Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Tesla shares 48V architecture with other automakers

electrek.co

Post reply on HN
Print view View original

171–180 of 504 posts

Re: Tesla shares 48V architecture with other automakers

#171

Post by myself248 »

tzs wrote: post #133
jnsaff2 wrote: post #83

The "expert" in the article got it wrong. The relationship between the voltage and the losses in the wires is not proportional. They are squared. Going from 12V to 48V is not a saving of 4x rather 16x. For some applications you could also consider Power over Ethernet in the car, get both shielded comms and power. Or can and power over twisted pair.

Hold on a second...4x the voltage means you only need 1/4th the current. The power loss in the wire is current^2 x the wire's resistance, so 1/4th the current does indeed mean 1/16th the losses. But 1/4th the current means you can use a higher gauge wire. Looking at a table of wire gauge current capacities it looks like if your maximum current is 1/4th you can switch to wire with 1/4th the cross section. And resistan…

There's also a minimum wire size, based on physical durability requirements. A significant number of wires in the harness already carry no appreciable current and are merely signaling wires, but they can't be infinitely thin.

Getting most of the power wires down into the range of signal wires is a huge benefit, because it means they can use common terminals and smaller connectors, but that's where it stops.

Re: Tesla shares 48V architecture with other automakers

#172

Post by CharlesW »

_ea1k wrote: post #161
hinkley wrote: post #115

Earlier quoted context omitted.

Tesla didn’t invent 48 volts either. The EV and hybrid electric world were talking about 48 volts when Musk still worked at PayPal, if not earlier. One of the examples pulled out at that time was that you could shave a couple pounds of copper off the alternator by running it at 4x the voltage. Much thinner wires.

Tesla's greatest innovation is simply leadership. Everyone knew castings were the way to go, but noone did it. Now people like Volvo are doing them, and I expect a lot of others to do it as well. Everyone knew that 48V would be a big benefit, but noone did it. TBH, in a few years, we may be saying similar things about drive-by-wire without a mechanical backup. But it is too early to say definitively.

> Everyone knew castings were the way to go…

The jury's still out on whether gigacasting is courageous, or just moves costs from production (which will not be passed to consumers) to repairs (which will).

> Everyone knew that 48V would be a big benefit, but noone did it.

Audi did in 2016 with the SQ7 TDI, no?

Re: Tesla shares 48V architecture with other automakers

#173

Post by ipaddr »

wnevets wrote: post #148
CamperBob2 wrote: post #146

Earlier quoted context omitted.

Also, "But don't you dare threaten to replace me with an LLM. Journalism is a sacred cornerstone of democracy and intellectual life!"

I don't know if I would call a self proclaimed content marketer a Journalist.

He said "Journalism". A non-journalist can produce material that can be considered journalism. A student can teach. A homemaker can even write working code.

The labels we give to others to divide us

Re: Tesla shares 48V architecture with other automakers

#174

Post by myself248 »

Tempest1981 wrote: post #152
myself248 wrote: post #118

Earlier quoted context omitted.

For battery-powered systems the nominal voltage is used. Telephone "48 volts" is 55.2 volts in practice, only falling near 48 if there's a power failure and the office generators don't autostart in a timely fashion. That's never caused any regulatory problems for Ma Bell, despite OSHA saying 50v is the cutoff. And personally having spent roughly a decade of my career crawling all over such systems, 55.2 doesn't bothe…

> That's never caused any regulatory problems for Ma Bell, despite OSHA saying 50v is the cutoff I seem to recall getting a buzz when touching phone wires - while the line was ringing. I think I measured around 100 VAC. Apparently that's "ok", safety-wise.

Ringing is 90VAC, 20Hz, current limited. And it's only on for 2 seconds and then off for 4, so it's not like you're gonna grab on and be unable to let go.

So, yeah, as a momentary thing it's not a hazard unless it tickles you off a ladder or whatever. Punchdowns and terminal blocks are normally mounted where they can be worked on from ground level so that's unlikely to be an issue.

Re: Tesla shares 48V architecture with other automakers

#175

Post by wnevets »

ipaddr wrote: post #173
wnevets wrote: post #148

Earlier quoted context omitted.

I don't know if I would call a self proclaimed content marketer a Journalist.

He said "Journalism". A non-journalist can produce material that can be considered journalism. A student can teach. A homemaker can even write working code. The labels we give to others to divide us

> The labels we give to others to divide us

They gave the label to themselves

Re: Tesla shares 48V architecture with other automakers

#176

Post by eternityforest »

ipaddr wrote: post #173
wnevets wrote: post #148

Earlier quoted context omitted.

I don't know if I would call a self proclaimed content marketer a Journalist.

He said "Journalism". A non-journalist can produce material that can be considered journalism. A student can teach. A homemaker can even write working code. The labels we give to others to divide us

I always wondered why there's not some kind of nonprofit volunteer journalism organization you can get involved with.

It doesn't appear to be something anyone tries to get normal citizens into, despite the fact that we constantly try to convince people to learn other stuff with much less individual scale value, sometimes even somewhat crazy stuff like home chemistry experiments with lead salts.

I always thought that's what I'd want to do with my life if I wasn't coding, and maybe I'd be happier if I had gone to college and studied journalism...

Re: Tesla shares 48V architecture with other automakers

#177

Post by CamperBob2 »

wnevets wrote: post #148
CamperBob2 wrote: post #146

Earlier quoted context omitted.

Also, "But don't you dare threaten to replace me with an LLM. Journalism is a sacred cornerstone of democracy and intellectual life!"

I don't know if I would call a self proclaimed content marketer a Journalist.

(Shrug) He called himself one, although admittedly in a former role before moving to Electrek.

The point stands. People who DGAF about their jobs are going to lose them, and that's not a bad thing.

Re: Tesla shares 48V architecture with other automakers

#178

Post by timerol »

rational_indian wrote: post #26

Could have gone higher. Worth it in copper savings alone. IIRC the cars use AC motors. It needs to go through inverters anyway so there is some flexibility in how high you can go. Edit: of course the motors are "AC" who would want a brush and commutator based motor in their car?

The main motors of an EV are not powered off of the 48V system. EVs generally have 300-400 V main batteries, with discussion of 800 V on the table (someone may have already done it, I haven't been keeping track).

Re: Tesla shares 48V architecture with other automakers

#179

Post by jrockway »

jnsaff2 wrote: post #83

The "expert" in the article got it wrong. The relationship between the voltage and the losses in the wires is not proportional. They are squared. Going from 12V to 48V is not a saving of 4x rather 16x. For some applications you could also consider Power over Ethernet in the car, get both shielded comms and power. Or can and power over twisted pair.

> Or can and power over twisted pair.

I was reading an anti-Musk subreddit over on Reddit and I think the cybertruck is doing this? They were mad that the cybertruck uses 48V and Ethernet cables, but to me, that seems perfect for CAN and power. We already use 48V (or similar) for PoE, and CAN needs a twisted pair... so why not buy that off the shelf instead of using a custom wiring harness?

I don't think the cybertruck is a particularly attractive vehicle, but I also don't think they're crazy for trying that. You can do 10Gbps over a cat-6 cable and it works great. So I'd expect that you can easily do CAN.

Re: Tesla shares 48V architecture with other automakers

#180

Post by [deleted] »

cogman10 wrote: post #129
mcguire wrote: post #81

Earlier quoted context omitted.

The rumor I heard was that the higher voltage resulted in lower switch lifetimes. Any truth to that?

Yes, but not meaningfully. The higher the voltage you get, the more arching there is when a relay trips (also depends on if there's any sort of inductive load, think the sparks you see when you unplug a vacuum without turning it off). But when you think about the impact that has on switches and relays, realize that in your own home you have 120V controlled by switches. Very cheap switches last decades (though admitte…

[deleted]
Post reply on HN