Interesting Find: Comments on Color Development & R1's are not actually Full Time All Wheel Drive

BigE

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In searching through some older videos of Rivian Overland shows, I came across this find. Two comments stood out that have been discussed on this forum in the past...Paint Colors: you can hear the engineer saying that Paint development takes a long time which others have shared here. Second, at ~5:18 the person asked, so is it Full-Time All-Wheel drive and the Rivian engineer says, Actually, it's not and goes on to describe how the rear motors can be decoupled at highway speed, essentially making it a front-wheel-drive to conserve energy as we have recently learned. This was back in 2019, we all just missed it.

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Zoidz

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Nice find!!! Rivian should be promoting this feature, *especially* if the EPA estimate was in 4WD mode. I'm very curious to find out how much additional range this would give. Realistically, it's probably 5%-10%. Even that would help with some of the 'range anxiety' people are having over the wheel/tire options.
 

Babbuino

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In searching through some older videos of Rivian Overland shows, I came across this find. Two comments stood out that have been discussed on this forum in the past...Paint Colors: you can hear the engineer saying that Paint development takes a long time which others have shared here. Second, at ~5:18 the person asked, so is it Full-Time All-Wheel drive and the Rivian engineer says, Actually, it's not and goes on to describe how the rear motors can be decoupled at highway speed, essentially making it a front-wheel-drive to conserve energy as we have recently learned. This was back in 2019, we all just missed it.

Look at those aero inserts in the 20s
 

Autolycus

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Nice find!!! Rivian should be promoting this feature, *especially* if the EPA estimate was in 4WD mode. I'm very curious to find out how much additional range this would give. Realistically, it's probably 5%-10%. Even that would help with some of the 'range anxiety' people are having over the wheel/tire options.
I believe the EPA data showed "partial AWD" or "part-time AWD". I think the EPA test was already using this function. I think people should temper their expectations for a big range jump from any mode changes. Maybe it'll happen, but I wouldn't count on it or get my hopes up too high.
 

kurtlikevonnegut

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I believe the EPA data showed "partial AWD" or "part-time AWD". I think the EPA test was already using this function. I think people should temper their expectations for a big range jump from any mode changes. Maybe it'll happen, but I wouldn't count on it or get my hopes up too high.
I think what is most telling on this front is in the MT video where it shows a range of 308 in Conserve Mode, and we know that they were on the ATs. If you do the math on the AT range degradation and then extrapolate that, I think you can expect about a 7-10% increase above the EPA range in Conserve if my math is right (and it rarely is).
 

electruck

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It will be interesting to see if this "Conserve" mode ends up being a production feature or if the R1 just automatically drops into 2wd mode on the highway when it deems appropriate. To me, this seems more like a developer/engineering mode feature and a cpability that Rivian would look to automate (and clearly MT had a pre-prod developer mode UI).

riv_developer_mode.png
 

ajdelange

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This has been kicked around here fairly recently. I don't think there will be a 2WD mode in which 2 of the motors are totally disabled. I think that for any given speed, grade and wind there will be a particular ratio of power delivered to the front motors to the power delivered by the rear motors that will be the most efficient. I believe the car will calculate that and set the power ratio accordingly. This might even be real time adaptive - the same idea as used in maximum power point tracking in solar converters.

The result will be that there are parts of the envelope where substantially more power is taken from one set of motors than the other. Remember that even if a motor is "turned off" (meaning that no torque is taken from it) its drive train is still being rotated and the associated mechanical losses are still being incurred.

The whole premise behind this is that one set of motors is more efficient than the other in some regimes and conversely. The peak in the efficiency plateau on the torque/speed graphs are pretty broad for this type of motor but they don't span the whole envelope so we assume that the motors are geared slightly differently.

As for "conservation mode" that is probably going to do nothing more than prevent you from accellerating very fast, insure that regen is full on, limit what the heater/air conditioner can do and turn off unnecessary lights.
 

Rivianmd

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This has been kicked around here fairly recently. I don't think there will be a 2WD mode in which 2 of the motors are totally disabled. I think that for any given speed, grade and wind there will be a particular ratio of power delivered to the front motors to the power delivered by the rear motors that will be the most efficient. I believe the car will calculate that and set the power ratio accordingly. This might even be real time adaptive - the same idea as used in maximum power point tracking in solar converters.

The result will be that there are parts of the envelope where substantially more power is taken from one set of motors than the other. Remember that even if a motor is "turned off" (meaning that no torque is taken from it) its drive train is still being rotated and the associated mechanical losses are still being incurred.

The whole premise behind this is that one set of motors is more efficient than the other in some regimes and conversely. The peak in the efficiency plateau on the torque/speed graphs are pretty broad for this type of motor but they don't span the whole envelope so we assume that the motors are geared slightly differently.

As for "conservation mode" that is probably going to do nothing more than prevent you from accellerating very fast, insure that regen is full on, limit what the heater/air conditioner can do and turn off unnecessary lights.
 

Rivianmd

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I am pretty sure I heard or read that the rear wheels decouple via clutch which could be done in an automated way within milliseconds - reducing drivetrain loss
 

DucRider

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I am pretty sure I heard or read that the rear wheels decouple via clutch which could be done in an automated way within milliseconds - reducing drivetrain loss
I hope not - it would take one clutch per wheel that they are disconnecting increasing weight, mechanical losses and overall complexity resulting in less range in all of the normal drive modes.

They have also stated that the Rivian must be towed on a flatbed which implies that none of the wheels can be decoupled.
 

ajdelange

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I am pretty sure I heard or read that the rear wheels decouple via clutch which could be done in an automated way within milliseconds - reducing drivetrain loss
You've probably also read that one can go forever by using the front wheels to drive the car while you use the rear wheels to recharge the battery. This is the internet!
 

Rivianmd

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You've probably also read that one can go forever by using the front wheels to drive the car while you use the rear wheels to recharge the battery. This is the internet!
Not sure the purpose of this response. Pretty straightforward and if memory serves it was mentioned in one of the MT videos.
 

ajdelange

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The purpose of the response was to emphasize what you should aready know: that the probability of obtaining accurate information from the internet is vanishingly small. Common sense tells us that there wont be clutches in a truck whose core design philosophy is orthogonal to such an idea.
 

Rivianmd

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The purpose of the response was to emphasize what you should aready know: that the probability of obtaining accurate information from the internet is vanishingly small. Common sense tells us that there wont be clutches in a truck whose core design philosophy is orthogonal to such an idea.
Ok…you should already know that there is no material way to increase efficiency with PM motors as you’ve highlighted in other posts without disengagement of the drivetrain. MT has flat out communicated that the truck goes into front wheel drive only. So what is the logical conclusion? Since we are in the same part of the country how about a friendly wager for a drink if we ever cross paths.
 
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