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Regen in conserve vs AP

Rtpdeacon

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Is there a difference in the amount of charge returned to the battery in regen mode vs AP? For example if you were to drive up a mountain in conserve and descend the mountain in AP, would you return more energy to the battery since you would have 4 motors generating charge?
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odingrey

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Not sure about the actual power, but the regen feels the same. I'm pretty sure I'd be able to tell if it was halved. Rivian doesn't (yet) do brake blending, so I assume it's the same.
 

godfodder0901

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Since the rear motors are physically decoupled when in conserve, yes, you would have less regen capacity. That is, unless the truck re-engages the rear motors during regen events, which is highly unlikely.
 

Taco

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Since the rear motors are physically decoupled when in conserve, yes, you would have less regen capacity. That is, unless the truck re-engages the rear motors during regen events, which is highly unlikely.
100% agree - There are times coming off the highway that I'm like "WHOAAAA no regen!"
 

Dark-Fx

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Not sure about the actual power, but the regen feels the same. I'm pretty sure I'd be able to tell if it was halved. Rivian doesn't (yet) do brake blending, so I assume it's the same.
It's not halved but it doesn't feel quite as strong. Most of the braking power is in the front wheels of a typical vehicle anyway, so you aren't losing much.

Hard to say which mode would be more efficient at returning energy to the battery though.
 

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CommodoreAmiga

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It is basically halved. The driver display even shows you this By greying out the bottom half of the regen display.
 

Rivian_Hugh_III

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It's not halved but it doesn't feel quite as strong. Most of the braking power is in the front wheels of a typical vehicle anyway, so you aren't losing much.

Hard to say which mode would be more efficient at returning energy to the battery though.
I’ve heard this said before (most braking in front) and I’ve never understood it. Not saying it’s not true, just seeking to learn why.

To me it’s akin to people saying there’s a difference in whether you push or pull a load. Why isn’t it the same?

Why don’t the front and rear brakes share the load equally?
 

Dark-Fx

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I’ve heard this said before (most braking in front) and I’ve never understood it. Not saying it’s not true, just seeking to learn why.

To me it’s akin to people saying there’s a difference in whether you push or pull a load. Why isn’t it the same?

Why don’t the front and rear brakes share the load equally?
Front tires have more weight on them under braking because it shifts forward. Forward momentum is trying to turn to angular momentum because you are stopping from the bottom side of the vehicle instead of from the middle.
 

jphillips97

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I’ve heard this said before (most braking in front) and I’ve never understood it. Not saying it’s not true, just seeking to learn why.

To me it’s akin to people saying there’s a difference in whether you push or pull a load. Why isn’t it the same?

Why don’t the front and rear brakes share the load equally?
I will offer the simple answer to help understand it and then look at the physics....

Simple analogy, remember riding your bike as a kid... Which brake felt stronger front or back?

Physics answer.... When you use brakes the vehicle weight shifts forward due to inertia. This puts more weight on the front and less on the rear. Road friction is proportional to weight (mass) and therefore so is braking power.... This is seen in all driving buy is at an extreme going downhill where your rear brakes are almost useless....
 

Rivian_Hugh_III

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Front tires have more weight on them under braking because it shifts forward. Forward momentum is trying to turn to angular momentum because you are stopping from the bottom side of the vehicle instead of from the middle.
Never thought about the angular momentum. That makes perfect sense to me. Thanks
 

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sb335xi

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Based on the interview with RJS on Munro, the front motors have a different gear ratio - which does explain some of the difference as well..
 

blturner

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I’ve heard this said before (most braking in front) and I’ve never understood it. Not saying it’s not true, just seeking to learn why.

To me it’s akin to people saying there’s a difference in whether you push or pull a load. Why isn’t it the same?

Why don’t the front and rear brakes share the load equally?
Like the others said it is because the weight shifts forward during braking.
But it is notable that the Rivian has a low center of Gravity and about 50/50 front to rear weight distribution. Most cars and especially pickup trucks have more weight on the front wheels to begin with.
 

yizzung

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The regen definitely feels more grabby in AP vs Conserve, IMO. Could just be that I’m feeling the torque grabbiness and not brake grabbiness. (Sorry to use such highly technical terms…)
 

Rivian_Hugh_III

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Like the others said it is because the weight shifts forward during braking.
But it is notable that the Rivian has a low center of Gravity and about 50/50 front to rear weight distribution. Most cars and especially pickup trucks have more weight on the front wheels to begin with.
That’s the answer I never understood. It’s not like the truck’s body is shifting at all. It’s all bolted together. The part most people don’t explain, perhaps because it is obvious to them, is that the shift is not so much happening back to front, but rotationally. That was what turned the light bulb on for me.

The front wheels become the center of a wheel of momentum because the center of mass is higher than the wheel center. As the truck brakes, the mass wants to rotate around the front wheel, lessening the significance of rear braking and increasing the significance of front braking, because of course the front brakes are now countering forward momentum and angular momentum.

So, many thanks. I was almost there. Just needed a nudge!
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