the engine RPM at which the transmission selects the next gear. Unless you have a CVT, gear ratios are dictated by the installed hardware.

 

[moosehead]

^JGard, presume you are referencing Rivian's single reduction gear motor to driveshaft, which is just one of my snow driving concerns - not having true gears to moderate snow speed especially downhill and/or at speed. Seems as though Rivian is just relying upon regen braking, traction management, and ABS in snow, which is what caused OOS/Kyle to have lockup in downhill snow even at speeds as low as 7 mph. It also led to him concluding Rivian could use a snow/mud mode.

I believe this was prior to Rivian's soft sand mode which was implemented after OSS snow vid, not sure. Note soft sand mode does seem to have a "low" regen option, perhaps others do too, but most are limited to Standard and Strong regen.

Given lack of downshift gearing like manual and auto ice rigs, and moderate to strong regen, that is perhaps why others are also asking for the ability to select low regen or varied regen for Rivian snow conditions. Since we don't have the paddle shift regen options like the VAG cars (Porsche Taycan/Etrons who also have lesser regen and avoid OPD) or the Hyundai I5, or their blended braking, perhaps the best route is selecting low regen, not sure.

Which brings us back to need for snow mode. When in high country, on extended downhills, or highways in snow, the driver may not want to or be able to reach for the screen to optimize the combinations of regen, throttle, rear-forward axle bias, traction control and whatever else Rivian's engineers have at their disposal.

 

[moosehead]

Attached below is the OOS snow vid. For those who dislike the length and commercials, like me, you can just go to about 19:25 of the video where Kyle turns around at the top of a snow-covered dirt hill and starts down. He recommends adding a snow mode even before the downhill lockup segment.

 

[moosehead]

Just picked up the 20" Dark wheelset and tires from Denver RSC this afternoon. Given the season change and fresh snow in the high country yesterday, timing was good.

Though they were not officially confirming so, the local RSC team did indicate a snow mode was in the works and would include low regen, moderated throttle, and other special sauce involving torque vectoring, certain wheel spin prior to ABS kicking in and other TBD features.

Further, they stated that the existing vehicle had certain of these changes enacted below 32F ambient temps, and another threshold at "single digit temps and below", whereby regen and throttle response were reduced further. A local customer in Nederland reported being surprised in yesterday's 9F temps and 8+ inches in snow to find regen was considerably lowered on the way down from Boulder. Seem to recall seeing something like this on the forums but not sure.

 

[moosehead]

Here’s the Scorpion vs AT tread.

The AT’s have a decent 8.4 snow rating on TIre Rack consumer ratings.

While they have some hum at speed, they are not nearly as loud as our GY Duratracs, a more aggressive and typical non EV designed AT tread.

 

[R1Sky Business]

Just picked up the 20" Dark wheelset and tires from Denver RSC this afternoon. Given the season change and fresh snow in the high country yesterday, timing was good.

Though they were not officially confirming so, the local RSC team did indicate a snow mode was in the works and would include low regen, moderated throttle, and other special sauce involving torque vectoring, certain wheel spin prior to ABS kicking in and other TBD features.

Further, they stated that the existing vehicle had certain of these changes enacted below 32F ambient temps, and another threshold at "single digit temps and below", whereby regen and throttle response were reduced further. A local customer in Nederland reported being surprised in yesterday's 9F temps and 8+ inches in snow to find regen was considerably lowered on the way down from Boulder. Seem to recall seeing something like this on the forums but not sure.

Looks great

 

[Ravenron]

Here’s the Scorpion vs AT tread.

The AT’s have a decent 8.4 snow rating on TIre Rack consumer ratings.

While they have some hum at speed, they are not nearly as loud as our GY Duratracs, a more aggressive and typical non EV designed AT tread.

Hey Moose, congrats on the new shoes! Are your original tires the 22”s? Be interested in the difference in efficiency you experience (i.e. is the sacrifice as much as stated?). I think I’m gonna try my 22”s for the first storm or two and see how it goes…take care…

 

[louisdeg]

I asked that question because I was surprised there was no snow mode and was advised to use sand mode. I haven’t tried sand mode. Any comments?

 

[COdogman]

I don’t have my truck yet, but from what I know about sand mode, it would have no reason to lower regen so that is probably still set as high as possible. Otherwise it probably would have settings that would help when going forward.

 

[Dark-Fx]

I don’t have my truck yet, but from what I know about sand mode, it would have no reason to lower regen so that is probably still set as high as possible. Otherwise it probably would have settings that would help when going forward.

Sand mode has greatly reduced regen. It's harder to find the "sweet spot" where the vehicle will just coast the motors under low traction conditions. The Rivian is easier than the polestar though, since the R1T has quite a bit of motor noise and the Polestar has basically none.

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