No Blended Braking Option R2?

[mkg3]

True but downshifting reduced speed much as regen does without the charging benefit...

Clearly no energy recovery on ICEV without some hybridization. Downshifting does not slow the vehicle down as much as regen. Since no sane person would downshift from the freeway speed to 2nd or 3rd gear, most MT traveling in the 6th or 7th gear would perhaps go down to 5th gear. The engine RPM need to match the speed for the particular gear to avoid damage. Engine braking (when downshifting) does not slow the vehicle down as much as regen, regardless of energy recovery aspect.

True, and that's why you only 'downshift' (engage regen) when you actually need to slow down faster than coasting would. Incidentally, I tried out the three regen options on the R2 during my two test drives and initially even the most relaxed version drove me crazy. However, in traffic and without Autonomy engaged, I actually preferred the tightest version. That said, I think passengers would prefer the softer version and, beyond that, simple coasting, which minimizes the 'seasick' feeling that people have complained about.

Friction brakes work better than regen and downshifting when slowing down is the priority. The main reason to downshift is to match the engine RPM vs power band for a given speed. In other words, if you want to pass someone on the freeway but in in the OD or top gear, so downshifting brings the RPM up to higher engine power to enable the vehicle to accelerate faster than in the tall gear.

You want to brake and downshift together so that when ready to continue and to accelerate, you are in the proper gear selection.

Just to summarize the discussion so far, it seems there are two parts to this debate:...

Why??? No need. The summarized comments are just another interpretation by a particular person. Another person may have a different take on the discussion.

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[MaskedRacerX]

Clearly no energy recovery on ICEV without some hybridization. Downshifting does not slow the vehicle down as much as regen.

I can tell you, as someone who drove several manuals (by choice, S2K, Z06/Vettes, Supra, RX7, Mustang) over a couple of decades and most of those for significant time on track (all over the Southeast US, Roebling, Road ATL, CMP, Sebring, etc.), this is not the case (re: bold).

It might be more "automated" in modern EVs, but the control in a manual, can be just as effective.

 

[MaskedRacerX]

True, and that's why you only 'downshift' (engage regen) when you actually need to slow down faster than coasting would. Incidentally, I tried out the three regen options on the R2 during my two test drives and initially even the most relaxed version drove me crazy. However, in traffic and without Autonomy engaged, I actually preferred the tightest version. That said, I think passengers would prefer the softer version and, beyond that, simple coasting, which minimizes the 'seasick' feeling that people have complained about.

That's what I love about being able to toggle between OPD (with several choices of regen, including adaptive), and "regular" mode with coasting. Toggle, OPD, around town, toggle highway, coasting, no surging.

One of the things I love to do, coming off the highway in D (coasting) mode, toggle over to B (OPD mode) on the exit, hahaha, it's like toggling the air brakes

 

[Qamera]

One of the things I love to do, coming off the highway in D (coasting) mode, toggle over to B (OPD mode) on the exit, hahaha, it's like toggling the air brakes

Exactly. Me too on the off ramp. That’s one thing I will miss on R2 although presumably one should be able to drop out of self-drive mode and into regen simply by tapping the brake or reverse tapping the shift controller.

 

[mkg3]

I can tell you, as someone who drove several manuals (by choice, S2K, Z06/Vettes, Supra, RX7, Mustang) over a couple of decades and most of those for significant time on track (all over the Southeast US, Roebling, Road ATL, CMP, Sebring, etc.), this is not the case (re: bold).

It might be more "automated" in modern EVs, but the control in a manual, can be just as effective.

I've only owned MT vehicles until the kids were born. Used to race Formula Fords (1600cc) in the 80s, have tracked vehicles over the years.

The downshifting limitation is the Rev limiter or max rev that the engine can rev on any given gear. Engine braking, which is a function of RPM dropping due to lack of fuel from throttle closing and all the forces against moving object (i.e., drag, rolling resistance, drivetrain mechanical losses), alone, does not decelerate/negative acceleration as much as regen braking can do. I am referring to what the motor can do to slow down, not necessarily R1 or R2.

Of course in a real driving situation, the driver continues to downshift with speed decline, and the process repeats. The driver probably applies brakes along the way to slowdown quicker; hence, I originally said braking and downshifting makes the most sense to slow down the vehicle. Of course the tires play a big part in slowing the vehicle down too.

I own an 8 speed DCT vehicle and drive it mostly in the sport or track mode set to manual transmission. While I still miss the 3PD and the center shifter, paddle shifting is so much faster. When it comes to downshifting, the modern DCT with auto rev matching, has taken away that piece of driving engagement though...

 

[mkhuffman]

Just to summarize the discussion so far, it seems there are two parts to this debate:

1. Whether friction brakes are applied to augment regen when regen is weaker than normal (ie battery full)
2. How the brake pedal actually causes deceleration, either with regen or friction

I think #1 is what we're calling Brake Assist and #2 is what we're calling Blended Braking. I.e. letting off the accelerator is intended to feel the same for a given regen setting no matter the state of the battery (you shouldn't feel the addition of friction brakes), and pressing the brake pedal should start with adding regen if possible and add friction only if it needs more stopping power.

Sounds like the objections in this thread are over Break Assist being active all the time, not over Blended Braking being used when pressing the brake pedal. I understand the desire to reduce wear on the friction brakes, but (a) they are a consumable item like on all cars, (b) the presence of regen will already make them last way longer than an ICEV, and (c) I'd much rather have consistent 1PD performance than go back to what the R1 did before brake assist. If the argument is that Rivian's algorithm might erroneously apply friction brakes when it doesn't need to, then the request should be to improve the algorithm, not bypass it entirely.

I'd also wager that if you disable brake assist and end up having to step on the brake pedal because regen is not as strong as you suggested, you are probably going to end up braking harder and later than the car would have, which may end up putting more wear on the brakes than just letting the car handle it.

There is no debate regarding what Brake Assist does. Rivian even states in the owner's manual.

The only debate is whether or not the R2 has blended braking. I don't think it does, but nobody has proven it either way. A comment from Kyle or some random engineer doesn't count. We need either to see it in the owner's manual, or someone needs to do a test that proves blending is used.

Until then, I am sticking to what we know: Rivian does not use blended braking.

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