Sandy Munro Cybertruck Engineering Analysis (Video)

[Petertsai]

Automotive ethernet, like the computer networks we're more familiar with, is still a point to point protocol. There are a few ways automotive ethernet architecture can be implemented. If what Munro is accurate, Tesla is implementing a type of ring network. So you'll have the Central Control Module (CCM) will be wired to one Zonal Switch, which will then communicate with local control units and one or two other switches. Another way to do it is a Star of Stars architecture, where the CCM will be connected to a few zonal switches, which in turn may be connected to sub zonal switches or components.

Either case, it's not clear if Tesla has gone all in and replaced all feature ECUs with smart actuators, delegating all computation to the CCM, or some hybrid configuration, where in ethernet protocol is used in lieu of CAN bus communications, but the zonal switches are recieving the ethernet packets and translating it to CAN protocol for use with the feature ECUs in their zonal geography. The former would require Tesla to strong-arm any tier 1's still providing them parts to change everything about their package or produce them all in house, while the latter would allow Tesla to still use tier 1 providers on some parts, but mix in their own smart actuators for other parts.

However they implemented it, it's not a completely novel ideal, as IEEE already has standards wriiten on it, but it will be the very first time it will be this deeply implemented in a production vehicle. They've been using automotive ethernet for diagnostics connections in lieu of the OBDII connection since the early days of the Model S, but not for intervehicle communications. As far as I know, no one has replaced CAN with ethernet on a production vehicle yet, but it does exist in the test world.

The ring network will require two connections at each point. It will allow for one physical disruption in the ring. Two disruptions and parts of the ring will collapse. Is this a token passing ring?

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[davelloydbrown]

This idea was seeded by Munro saying in the Musk interview #2 that the CyberTruck is the “best vehicles I’ve worked on”

Munro seems a bit confused or sloppy/worded these days, so

I admit that Sandy is showing his 75 years and is not as accurate as he used to be. But I don't question his ethics and if he was working for tesla for either promotion or product research, he would admit to that upfront.

Back in the good old days when Tesla was worth $400/ share, I remember Sandy saying that they (he and his employees) sold all their tesla stock and did not hold any because it was a conflict of interest.

 

[JBee]

Need a new guard of engineers to create content.

Kyle from out of spec gets my vote atm. At least a reasonable level of technical detail, so you get something new out of watching. I'm getting tired of the seemingly endless regurgitation between channels.

 

[cvalue13]

I admit that Sandy is showing his 75 years and is not as accurate as he used to be. But I don't question his ethics and if he was working for tesla for either promotion or product research, he would admit to that upfront.

Back in the good old days when Tesla was worth $400/ share, I remember Sandy saying that they (he and his employees) sold all their tesla stock and did not hold any because it was a conflict of interest.

I mean, that’s all well and good - and Munro may have misspoken, but it’s his words that he’s worked on the cybertruck project


at 27:12, Sandy says:

" "...I think that I think that I think that this is without a question of a doubt the most brilliant product that I've worked on..."

 

[davelloydbrown]

I mean, that’s all well and good - and Munro may have misspoken, but it’s his words that he’s worked on the cybertruck project


at 27:12, Sandy says:

" "...I think that I think that I think that this is without a question of a doubt the most brilliant product that I've worked on..."

yes, I remember hearing that and to be honest I am not quite sure what he was talking about. I assume he misspoke as he often does.

 

[cvalue13]

yes, I remember hearing that and to be honest I am not quite sure what he was talking about. I assume he misspoke as he often does.

all else equal, I would have arrived at the same certainty


it’s just that combined with Munro’s other behaviors of the past several months, Cory’s departure, etc., it causes me to be at best uncertain either way

Yours is probably the cooler headed conclusion, and I’m just disappointed in how un-critical (in terms of critical thinking) and uninteresting Munro has become when it comes to the CyberTruck and Tesla in general

 

[Gurule92]

all else equal, I would have arrived at the same certainty


it’s just that combined with Munro’s other behaviors of the past several months, Cory’s departure, etc., it causes me to be at best uncertain either way

Yours is probably the cooler headed conclusion, and I’m just disappointed in how un-critical (in terms of critical thinking) and uninteresting Munro has become when it comes to the CyberTruck and Tesla in general

Tbh. My theory on Corys departure is.

His head blew up a little bit with being basically the reason that Munro live exists and doing interviews and stuff.

I remember everyone used to make subtle comments about how Cory would get mad if they didn't plug the subscribe button and other influencer type things.

It was a common enough occurrence that it felt like there was truth to it. Like maybe he wasn't so nice to the crew.

And possibly he went off on someone. Forcing sandy to take action.

BUT this is just a theory, a YouTube theory.. aaaand cut.

But really I have no actual idea.

 

[Dazureus]

The ring network will require two connections at each point. It will allow for one physical disruption in the ring. Two disruptions and parts of the ring will collapse. Is this a token passing ring?

Here's a site that goes into a little detail about a ring type topography for an automotive ethernet zonal implementation rather than an star-of-stars topography.

IEEE automotive ethernet is using ethernet protocol and not token ring. Each device on the network will have a MAC address, rather than using an IP address. I believe the ethernet frames contain both the sending and receiving MAC address, along with the packet payload and other frames. Ethernet is preferred to ring token since, like a more familiar computer network, it can scale easier and also expand to other sub zones if needed.

I think within the next 5-8 years, this will also cause an interesting shift of engineering work away from Tier 1 suppliers into the OEMs. Unless the tier 1 suppliers start selling software (Saas) rather than parts, their functionalities will be swallowed up by the OEMs as they start to bring in all the functionalities into the Central Control Module.

 

[davelloydbrown]

Tbh. My theory on Corys departure is.

His head blew up a little bit with being basically the reason that Munro live exists and doing interviews and stuff.

I remember everyone used to make subtle comments about how Cory would get mad if they didn't plug the subscribe button and other influencer type things.

It was a common enough occurrence that it felt like there was truth to it. Like maybe he wasn't so nice to the crew.

And possibly he went off on someone. Forcing sandy to take action.

BUT this is just a theory, a YouTube theory.. aaaand cut.

But really I have no actual idea.

It is pretty obvious that Sandy wanted Cory to take over.

What happened no one will know, it could have been Cory couldn't handle the stress, they may not have been able to work it out financially, who knows.

It's a shame because I really think that Sandy would like to step back and there doesn't appear to be anyone to fill his shoes.

 

[flowerlandfilms]

Or maybe Cory was just offered a great job that he thought he could genuinely make an impact in and left on good terms without any misunderstandings or conspiracy theories involved.

 

[JBee]

Or maybe Cory was just offered a great job that he thought he could genuinely make an impact in and left on good terms without any misunderstandings or conspiracy theories involved.

Cory said at the time he doesn't know where he will end up yet. It didn't sound like it was voluntary on his part at all.

Honestly though, from Monroes interview with EM it sounds like they were really struggling at the beginning of this year as a company. That sounds to me that they had to let people go as well.

But it also means to me that they don't have the clientele they once enjoyed, if youtube is becoming an income stream for them at those subscriber/viewing numbers.

Tough business to be in, and you can see that in their pivots like trying to sell 4680 cells and memorabilia etc. It's also not really rocket science to take vehicles apart, label and document the peices. The added value was always in their design consulting, not really the teardowns themselves, and it's hard to tell how much of that they still do.

 

[cvalue13]

Ok then let’s dig in to Munro’s commentary:

• can someone explain how higher system voltages means “electricity moves faster”? Because I thought the speed at which electricity travels in a conductor is not determined by the voltage, but by the properties of the conductor itself? Dont microprocessors run at like 1.3v.

• he says the range extender is $9K (“AWD is between 79K and 88K depending on if you buy the extended range thing”) - has *anyone* seen anything other than the $16K evidence?

• on Range, he fails to mention that all his range stats assume the truck is on tires that aren’t yet available to purchase (or that fee people want) - fair?

• his 78% reduction in weight savings comes from where? He has inside info? Or has Tesla said this somewhere?

• @JBee touched on how Munro’s comments RE 48v arch making 800v battery possible. Aren’t there several cars available with 800v batteries, but still on 12v systems?

• he says the 48v arch is what allows for “dual direction charging” (eg V2X)

• all-in, the 48v advantage to reduce to cost savings and to consumer seems to reduce to weight savings (so that you get a a few more feet if range in a 6,900lb truck?) - which means it’s cost savings, but in thinner/more brittle wire? What am I missing?

• he suggests that SBW is good for off-roading. That opinion surprises me.

• he says a rifle can’t shoot through the SS?

• he says he doesn’t think there’s much change in the CT motors? As touched on by @JBee, can’t be.

• finally, he says Cuisinart makes good pans. C’mon.



I just can’t help but stress attention on the title of the video.

 

[CyberGus]

IEEE automotive ethernet is using ethernet protocol and not token ring

Probably for the best, since Token-Ring speed tops out at 0.016Gb

 

[JBee]

Ok then let’s dig in to Munro’s commentary:

• can someone explain how higher system voltages means “electricity moves faster”? Because I thought the speed at which electricity travels in a conductor is not determined by the voltage, but by the properties of the conductor itself? Dont microprocessors run at like 1.3v.

• he says the range extender is $9K (“AWD is between 79K and 88K depending on if you buy the extended range thing”) - has *anyone* seen anything other than the $16K evidence?

• on Range, he fails to mention that all his range stats assume the truck is on tires that aren’t yet available to purchase (or that fee people want) - fair?

• his 78% reduction in weight savings comes from where? He has inside info? Or has Tesla said this somewhere?

• @JBee touched on how Munro’s comments RE 48v arch making 800v battery possible. Aren’t there several cars available with 800v batteries, but still on 12v systems?

• he says the 48v arch is what allows for “dual direction charging” (eg V2X)

• all-in, the 48v advantage to reduce to cost savings and to consumer seems to reduce to weight savings (so that you get a a few more feet if range in a 6,900lb truck?) - which means it’s cost savings, but in thinner/more brittle wire? What am I missing?

• he suggests that SBW is good for off-roading. That opinion surprises me.

• he says a rifle can’t shoot through the SS?

• he says he doesn’t think there’s much change in the CT motors? As touched on by @JBee, can’t be.

• finally, he says Cuisinart makes good pans. C’mon.



I just can’t help but stress attention on the title of the video.

A couple of points:

- Technically, there is a relationship between unit's of electric charge in Coulombs, being charge delta over a distance, and therefore velocity dependent if measured over time. In the scale of a vehicle though, it hardly constitutes any meaningful result, because the distances travelled are so short, that even just measuring the difference becomes difficult.

Also note that the electron velocity is not the same as the seemingly "instantaneous" change in electrical charge at the end of the cable, when you flick a switch. Imagine a hose pipe "full" of water, and you place a marble in one end, and push it through with water pressure. The water at the other end of the hose flows nearly instantaneously when you push more water in, but it takes the marble some time to get to the other end and come out the hose. The same with electrons, in that stuffing them in one end of a cable makes "other" electrons come out the other end, but it takes the electron you put in some time to traverse the microscopic world at the speed of light to get to the other end. Some say it only travels about 1mm/sec in a cable, so pretty slow.

In fact your CT travelling at 60mph is around 27,000mm/s and is as such going much faster than the electricity in your EV cables. This gets even weirder in that unlike DC, AC doesn't actually move the electrons in a direction at all. This is because energy is transferred in a wave, and a cable is essentially a "electromagnetic wave" tunnel that contains it inside it's perimeter. Similar to much higher frequency optical cables that funnel lasers. The energy actually propagates as a oscillation. Imagine a tug of war with a spring and the "work"-out you get with that.

Or you can imagine a boat on the sea, with the wave passing underneath the boat until it reaches shore and is accelerated onto the beach as the "wave breaks". Note that the boat and the particles of water in said wave do not move together with the visible wave, rather they only oscillate up and down as the wave passes, but do not travel horizontally themselves.

But back to Monroe; I think he was more referring to how the "energy" gets from one place to another in a 48V system, should it have the same cable as a 12V system. Technically this is true, in that at a higher voltage more energy can flow through a cable, but, in the context of the CT 48V, this is also the reason why they can make the cables smaller to save weight and cost, as there is less energy lost in heat from the resistance of smaller cables.

At some point the electrical load must be carried for whatever must be driven by the cable at that particular voltage, so it's a balance between the two. The wire thickness need not be an indication of a cables ductility properties, as this would be different from material to material. But copper, and in particular gold is pretty good even at tiny dimensions like in microchips.

CPU/GPU/MCU/ECU logic typically operate in the 1.2-5V range. All of these devices have dedicated power supplies to make sure they are protected from voltage spikes and wrong connections etc. There used to be a lot of signal conditioning on MCU's but often these are neglected as there are different way to overcome those issues. Most CPU's use mainboards with 12V/5V/3.3V supply rails that is then lowed to down to the actual CPU voltage under 2V. So it's highly likely there is 12V somewhere near the main proccing.

- This leads to the 48V making 800V "possible". I can't see any correlation of them being interdependent in any way. Technically the 800V pack is just two 400V packs like any other Tesla/EV, and either 800V or 400V would require a step down DC-DC converter for 48V or 12V anyway. There could be some improvement in conversion efficiencies by only going to 48V instead of 12V from 800V, but they are unlikely to be high enough to warrant the change, and are likely only in the 10's of watts overall, or fractions of a mile range per hour. The cable weight reductions will result in similar very minimal losses in range from extra rolling resistance.

It could be that significant cable mass was reduced, possibly even 78%, but as Monroe says, and I've mentioned countless times before it's primarily through the change in the wiring bus, which reduced cable lengths in general, with the remaining cable "thicknesses" being reduced by the 48V. This is a significant manufacturing and cost reduction, but has minimal range improvements.

But, for diagnosing and implementing other features this change was essential, as he mentioned the SbW steering would have been compromised running off just 12V due to the power levels they are using for those SbW motors. But this brings up another point, in that actuation of Optimus or manufacturing robots is yet another space Tesla is heavily involved in, and the 48V seems an obvious cross reference to those systems as well, for the power levels they require.

This is also the case for Powerwall, in that most units until now are internally configured to 48V, and I think the PW3 is as well.

Now the similarities between PW3 and CT's V2X might be by chance, but I dare say are not. The V2H output of the CT has the same limit as the PW3 inverter, so maybe their are similarities in the components used there, in that this inverter would be able to handle the by-directional feed through the V2H NACS plug, to both charge the CT and discharge the EV to the house, grid or other vehicle. Just like the PW3 can.

The next part here is that if that is the case, this inverter will be able to even handle V2G, which btw has not yet been addressed so far. This is not the same as V2H, V2P or V2V as per the current website. The main difference here is that if the PW3 internals are used, then the CT would also have the ability to synchronize to the grid and backfeed energy into the grid for use there. This opens many opportunities for autobidder and Tesla's Virtual power plans. It also means that multiple CT's could be used to buffer microgrids and the like...of which the implications are actually huge. Other Teslas have long been reported to have this ability disabled, and even the first Roadster had V2X. So this is a "step back". The timing of which eludes me.

There's another "hypothetical" part, which would seem unconventional, but might actually be the case, in that they might be even be using a variation of the solar MPPT input circuits of the PW3 to create the 48V charging from the main pack in the CT. These are rated for up to 20kW, which would more than suffice for the 48V supply in the CT, have 4 channels @ 5kW (so maybe one per module?) and together with a 48V battery buffer would provide power redundancy for the SbW at the same time. The only issue I see, is how they deal with the 800V motors, because PW3's 600V PV limit might require a different set of IGBTs/MOSFETs in the CT.

Unless they are running off the split pack, and maybe even the motors switch to 400V as well when not under full load? There's some variables in there we just don't know, so it could be possible they only use 800V to charge the pack so they don't end up with huge SC cables to get the SC V4 rates, but then only run the vehicle in 400V mode, and therefore the motors are actually still 400V?

This to me would be a weird design choice, as this negates the advantages of 800V motors would have, but unless we get some details from Tesla we wouldn't know until someone stuck a multimeter on there while it's running, or even better grabbed some motor/battery data off that ethernet bus they use. In all, the motor will run off a fairly wide voltage range, and whatever the battery can supply at the time, so sticking to a higher voltage might not even make sense all the time, especially so under partial load in cruise. Note that in both PM and induction motors frequency controls RPM and not voltage by itself.

I suppose the point here is that Monroe might of actually let something slip that he did not quite understand, or potentially intentionally misstated, in that the 48V is in fact common throughout the Tesla power range, and that they reused parts for each of the new designs, being PW3 and CT, to reduce part count overall. This wouldn't be the worst choice, seeing there's a couple of opportunistic similarities if done right, and if it doesn't cause other issues.

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