Snow Driving And Regen Braking

[R1Tom]

I am curious if anyone can comment on regen braking on snow/ice covered surfaces.

I have always found with ice vehicles(pun sort of intended this time)that when going over icy road surfaces, such as bridges, etc... in winter driving, that zero change in throttle, no braking, no steering...is best way to go over the ice and prevent loss of control.

How do people with regen, like we have, find driving in those situations?

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[cmtaylor963]

I haven't driven in the snow in my R1T, but in my AWD Mach E, the regen did make it skid at stops and hills. It has settings to turn off 1pedal driving and a mode that simulates coasting that seemed to work well. We'll see how it goes trying to feather the accelerator in the R1T until we get a snow mode.

 

[bhopkins]

Haven't driven my R1T in snow (yet) but with my Tesla Model S, it worked fine. I never reduced my regen setting. You learn how to moderate the accelerator to hit the sweet spot where you're basically coasting (neither adding power nor having region kick in very much). I imagine the R1T is similar. I'm guessing that if I were to go into a skid, normal reactions would kick in and I'd strongly depress the brake pedal and let the antilock brakes do their thing while I steer in the direction of the skid.

 

[R1Tom]

Haven't driven my R1T in snow (yet) but with my Tesla Model S, it worked fine. I never reduced my regen setting. You learn how to moderate the accelerator to hit the sweet spot where you're basically coasting (neither adding power nor having region kick in very much). I imagine the R1T is similar. I'm guessing that if I were to go into a skid, normal reactions would kick in and I'd strongly depress the brake pedal and let the antilock brakes do their thing while I steer in the direction of the skid.

Do we know if during regen, if the tires start sliding from drag, does it behave like abs, or does it simply drag to point of loss of control? I am thinking it simulates abs, but not sure...

 

[Dark-Fx]

Do we know if during regen, if the tires start sliding from drag, does it behave like abs, or does it simply drag to point of loss of control? I am thinking it simulates abs, but not sure...

Most of my skids have been at low speed on gravel. Even the day we had some snow on the ground when I first got my truck, I didn't have problems with the 22" tires on the wet stuff. But that was back in early April and it's entirely possible that Rivian has made additional changes to how they handle skids. At low speed it seems to just pause regen momentarily and reapply it slowly. Hard to really say though since it's over so quick.

 

[R1Tom]

Most of my skids have been at low speed on gravel. Even the day we had some snow on the ground when I first got my truck, I didn't have problems with the 22" tires on the wet stuff. But that was back in early April and it's entirely possible that Rivian has made additional changes to how they handle skids. At low speed it seems to just pause regen momentarily and reapply it slowly. Hard to really say though since it's over so quick.

Very good! Maybe I am overthinking this. Still wouldn't mind a "no regen" setting for certain uses. But otherwise I am a full regen 1 pedal driver.

 

[MountainBikeDude]

Very good! Maybe I am overthinking this. Still wouldn't mind a "no regen" setting for certain uses. But otherwise I am a full regen 1 pedal driver.

This is the best video I can point you to. It starts at the point he goes down hill. The entire video is very informative and showcases the driving dynamics in all modes in on road snow conditions. The desent portion is on a gravel deep snow road.

TLDW
The Regen is too harsh, and once you get to about 6mph, the wheels lock up. This was several months ago however, and the software has been tweaked since, and I also reached out to their main guy a few weeks back, and he said a "snow like mode" was coming soon (actually soon) and it would further deal with the regen issue more intelligently on slippery desents and general driving.

 

[cohall]

I continue to be hopeful they release a snow mode very soon. Dialed back throttle, limited regen, etc.

Seems like that would be more useful than some of the other driving modes they’ve prioritized, ie Sand mode.

 

[mindstormsguy]

Do we know if during regen, if the tires start sliding from drag, does it behave like abs, or does it simply drag to point of loss of control? I am thinking it simulates abs, but not sure...

I’ve had this happen on a gravel road. ABS kicks in as you would expect. It’s not terrible, but I’d really really prefer a way to turn off one pedal regen for snow use, and use regen on the brakes pedal only.

I wish Rivian did brake by wire so they could have accomplished this without sacrificing efficiency (mapping the brake pedal to 100% regen and 0% friction brakes unless your braking hard enough to require friction blended in), but they choose an older style Bosch brake system, so we would give up some effectively without 1-pedal. I’d still appreciate an option though.

 

[R1Tom]

I’ve had this happen on a gravel road. ABS kicks in as you would expect. It’s not terrible, but I’d really really prefer a way to turn off one pedal regen for snow use, and use regen on the brakes pedal only.

I wish Rivian did brake by wire so they could have accomplished this without sacrificing efficiency (mapping the brake pedal to 100% regen and 0% friction brakes unless your braking hard enough to require friction blended in), but they choose an older style Bosch brake system, so we would give up some effectively without 1-pedal. I’d still appreciate an option though.

Thanks! Part of reason I bought the Rivian was I wanted to really learn about BEV world, and you taught me something! Very appreciated!

 

[mindstormsguy]

No problem. If you’re curious, the Audi etron (and I think all German BEVs) allow an option for what I’m describing. They also allow you to enable 1-pedal driving, if you prefer. The etron can’t regen nearly as strong as the Rivian does, but that’s more related to limitations of the electric power train than it is the brakes.

Rivian definitely does 1 pedal better than Audi, but I still miss the option to choose.

page 61 here (and the preceding pages describing the brake system) is a very interesting read: https://static.nhtsa.gov/odi/tsbs/2019/MC-10155750-9999.pdf

 

[zefram47]

No problem. If you’re curious, the Audi etron (and I think all German BEVs) allow an option for what I’m describing.

Definitely not all German BEVs. While my car is a MINI, it's really a BMW under the hood. I have two settings for regen strength and the lowest still has some regen. Likewise, because it was a converted ICE platform the brakes are purely friction and no blending. I had blended braking on my Spark EV and hated the feel of the pedal because you never really knew how much travel you'd need to get the right level of braking. In later GM EVs they added the regen paddle so that you could always get full regen when you wanted without making the throttle feel weird and while leaving the brake pedal as friction only with decent feel.

 

[mindstormsguy]

Definitely not all German BEVs. While my car is a MINI, it's really a BMW under the hood. I have two settings for regen strength and the lowest still has some regen. Likewise, because it was a converted ICE platform the brakes are purely friction and no blending. I had blended braking on my Spark EV and hated the feel of the pedal because you never really knew how much travel you'd need to get the right level of braking. In later GM EVs they added the regen paddle so that you could always get full regen when you wanted without making the throttle feel weird and while leaving the brake pedal as friction only with decent feel.

Ah, yeah, I was thinking more i4, iX, Taycan, etron GT, etc. I forgot about the older platforms.

I also had a Bolt several years back, and it had the same sort of hybrid vehicle style master cylinder that "blends" friction braking and regen. I agree that it is not a good experience. I think the Rivian has the exact same technology, you just don't notice because you're already at strong 100% regen before you get your foot on the brake pedal.

The purely electronic brake blending on the Audi etron is, quite frankly, amazing. It took me owning the vehicle for quite a while for me to be able to confidently decern regen from friction braking. I don't think "normal" drivers ever would notice. It is nothing like the Bolt or other hybrid-style blended brakes.

 

[evergreenmachine]

I am curious if anyone can comment on regen braking on snow/ice covered surfaces.

I have always found with ice vehicles(pun sort of intended this time)that when going over icy road surfaces, such as bridges, etc... in winter driving, that zero change in throttle, no braking, no steering...is best way to go over the ice and prevent loss of control.

How do people with regen, like we have, find driving in those situations?

Hey All! So after a couple snow storms here in Colorado, I can say that the R1T on steep descents in snow (I'm running the 20" Pirelli ATs) can be really sketchy.

I have a steep grade dirt road with left curve near my house, and first snow, with All-Purpose mode, high regen, the truck would lock tires and slide sideways with the grade....it was not much fun at ALL (like a serious O-SH*T moment!).

Next snow, I reduced the regen to standard, which seemed to help a bit, but it was still really hard to feather the accelerator to keep the wheels moving at a low speed without sliding out....but seemed to be much better than high-regen mode. I'll try Sand mode on the next snow and see if that makes it more manageable.

The tires are 3-Peak rated (which should make them totally fine on light to moderate snow, thought perhaps not as good as a dedicated snow tire), but I think that with the heavy weight of the vehicle, keeping the wheel rotational speed low but consistent to where the tires won't break away is a learning process at least for me. In a standard ICE diesel truck (Dodge 3500), we just leave the gear in low (1st), and the descent is never a problem even in super deep snow.

That being said, going uphill with the R1T, with weight and AT tires, its like the thing is on rails...I can rip uphill WAAAYYYY faster than I should for sure...our 3500 fishtails like crazy with now weight in the back, the R1T, not even a slip on the uphill.

Be interested to hear if anyone has figured out the descent part on steep grades as I am still personally in Learn Mode!

I am curious if anyone can comment on regen braking on snow/ice covered surfaces.

I have always found with ice vehicles(pun sort of intended this time)that when going over icy road surfaces, such as bridges, etc... in winter driving, that zero change in throttle, no braking, no steering...is best way to go over the ice and prevent loss of control.

How do people with regen, like we have, find driving in those situations?

From a post I made in another thread, hope it helps a bit!

Hey All! So after a couple snow storms here in Colorado, I can say that the R1T on steep descents in snow (I'm running the 20" Pirelli ATs) can be really sketchy.

I have a steep grade dirt road with left curve near my house, and first snow, with All-Purpose mode, high regen, the truck would lock tires and slide sideways with the grade....it was not much fun at ALL (like a serious O-SH*T moment!).

Next snow, I reduced the regen to standard, which seemed to help a bit, but it was still really hard to feather the accelerator to keep the wheels moving at a low speed without sliding out....but seemed to be much better than high-regen mode. I'll try Sand mode on the next snow and see if that makes it more manageable.

The tires are 3-Peak rated (which should make them totally fine on light to moderate snow, thought perhaps not as good as a dedicated snow tire), but I think that with the heavy weight of the vehicle, keeping the wheel rotational speed low but consistent to where the tires won't break away is a learning process at least for me. In a standard ICE diesel truck (Dodge 3500), we just leave the gear in low (1st), 2 year old Mich LTXs, and the descent is never a problem even in super deep snow.

That being said, going uphill with the R1T, with weight and AT tires, its like the thing is on rails...I can rip uphill WAAAYYYY faster than I should for sure...our 3500 fishtails like crazy with now weight in the back, the R1T, not even a slip on the uphill.

Be interested to hear if anyone has figured out the descent part on steep grades as I am still personally in Learn Mode!

 

[moosehead]

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