Dual CT running on one motor

[Diehard]

We can be quite certain that the truck will be engineered to protect itself just as the cars are today. If a failure occurs that requires attention or is likely to require attention in the near future you will get, as you do today, a message on the screen informing you that service is needed, In extreme cases the truck will shut down or reduce power delivery to a level such that it can only be moved a few feet per minute sufficient to get it off the road and on to a trailer truck.

We are not qualified to interpret the multiple sensors whose readings are uses to make the decisions as to what action is appropriate, You want the car and/or the Tesla technician to make that determination so that the entire liability falls on them. If you are smart you don't call your HVAC people and tell them the TXV is hunting. You tell them something is wrong with your air conditioner. It's the same thing here.

You can search "Tesla motor failure" on the web. Fortunately you won't find much but you will find a few anecdotes about motor failure in multi motor Teslas.

when a truck today tries to protect itself, you stick a code reader in it. It tells how she is really feeling, you google some stuff, watch some YouTube and get to the heart of the problem. Order some OEM or aftermarket parts, replace it and 9 out of 10 you relationship is fixed for a good while. I have a feeling Cybertruck is going to be like that hot chick with bad communication skills that have so many guys lined up to take her out that does not feel obligated to tell you what is really wrong. After any argument, you have to apologize, buy flowers, take her out to dinner (dealership), come home with a lot lighter wallet and if you are lucky things will get better without you ever knowing what was really wrong. I have no doubt CT would be a great girlfriend (lease) but would I want to put a ring on it? For those of you manly guys that are into chick flicks when no one is watching, Nothing Hill kinda deal. I am just airing out my personal issues I need therapy for. This is not a logical argument.

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[ajdelange]

I suppose that the first thing you'll need to appreciate is that a BEV has many, many fewer replaceable parts than an ICE vehicle. It doesn't have idle air control valves or spark plugs or ignition modules. It, in fact, has many more parts than an iCE vehicle (billions of transistors in the chips in the auto pilot) but you don't replace them. You replace the whole computer. Similarly you don't put a new transistor in one of the bridges in an inverter. You replace the whole drive unit. Now they don't throw the old one away. I'm sure it goes back to Fremont where it is probably refurbed but probably not below the board level.

You should probably think of your BEV more in the way that you think of your laptop, tablet or smart phone than in the way you think of your ICE vehicles. The BEVs obviously have some components in common with ICE vehicle but the core is entirely different. The motors are really computer peripherals. The probability of a shorted turn in a motor stator or a seized motor bearing is very low relative to the probability of, for example, a transistor failure. But that's immaterial to you. The field replaceable unit contains the motor and the transistors. You are, if you want to drive a BEV, are going to have to get used to the fact that if the car shuts down because a drive unit or computer failed they are going to replace the drive unit or computer and if you ask them why they are going to tell you "because it needed to be replaced". They don't know what was wrong with it and at the field level they don't care. You aren't going to get a code that translates to "Q142 source - drain short", order a replacement for Q!42 from Amazon and replace it, Frustrating to some but not to most. The days when i took motors out of cars are long past.

At a much less serious level (but still one that can leave you at the side of the road) is the 12 V battery. If it acts up you will get a message on the screen indicating that it should be replaced (no need to plug into the OBD port). You can then just replace it or take it to a service center and let them replace it.

A third type of repair is the OTA repair - software based fixes that are done over the internet.

 

[ajdelange]

when a truck today tries to protect itself,

If you look at the bottom of one of your posts you will see a button labeled "edit'. This allows you to change, delete or add to the text of the post. No need to repeat the whole thing in another post with a few lines different. Much less confusing to the readers!

 

[Diehard]

If you look at the bottom of one of your posts you will see a button labeled "edit'. This allows you to change, delete or add to the text of the post. No need to repeat the whole thing in another post with a few lines different. Much less confusing to the readers!

The booboo happened because first submit went to the next page and refresh kept me in the current page (a bug in the program) so I thought I lost the whole thing and retyped. Now one is deleted.

 

[Diehard]

You should probably think of your BEV more in the way that you think of your laptop, tablet or smart phone

I do. That is the reason for the freak out.. Replacing a $500 tablet or smartphone is within my risk tolerance. Replacing a $50K Cybertruck, not so much. I guess longer warranty on battery that is going to be a part of the structure helps a little.

At a much less serious level (but still one that can leave you at the side of the road) is the 12 V battery. If it acts up you will get a message on the screen indicating that it should be replaced (no need to plug into the OBD port). You can then just replace it or take it to a service center and let them replace it.
.

Knowing that at least there is something I can replace helps with my therapy and accepting the inevitable truth that I will have to lose my independence and be at mercy of someone else. Cybertruck will get me ready for nursing home.

Thanks.

 

[HaulingAss]

I don't know what kind of lockout the car may impose to prevent "limping" furthther than to the side of the road.

I'll try to keep this as simple as possible:

The car can self-diagnose some problems but only to a point. It's not perfect and doesn't have an unlimited number of sensors to perfectly diagnose every conceivable problem. What this means is that Tesla engineers had to determine at what point the symptoms were such that it wasn't advisable to drive the car at all and when it could go into limp mode. Some issues only result in a warning that the car needs service but it can be driven normally, some require limp mode, some require a complete shut-down - It all depends upon the symptoms.

A really serious failure will result in complete shut-down. This could be to prevent a fire or other safety hazards. At that point the system will not apply any power to the motors and you won't be able to move at all.

"Limp Mode" is applied when the symptoms are such that it's unlikely to cause further damage or danger by driving it but full power could be problematic. So you can drive under reduced power until the car is repaired or the symptoms escalate.

As for towing to charge the manual makes it quite clear that you must not do that nor in fact tow it at all if its wheels are in contact with the ground.

From the X manual (caps are theirs):

"Warning: NEVER TRANSPORT YOUR VEHICLE WITH THE TIRES IN A POSITION WHERE THEY CAN SPIN. DOING SO CAN LEAD TO SIGNIFICANT DAMAGE AND OVERHEATING. IN RARE CASES EXTREME OVERHEATING MAY CAUSE THE SURROUNDING COMPONENTS TO IGNITE."

Later paragraphs indicate that allowing the wheels to spin while towing voids the waranty.

Yes, a lot of car's manuals instruct the same thing these days for various reasons. Generally, the reasons are valid only under a limited set of circumstances but some cars are truly not suitable to be towed at all. For example, they may have a transmission that relies upon the motor running for lubrication. But in many more cases, these prohibitions against towing are stated as an absolute prohibition just because the manufacturer doesn't want to take any warranty responsibility for a corner case in which there really is a valid reason not to tow.

I would never tow a Tesla to get from A to B on it's wheels unless a driver was in the car and the car in "Drive" and functioning normally. This is impractical anyway because the the driver would need to perfectly match the throttle setting with the speed and it would consume a small amount of power anyway. Too much throttle would cause the tow line to go slack while too little throttle would cause excessive regen braking. There is no point in doing this because it assumes the car is working. Why would you tow a fully functional car when it would be easier and safer to simply drive it to it's destination?

But if the car is almost out of battery power, but otherwise working normally, I would feel completely safe using a tow line to charge the battery using regen (regardless of the language used in the manual). Here's why:

First, the car has to be "on" and in Drive to do this and functioning normally except for the low state of charge - just as if you were driving under your own power. The car has absolutely no way of knowing whether it's being towed or whether it's descending a long, gradual mountain grade under regen braking. In other words, the built-in self-monitoring will monitor the regen and adjust accordingly. If regen went away for any reason, or error messages appeared, I would immediately stop. But this kind of "regen towing" has been done under various conditions without any issue. Indeed, unless the car would fail under regen braking from descending long grades, there simply wouldn't be a problem doing this. Not even a little one.

Now it stands to reason that if you are strongly advised to not passively drag the motors while towing you ought not to drag one of the motors with the other.

Dragging one motor while the other is under power is a seperate case altogether because you would have power going both to and from the battery (without the car's CPU taking appropriate action). This should only be done by the car itself. It self-monitors and knows what to do and when it's safe to do that. So, if one motor fails, and the failure is such that it's safe to drag one motor with the other, it will handle the electrical flow properly and allow you to carry on, typically at reduced levels of power. But only in those cases in which it's programmed to allow.

I don't know why this is. I can think of lots of questions about it I'd ask a Tesla engineer if I had access to one. Rivian says that you can indeed charge their trucks by towing them. When asked about limping on a failed motor or motors the CS person said she would have to research that and get back to me. Never did.

All modern cars run using hundreds of thousands lines of code. It's not trivial to program the car to be safe and effective with only one functional motor. The list of considerations are long. What if the car is on snow or ice, are the driving dynamics still safe? That's just one of many. This kind of functionality costs hundreds of thousands of dollars in development and testing to insure it's safe to deploy. Tesla has done this, at least to a basic degree - the functionality will probably improve further over time as they program more allowable cases (and perhaps remove a few that shouldn't have been allowed in the first place).

My guess is that Rivian had not yet done any of the necessary work to provide this kind of "corner case" functionality yet. Designing and releasing a new car is hard work, this just adds to the "to do" list. Hopefully your question spurred them to tackle it. They might release the car without this functionality and add it over time. It's much easier to just disable the car if serious malfunctions are detected because it avoids thousands of hours of development and testing.

 

[Crissa]

Rivian specifically has done this sort of testing. But I suspect their manual will have similar warnings.

When something is wrong, you can't know if it's safe or not.

-Crissa

 

[FutureBoy]

The car has absolutely no way of knowing whether it's being towed or whether it's descending a long, gradual mountain grade under regen braking.

Technically... A CT could distinguish between gravity or towing regen. It will have to be able to level itself using the air shocks so it will have a way to determine the angle of the current path relative to the pull of gravity. So at a minimum it could know if regen was happening while going up or downhill. But with the air shocks it could also surmise the current loaded weight. Which combined with the angle of travel could be used to calculate the expected acceleration. A deviation to have more regen than expected from gravity would suggest towing regen.

But this is all speculative on my part. I have no idea if this kind of code has been added to Tesla vehicles.

 

[HaulingAss]

Technically... A CT could distinguish between gravity or towing regen. It will have to be able to level itself using the air shocks so it will have a way to determine the angle of the current path relative to the pull of gravity. So at a minimum it could know if regen was happening while going up or downhill. But with the air shocks it could also surmise the current loaded weight. Which combined with the angle of travel could be used to calculate the expected acceleration. A deviation to have more regen than expected from gravity would suggest towing regen.

But this is all speculative on my part. I have no idea if this kind of code has been added to Tesla vehicles.

Mostly true, and it's irrelevant because Tesla would never design the Cybertruck to fail BECAUSE they detected it was being towed. The point is, you're not going to break anything by tow-charging it (regardless of the boilerplate in the manual).

I said "mostly true" because the truck would also need wind sensors to tell the difference between being towed or blown by a 100 mph wind.

 

[HaulingAss]

Rivian specifically has done this sort of testing. But I suspect their manual will have similar warnings.

When something is wrong, you can't know if it's safe or not.

-Crissa

I will just point out there is a difference between failure testing and writing code to deal with every failure in the most elegant way.

I was making the assumption that since the Rivian customer service rep never got back to ajdelange as promised that the answer was not a positive one. But that's probably not a good assumption.

 

[FutureBoy]

Mostly true, and it's irrelevant because Tesla would never design the Cybertruck to fail BECAUSE they detected it was being towed. The point is, you're not going to break anything by tow-charging it (regardless of the boilerplate in the manual).

I said "mostly true" because the truck would also need wind sensors to tell the difference between being towed or blown by a 100 mph wind.

LOL. Hurricane regen.

 

[Diehard]

LOL. Hurricane regen.

Hopefully Drag coefficient is good enough that you won’t get much regen out of that. Speaking of wind, has anyone heard of any useful third party portable mini wind turbine or anything to get power out of a river, how they would compare with solar...... basically what is the most practical backup plan for when you go to places you shouldn’t be going.

 

[ajdelange]

There are many companies that sell the equipment for hydro generation to those fortunate enough to own property with a stream. Something that goes into the back of the truck that you can toss into the creek at your campsite is another matter - never heard of such a thing nor does my common sense suggest it's possible.

 

[Crissa]

It is possible, but the amount of power would be minimal.

-Crissa

 

[HaulingAss]

Hopefully Drag coefficient is good enough that you won’t get much regen out of that. Speaking of wind, has anyone heard of any useful third party portable mini wind turbine or anything to get power out of a river, how they would compare with solar...... basically what is the most practical backup plan for when you go to places you shouldn’t be going.

You are bring up a real corner case:


1) There are no structures nearby that I could slow charge from
2) I don't have a solar system suitable for charging.
3) There are no gas stations nearby (all gas stations have electricity).

and, finally, the BIG ONE TWO THREE

4) I didn't plan my trip adequately to not run out power in the middle of nowhere.
5) I just happen to have a portable hydroelectric turbine and associated power converters and equipment with me.
6) There just happens to be a suitable hydro stream source nearby.

I think that's a real corner case. That said, if you have a remote stream you want to charge from regularly, the best way to do it with the most minimal impact is with a long hose or pipe fed downhill to a Pelton wheel that discharges back into the same creek. No dam is necessary, just a small screened box or drum to keep leaves and sticks out. The stream needs to have enough elevation drop that you can get a decent head pressure. 30-50 vertical feet is good. A waterfall location is ideal but any stream that has 30 feet of drop within the length of your hoses or pipes is good. A firehose type diameter would be a good minimum although I'm sure you could setup a trickle charger with a 3/4" garden hose.

But you will also need a mini-power station to covert and regulate the electricity to 120V or 240V clean enough to charge with. Probably the easiest, off the shelf method would be with a portable battery "generator" with a built-in inverter. This way you can feed DC from the generator into the batteries charge controller and charge off the inverter. Expect about 25% loss from these conversions.

Most sites like this will have some solar exposure so installing a "solar carport" would probably be the lowest hassle way to charge, even if it's temporary. That would require much of the Cybertrucks cargo capacity (as would a mini-hydro system) but would be super cool - It would be like having your own personal gas station at your remote site!

I use good trip planning skills so I never ran my gas cars completely out of gas even though I travelled in some pretty remote areas of Mexico and had less range than the Cybertruck. Remember this: If there's a gas station, there is electricity. If you travel in the wilds of the Rural West, your best bet for the last top up before going into the wilds might be a 30-50 amp plug at a campground or a mom-n-pops motel with a 30 amp window a/c outlet.

The good thing is electric vehicles are very efficient at the slower speeds you are likely to be travelling (this is the opposite of a gas vehicle that can experience plummeting range at very low speeds). Sure, up-hills can lower your range dramatically but you tend to get most of it back when descending the other side (unlike a gas vehicle).

There are very few places in the lower 48 you cannot take a Cybertruck due to range issues as long as you exercise reasonable trip planning.