And it's not even close. Just watch the teardown of Cybertruck and compare its wiring to something like F150.
For the record, 42V systems were experimented with in the 1990s:
* https://en.wikipedia.org/wiki/42-volt_electrical_system
In the 2011 German automakers agreed to 48V as the next step after 12V:
* https://en.wikipedia.org/wiki/48-volt_electrical_system
BMW was the first the first with Ethernet:
* https://www.marvell.com/blogs/the-right-stuff-a-past-and-fut...
I have no explanation for this.
Tooling all their shit to 48V is a massive undertaking with pretty much zero advantages.
You really need some special component that is much better at 48 for it to be worth it, otherwise a delayed platform switch is better; one some competitors have moved and the suppliers exist.
They _all_ benefit from 48V.
It's very, very hard to get insulation that's not good for at least 100V and I suspect that just about any generic wire is good for more like 300V.
The only exception that comes to mind is wire that's specifically for "household low voltage" like 24V AC for thermostat, doorbell, sprinklers, landscape lighting. Also normal ethernet. But these are almost all what you'd call signalling wiring rather than power wiring.
Your average hook-up wire that you could buy at the auto parts store to make some repairs is almost certainly rated for 300V already. Mostly because of chafe resistance. Wikipedia says that the dielectric breakdown strength of PVC is 40 millions volts per meter https://en.wikipedia.org/wiki/Polyvinyl_chloride.
Divide both sides by 1 million and you get 40 volts per micron. OK so you need 1/3 of a micron to insulate enough for 12V and you need 1.25 microns for 48V. Now let's have a reasonable safety factor of say 10 or so and we're looking at 3 microns vs 12.5 microns. The only wire I can think of that might have insulation that thin is enamel coated magnet wire for the inside of motor windings. But even that is probably thicker.
Any kind of plastic insulation is going to be significantly thicker than this just to be able to be coated onto the bare copper wire and stick.
You're not wrong that the insulation needs to be thicker as the voltage goes higher. But you're unaware of just how ridiculously over-insulated everything already is due to other constraints of manufacture.
The integrated starter generator(ISG) is usually a pancake shaped motor that replaces clutch/torque converter in ICE car, nothing like the regular starter motor.
MHV was not even real hybrid, and is no longer relevant, so was 48V, at least for a while.
Tesla didn't have any existing, so their clean-slate math was clearly in favor of 100% new technology.
(Well, they did have 12v existing in their other cars, but they were clean-slate in the truck.)
Major car components like doors or front axles are assembled in parallel to miscellaneous parts on the main body, and all .join() at the final assembly. This had been the case for past 30-50 years, possibly more, in case this needs to be said.
> Major car components like doors or front axles are assembled in parallel
And doors (and tailgates) are the biggest body component that is _sometimes_ assembled independently. Then workers manually route cables through the body.
Pre-routing cables inside panels that can then just be welded together can save a lot of labor.
Sometimes? What and when on Earth is this about? Pre-WWII?
They wash and paint and dry the whole body at once _for paint consistency_, then take off doors and trunk lids and bumpers and send them into separate assembly lines. Those major parts flow parallel "threads" in sync and converge near the end, where connectors are plugged in and those major parts are bolted back in and plastic trims are pushed in to tuck everything under. Cars were basically always done that way for a long time everywhere. I think even lots of hand made supercars are like that, only except tact times are magnitudes longer.
> Then workers manually route cables through the body.
> Pre-routing cables inside panels that can then just be welded together can save a lot of labor.
What do these even mean? Are you hallucinating workers crimping cables in-situ? They just clip on harnesses and plug in couplers in "the line". Never seen under a door trim?
It sounds like you're either extremely ill-informed, or worse yet, potentially, intentionally misinformed about car manufacturing that what you see is advanced manufacturing. I think you should... look more closely into what "legacy auto" have been doing forever.
Workers still need to pull the wiring bundles through the car body and clip them, after the body is welded together. The connectors are impractically bulky to put several of them along the cable routes.
Pre-assembled panels can have cable runs attached to them during the individual panel assembly.
I designed some stuff along these lines 15 years ago. At that time, 12 volt stuff was not just available, it was available with great economies of scale and a huge range of options, off the shelf. You need an automotive-qualified relay? A light? A solenoid? A DC-DC converter module? A fan? You'd have 100 choices at 12v, 30 choices at 24v and 3 choices at 48v.
The microcontroller still runs at 5/3.3/1.8 V.
BMW ENET is non-standard, DoIP is standard. :)
That said, it all seems like inside baseball to me. The BMW 850i pioneered the CAN bus, but that car was forgettable and although CAN bus took over the car industry that did not seem to create any durable advantages for BMW.
Ethernet seems like the inevitable replacement for CAN, in light of VW's investment in Rivian, and 48V vs. 12V for the low-voltage systems seems like a wash.
And some schooling. They shall learn about pokayoke.
What is ethernet bringing to the picture?
Over 3 orders of magnitude faster datarates.
CAN FD: up to 5Mb/s
Automotive Ethernet: up to 10 Gb/s
60 Hz * 3840 * 2160 * 14bit is 6.96 Gbps.
What you'll actually be sending is a high bitrate mpeg stream, probably 54Mbps or thereabouts, you could probably fit 50x camera streams on a shared 10Gbps bus.
My Chevy Volt had 4 different CAN buses and one additional LIN bus.
This can all be replaced with just two Ethernet buses: for safety-critical and non-critical uses. And the gigabit speed provides plenty of bandwidth for any reasonable sensor traffic, even including camera feeds.
The current architecture was justified in 90-s when LIN PHYs were an order of magnitude cheaper than even CAN PHYs. Now Gigabit Ethernet PHYs cost less than a dollar.
The "main" bus was saturated with data, more than 80% of bandwidth utilization at 512kbs. And it kinda had a mix of everything, from street names to be displayed on the dashboard to ECU messages. The other two buses had some random messages, with no rhyme or reason for the split ( https://vehicle-reverse-engineering.fandom.com/wiki/GM_Volt ).
More speed and zonal architecture:
* https://www.electronicdesign.com/markets/automotive/article/...
* https://www.bosch-mobility.com/en/solutions/control-units/zo...
Bandwidth: you can't ship backup camera video or entertainment system audio over CAN, for example.
CAN was meant for short, real-time packets. 8 bytes in initial configuration. CAN FD allows 64 byte packets.
You spend a LOT of protocol doing packet fragmentation and assembly using CAN--which then negates a lot of the real-time guarantees.
CAN should be used for the short safety critical stuff. Ethernet should be used for everything else.
10BASE-T1S is a new standard geared for automotive. It uses physical layer collision avoidance instead of classic Ethernet exponential backoff. This provides deterministic maximum latency.
Though you can get max latency guarantees with switched Ethernet and the appropriate switch QoS and hardware.
They can probably develop for a car ethernet lan with a desktop pc and car "peripherals".
Not that there aren't canbus cards for pcs, but still.
I can imagine a container to simulate each hardware unit, a small inter-contaner lan, and develop code that way.
I think the bigger factor is that innovation in the CAN ecosystem has been lagging behind Ethernet for decades now. Only reason it's had such staying power is industry inertia.
1. https://netmodule-linux.readthedocs.io/en/latest/howto/can.h...