2 or 3 motor vs 4 motor off road capabilities

[Bill906]

You literally cannot put four internal combustion engines in a car and even if you did, they wouldn't give you minute positive and negative traction control.

Thanks @Crissa I love that you said this.

When talking to people about EV's vs. ICE vehicles I often internally do a thought experiment. What if EV's came out first and someone was trying to switch us from EV to ICE. I first used this idea with the argument that EV's catch on fire when they get into an accident. In my alternate universe, I can see EV people saying things like " Do you really feel safe with 20 gallons of flammable liquid in your car? In an accident it's going to spill all over you and catch on fire!"

Putting one ICE at each wheel is also a fun argument to have in this alt universe.

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[S.H.Peterson]

Well here goes for my 2 bits worth of experience:

With one motor driving 2 wheels, a mechanical LSD or Locker is superior to the computer trying to control wheelspin with appling brakes to the slipping wheel when there is one motor controlling 2 wheels.
I have a stout Dodge Charger and it would still pegleg a bit on hard acceleration. The computer fighting the spin with brake application stressed components unneccesarily and didnt respond as positively as a mech system and wastd mechanical power.

THAT being said, this is what would make sense to me:

Dual motor: have a mech LSD/locker on both axles with custom mode programming to help the computer deal with things. Use the brakes only to 'hold' the wheel from any rotation.

Tri-motor: One mech LSD/locker on the single motor axle. Use the brake to on 'hold' each wheel from any rotation.
The computer can control the axles VERY well using the dual motors on the other end. Dual mech diffs would be neccessary when using torque vectoring. There is no need to lock the dual motors together. Each wheel on the dual motor axle would be precisely controlled and the axles are not connected to the opposite side anyway. Use the brakes only to 'hold' the wheel from any rotation.

Quad motor: Ultimate control of each wheels torque vectoring. This would optimise for power vs grip vs demand the insdividual wheel. Use the brakes only to 'hold' the wheel from any rotation.

Thats as simple as I can see it.

 

[CyberGus]

Rivian made a great product, the real problem is that people can't afford to pay as much as it costs to build them. So, Rivian could sell a few at a very high price (which wouldn't be enough to pay off their fixed costs) or they could sell millions at a low price (which would result in losing tens of thousands of dollars per vehicle).

The vehicle could be re-designed to be cheaper to manufacture, but that would cost a lot of time and money, and there is no guarantee Rivian could manufacture it efficiently enough for it to be profitable. Their only hope is to switch to making delivery vans (but that also requires threading the needle and making them for a profit). There is a tendency for people with no experience in the auto industry to think you just make cars and sell them for a profit, it's not that difficult. Everyone does it, right? I'm sure even Rivian management believed that too, at one point in time.

The harsh reality is manufacturing and selling cars while managing supply chains with huge multi-year lags, is difficult to get right. Rivian has never manufactured a vehicle profitably and most companies who attempt this fail. In fact, out of over a hundred new companies founded in America in the last 100 years, only one of them has ever succeeded, Tesla. More than 100 failures and one success. Many of them had good products. Do those odds make you want to be an automaker?

Rivian was founded in 2009 and they still haven't managed to release one profitable product in those 14 years. Please note, I'm not talking about the overall company being profitable, I'm talking about selling a vehicle for more than it costs to manufacture it.

What I find amazing is how much crap people pile on Elon Musk when his daily decisions have created the only new profitable American automaker in over a century and every one of their models was able to be sold at a gross profit very early in their production ramp. People who claim to know better will tell you nearly everything Elon does is a mistake, that almost every decision is a mistake. And yet his success, against all odds, proves otherwise. You need to make nearly 100% correct decisions, nearly every step of the way, to build a sustainable auto company.

Munro did a number of videos on their Rivian teardown, like this one:




The recurring theme seems to be "over-engineering": 3x more NVH mitigation than needed, vast arrays of threaded fasteners, heavy and complex structure, etc.

Rivian aimed to make the best ever without cost consideration. Conversely, Tesla drives cost-reduction into every decision.

 

[Crissa]

Bankruptcy is Bankruptcy. Bye Bye. Unless you get a bail out.

Not in the US. There are different chapters that can give a person or organization time to pay off their bills before actually facing liquidation.

Often there's more than enough assets and income to balance the books - but just not in the time period that their current terms allow. See also, Silicon Valley Bank. They had plenty of assets. They were also liquidated, because that's how the Fed runs. But if they weren't a bank, they'd have taken to Chapter 11 and forced their lenders into a payment program they could meet. They wouldn't have had to face 7 or 13 and liquidation.

Bankruptcy is a complex thing.

-Crissa

 

[charliemagpie]

Countries are legislating against ICE and setting deadlines for its demise.

If an ICE company files for bankruptcy, I'd love to see the plan which will enable them to trade through the problem.. or for creditors to forgive or extend debt.

Tis why I'm saying they are goneski. Rules or no rules.. USA or anywhere... Unless you are in fairyland or like to labor a point.

When you are totally F,,,,d it is what it is.

 

[cvalue13]

Physics is reality, this is as close to 'business physics' as you can get.

me thinks you haven’t taken second semester yet

 

[cvalue13]

What I find amazing is how much crap people pile on Elon Musk when his daily decisions have created the only new profitable American automaker in over a century and every one of their models was able to be sold at a gross profit very early in their production ramp.

come again?

I’m not sure I’m following what seems to be a jumping between methods of calculating these things

are you talking about what it costs the business to sell a unit on an all-in basis?

or are you talking about some narrower sense of the cost of components and labor to sell a unit?

 

[charliemagpie]

come again?

I’m not sure I’m following what seems to be a jumping between methods of calculating these things

are you talking about what it costs the business to sell a unit on an all-in basis?

or are you talking about some narrower sense of the cost of components and labor to sell a unit?

He is talking it cost some chicken eggs, and not the chicken.

Semester 2++++++++++++

 

[cvalue13]

Semester 2++++++++++++

FUD degree earned!

 

[charliemagpie]

Tell us again how good you are.

 

[Tinker71]

The brakes don't overheat in this situation because the amount of power that can be transferred between tires and icy roads is very low. The brakes are not even being given a decent workout and its cold outside to boot. The amount of braking does not exceed the amount of traction. If you don't want the braking to happen, then don't drive in a manner and in conditions that require it to maintain traction. It's better to have the traction control braking vs. sliding around.

A steep icy road is not technical or even all that abnormal around here. Braking the slipping wheel is a good solution on an open differential. The lightest amount of braking allows one to maintain forward motion up the hill. Of course it's better to have a dedicated motor for each wheel and eliminate the differentials altogether.

I did find it hard to believe that brakes would overheat on an icy road, mud maybe. As you said this is a non issue for a quad and will not happen much with a tri motor. Even with a dual motor just slow down a little for conditions and it should not be a non issue. It is good to understand what the vehicle will be trying to do in a rally situation.

Whether there is a tri or quad and what model will launch first is very much up in the air IMO.

 

[cvalue13]

Tell us again how good you are.

after you: tell us again the impending doom of all automakers other than Tesla alone, and your resulting glee?

 

[charliemagpie]

ahh , you got butt hurt. Thats why you have a condescending attitude towards me. And I notice you dish out the same to others who share a similar opinion.

Ignore me.

I am about to ignore you ... again.

 

[Crissa]

ahh , you got butt hurt. Thats why you have a condescending attitude towards me. And I notice you dish out the same to others who share a similar opinion.

Ignore me.

I am about to ignore you ... again.

Do you need a hug, Charlie? 'Cause I'm not arguing with you, and even if I were, I'd give ya a hug.

The forum has been pretty flakey for me the last couple weeks.

-Crissa

 

[CyberGus]

Do you need a hug, Charlie? 'Cause I'm not arguing with you, and even if I were, I'd give ya a hug.

The forum has been pretty flakey for me the last couple weeks.

-Crissa

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