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Running Tesla Model 3's computer on my desk using parts from crashed cars

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Re: Running Tesla Model 3's computer on my desk using parts from crashed cars

#101

Post by adrian_b »

girvo wrote: post #10

It's funny to hear LVDS be described as an "automotive" cable when all of my run-ins with it are for connecting laptop displays to their main-boards! (though that has a very different connector on it, and its a very general term for the signalling protocol from what I remember)

Most modern laptops no longer use LVDS for connecting the screen, but they use eDP (embedded DisplayPort).

So LVDS is more likely to linger in automotive displays, while in less obsolete devices it has been replaced by either eDP or by MIPI DSI (used e.g. in smartphones).

Re: Running Tesla Model 3's computer on my desk using parts from crashed cars

#102

Post by kvuj »

longislandguido wrote: post #58
kube-system wrote: post #13

> Turns out that actual cars don’t have individual cables. Instead they have these big “looms”, which bundle many cables from a nearby area into a single harness. This is the reason why I could not find the individual cable earlier. They simply don’t manufacture it. I was really surprised to read this at the end of the article -- how could someone be this deep into a project of this depth and not realize this?! Not o…

Software people tend to overestimate their knowledge of other disciplines, writing it off as "easy" or work beneath them. Being overpaid compared to your peers certainly doesn't help dispel this feeling. Some people have built entire careers around designing wire looms.

What a rancid comment. The first thing you can think of when seeing someone earnestly sharing their learning process, is to insult them of being vain.

Re: Running Tesla Model 3's computer on my desk using parts from crashed cars

#103

Post by numpad0 »

nandomrumber wrote: post #62
mixdup wrote: post #45

Earlier quoted context omitted.

14v is not a transient, if your voltage was 12v with the car running, there's something wrong with the charging system (DC-to-DC in an EV, alternator/generator in an ICE) 13-14v is normal in all 12v automotive systems as the charging voltage

If I recall correctly, a fully charged lead acid battery has an open circuit voltage of 13.6V. So the alternator has to put out at least something higher than if it’s planning on recharging the battery after 500 to 700 amps have been pulled from it for a few seconds to start the engine.

Yeah, max CV charging voltage is ~14V, max charging C rate is ~0.2C, open circuit voltage at 100% is that 13.x range. And lead acids like to stay at 100% unlike Li-ion which likes 50% +/-30%, so "12V" ICE cars just use a bus voltage of 13-14V and wire the battery there. At any given moment, the car's "12V" bus voltage MUST be above 13.x and below 14.4(absolute max).

It's a bit perplexing that those lead acid systems are referred to as "12V" systems when that figure is effectively the 0% voltage, whereas 3.7V for single Li-ion cell is the 50% voltage.

e: also, ICE transients can be in kV range, coming from ignition mechanisms. I've heard that you can literally measure engine RPM by selecting 1/dt on an oscilloscope and dividing that by cylinder count.

Re: Running Tesla Model 3's computer on my desk using parts from crashed cars

#104

Post by gedy »

longislandguido wrote: post #58
kube-system wrote: post #13

> Turns out that actual cars don’t have individual cables. Instead they have these big “looms”, which bundle many cables from a nearby area into a single harness. This is the reason why I could not find the individual cable earlier. They simply don’t manufacture it. I was really surprised to read this at the end of the article -- how could someone be this deep into a project of this depth and not realize this?! Not o…

Software people tend to overestimate their knowledge of other disciplines, writing it off as "easy" or work beneath them. Being overpaid compared to your peers certainly doesn't help dispel this feeling. Some people have built entire careers around designing wire looms.

I don't know, I've had more non-technical people and trades try and mansplain bullshit they don't understand than tech people have.

Re: Running Tesla Model 3's computer on my desk using parts from crashed cars

#105

Post by creantum »

FireBeyond wrote: post #65
kube-system wrote: post #13

> Turns out that actual cars don’t have individual cables. Instead they have these big “looms”, which bundle many cables from a nearby area into a single harness. This is the reason why I could not find the individual cable earlier. They simply don’t manufacture it. I was really surprised to read this at the end of the article -- how could someone be this deep into a project of this depth and not realize this?! Not o…

> and to Tesla's credit they have amazing free docs Not to Tesla's credit, they had to be dragged kicking and screaming into it (primarily by Massachusetts) and their right to repair legislation through a solid chunk of malicious compliance: 1. When told that they had to have a site for people to order parts, Tesla put up a site that had every single item as "Call us", including the most simple of bolts. And when a f…

Wrong. They’ve always been open, even with their patents too. All free to use, no royalties

Re: Running Tesla Model 3's computer on my desk using parts from crashed cars

#106

Post by fortran77 »

longislandguido wrote: post #64
spuz wrote: post #44

Earlier quoted context omitted.

Even if you know that cars consist of a single wiring harness, it's not implied that they aren't modular and the individual cables cannot be purchased separately.

[flagged]

Why are you so hostile towards someone who's experiment with an interesting computer? What's wrong with you?

Re: Running Tesla Model 3's computer on my desk using parts from crashed cars

#107

Post by rpmisms »

kvuj wrote: post #102
longislandguido wrote: post #58

Earlier quoted context omitted.

Software people tend to overestimate their knowledge of other disciplines, writing it off as "easy" or work beneath them. Being overpaid compared to your peers certainly doesn't help dispel this feeling. Some people have built entire careers around designing wire looms.

What a rancid comment. The first thing you can think of when seeing someone earnestly sharing their learning process, is to insult them of being vain.

He's right about the rest. We software people can definitely be annoying.

Re: Running Tesla Model 3's computer on my desk using parts from crashed cars

#108

Post by phil21 »

msisk6 wrote: post #66
kube-system wrote: post #43

Earlier quoted context omitted.

The passenger side kick panel or behind the glove box are two very common places for vehicle computers -- some cars have them under the hood, which I always thought was a bad idea.

My RAM truck with the Cummins diesel engine has the engine computer mounted on the engine block. You'd think the heat and exposure to the elements would make that a bad idea, but I suppose Cummins knows what they're doing.

My car has it under the passenger seat.

Sounds alright until you realize after spilling a bunch of flower vases in the trunk (hatchback) that the computer has literally no case on it and immediately shorts out while driving. Or a passenger spills a drink in the rear seat cup holder.

There is now a recall notice to pull the back seat out to install a $5 plastic cover over the thing.

And yep, it’s the main computer for the car which controls the electronic transmission etc. Immediate full on engine-shuts-off at speed on the freeway and you require a flatbed to tow it away level of broken. I’m sure the engine ECU is in the engine bay, but holy hell what a surprise!

Re: Running Tesla Model 3's computer on my desk using parts from crashed cars

#109

Post by K0balt »

numpad0 wrote: post #103
nandomrumber wrote: post #62

Earlier quoted context omitted.

If I recall correctly, a fully charged lead acid battery has an open circuit voltage of 13.6V. So the alternator has to put out at least something higher than if it’s planning on recharging the battery after 500 to 700 amps have been pulled from it for a few seconds to start the engine.

Yeah, max CV charging voltage is ~14V, max charging C rate is ~0.2C, open circuit voltage at 100% is that 13.x range. And lead acids like to stay at 100% unlike Li-ion which likes 50% +/-30%, so "12V" ICE cars just use a bus voltage of 13-14V and wire the battery there. At any given moment, the car's "12V" bus voltage MUST be above 13.x and below 14.4(absolute max). It's a bit perplexing that those lead acid systems…

The nominal range for automotive systems is 10-16v. If you are designing anything for automotive use that doesn’t work reliably in that range, you are manufacturing problems for people.

Re: Running Tesla Model 3's computer on my desk using parts from crashed cars

#110

Post by FireBeyond »

creantum wrote: post #105
FireBeyond wrote: post #65

Earlier quoted context omitted.

> and to Tesla's credit they have amazing free docs Not to Tesla's credit, they had to be dragged kicking and screaming into it (primarily by Massachusetts) and their right to repair legislation through a solid chunk of malicious compliance: 1. When told that they had to have a site for people to order parts, Tesla put up a site that had every single item as "Call us", including the most simple of bolts. And when a f…

Wrong. They’ve always been open, even with their patents too. All free to use, no royalties

Confidently incorrect.

https://www.reddit.com/r/teslamotors/comments/utivlj/tesla_s...

> This used to cost $3187.50

https://driveteslacanada.ca/news/tesla-service-manuals-free-...

> The access story has been inconsistent over the years. Tesla has opened up free access to both the service manuals and diagnostic software in the past, but that was apparently a mistake, and loopholes were quickly closed.

https://www.teslaownersonline.com/threads/tesla-service-manu...

"Always ... all free to use". Not so much. And before that, even less available.

I will grant you for number 2, there seems to be some ambiguity - some people claimed it was only if you needed to actually use their diagnostic tools, because Tesla wouldn't sell them to anyone at the time (which is also in contradiction to your "everything you need, all free, always").

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