Hydroplane-like feeling regenerating downhill

[SolartoEV]

What you are talking about isn't an issue. It's programmed in. It can't only regen so much in a set period of time.

When what you are explaining happens to me I move my foot 4 inches to the left and apply pressure to the brake pedal to slow my rate of speed as needed.

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[Dark-Fx]

I can’t rule that out, as the highway was slightly damp (although clear, and it hadn’t rained all day). The grade was negative five percent. But given that the Rivian has four motors, I would expect all wheel regen all the time. If not, that’s a problem in its own right.

The problem is if you only have one wheel slipping, and you don't interrupt the opposite wheel, it'll cause the vehicle to brake dive in the direction that still has traction. They should be able to do this per-axle in theory. But, either they aren't, or the single axle interruption is significant enough it makes it feel like the vehicle stops slowing suddenly.

 

[NineElectrics]

I think it might be this issue: https://www.rivianforums.com/forum/threads/mitigating-limitations-of-regenerative-braking.9782/

I didn’t get a warning, but perhaps I missed it, or the overload was too fast.

If regen has to turn off, fine. But it needs to blend in the real brakes while doing so; it shouldn’t turn off suddenly in the middle of a braking event. There was heavy traffic on this road and it could have caused an accident. Change my view that this isn’t a recall. I want it fixed.

 

[SolartoEV]

What's your thoughts about phantom braking in traffic?

 

[Dark-Fx]

I think it might be this issue: https://www.rivianforums.com/forum/threads/mitigating-limitations-of-regenerative-braking.9782/

I didn’t get a warning, but perhaps I missed it, or the overload was too fast.

If regen has to turn off, fine. But it needs to blend in the real brakes while doing so; it shouldn’t turn off suddenly in the middle of a braking event. There was heavy traffic on this road and it could have caused an accident. Change my view that this isn’t a recall. I want it fixed.

Leave more space and be ready to apply the mechanical brakes yourself if it's causing you to be that close to having an accident.

 

[NineElectrics]

What's your thoughts about phantom braking in traffic?

I hate it, and that’s one of the reasons I got rid of my Teslas. Have you experienced any in a Rivian?

 

[NineElectrics]

Leave more space and be ready to apply the mechanical brakes yourself if it's causing you to be that close to having an accident.

If I lose braking capability for a small period of time, I need to brake even harder over the next few seconds to make up for that loss and still maintain safe distances. That increases the chances I will lose traction, or that someone who is following me too closely will hit me. When you leave a lot of space, often times other cars will cut in front of you, too, and you’ll be a back to an unsafe following distance. So, I would really prefer to know that the car is going to brake at the level I ask it to, without flakiness. And I don’t want to constantly be slamming on by brakes because, while I want to decelerate at the level regen gives me, I need to be more conservative. Other drivers won’t expect that. One solution is to turn regen down to low and pray it doesn’t happen then either.

 

[Dark-Fx]

If I lose braking capability for a small period of time, I need to brake even harder over the next few seconds to make up for that loss and still maintain safe distances. That increases the chances I will lose traction, or that someone who is following me too closely will hit me. When you leave a lot of space, often times other cars will cut in front of you and you’ll be a back to an unsafe following distance. So, I would really prefer to know whether the car is going to brake at the level I want it to, without interruption. One solution is to turn regen down to low and pray it doesn’t happen then either.

Temporary complete loss like that aside, I have noticed when regen braking starts being limited and the truck is displaying the hash marks on the bar, that once you are into regen enough to illuminate the hashed part of the bar that there is still considerable regen still available. Using it will cause the hashed area to start growing and eventually become so large that at some point it is reduced so much it feels like the truck is just coasting. If you can stay out of the 'extra' regen it doesn't seem to do that.
Ultimately I do agree that Rivian still has some tuning to do here, and that it would be nice to have mechanical brakes blended in when regen is extremely limited.

 

[Scoiatael]

The temperature was in the low 40s. The regen limited warning was never shown and regen was working fully for the entirety of the trip. Even if regen was limited, it shouldn’t decide to turn off going 50 mph down a mountain pass, 50 miles into the trip.

I think what happened was this:
- regen was applied fully, and working fully
- the downhill slope caused the regen to be overloaded somehow (too much current to the battery?)
- regen turns off completely (!)
- car lunges forward
- regen ramps up again

That, my friends, is a BRAKE FAILURE and a non-negotiable safety issue. If regen chokes for whatever reason, the real brakes have to compensate instantly. I can’t have the car braking, then stop braking immediately because of black magic reasons. This is just shit engineering.

This is par the course for EVs. My Model Y did the exact same thing. There should have been a warning sign saying regen is limited. I went down a mountain a few weeks ago in my R1T and had to use the brakes most of the way.

 

[Dark-Fx]

This is par the course for EVs. My Model Y did the exact same thing. There should have been a warning sign saying regen is limited. I went down a mountain a few weeks ago in my R1T and had to use the brakes most of the way.

I get 3-4 messages a day on my morning commute. It flaps back and forth between limited due to cold and limited due to charge. The message displayed doesn't always match the icon next to the graph either.

 

[SolartoEV]

I hate it, and that’s one of the reasons I got rid of my Teslas. Have you experienced any in a Rivian?

I experienced it in my 2011 Jeep Grand Cherokee with Mercedes Benz radar, I experience it in my 2019 Rav4 Hybrid, I experience it with my 2022 R1T.

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