Let's remove the Conserve Mode stigma

[emoore]

An additional 10% range for half the power…no thanks. Potentially more tire wear, there go “cost” savings. I doubt many people need that extra 10% energy/cost savings if they paid $80k for a vehicle. If I wanted a 400hp truck I would’ve bought something else. For my use, that extra 30 miles will rarely, if ever, make a difference. If I was that concerned about energy efficiency, I should’ve bought something else.

It’s not just about efficiency. It’s also about going thru charging deserts and remote locations. That will eventually get better with more chargers but right now it might be the only way to make a trip work.

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[LevelHeaded]

It’s not just about efficiency. It’s also about going thru charging deserts and remote locations. That will eventually get better with more chargers but right now it might be the only way to make a trip work.

Agreed. Something tells me @ads75 doesn’t do much adventuring with his adventure vehicle if he thinks HP is the most important number and doesn’t realize how few chargers are in remote locations.

 

[ads75]

Agreed. Something tells me @ads75 doesn’t do much adventuring with his adventure vehicle if he thinks HP is the most important number and doesn’t realize how few chargers are in remote locations.

I mentioned in my post that for my use, I doubt I would ever use conserve. Your use may be different. My sense of adventure doesn’t include me wondering if I’ll make it to the next charger.

 

[Whale Blubber]

I don't adventure, but I do drive to soccer tournaments and live in a state larger than many (most?) countries, so having 10% range boost on a given Friday night road trip is golden. But I take the point that this is very much a YMMV situation (ha).

 

[underkuver]

We started using conserve mode on highways on road trips. VA has numerous RAN chargers but seems like very few are near our final destinations. It's nice to stretch the distance b/w stops if possible - especially on the way home where we don't care how low the charge is as long as we get home. Have had less than stellar public charging outside of DC on I-95 (lots of folks in EV rentals that did not want them to start with trying to charge).

We us AP in standard height 99% of the time on daily commutes. Our R1S can't get up our gravel mountain driveway in conserve mode well

 

[CruxOp]

We started using conserve mode on highways on road trips. VA has numerous RAN chargers but seems like very few are near our final destinations. It's nice to stretch the distance b/w stops if possible - especially on the way home where we don't care how low the charge is as long as we get home. Have had less than stellar public charging outside of DC on I-95 (lots of folks in EV rentals that did not want them to start with trying to charge).

We us AP in standard height 99% of the time on daily commutes. Our R1S can't get up our gravel mountain driveway in conserve mode well

Later this month we're going to be heading deep into the charging wasteland that is Maryland with two kayaks on the roof, definitely going to be conserving battery as much as possible on the run down.

 

[RexRemus]

Can someone submit the question to Rivian for their weekly responses on Reddit? Seems like they should be able to answer it.

This is a great suggestion! Best to just get an answer from the source

 

[VSG]

This is a great suggestion! Best to just get an answer from the source

What, and spoil all the fun with actual facts?

 

[RexRemus]

What, and spoil all the fun with actual facts?

Whoops, my bad... Carry on!

 

[Nuclianba]

<Rant>
I used to work for an EV company and worked on the design for our automatic clutch, which needed to operate at speed. The thing people don't always get is that most of what you read about clutch longevity and reliability etc is based on a HUMAN operating the clutch (or more accurately, a "dumb" clutch that will do whatever you tell it to when you pull the cable). When a computer is driving the clutch with knowledge and control of the shafts on either side, you can do a bunch of stuff with the design that would 100% blow up if a human was in charge. That means for all the hand wringing about cycles on the quad disconnect clutches, there really shouldn't be an issue (BIG ASTERISK: All this is assuming Rivian programmed these things correctly!).

Basically, this isn't like your 16 year old jamming the clutch with the engine at standstill and tires at like a million RPM where the clutch has to handle the torque and stress of bringing both sides to the same speed and power (or blow up in the process of trying). With software, you can measure the rotational speed of both sides of the clutch, and then you can spin the motor up/down to make the speed on both sides match. When done correctly, the computer will spin up the motor to NEARLY match the wheels, like within a couple RPM, and then engage the clutch. It doesn't matter if the wheel is at 1 RPM or 10,000 (slow down there fella), its the relative difference in the RPM of the two sides of the clutch that matter. You actually want some small amount of difference so that the teeth engage. Software can ensure a nice and gently engagement/disengagement no matter what the truck is doing, all within a couple hundred milliseconds.

Even if you are accelerating with those front wheels, or using mechanical brakes on the rears, that doesn't imply a loaded clutch, it only implies that the RPM on the wheel side is changing, but the rate of change is minuscule compared to what the computer is able to measure...you can readily control for that and be ramping/slowing the motor in real time to match. The motor dynamics mean you can ramp it up/down much faster than the wheel speed is going to be able to change. Software is magic.

Sounds easy....the difficulties are in understanding the dynamics of your physical system. Software can sense the rotational speeds instantaneously (basically). It can apply control commands to the motor just as fast. The motor though has mass, it has rotational inertia, so it takes time for it to respond. This means engage/disengage is not instantaneous, the computer has to wait for the motor to ramp up/down to match the wheel, and if wheel speed is changing, it may take a bit longer as the computer adjusts the motor ramp to compensate. And then engaging the clutch is also not instantaneous, it takes a moment for the mechanism to function. Here is where the software part being done right matters....if the rate of change of wheel speed is high (heavy accel/decel), that can matter over the timeframe of the clutch mechanism moving to engage/disengage. You can end up loading the clutch in this moment of partial engagement and breaking things. But again, proper software control can solve ALL of this.

Anyways, no reason the quad clutch should have any less life than that of the dual if the software is written well (engaging/disengaging at a constant vehicle speed will mitigate the 'they programmed it poorly' risk).

BTW, The redesign on the dual to me looks like form factor/packaging (the new design fits in its space better and takes less room) but mostly speed of engagement/disengagement (lots of little teeth instead of a few large dogs, engage/disengage velocity is faster, making it more responsive). That speed matters because of how the dual's are setup...if you hit the accel and need more power, you want to engage those rear motors REALLY fast...even a 50ms delay will be noticed by the driver. I bet the quad design with the dogs would have a hard time getting below 100ms on engage/disengage given its design.
</rant>

 

[jimmyb2]

<Rant>
I used to work for an EV company and worked on the design for our automatic clutch, which needed to operate at speed. The thing people don't always get is that most of what you read about clutch longevity and reliability etc is based on a HUMAN operating the clutch (or more accurately, a "dumb" clutch that will do whatever you tell it to when you pull the cable). When a computer is driving the clutch with knowledge and control of the shafts on either side, you can do a bunch of stuff with the design that would 100% blow up if a human was in charge. That means for all the hand wringing about cycles on the quad disconnect clutches, there really shouldn't be an issue (BIG ASTERISK: All this is assuming Rivian programmed these things correctly!).

Basically, this isn't like your 16 year old jamming the clutch with the engine at standstill and tires at like a million RPM where the clutch has to handle the torque and stress of bringing both sides to the same speed and power (or blow up in the process of trying). With software, you can measure the rotational speed of both sides of the clutch, and then you can spin the motor up/down to make the speed on both sides match. When done correctly, the computer will spin up the motor to NEARLY match the wheels, like within a couple RPM, and then engage the clutch. It doesn't matter if the wheel is at 1 RPM or 10,000 (slow down there fella), its the relative difference in the RPM of the two sides of the clutch that matter. You actually want some small amount of difference so that the teeth engage. Software can ensure a nice and gently engagement/disengagement no matter what the truck is doing, all within a couple hundred milliseconds.

Even if you are accelerating with those front wheels, or using mechanical brakes on the rears, that doesn't imply a loaded clutch, it only implies that the RPM on the wheel side is changing, but the rate of change is minuscule compared to what the computer is able to measure...you can readily control for that and be ramping/slowing the motor in real time to match. The motor dynamics mean you can ramp it up/down much faster than the wheel speed is going to be able to change. Software is magic.

Sounds easy....the difficulties are in understanding the dynamics of your physical system. Software can sense the rotational speeds instantaneously (basically). It can apply control commands to the motor just as fast. The motor though has mass, it has rotational inertia, so it takes time for it to respond. This means engage/disengage is not instantaneous, the computer has to wait for the motor to ramp up/down to match the wheel, and if wheel speed is changing, it may take a bit longer as the computer adjusts the motor ramp to compensate. And then engaging the clutch is also not instantaneous, it takes a moment for the mechanism to function. Here is where the software part being done right matters....if the rate of change of wheel speed is high (heavy accel/decel), that can matter over the timeframe of the clutch mechanism moving to engage/disengage. You can end up loading the clutch in this moment of partial engagement and breaking things. But again, proper software control can solve ALL of this.

Anyways, no reason the quad clutch should have any less life than that of the dual if the software is written well (engaging/disengaging at a constant vehicle speed will mitigate the 'they programmed it poorly' risk).

BTW, The redesign on the dual to me looks like form factor/packaging (the new design fits in its space better and takes less room) but mostly speed of engagement/disengagement (lots of little teeth instead of a few large dogs, engage/disengage velocity is faster, making it more responsive). That speed matters because of how the dual's are setup...if you hit the accel and need more power, you want to engage those rear motors REALLY fast...even a 50ms delay will be noticed by the driver. I bet the quad design with the dogs would have a hard time getting below 100ms on engage/disengage given its design.
</rant>

Thank you for that “rant”.

Although I suspected much of what you explained it is always good to have verification from someone who has “been there, done that”. Much appreciated.

 

[HyperionMark]

To those of you that keep saying it's only a 10% range increase....no...no it's not. Yes, I understand that is what the EPA numbers are. But you do realize a manufacturer can lower any numbers they want at their discretion? There are actual graphs on other threads that show it's better than 10%, probably 20%+ in the real world. Please don't just say it's 10% better if you don't routinely use it.

 

[Brewbud]

Stigma? Has someone been calling Conserve Mode the Peasant Mode?

 

[CharonPDX]

Rivian said that the dual motor will switch to one motor automatically on highway. From testing others have done on this forum is a large part of the difference between dual and quad EPA numbers.

Therefore for everybody who is avoiding use of conserve because of tire wear, I don't see why there would be any difference between a dual motor automatically disengaging the rears versus a quad motor in conserve **if** set at standard right height.

I've started using conserve on hwy trips over 20 mi once the car is up to speed but have conserve set for standard ride height. Anyone else doing the same?

Because if you need more torque than is healthy for the front tires, the dual will automatically enable the rear motor to spread the load. On the quad, it won't, you'll just over-torque the front tires.

For steady-speed use, Conserve is just fine on the quad. You just don't want it in around-town driving unless you're ALWAYS super-gentle on the accelerator pedal.

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