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Don't forget, Toyota already has self-charging vehicles! (I didn't watch the last LeMans race but I am assuming they never stopped for gas.)
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This is using regen for a quick speed boost. Ferrari has has it for years. Regen brake into a corner then get an extra hp boos from the electric motor on exit. It dosn’t store it for long and ICE is by far the primary power
 

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Discussion Starter · #22 ·
Wow this place got freaking weird.

So there's an argument being made to run the batteries of not 1, but 2 Rivians down to zero?
The simple logic of dragging another Rivian with Regen (let alone trying "push" one with Regen) just means you will now have TWO dead Rivians.
So you got about 50% further than you would have with just one Rivian?
Good luck with that.
Now you can have TWO times the fun re-charging BOTH vehicles fully.
Sheeeeeesh.
No, the logic is starting with one Rivian that has a full battery, towing another Rivian that has an empty battery. The empty Rivian being towed will regenerate the battery, just as they do when coasting down a hill now. When the front Rivian runs out of battery, how much of the second Rivian's battery will have been regenerated by it effectively having coasted down a 100 mile hill (being towed instead).
 

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Discussion Starter · #24 ·
You seem to be forgetting about the "getting up the 100 mile mountain" part
"The mountain" was a metaphor. Towing the second Rivian is effectively providing the second Rivian with that 100 mile mountain to coast down (by towing it 100 miles).
That is the question that remains to be answered. Can the first Rivian, (the one doing the towing), tow another Rivian at least 100 miles on the power available to it? Reports suggest around a 50% loss towing 9,000 lbs. Not sure what the equivalent weight of the 7,000 +/-lb Rivian would be with regen also pulling against it.

In no way, would it be "practical" to do on a daily basis in the real world. The question only being, is it possible? Under the best possible circumstances (good weather, constant 30 mph speed where aero won't play much of a role, roughly level topography, etc)? Many believe it's not. I'm on the fence that it might be possible, under the right circumstances.
 

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What does it matter?
You're still going to be be left holding the bag on two depleted Rivian's somewhere on one of these metaphorical hills, based on actual science.
The pesky first law of thermodynamics will never be overcome, especially on round planet with gravity, friction, weather, hills & valleys.
 

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The problem with this concept is Regen is at best 50% efficient. With 8 years in Teslas it is way more efficient to drive in a way where you use regen as little as possible, that is anticipate slows and stops and modulate the accelerator to coast rather then slow down too much that is rather then speed up and regen back down then speed up…
 

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Discussion Starter · #27 ·
The problem with this concept is Regen is at best 50% efficient. With 8 years in Teslas it is way more efficient to drive in a way where you use regen as little as possible, that is anticipate slows and stops and modulate the accelerator to coast rather then slow down too much that is rather then speed up and regen back down then speed up…
I think most will disagree on this one. Companies are spending billions of dollars on regenerative technology for a reason. EV makers specifically state that utilizing regenerative braking is more efficient. I've had EV's for years and years now. Had no clue what it was when I had my Volt some 10 years go. I assumed the same as you and figured it was stupid at the time to use "Low", which is how it was labeled in the Volt. That was the Volt's problem, excellent concept, but they did little to educate people. Based on what EV's are capable of today, if someone would develop a plug-in hybrid that had 100 miles in real world range with a gas backup, I think it would suit just about everyone. Again, based on today's EV tech. Back to your original point, I learned on my own through trial and error that "Low" mode was was measurable more efficient when driven properly. I've had Tesla's since 2013 and tried multiple times to use "Coast" and never has been more efficient, at least for me. But I'm one that almost never uses my brake pedal, except to come to a complete stop. Not a fan of Tesla's version that will allow you to come to a complete stop as it use the brakes for the last 3-4 mph and does so pretty abruptly. Have had better results with the original format of it and just gently tapping the brakes to complete the stop, rather than having to modulate the accelerator all the way to a stop to prevent the abrupt stops. What's your wh/mi average over the last 10,000 miles? I'm at 290 in a Model S, and I don't drive like a grandma by an means. Could certainly be much higher if I accelerated more gently than I do most of the time. I haven't tried coast mode in a couple of years, maybe I'll give it a try just for fun to see. I do like that I've never had to replace brake pads on any EV that I've owned! If the cost of brake pads are factored into the equation, that contributes to regen being more efficient. For me, time is money as well. Thus, factoring in not having to start slowing down LONG before the red light in coast mode does speed up the trip as well. If for nothing else, over the past 10 years, I've become so accustomed to one pedal driving, would struggle with an ICE vehicle. I rented a car once and almost rear-ended someone pulling out of the parking lot since it didn't slow down when I lifted off the gas! LOL Was an adjustment to go back the the pre-historic driving style! :)
 

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Discussion Starter · #28 ·
Also, Tesla's only have two motors to regen from. Rivian's theoretically should be better being able to utilize four motors to regen power from.
 

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I think most will disagree on this one. Companies are spending billions of dollars on regenerative technology for a reason. EV makers specifically state that utilizing regenerative braking is more efficient.
Regen is more efficient than conventional brakes. But the most efficient is to not consume energy if not necessary.

Also, Tesla's only have two motors to regen from. Rivian's theoretically should be better being able to utilize four motors to regen power from.
Unless the regen demand exceeded the capacity of the motors, the number of motors wouldn’t matter.
 

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I think most will disagree on this one. Companies are spending billions of dollars on regenerative technology for a reason. EV makers specifically state that utilizing regenerative braking is more efficient. I've had EV's for years and years now. Had no clue what it was when I had my Volt some 10 years go. I assumed the same as you and figured it was stupid at the time to use "Low", which is how it was labeled in the Volt. That was the Volt's problem, excellent concept, but they did little to educate people. Based on what EV's are capable of today, if someone would develop a plug-in hybrid that had 100 miles in real world range with a gas backup, I think it would suit just about everyone. Again, based on today's EV tech. Back to your original point, I learned on my own through trial and error that "Low" mode was was measurable more efficient when driven properly. I've had Tesla's since 2013 and tried multiple times to use "Coast" and never has been more efficient, at least for me. But I'm one that almost never uses my brake pedal, except to come to a complete stop. Not a fan of Tesla's version that will allow you to come to a complete stop as it use the brakes for the last 3-4 mph and does so pretty abruptly. Have had better results with the original format of it and just gently tapping the brakes to complete the stop, rather than having to modulate the accelerator all the way to a stop to prevent the abrupt stops. What's your wh/mi average over the last 10,000 miles? I'm at 290 in a Model S, and I don't drive like a grandma by an means. Could certainly be much higher if I accelerated more gently than I do most of the time. I haven't tried coast mode in a couple of years, maybe I'll give it a try just for fun to see. I do like that I've never had to replace brake pads on any EV that I've owned! If the cost of brake pads are factored into the equation, that contributes to regen being more efficient. For me, time is money as well. Thus, factoring in not having to start slowing down LONG before the red light in coast mode does speed up the trip as well. If for nothing else, over the past 10 years, I've become so accustomed to one pedal driving, would struggle with an ICE vehicle. I rented a car once and almost rear-ended someone pulling out of the parking lot since it didn't slow down when I lifted off the gas! LOL Was an adjustment to go back the the pre-historic driving style! :)
I’ve got over 100k miles in our 2 teslas (S and 3)
over 8 years. What I was getting at: Say you are on a slightly uphill road. It is more efficient to accelerate to 50 mph then coast to a stop then accelerate to 50 mph then regen to a stop. Or if you have a large downhill followed by uphill it is more efficient to free roll down then use momentum up the other side then regen down at a set speed then use electrons to go up the other side.

Personally I don’t think regen does all that much to add range aside from when going down long hills. In my teslas I switch regen to low when I put on my winter tires (in mid October) and leave it there until May when I take them off. I notice almost no difference in Wh/mi when I switch to low.

The best most efficient magnetic generators made (effectively regen) are 82% efficient, most are closer to 70%. I think it will be a long time before regen gets close to or better then that.
 

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Many will laugh this off, but, I'm beginning to think it may be a valid question....

Now that we have pickups coming to market that are capable of towing, got me thinking, could you just take two Rivian's, tow one to charge it with regenerative braking and switch back and forth?

I've had EV's for 9+ years. Always noticed how much range I got back on a long steep downward sloping hillside from regenerative braking. While I don't have scientific stats, the range gained over a 4 mile down hill run was significant. Certainly more than the 4 miles travelled.

Tried searching the internet and found where someone towed a Model 3 around a 1.4 mile track and gained more than 1.4 miles in range. Was closer to 3.5 miles gained. Hence, regenerative braking seems to charge much faster than the distance travelled.

The question would be, how much range loss would you experience from towing? If you can gain 3.5 miles in range by towing over a 1.4 mile distance, or more simply put, gain 2.5 miles by towing 1 mile, so long as your range doesn't decline by that much from towing, seems like you could just switch off and never have to charge?

Rivian has 314 miles in range. Towing we know drastically lowers that range.
Based on the Tesla towing test, Towing 100 miles would theoretically add 250 miles in range to the other Rivian. Could be more or less depending on the actual regenerative power, which in my test drive of the Rivian felt stronger than a Tesla. But, it was only a 1 mile drive, so no clue how much actual range I was gaining. But theoretically, If I can gain 250 miles of range in 100 miles, that means that, you'd only have to accomplish a range of 100 miles from the 300 mile range battery to be net zero. Seems possible, no??

Get a tow-bar to attach the two vehicles together. Would have to have a driver in each vehicle with both vehicles on and shifted in to "Drive". If the Rivian's regen is equal to the Tesla and really will add 2.5 miles in range for every 1 mile driven, then simply towing a second Rivian would theoretically give you endless range? Assuming you can get 100 miles in range out of the battery while towing the other Rivian.

May not be the greatest on the motors and charging system, but the question being, "could it be done?". Not "should" it be done. In a pinch, could be useful. Keep the speeds reasonable. The Tesla test was at about 30 miles per hour, so not that fast.

Anyway, just a thought for fun, but that thought , when thinking further, seems like it could actually be a reality. Until now, there were no EV's practically capable of towing. Now, with the Ford, Hummer & Rivian, there is. Will be interesting to see if someone tests this out. Seems like it could work. Your batteries and drivetrain may not last as long as a result, but that's not the point to the question. If you ended up in the middle of a desert somewhere, 1,000 miles from the nearest charger, and had one charged up Rivian and one on empty, could you get to the that charger 1,000 miles away by connecting the two vehicles together?

I do see that Ford filed a patent for recharging by towing. So, clearly they've thought of it. The only question is, how far could you tow versus how much range is gained on the second vehicle from the regenerative power? Seems like 100 miles is certainly possible, especially at just 30 MPH. In this scenario, with a solid enough tow bar, rather than switching back and forth, the Rivian behind could just push the Rivian in front once it runs out, which would be the same as towing and recharge the front Rivian while it's being pushed, instead of towed. I remember, even in my Chevy Volt years ago, coasting down the grapevine gave me several miles of range back, far more in that short distance than I ever got from plugging in the car over the same amount of time.

I don't know. Thinking it might be possible. Maybe not practical, but certainly possible?
Regen breaking adds to your total range Going down a severe downhill,grade. Adding to your range on flat roads .. not gonna happen.
 

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Wow this place got freaking weird.

So there's an argument being made to run the batteries of not 1, but 2 Rivians down to zero?
The simple logic of dragging another Rivian with Regen (let alone trying "push" one with Regen) just means you will now have TWO dead Rivians.
So you got about 50% further than you would have with just one Rivian?
Good luck with that.
Now you can have TWO times the fun re-charging BOTH vehicles fully.
Sheeeeeesh.
Maybe Scottie can shave off some small Dilithian Crystals and insert them into the secrete Rivian converter Gizmo?
 

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The problem with this concept is Regen is at best 50% efficient. With 8 years in Teslas it is way more efficient to drive in a way where you use regen as little as possible, that is anticipate slows and stops and modulate the accelerator to coast rather then slow down too much that is rather then speed up and regen back down then speed up…
exactly.
 

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I’ve got over 100k miles in our 2 teslas (S and 3)
over 8 years. What I was getting at: Say you are on a slightly uphill road. It is more efficient to accelerate to 50 mph then coast to a stop then accelerate to 50 mph then regen to a stop. Or if you have a large downhill followed by uphill it is more efficient to free roll down then use momentum up the other side then regen down at a set speed then use electrons to go up the other side.

Personally I don’t think regen does all that much to add range aside from when going down long hills. In my teslas I switch regen to low when I put on my winter tires (in mid October) and leave it there until May when I take them off. I notice almost no difference in Wh/mi when I switch to low.

The best most efficient magnetic generators made (effectively regen) are 82% efficient, most are closer to 70%. I think it will be a long time before regen gets close to or better then that.
I can pick up depending the SOC about 12-15 miles of range going from 5200’ to zero. That’s it. On flat roads regents adds Nothing. Just helps slow the car down and saves on the Breaks.
 

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Also, Tesla's only have two motors to regen from. Rivian's theoretically should be better being able to utilize four motors to regen power from.
In theory, Not really. 50% efficient regen is 50% efficient regardless of number of motors. You get 50% back. The only way more motors could possibly help is to shorten stopping distance under regen.


Another way to think of this wildly out there theory.

Imagine I’m driving along in my Rivian getting the rated range efficiency of 429 Wh/mi. Then just for simplicity (but the same concept) instead of towing another Rivian you could regen brake the rear wheels while driving forward with the front wheels. Less just for easy math add an additional 100wh/mi of energy expended to travel at the same speed to overcome the regen for a total of 529 Wh/mi. Then say if it is 70% efficient (which I think we are no where close to that) you would gain 70 Wh/miles back. Then to regen brake while going forward you would be using 499 Wh/mi and your range just dropped to 294 miles. With a more real 50% looking at more like 281 miles.

It will pretty much never add up. Even if regen was 100% efficient then it would be a wash. If you put 100wh/mi extra into regen then you would get 100 Wh/mi back in regen, gaining you a net zero of electricity or range.
 

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Still waiting for OP to reveal this thread is a joke and move this to the Rivian Humor section...and if that doesn't exist, someone should create it and put this thread in it.

Otherwise, if the OP isn't making a joke, it's kinda terrifying to think that someone with such a basic misunderstanding of high-school level physics will soon be driving around in a radically overpowered 7000lb behemoth...
 

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Discussion Starter · #37 ·
Still waiting for OP to reveal this thread is a joke and move this to the Rivian Humor section...and if that doesn't exist, someone should create it and put this thread in it.

Otherwise, if the OP isn't making a joke, it's kinda terrifying to think that someone with such a basic misunderstanding of high-school level physics will soon be driving around in a radically overpowered 7000lb behemoth...
And, these forums always bring out at least one that has to get nasty about it. Read later posts, just having fun. Lighten up. It's an internet chat forum.
 

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Discussion Starter · #38 ·
In theory, Not really. 50% efficient regen is 50% efficient regardless of number of motors. You get 50% back. The only way more motors could possibly help is to shorten stopping distance under regen.


Another way to think of this wildly out there theory.

Imagine I’m driving along in my Rivian getting the rated range efficiency of 429 Wh/mi. Then just for simplicity (but the same concept) instead of towing another Rivian you could regen brake the rear wheels while driving forward with the front wheels. Less just for easy math add an additional 100wh/mi of energy expended to travel at the same speed to overcome the regen for a total of 529 Wh/mi. Then say if it is 70% efficient (which I think we are no where close to that) you would gain 70 Wh/miles back. Then to regen brake while going forward you would be using 499 Wh/mi and your range just dropped to 294 miles. With a more real 50% looking at more like 281 miles.

It will pretty much never add up. Even if regen was 100% efficient then it would be a wash. If you put 100wh/mi extra into regen then you would get 100 Wh/mi back in regen, gaining you a net zero of electricity or range.
After my later posts, where I theoretically suggested added four more motors, wheels/tires and a second battery, to save the weight of the entire truck, I thought, Rivian is kind of halfway there. Until now, most EV's were 1 or 2 motors. Rivian doubled up with four. Whether the battery or entire system can take in the max regen from all four motors remains to be seen. Logically, would seem that the Rivian should have better Regen than a Tesla since it has 4 motors to regen from? Given, each is not as powerful as each of the two Tesla motors, so likewise, they may not produce the double the regen power back to the battery.

While towing the Rivian may not result in a net zero and recapture all of the energy used by the Rivian doing the towing, I do think it will certainly do much better than just 50%. If I had to venture a guess, I think probably in the 75-80% range. But, in perfect conditions, at a constant EV friendly 30 MPH in 75 degree weather, maybe even better???

I can pick up depending the SOC about 12-15 miles of range going from 5200’ to zero. That’s it. On flat roads regents adds Nothing. Just helps slow the car down and saves on the Breaks.
How many miles of travel was that 5200' elevation drop? All coasting? Never touching the accelerator?

As far as the regen goes, I was just going based on what the test of the Tesla showed. A small sample size at just 1.4 miles. But, that 1.4 mile tow, similar to regenerative braking from going down a hill, generated 3.5 approximately miles in range. So, if your down hill run was in the 4 mile range and you never had to touch the accelerator, then your 12-15 mile range recaptured, would back up the test numbers from the test of towing the Tesla.

With 4 motors, can Rivian produce even more? Driving it, it certainly slows down much quicker than does my Tesla. Given that it's also a 7,000 lb vehicle versus my Model S at around 5,000, just seat of the pants feel says it's got pretty good regen, and likely better than the Tesla. Whether it actually puts more energy back to the battery however, is still an open question. With the Tesla, we know for certain, towing it 1.4 miles will add approximately 3.5 miles in range back to the battery. If the Rivian can match that, my original question isn't that unreasonable. If it can do even better with 4 motors doing the work, possibly towing the Rivian will recapture more than 3.5 miles over 1.4 miles?? Then the original question still remains, how far can one Rivian tow another Rivian on a single charge?

In 7 or 8 months, if Rivian delivers as promised, I'll find out! :) Or, if someone beats me to it and tries it first, that would be great too.
 

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After my later posts, where I theoretically suggested added four more motors, wheels/tires and a second battery, to save the weight of the entire truck, I thought, Rivian is kind of halfway there. Until now, most EV's were 1 or 2 motors. Rivian doubled up with four. Whether the battery or entire system can take in the max regen from all four motors remains to be seen. Logically, would seem that the Rivian should have better Regen than a Tesla since it has 4 motors to regen from? Given, each is not as powerful as each of the two Tesla motors, so likewise, they may not produce the double the regen power back to the battery.

While towing the Rivian may not result in a net zero and recapture all of the energy used by the Rivian doing the towing, I do think it will certainly do much better than just 50%. If I had to venture a guess, I think probably in the 75-80% range. But, in perfect conditions, at a constant EV friendly 30 MPH in 75 degree weather, maybe even better???


How many miles of travel was that 5200' elevation drop? All coasting? Never touching the accelerator?

As far as the regen goes, I was just going based on what the test of the Tesla showed. A small sample size at just 1.4 miles. But, that 1.4 mile tow, similar to regenerative braking from going down a hill, generated 3.5 approximately miles in range. So, if your down hill run was in the 4 mile range and you never had to touch the accelerator, then your 12-15 mile range recaptured, would back up the test numbers from the test of towing the Tesla.

With 4 motors, can Rivian produce even more? Driving it, it certainly slows down much quicker than does my Tesla. Given that it's also a 7,000 lb vehicle versus my Model S at around 5,000, just seat of the pants feel says it's got pretty good regen, and likely better than the Tesla. Whether it actually puts more energy back to the battery however, is still an open question. With the Tesla, we know for certain, towing it 1.4 miles will add approximately 3.5 miles in range back to the battery. If the Rivian can match that, my original question isn't that unreasonable. If it can do even better with 4 motors doing the work, possibly towing the Rivian will recapture more than 3.5 miles over 1.4 miles?? Then the original question still remains, how far can one Rivian tow another Rivian on a single charge?

In 7 or 8 months, if Rivian delivers as promised, I'll find out! :) Or, if someone beats me to it and tries it first, that would be great too.
The part of all this theory you are missing is how much resistance is required to generate the amount of electricity you are talking about. It isn’t like you can freewheel flat tow one one and generate 400 Wh/mi. Think about Newton’s 3rd law: When an electric motor drives forward it produces power (wh), then the opposite of that, it takes the same amount of power against the motor in motion to get it back to stopped. So if you use 300 Wh to go from 0-60 it takes 300wh to go from 60-0. So even with 100% efficient you will never create more range you would just be gaining back the extra energy required to overcome the regen. Absolute best case theoretical scenario It is always a net zero gain.
 

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After my later posts, where I theoretically suggested added four more motors, wheels/tires and a second battery, to save the weight of the entire truck, I thought, Rivian is kind of halfway there. Until now, most EV's were 1 or 2 motors. Rivian doubled up with four. Whether the battery or entire system can take in the max regen from all four motors remains to be seen. Logically, would seem that the Rivian should have better Regen than a Tesla since it has 4 motors to regen from? Given, each is not as powerful as each of the two Tesla motors, so likewise, they may not produce the double the regen power back to the battery.

While towing the Rivian may not result in a net zero and recapture all of the energy used by the Rivian doing the towing, I do think it will certainly do much better than just 50%. If I had to venture a guess, I think probably in the 75-80% range. But, in perfect conditions, at a constant EV friendly 30 MPH in 75 degree weather, maybe even better???


How many miles of travel was that 5200' elevation drop? All coasting? Never touching the accelerator?

As far as the regen goes, I was just going based on what the test of the Tesla showed. A small sample size at just 1.4 miles. But, that 1.4 mile tow, similar to regenerative braking from going down a hill, generated 3.5 approximately miles in range. So, if your down hill run was in the 4 mile range and you never had to touch the accelerator, then your 12-15 mile range recaptured, would back up the test numbers from the test of towing the Tesla.

With 4 motors, can Rivian produce even more? Driving it, it certainly slows down much quicker than does my Tesla. Given that it's also a 7,000 lb vehicle versus my Model S at around 5,000, just seat of the pants feel says it's got pretty good regen, and likely better than the Tesla. Whether it actually puts more energy back to the battery however, is still an open question. With the Tesla, we know for certain, towing it 1.4 miles will add approximately 3.5 miles in range back to the battery. If the Rivian can match that, my original question isn't that unreasonable. If it can do even better with 4 motors doing the work, possibly towing the Rivian will recapture more than 3.5 miles over 1.4 miles?? Then the original question still remains, how far can one Rivian tow another Rivian on a single charge?

In 7 or 8 months, if Rivian delivers as promised, I'll find out! :) Or, if someone beats me to it and tries it first, that would be great too.
About 15 Miles. All down hill. No breaks needed. Just cruising down the mountain. When you get to the bottom you pick pick up range. And then it’s gone like a fart in the wind. Lol.
 
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