I had a similar occurrence driving my 2015 Tesla down the off-ramp on an interstate at night. The car had very nearly run out the battery, and I was near '0 miles' of range.
Sadly, the software in the car is dumb enough to allow you to convert momentum to 'regeneration' at exactly the time that the battery is unable to take charge at anything faster than a trickle. Outcome: rather than allow the car to _coast_ without regeneration, the car decided to force-feed the battery kW from the motor/generator until the some threshold was exceeded, and the car shut down the main traction battery.
Dumb, dumb, dumb. But there is no way to realistically communicate this to the Tesla SW developers. Long story short, I flipped the car into 'tow mode' using the last 30 minutes of 12v battery power, and I solicited help from a passerby and a policeman to push the car 200 yards to a supercharger, where the battery, first, nibbled at a little bit of kW, and then after 5 minutes, when nursed back to good health, it inhaled high kW.
Is the car computer in these things monolithic? Does the computer that controls all that touch screen shit also handle core vehicle control? If so, that is completely and utterly insane and should probably be prohibited by design codes.
If there is no mechanical override, whatever computer is controlling core functions had better fucking be isolated and running code that has been through "industrial grade" review processes and such. If everything else dies, that computer should still work. It should even have its own little local backup power of some kind, or be able to pull power from something other than the main vehicle power system. I'd add that it also should not permit OTA software upgrades at all, and its connection to the higher level systems should be least-privilege.
There really should be a manual override, but in the absence of one that is the only acceptable design for a fly by wire system.
I just opted for a 2022 Nissan Leaf over a Tesla Model 3. Cost was a major factor (and I'm not a frequent road tripper so the faster Tesla recharge was less critical), but so was this kind of stuff. The Tesla is far sexier with a better design and has a lot of desirable features, but I am glad that I did.
As near as I can tell the Leaf is designed like a normal car. It seems electronically controlled (I have not looked for mechanical overrides but I might), but I get the strong sense that the computer and electronics controlling that are not the same as what's running the infotainment system or even the lane keeping (it has level 2 self-drive). They are probably discrete systems. It also has a 12V lead-acid battery that can power all the electronics if the main power system totally eats itself, which is not an impossible scenario given that an EV's main power system is some hard-core high voltage electronics. Nissan can also align panels.
I really really really want to like Tesla, but this is beyond insane.
I sincerely hope that SpaceX avionics are not designed this way. They probably are not because NASA would not let its astronauts fly in it otherwise... different market with much more informed customers.
> I just opted for a 2022 Nissan Leaf over a Tesla Model 3
If you want Leaf because you want lower price, feel free. No problem with it.
But if you think the electronics or architecture in the Leaf are superior in any you are simply wrong.
> I really really really want to like Tesla, but this is beyond insane.
You are simply wrong on your assumptions about how Tesla works.
Yes Tesla has unified a lot of functionality into one core system, but literally every car maker is copping that strategy. In fact the older 10-100s of chips distributed system talking over buses was actually much, much more prone to bugs.
Even if that main system fails, the Tesla can still drive, this has been shown often by many people who rebuild Tesla or had issues with the core computation.
> I sincerely hope that SpaceX avionics are not designed this way.
Go look at the teardown and analysis of Tesla. Seriously, I highly recommend Sandy Munro. They do incredibly detailed teardowns of cars including Tesla. They have been doing it for decade and their business is selling that information to other car makers for (50k a pop).
Its actually the other way around. Tesla cars are designed more like SpaceX rockets or fighter
jets in terms of electronics.
You can actually get their documents of the BMW i3 for just 10$ and you can basically rebuild the car yourself.
And literally everything they said about Tesla in terms of electronics was positive and well ahead of industry standards.
> It also has a 12V lead-acid battery that can power all the electronics if the main power system totally eats itself
So does every Tesla except new generation Model S. They have a 12V LiIon battery instead. And it has the same function as in a Leaf.
Elon has for a long time wanted to switch to 48V systems but they have not managed it yet. I hope they will get it with next generation Y or the Cybertruck.
> Its actually the other way around. Tesla cars are designed more like SpaceX rockets or fighter jets in terms of electronics.
Yeah, the SpaceX and Tesla software stacks for their firmware are similar in a lot of ways, they both heavily use buildroot(https://buildroot.org/) for at least a good bit of their Linux based firmware, good luck getting proper GPL source from them though, Tesla last I checked at least made some effort to publish what appears to be incomplete buildroot source code(https://github.com/teslamotors/buildroot).
SpaceX just inaccurately claims "Because we are not distributing buildroot, we are not legally required to distribute the source code under the GPLv2 license." then ignores you even though they very obviously distribute buildroot based firmware to customers as it's used in the Starlink Dishy antenna(I asked for their buildroot source and have a Dishy antenna, that was their response...and to top it off I'm even a major buildroot contributor). They def have a bunch of cool tech but are super secretive about everything it seems, they don't appear to ever upstream patches or interact with outside software developers.
No, the computer isn’t monolithic. The car will still drive even if infotainment and autopilot computers melted. Afaik there’s Infotainment, Autopilot, BMS, and Drive computers/controllers.
Tesla also uses a 12v battery to power all the computers if the HV pack fails.
> Nissan can also align panels
Afaik the panel gap problem was resolved a year or two ago.
Even if the computer isn't monolithic, it seems that some failure higher in the stack can make the car into a brick. Does the real control system depend on the infotainment system or other higher level systems for UI interaction? If so then that's basically the same thing.
Sadly, the software in the car is dumb enough to allow you to convert momentum to 'regeneration' at exactly the time that the battery is unable to take charge at anything faster than a trickle. Outcome: rather than allow the car to _coast_ without regeneration, the car decided to force-feed the battery kW from the motor/generator until the some threshold was exceeded, and the car shut down the main traction battery.
Dumb, dumb, dumb. But there is no way to realistically communicate this to the Tesla SW developers. Long story short, I flipped the car into 'tow mode' using the last 30 minutes of 12v battery power, and I solicited help from a passerby and a policeman to push the car 200 yards to a supercharger, where the battery, first, nibbled at a little bit of kW, and then after 5 minutes, when nursed back to good health, it inhaled high kW.