The Rivian R1T electric truck was a near-perfect rig for the 2021 Rebelle Rally [CNET Roadshow Article]

[RexRemus]

I feel like there are a few ways to take the "issues" portion of that article - but I think the way I look at it is this:

They didn't have a single day without issues, sometimes major (2WD, top speed capped, no suspension damping), and then had some human error on top of it and yet managed to finish in 5th place out of a field of~50 vehicles and even managed to win one of the stages all in a pre-production, totally stock, electric vehicle.

THAT speaks hugely to the potential of the R1T/S. Imagine this race without them being hindered pretty much every day of it, and with a proper sand dune driving mode that controls and adapts the regen to allow for much less burden on the driver. It is my sincere hope (and assumption) that Rivian is using this FOR that kind of data collection to directly develop new, or enhance existing, driving modes and to determine what readouts/gauges to add and display to make the driving experience as simple as possible.

My one concern is the "plastic" underbody and so easily being able to damage the battery cooling pump - I'm actually baffled by it and sincerely hope that pump is repositioned and significant enhancement is done to protect the battery pack. The potential to not only spark a fire that costs you your vehicle but, especially out west, is the catalyst for a potentially massive forest fire is pretty much untenable. The battery compartment needs to be fort knox as far as that goes.

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[Ralph]

I don't think Emme is known for having much of a filter (this is a positive).

Not having regenerative breaking is expected when full. You either have to not charge the battery to "full" or access you won't be able to unplug and immediately add energy. There's nowhere to store it, and you can't pump in a lot of power when full anyway (example, charging speeds decrease as you approach fully charged).

I'm sorry, I didn't mean to imply that that the tech was not well understood. Only that it is a real disadvantage in some off-road situations in particular. I've not seen that discussed previously.

 

[SeaGeo]

I'm sorry, I didn't mean to imply that that the tech was not well understood. Only that it is a real disadvantage in some off-road situations in particular. I've not seen that discussed previously.

Understood. Just saying that it makes sense and you still have the full mechanical breaks.

I *think* what you're getting at is for the consistency with for the driver it'd be good to continue having one pedal driving. Which I would think they could implement by depressing the break pedal on liftoff consistent with what you'd expect from regen breaking, but there may be a hardware limitation there.

 

[Ralph]

Understood. Just saying that it makes sense and you still have the full mechanical breaks.

I *think* what you're getting at is for the consistency with for the driver it'd be good to continue having one pedal driving. Which I would think they could implement by depressing the break pedal on liftoff consistent with what you'd expect from regen breaking, but there may be a hardware limitation there.

Consistency would be good, but I'm not hung up on one pedal driving and I don't think a ton of other people who off-road in an EV, at least initially are/will be either.

The context of my first note was in regard to Rivian being marketed or thought of by some as the "Perfect off-road" machine or some such. There are circumstances where engine braking (ICE) or regen (EV) is superior to using conventional brakes. Emme noted that when topping dunes the EV was different than and ICE, but seemed to imply she could get used to it (applying the correct amount of pedal). But if "full", there is no regen available.

Thus a circumstance that must be overcome in some other way. That's all I was getting at.

Does that make more sense?

 

[SoCal Rob]

You could have electric locking mechanisms for the times you cared about securing the compartments but have the immediacy and convenience of a direct mechanical release mechanism at all other times.

That’s a good point, but without a locked/unlocked indicator you run the risk of people yanking on the console with a mechanical release secured by an electric lock which could lead to issues. Some people have a thought process of, “It worked last time, maybe I need to exert more force.” if they don’t know that under certain circumstances the console may or may not be locked.

Also, an electric lock may fail safe/unlocked or fail secure/locked. An electric latch which needs to be powered to release will always fail secure.

There are reasons to go with different solutions and someone would need to talk to a Rivian designer and/or engineer to find out why they chose the solution they did. Heck, if they see a lot of issues when they start getting data on warranty claims they may even make some revisions.

 

[SoCal Rob]

My one concern is the "plastic" underbody and so easily being able to damage the battery cooling pump - I'm actually baffled by it and sincerely hope that pump is repositioned and significant enhancement is done to protect the battery pack. The potential to not only spark a fire that costs you your vehicle but, especially out west, is the catalyst for a potentially massive forest fire is pretty much untenable. The battery compartment needs to be fort knox as far as that goes.

I agree with this 100%. Whether plain plastic or carbon fiber, the damage to the pump should tell Rivian that something needs to be changed. The reason I’m spending money on the off-road upgrade is for the improved underbody protection. I don’t want to be stranded in the desert, spark a major fire, and, especially, die from the resulting fire because the vehicle landed on a rock and the protection I paid for didn’t prevent the problem it was supposed to prevent.

 

[Laurent]

Understood. Just saying that it makes sense and you still have the full mechanical breaks.

I *think* what you're getting at is for the consistency with for the driver it'd be good to continue having one pedal driving. Which I would think they could implement by depressing the break pedal on liftoff consistent with what you'd expect from regen breaking, but there may be a hardware limitation there.

Unfortunately, the problem is not limited to off-road situations. I've actually found it to be a safety issue at times on my Model S when you expect the car to slow down and it doesn't. That's one of the reasons I never charge the battery to 100%, unless I'm going on a road trip. When I do, I have to remember that I won't have any regen for the first 10-15 minutes of the trip.

 

[dleewla]

Unfortunately, the problem is not limited to off-road situations. I've actually found it to be a safety issue at times on my Model S when you expect the car to slow down and it doesn't. That's one of the reasons I never charge the battery to 100%, unless I'm going on a road trip. When I do, I have to remember that I won't have any regen for the first 10-15 minutes of the trip.

That seems like a safety oversight that the vehicle will not regen brake when you expect it to because the battery is full. Can see someone getting into an accident because the driving dynamics change like that. Sure most people will be aware and compensate but there's going to be times someone forgets or gets caught off guard and panics or over compensates. Yikes.

 

[Scott]

That seems like a safety oversight that the vehicle will not regen brake when you expect it to because the battery is full. Can see someone getting into an accident because the driving dynamics change like that. Sure most people will be aware and compensate but there's going to be times someone forgets or gets caught off guard and panics or over compensates. Yikes.

In my ID.4 there is a visual indication of the amount of regen breaking available. I noticed it for the first time a few weeks ago after charging to full up in the mountains before driving home for 4 hours. The first 20 minutes were all downhill and I noticed there was no regen and the visual immediately made me understand why. I was fairly impressed with the UX there. However, I expect very little of VW's UI design so that was partially just exceeding very low expectations..

 

[SANZC02]

That seems like a safety oversight that the vehicle will not regen brake when you expect it to because the battery is full. Can see someone getting into an accident because the driving dynamics change like that. Sure most people will be aware and compensate but there's going to be times someone forgets or gets caught off guard and panics or over compensates. Yikes.

I can tell you from experience it sounds way worse than it is and in any panic situation your foot grabs the brake without any hesitation regardless of the regen.

 

[SoCal Rob]

That seems like a safety oversight that the vehicle will not regen brake when you expect it to because the battery is full. Can see someone getting into an accident because the driving dynamics change like that. Sure most people will be aware and compensate but there's going to be times someone forgets or gets caught off guard and panics or over compensates. Yikes.

My understanding is that the electric power generated by electric motors has to be used by something in order for the motors to provide resistance to rotation.

Normally, the power generated goes to the batteries and that’s how regen works. When the batteries are full there is no place for the electric power to go so there is no braking effect.

Maybe a manufacturer could add a giant resistance heating element which could be connected to the motor output only when the battery is full and there is zero throttle. This could turn the excess electrical energy into waste heat. It would mimic the way friction brakes turn mechanical energy into waste heat. Manufacturers haven’t done this, as far as I know, so it must not be worth the expense.

 

[thrill]

...Maybe a manufacturer could add a giant resistance heating element which could be connected to the motor output only when the battery is full and there is zero throttle. This could turn the excess electrical energy into waste heat. It would mimic the way friction brakes turn mechanical energy into waste heat. Manufacturers haven’t done this, as far as I know, so it must not be worth the expense.

I think it'd be easier to have the computer blend in friction braking as needed (when the pedal is lifted) to maintain the deceleration g-force set in the regen selection.

 

[RexRemus]

I think it'd be easier to have the computer blend in friction braking as needed (when the pedal is lifted) to maintain the deceleration g-force set in the regen selection.

Yeah, it seems like if the customer selects and expects one-pedal driving, but the experience of that is... variable... that could be bad. And to your point, it feels very solvable via accelerometer data mapped to pedal position sensor data to ensure a fixed amount of braking regardless of the state of charge of the battery. Rivian can know the expected maximum amount of regen braking force based on the user's selection (low/med/high or whatever) and map those deceleration curves against the pedal range and then feather in the friction brakes as needed when the accelerometer data doesn't line up with the pedal position. I'm somewhat amazed this doesn't happen in other vehicles - my R1S will be my first BEV so my expectation was that this was a long-solved problem to enable one-pedal driving - otherwise it shouldn't be called one-pedal driving if it's only "mostly" one-pedal driving (emergency situations aside)

 

[SoCal Rob]

I think it'd be easier to have the computer blend in friction braking as needed (when the pedal is lifted) to maintain the deceleration g-force set in the regen selection.

I agree it would definitely be easier and cheaper to use the friction brakes since it shouldn’t require additional components. I don’t know if it will be easy to duplicate the feel of braking with regen so that the two are indistinguishable. I haven’t ever driven a vehicle with one-pedal driving enabled and disabled.

I’m not proposing this as a practical solution as much as showing an example of what it would take to accomplish exactly the same effect as regen braking with a full battery.

 

[Scott]

I agree it would definitely be easier and cheaper to use the friction brakes since it shouldn’t require additional components. I don’t know if it will be easy to duplicate the feel of braking with regen so that the two are indistinguishable. I haven’t ever driven a vehicle with one-pedal driving enabled and disabled.

I’m not proposing this as a practical solution as much as showing an example of what it would take to accomplish exactly the same effect as regen braking with a full battery.

It is definitely possible. All of the VW group EV's do this with the brake pedal. You can disable lift off regen (or turn it lower with paddle shifters in the case of the more expensive models). When you press the brake pedal it uses regen braking until a certain deacceleration threshold. Then, depressing further switches to friction brakes. The brake pedal lets you request a certain amount of deacceleration and the car figures out the most efficient way to create that deacceleration. It is very hard to feel the transition, the brakes feel like they have a pretty linear response. It is one of the more well done features in my ID.4. It should be possible to wire up the same system to a range of the "go" pedal as well so lift off braking uses the same algorithm to pick a braking method. Not sure I would want it, but it is possible.

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