Regenerative braking - revisited

[SoCal Rob]

Can we at least agree that coasting makes a flat line graph of energy +/- and whether you are the worst or best manual/automatic driver in the world we will never attain the same efficiency trying to flatten out our curve on the same energy consumption/regeneration graph? The limit might approach 0 but coasting is 0.
I so often see people say regen is 99% efficient which is just wrong. Coasting (and then never touching the brake) is more efficient than OPD.

Did that make sense without a visual graph? No? sorry.

Edit: @SoCal Rob My post ended up lining up fairly well to your post I hadn't read yet. Your warning might need to say adversely impacted in some situations, positively impacted in my use case.

While it may be true that some will be able to coax more efficiency out with coasting, there is no way for Rivian to know how each person will drive so in today’s business environment it would be safest for them to warn about the negative impact and let some be pleasantly surprised.

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[Q-ship]

I’m surprised nobody has mentioned the excellent driving experience the Riv provides during extended, or multiple alternating, hill descents. Depending on the degree of incline and road variables, the regen settings make it superbly enjoyable whether looking to just relax and cruise down long inclines, or effortlessly attack switchbacks. The mileage regen is an added extra bonus. I can’t imagine having an EV where you’d have to feather the brake constantly like an ICE to get the same effect… I have to believe the engineers had this scenario in mind when designing as they did.

Yes! I live in Utah, and love being able to drive up and down mountain passes without using the friction brakes. I can drive down a canyon with a 3500 foot descent in 8 miles and tight turns just by modulating the accelerator. So much better than downshifting and braking.

 

[SSteveEV]

While it may be true that some will be able to coax more efficiency out with coasting, there is no way for Rivian to know how each person will drive so in today’s business environment it would be safest for them to warn about the negative impact and let some be pleasantly surprised.

Fair enough, so long as I can coast again!

In today's environment some shareholders would end up suing Rivian for not properly advertising the potential benefits of coasting alongside the warning.

I'm still pretty sure this isn't even a Rivian issue but an EPA testing issue. Think this is tied to the testing methods not factoring in coasting in my use case and requiring it to be the standard boot up test mode. Same reason why an AMG starts in Eco mode

 

[Zoidz]

Fun comparison of your vehicles, but how often do you try to coast that tractor off an exit ramp?

You would be surprised how similar OPD regen braking is to driving a 7,000 lb farm tractor and trailer down a hill the length of an exit ramp. I'd MUCH rather have hydrostatic braking than coasting and braking.

 

[PBRAZ]

On a related topic, with then new update we get to see where the regen is being applied...and it looks like the front tires get the majority of it. Guessing this is contributing to the increased tire wear people are seeing on the front possibly? Wondering if it's possible to move more of it to the rear to help with that. I go down a 3 mile steep hill every day and those two front tires are seeing a lot of friction with regen.

 

[CrazyOne]

On a related topic, with then new update we get to see where the regen is being applied...and it looks like the front tires get the majority of it. Guessing this is contributing to the increased tire wear people are seeing on the front possibly? Wondering if it's possible to move more of it to the rear to help with that. I go down a 3 mile steep hill every day and those two front tires are seeing a lot of friction with regen.

Yeah, it stresses front tires too much. I have the Rivian squealing at full Regen and a moderate turn at about 35 mph. Most cars prioritize rear brakes to reduce dive at mild/moderate brake application. Atleast, both my other cars seem to do it.

 

[AlanP]

Not a fan of the R1S regen implementation. My Solterra does it perfect. Multiple selectable levels of regen for normal driving, flat versus hilly AND a pushbutton that implements single pedal driving when desired.
It’s also horrible on steep inclines trying to go slow in either direction due to brake hold.
Mine is also very inconsistent in stopping distances even at the same charge level. Never know when regen is going to “kick in”.
By far the quirkiest car I’ve owned out of 20+ vehicles. Do love the acceleration….

 

[carsly]

I recall on my R1S demo drive the salesperson (they are salespeople, aren't they?) warned me about the one pedal driving and that some people have issues adjusting. Did I mention my demo drive was in lower Manhattan? Hardly a place to learn about throttle/brake modulation.

As I had driven there in my Model S it took me about zero time or thinking to adjust to the R1S. Zero. As in none. Didn't think about it once and it was super smooth and easy to manage, very similar to a Tesla. I think I used the actual brake pedal one time, so that I knew how it would feel if needed.

I had adjustable regen in my Polestar 2, that was far trickier to master. I've also test driven a Q4 etron, hated that experience with the infinite coasting and basically no regen. If I wanted a old fashioned gasser I'd buy an old fashioned gasser. Being able to adjust the regen seems like something that shouldn't be an adjustment, how often do you adjust the brake feel in your ICE vehicles? Maybe if you'e got an M BMW (not an M-sport, sorry) you could give it a go but unless you're constantly on/off tracks, road and rally circuits I don't see a point.

I don't think that regen is for everyone, just like manual transmissions haven't been for everyone for a few decades. Or high performance cars are for everyone. Or twin turbochargers are for everyone. Or variable valve timing is for everyone. Or CVT transmissions are for everyone. Or SMG transmissions are for everyone.

Technology requires adaptations in driver behavior to get the most out of the package, you can accept and embrace or try and fight it. But if you insist on fighting it, why not just buy a different vehicle that better suits your preferences? You're not going to find me wasting time on Mercedes forums besmirching their willowly handling, unbolstered seats and spongy brakes.

 

[SRO]

22,000mi and it's definitely the biggest complaint. I can do it, I'm very good at it, but it's not natural. Keeping your foot on the pedal with pressure while something ahead of you is requiring you to slow down, is not a good way to drive. It's also pretty often that I naturally jerk my foot off the pedal due to someone or something giving me a scare. While on a higher speed road where you need to turn off quickly and sharply (fairly common in more rural but still crowded Texas), the process is something like this, slow using Regen with your foot off the pedal, now hit the brakes, now jump back on the accelerator to try and coast through the turn (this takes an educated guess as to how much pressure to reapply as to not be slowing down more and not being a hooligan on your way out of the corner), then let everyone else in the car know how well you executed said difficult maneuver. It's fun for the driver in a challenge sort of way, but part of the ownership experience is complaints of carsickness. There is no good reason to not be able to turn off OPD, I couldn't care less about lost efficiency or range due to not having it. I will say that when driven very hard and fast, it's not an issue at all, or I'm having way too much fun to care. One more thing, it is nothing like a clutch other than with a clutch you feather the pedal for a very brief moment, and I am a pretty successful amateur race car driver, so being smooth with the pedals is second nature.

I’ve had regen braking since 2017. I love it. However I loved it after three or four months. And now anything else is unnatural to me.

 

[CommonSense]

ay, everyone will be

Yes! I live in Utah, and love being able to drive up and down mountain passes without using the friction brakes. I can drive down a canyon with a 3500 foot descent in 8 miles and tight turns just by modulating the accelerator. So much better than downshifting and braking.

Just to be clear, this way of driving is possible in every regen car I've ever driven, one pedal or two control, does not matter. In the two pedal setup when you step on the brake pedal it starts with regenerative braking only. Only if you push the brake pedal hard enough to call for braking that exceeds max regen does it start to engage the actual brake pads for friction braking.

 

[zoomer0056]

22,000mi and it's definitely the biggest complaint. I can do it, I'm very good at it, but it's not natural. Keeping your foot on the pedal with pressure while something ahead of you is requiring you to slow down, is not a good way to drive. It's also pretty often that I naturally jerk my foot off the pedal due to someone or something giving me a scare. While on a higher speed road where you need to turn off quickly and sharply (fairly common in more rural but still crowded Texas), the process is something like this, slow using Regen with your foot off the pedal, now hit the brakes, now jump back on the accelerator to try and coast through the turn (this takes an educated guess as to how much pressure to reapply as to not be slowing down more and not being a hooligan on your way out of the corner), then let everyone else in the car know how well you executed said difficult maneuver. It's fun for the driver in a challenge sort of way, but part of the ownership experience is complaints of carsickness. There is no good reason to not be able to turn off OPD, I couldn't care less about lost efficiency or range due to not having it. I will say that when driven very hard and fast, it's not an issue at all, or I'm having way too much fun to care. One more thing, it is nothing like a clutch other than with a clutch you feather the pedal for a very brief moment, and I am a pretty successful amateur race car driver, so being smooth with the pedals is second nature.

So rediculous. You're making this waaaay more complicated than reality. You definitely have not learned how to use regen and, after 22,000 miles, I don't think you'll ever learn how to do it.

 

[SANZC02]

So rediculous. You're making this waaaay more complicated than reality. You definitely have not learned how to use regen and, after 22,000 miles, I don't think you'll ever learn how to do it.

I agree, after 22k miles if not adjusted it will not happen.

My wife was not a fan on the first drive. But she had to drive the Rivian for a couple of days and now loves the one pedal driving and feels the vehicle is very controllable being able to modulate the pressure on the accelerator.

 

[HaveBlue]

Has anyone tried just leaving it in snow mode? Maybe that's more like a stick or motorcycle with some engine braking but not violent.

I went with a few friends across LA in a new Model Y. There was some stop and go traffic. On the way home I was thinking I needed to rest my head on the head rest because I felt like a bobblehead. The driver also owns a Mini Cooper S with a performance clutch but maybe his driving sucks. We got back to his house and three of us were getting back in my Audi and one said he was sick to his stomach from the backseat ride in the Model Y. Interestingly he also owns a Model Y. He sat up front in my car for the rest of the drive and felt better. Not excited about people getting car sick in my R1S. I'm hoping that's not a normal thing. I tend to prefer picking a gear and speed in traffic and not be on the brakes constantly though.

 

[jimmyb2]

In my opinion, it all comes down to adaptability. How easily can one adapt or how willingly one adapts to something different from what they have “always done”.

I suspect that all who dislike OPD would feel the exact opposite if they had first learned on, and then spent several years driving a OPD EV. They would probably then have difficulty accepting how an ICE vehicle drives.

 

[mkg3]

In my opinion, it all comes down to adaptability. How easily can one adapt or how willingly one adapts to something different from what they have “always done”.

I suspect that all who dislike OPD would feel the exact opposite if they had first learned on, and then spent several years driving a OPD EV. They would probably then have difficulty accepting how an ICE vehicle drives.

Regen issue is not just about OPD. There are two aspects to it.

- Agree that OPD can be learned easily and many people like it. I do too when appropriate.

My issue isn't about that at all with Regen. My recent road trip to Tahoe, I experienced 2% increase in the R1S SOC during decent from 7K ft altitude to 4.5K (NV207 coming over the mountain from Tahoe to Minden). Short distance and great. I hardly touched the brakes and found having to maintain throttle on often to keep the speed consistent.

Unfortunately, the rest of the drive, for the most part after Mammoth on 395 is essential all down hill or on declining grade. The ability to coast in low regen increase the range significantly (have experienced it with my Tesla).

It's worth noting that on the freeways, I typically drive at 80+ mph and faster the vehicle goes, more it makes the difference since it requires higher energy to overcome the vehicle drag. Costing offsets the need for the constant energy input.

I just like the option to be able to control the amount of regen as needed. There are times its almost priceless (e.g., traffic) and there are times its a hindrance to way I want drive. It is not about adapting to it.

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