My turn for Critical Error, week 2

[stevegshi]

A single component failure should not cascade through other critical sysytems upon failure. This is the fastest way to get a flight crash investigation episode on TV.

If they are not isolated from eachother that means the design allowed for the connection to exist. That is a design problem as well as a component failure problem. The design should always accommodate and isolate the component failure, regardless of the cause.

In GA there is not much FbW, and autopilots rely on trim to maneuver in flight, not the full control surfaces. This means pilots can use their physical control inputs to maintain attitude control regardless of what the autopilot wants to do or not, because the larger control surfaces are linked to the pilot controls and only the smaller trim tabs to the AP. Obviously passenger sized aircraft FbW is different again.

The avionics typically have a backup, especially the electronic ones, but often you also have steam gauges for backup of the essentials.

The difference here is that the CT has no mechanical linkage at all, unlike the GA, so if there is no power to the SbW there is also no steering at all.

But that a steering failure also takes out the brake booster is not at all the way to safely manage such a failure. This seems to be a bigger problem, which only a redesign can fix, and replacing components won't be able to change.

In the older Tesla with traditional 12V lead-acid car battery, you will receive numerous error messages from multiple systems when the 12V battery dies.

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[Carlos Thomas]

When the failure happened it said the rear wheel steering was disabled (amongst other things like AC, Adaptive Ride Height, No Charging, No Brake Regen). So I only had the front two wheels turning like a normal car.

What ever was the cause, took out several other systems. Below is another photo from yesterday to give you more insight.

 

[84Apollo3]

A single component failure should not cascade through other critical sysytems upon failure. This is the fastest way to get a flight crash investigation episode on TV.

If they are not isolated from eachother that means the design allowed for the connection to exist. That is a design problem as well as a component failure problem. The design should always accommodate and isolate the component failure, regardless of the cause.

In GA there is not much FbW, and autopilots rely on trim to maneuver in flight, not the full control surfaces. This means pilots can use their physical control inputs to maintain attitude control regardless of what the autopilot wants to do or not, because the larger control surfaces are linked to the pilot controls and only the smaller trim tabs to the AP. Obviously passenger sized aircraft FbW is different again.

The avionics typically have a backup, especially the electronic ones, but often you also have steam gauges for backup of the essentials.

The difference here is that the CT has no mechanical linkage at all, unlike the GA, so if there is no power to the SbW there is also no steering at all.

But that a steering failure also takes out the brake booster is not at all the way to safely manage such a failure. This seems to be a bigger problem, which only a redesign can fix, and replacing components won't be able to change.

This is inaccurate in several places as far as your aviation references and also pure speculation on the cause of these error codes. How do you know that a single component failure caused the critical failure and cascading issues?

Why don’t we wait until we have an accurate picture of the cause and effect or the factual circumstances before we start calling this a doomed design flaw?

 

[Sjohnson20]

In the older Tesla with traditional 12V lead-acid car battery, you will receive numerous error messages from multiple systems when the 12V battery dies.

yeah this reminds me of the model 3s that had the 12v die in them early on.

I wonder if the 48v battery isn’t being charged properly by the truck? I guess we will find out soon.

 

[JBee]

This is inaccurate in several places as far as your aviation references and also pure speculation on the cause of these error codes. How do you know that a single component failure caused the critical failure and cascading issues?

Why don’t we wait until we have an accurate picture of the cause and effect or the factual circumstances before we start calling this a doomed design flaw?

You are not reading what I wrote correctly.

I didn't say it was a single component failure that caused it, rather I said that "if it was" a single component, it should not cause any further failures, and "if" it did, then there is a problem with the design.

Either way this type of failure is far from normal, and could have serious consequences. Not a good way ti start SbW if that was at fault, or 48V if that was the cause (which seems most likely given the error messages).

If you want to correct my GA FbW statement's then go ahead, but I'll let you know in advance I develop UAV flight controllers with redundancy for SAR, so I have some understanding of how these things "should" be designed to behave.

Not doom and gloom, just making a educated guess as to be prudent about the risks involved.

 

[Djcoolchris]

This sounds almost identical to what happened to me. My truck has been at service for a week now waiting for parts. They believe it’s the “PCS” or power conversion system.
#18 on the diagram.

 

[JBee]

This sounds almost identical to what happened to me. My truck has been at service for a week now waiting for parts. They believe it’s the “PCS” or power conversion system.
#18 on the diagram.

PCS manages most of the loads on 48V and the SbW steering from memory. Would most definitely be capable of causing the error messages listed.

I suppose the good news is that it's probably not a SbW fault, but the bad news is that SbW doesn't work well without power?

I'd be keen to gather any feedback on the exact issue. I'm assuming that if it is indeed the PCS and not the low battery browning out systems, that it might be the electronic isolation breakers if they can be reset? The bidirectional h-bridge power conversion circuits should be overrated and shouldn't really have an issue with peak loads or lower voltages, plus they tap the main pack. The PCS is also the charger so would cover that error, provided its not the 48V battery throwing a code.

 

[Djcoolchris]

PCS manages most of the loads on 48V and the SbW steering from memory. Would most definitely be capable of causing the error messages listed.

I suppose the good news is that it's probably not a SbW fault, but the bad news is that SbW doesn't work well without power?

I'd be keen to gather any feedback on the exact issue. I'm assuming that if it is indeed the PCS and not the low battery browning out systems, that it might be the electronic isolation breakers if they can be reset? The bidirectional h-bridge power conversion circuits should be overrated and shouldn't really have an issue with peak loads or lower voltages, plus they tap the main pack. The PCS is also the charger so would cover that error, provided its not the 48V battery throwing a code.

yeah, it’s all above my head to be honest. Haha, but I roughly follow and it seems to make sense. I know with all of these errors my AC power outlets were not working either. It just keeps asking me to reset which does nothing.

 

[JBee]

yeah, it’s all above my head to be honest. Haha, but I roughly follow and it seems to make sense. I know with all of these errors my AC power outlets were not working either. It just keeps asking me to reset which does nothing.

It's not really too complicated. They seem to have borrowed the setup from the Powerwall3 (same capacity and battery voltage).

The PCS has 3-4 of these AC to DC bidirectional converters modules, which means they can also do DC to AC.

If you are plugged in a AC circuit it will take 240/120V AC and convert into DC pack voltage to charge your main pack, thats AC to DC. Same for 48V rail and 48V battery charging, but one module can only output one voltage at a time.

The running in inverter mode DC to AC you can use two modules together for 240V split phase which also gives you 2x 110V circuits. That is your powerpoint outlets in AC that comes from the pack.

This is also likely why the outlets switch off when you are 240V AC charging the vehicle, because they can only work one direction at a time. When you DC charge at a Supercharger it should not need to turn off as it doesn’t need a PCS converter module to charge and can use the Supercharger instead.

It should also be possible to operate the outlets whilst AC charging, but that would need to actively monitor your bed outlet load to derate your charging, so it doesn't exceed the charge cable rate.

So if you can't charge and you can't use the 120/240V outlets then it's nost likely that one or more of those bidirectional converter modules is out of service.

Now whilst driving at least one of those modules (probably two) is providing 48V to the vehicle systems, and redundant power to the SbW, and one is maintaining/charging the 48V battery as well. When those conversion modules fail to provide 48V from power in the main pack, then it's just going to run from the 48V battery. At that point it will not be very happy, because that ridiculously small 48V pack will only last long enough to park it or load it on a transport. If that battery dips under voltage your steer by wire is gone, (you are going mostly straight ahead from then on). It looks like the brake booster also doesn't operate from the 48V battery (or maybe it has a low voltage cutout so u can steer till the end) and operates only from the converter modules in the PCS.

If this is the setup then it's poorly managed. The likelihood of having a second or third power converter failure, without a more serious main pack fault or impact accident, is pretty slim overall. Having it all in the same PCS package doesn't really help either if it's a high voltage problem.

For SbW this is the equivalent of a steering linkage failure, or your steering wheel coming off in your hands. It should "never" be happening.

 

[SlegMD]

@JBee salivating over a thread with real technical details, they have been rare lately.

Thx for the info, it is enjoyable to read ?

 

[Cybertruck 1974]

105 Cybertrucks is a small fraction of the number already delivered to customers.

This is what Tesla is good at fixing. Not worried at all.

Where's my Cybertruck?

absolutely agree. I picked up my truck and asked how many they were delivering and they said 2-4 a day for 1.5 months now. Dublin, CA so the numbers here are way way off. Also the truck has been in BETA for a long time now been all over the world. Tested to it's extreme. All computers have issues. There's some really delicate parts and some robust and software will always have issues. I've seen some issues with raising and lowering the truck but when I turn off truck or get out it fixes itself. I think that will be a software upgrade and phone calls won't cancel or answer using screen a couple times.

 

[Gigahorse]

@JBee salivating over a thread with real technical details, they have been rare lately.

Thx for the info, it is enjoyable to read ?

Same, a lot of bird poop stains and rail dust posts but nice to be getting some info on technical parts of the vehicle, both good and bad.

 

[HaulingAss]

there is more like 150 CT delivered here just the "official" list is not as accurate as it could be

150 is a tiny fraction of all Cybertrucks already delivered to customers.

 

[JBee]

@JBee salivating over a thread with real technical details, they have been rare lately.

Thx for the info, it is enjoyable to read ?

Thanks!

Sorry I haven’t been to active lately, I've been looking in from time to time, but there has been lots of new traffic and it was getting a bit tiresome keeping up and reposting old topics.

I wanted to setup a CT wiki instead, just to make info easy to find and just point to it, but just haven't had time. This power bug is new and interesting I suppose, and somewhat concerning, so should be brought to peoples attention until it gets permanently fixed.

 

[Sjohnson20]

So I wonder if you put a 48v jump pack on the battery would it get rid of the errors and at least allow it to drive for enough distance to get it home or to service? I always carry a 12v pack in my model y. My model 3 12v died with no warning once and the jump pack got the electronics going.

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