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Tesla shares 48V architecture with other automakers

electrek.co

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Re: Tesla shares 48V architecture with other automakers

#461

Post by petre »

bigallen wrote: post #451
lmpdev wrote: post #369

Earlier quoted context omitted.

I get this a lot I work at an electronics store in Australia This week I had a customer dumbfounded why his 3,500W inverter almost caught fire He was using 8-gauge wire (~56A max) He needed 00-gauge (almost 300A max) If he’d have run the system at 48V instead of 12V he’d have saved $200+ per metre on cabling his inverter My advice on voltage selection for a vehicle is once you’re needing more than a few metres of 0-g…

How do you integrate the 48V system with the existing 12V system when doing aftermarket/DIY work? Do you add a 48V inverter? A buck-boost DC-DC converter? between the battery (or main fuse block) and the 48V system?

You don't. 48V battery and separate circuits if it's an RV, otherwise forget it.

Re: Tesla shares 48V architecture with other automakers

#462

Post by petre »

DannyBee wrote: post #272
mmaunder wrote: post #246

Many comments here seem to be confusing the accessories circuit voltage with the electrical vehicle motor and drive system. The vehicle motors have a combined power output of 450KW which requires a high voltage 800V system or the wiring would be so heavy it would not be feasible. This spec appears to be the accessories circuit with Tesla pushing for a new 48V standard. That’s super smart because it immediately means…

48V has been considered for automotive for decades. The problem was not know how. It simply has never been worth it before to retool things in practice. It's also electrically a lot more noisy. The limit of what is considered low volt is like 60v or something.

How is DC more noisy?

Re: Tesla shares 48V architecture with other automakers

#463

Post by poisonborz »

yinser wrote: post #39

I liked the interview with auto engineer Sandy Munro discussing the change https://youtu.be/ADwGGEj8sqQ?si=qp6akvy1yyWPTYNe - moving the voltage up means you can drop current - increase the data rate by using ethernet and PoE - using ethernet and PoE means you don’t have to run one off wires to each device, they can share a bus which results in half the copper being used in a lower voltage car - moving the voltage up…

But doesn't that mean a single point of failure, a single network problem stopping the whole car? I guess there must be a historic reason for mostly direct CAN connections.

Re: Tesla shares 48V architecture with other automakers

#464

Post by TaylorAlexander »

SigmundA wrote: post #445
TaylorAlexander wrote: post #92

Earlier quoted context omitted.

Sure but they can feed the system through a regulator if they'd like. Do we have any reason to believe they are tapping directly on to a pack for this part of the system?

Normally the battery is the regulator it serves to buffer inrush loads and absorb spikes.

> Normally the battery is the regulator

For a 12v system, of course. But on a modern 48v system who knows what they decided. Having a switching regulator with built in current limits might be helpful.

Re: Tesla shares 48V architecture with other automakers

#465

Post by accrual »

1970-01-01 wrote: post #444
accrual wrote: post #310

Earlier quoted context omitted.

I wasn't sure, so I asked: > Higher voltage systems experience lower power losses over the same distance compared to lower voltage systems. This is due to the fact that power loss in a conductor is proportional to the square of the current. By using higher voltage, you can transmit the same amount of power with less current, reducing resistive losses in the wires.

Woosh. There's potentially a joke in there if you read it again while understanding the applicable equation for electrical power. (V^2)/R

Woosh indeed, haha. I'm no EE but it sounded plausible. Maybe I'll get the joke if I do some actual reading. :)

Re: Tesla shares 48V architecture with other automakers

#466

Post by sowbug »

myself248 wrote: post #60
intrepidhero wrote: post #5

Why would a car need a 48V system for accessories? In general the things a car's 12V system powers have gotten less power hungry over time (LED's, heat pump) and in particular, an EV loses the highest power electrical device on the 12V bus, the starter. The typical equipment used for the entertainment and control systems are going to be much more available with 12V supplies, just because that's the industry standard.…

Hi, automotive electrical is my job. There's quite a bit of very thick wiring in a car, not just the starter wire, but boring stuff like audio amplifiers, rear window defrosters, power seat motors. Those things don't draw a ton of power, like maybe just a few hundred watts, but at 12 volts even modest powers require extraordinarily thick wires, especially when you account for bundle derating. This requires large term…

Thanks for this detailed answer. The chassis is normally grounded. Has anyone tried sending a positive charge through part of it? Combined with a Powerline-style signaling system, some components wouldn't need wires at all.

I already can think of several reasons why this wouldn't work, but I wonder whether there's a good idea in there somewhere.

Re: Tesla shares 48V architecture with other automakers

#467

Post by merb »

mmaunder wrote: post #246

Many comments here seem to be confusing the accessories circuit voltage with the electrical vehicle motor and drive system. The vehicle motors have a combined power output of 450KW which requires a high voltage 800V system or the wiring would be so heavy it would not be feasible. This spec appears to be the accessories circuit with Tesla pushing for a new 48V standard. That’s super smart because it immediately means…

up till now most ev‘s used 400v there are some with 800v and more premium models do get 800v

Re: Tesla shares 48V architecture with other automakers

#468

Post by Kirby64 »

elihu wrote: post #389
dreamcompiler wrote: post #265

Earlier quoted context omitted.

Now we have MOSFETS and IGBTs that can switch DC without sparks. I suspect most DC switching in the Cybertruck is relayed through these. (Except the main contactor and pyro fuse of course.)

And given that this is a Tesla, it wouldn't really have had many mechanical switches in the first place. Maybe the turn indicator? Which could happily run at 5 volts or something and blink the lights via CAN bus messages.

None, unless you count the physical buttons as 'mechanical switches'.

The turn signals on a Tesla don't even make the 'clicking' noise if the Infotainment is rebooting, because it's literally just a noise piped through the infotainment.

Re: Tesla shares 48V architecture with other automakers

#469

Post by 15155 »

myself248 wrote: post #438
15155 wrote: post #349

Earlier quoted context omitted.

> If they'd just had some foresight and gone 48v in 1955 How would they have done this without cheaply-available high-speed switch-mode power supplies with low-DCR inductors/MOSFETs?

Why would they need those? All the stuff that's natively 12 volts now could simply have been made natively 48 volts. You can make a 48-volt lightbulb as easily as a 12-volt lightbulb. You can make a 48-volt motor as easily as a 12-volt motor. Actually, motors for higher voltage tend to be smaller and lighter, which is why industry tends to go straight for 4160-VAC motors whenever 480VAC is inadequate. What applicatio…

> Why would they need those?

To convert voltages to useful levels without suffering massive losses in efficiency.

> What applications cannot be made to work at 48?

Basically every logic-level transistor will not work at 48V. It's nice that these last-century analog devices could be made to operate at different voltages: present-day semiconductors are not so conveniently flexible.

Simple physics dictates that required inductors to step between voltages increase in physical size (and weight, and material cost) as that voltage disparity increases. Capacitance required, etc. all increases with it. Efficiency plays into both of these as a triangle. Heat increases as this disparity increases. These properties are unacceptable for a myriad of use cases.

Re: Tesla shares 48V architecture with other automakers

#470

Post by hef19898 »

grecy wrote: post #460
hef19898 wrote: post #419

Earlier quoted context omitted.

As others pointed out lready, others did it, too.

Re-read the comments, others have not done it. Audi has a mild-hybrid 48V (as do many others) that also runs some other things like active roll control and the power steering pump. They still have a 12v system running infotainment, seat heaters, defrosters, powered seats, lights, etc. etc.

As I never knowingly listen to music on 48V, is it reall so much better than 12V?
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