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Tesla shares 48V architecture with other automakers

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Re: Tesla shares 48V architecture with other automakers

#221

Post by Turskarama »

_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.

The mechanical backup for a drive-by-wire system is different to all those other things in that it's a critical safety issue. If _anything at all_ happens to the electronics while driving then it's important that you can stop the vehicle safely. That mandates manual brakes and steering, even if they're barely effective at all without power it's a lot better than nothing.

Re: Tesla shares 48V architecture with other automakers

#222

Post by dmix »

eqvinox wrote: post #202
elp wrote: post #11

48Vdc is supposedly the highest voltage that is still considered safe. ( https://electronics.stackexchange.com/questions/267789/how-s... ) It certainly sounds like a smart move on the copper savings alone.

It's a bit of an arbitrary determination; 60V is the international common denominator on what various legal or civic (e.g. insurance) regulations consider safe; https://en.wikipedia.org/wiki/Extra-low_voltage#Separated_or... 48V is somewhat of a dinosaur from the days when you designed things with a 20% margin since that's what was cheaply attainable. Regular PoE is 54V these days (10% margin), and some more specific…

What's a commonly produced thing that's 48v? I don't know much about this subject. Is it most industrial type stuff or is there consumer tier products using it?

Re: Tesla shares 48V architecture with other automakers

#223

Post by grecy »

Moto7451 wrote: post #189

Audi also has a 48v architecture in use for mild hybrids like my SQ5. This is an older article but explains it well https://www.greencarcongress.com/2017/06/20170602-audi.html My 2021 is fully 48v except for an inverter for necessary 12v circuits (like cigarette outlets and the jumper pins) and a small motorcycle battery that is used for minimal 12v functionality. The mild hybrid battery is under the rear seats and s…

> This is an older article but explains it well

https://www.greencarcongress.com/2017/06/20170602-audi.html

From the article:

> The 12-volt system is connected to the main electrical system via a DC/DC converter

> Audi also offers the new MHEV technology with the conventional 12-volt electrical system

> 48-volt vehicle electrical system. In a different layout—without MHEV—the 48-volt constant voltage system already entered volume production in 2016 as the Audi SQ7 TDI. In this vehicle, the alternator still operates on a 12-volt basis, and a DC converter couples the 48-volt electrical subsystem

> Small consumers such as control units or lights will remain in the 12-volt system well into the future, however

The article makes it very clear that what Audi are doing is not similar to what Tesla have done with the Cybertruck. The Cybertruck has no 12v system, everything runs on 48v. The power seats. The seat heaters. The rear defroster, the interior lights, literally everything. They can have much smaller and lighter wires and use way less copper.

Using a 48V system for a mild hybrid is very common, even Jeep do that.

Re: Tesla shares 48V architecture with other automakers

#224

Post by nippoo »

hinkley wrote: post #117
wongarsu wrote: post #88

Earlier quoted context omitted.

However there is a lot of leeway on the "48V is the highest safe voltage" statement too. 48V has a special place in regulations because of its use in telco, but 60V DC is still very safe.

Doubling again to 96 is not safe, however. I’m not sure why they settled on powers of two. Something perhaps to do with noise filtration, and fewer new tricks to learn?

A lot of 48V infrastructure comes from the marine world - where 4 x 12V lead-acid batteries in series is common for this reason. So a lot of components already exist and can be made to work in the automotive sector with simple modifications. (In the marine world, it's much simpler to combine and split batteries in powers of 2 for cell balancing - you can take 4 x 12V batteries and charge them in parallel, discharge them in series)

Re: Tesla shares 48V architecture with other automakers

#225

Post by grecy »

hinkley wrote: post #115
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.

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.

> The EV and hybrid electric world were talking about 48 volts when Musk still worked at PayPal, if not earlier.

You are confounding the two electrical systems in an EV or hybrid (or mild hybrid).

One is used to drive the wheels - these are very commonly 48V in a mild hybrid and something like 200V or 400V or 800V in an EV. This is only used to power the wheels - nothing else.

The other electrical system is used to power literally everything else. The infotainment system, heated seats, power windows, lights, powered seats, electric power steering, electric assist brakes, etc. This has always been 12V in every car ever ^ (ICE/hybrid/EV) (including every Tesla).

The Cybertruck is the first vehicle ever to move the 12V system to a 48V system.

^ Before about 1955 it was 6v. The move to 12v then was the last time it has changed.

Re: Tesla shares 48V architecture with other automakers

#226

Post by dreamcompiler »

jrockway wrote: post #179
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 cybertru…

Musk has publicly stated that CAN is too slow for modern cars, which is why they chose ethernet for the Cybertruck.

https://youtube.com/watch?v=ky1Z2klPalw

Re: Tesla shares 48V architecture with other automakers

#227

Post by erupt7893 »

SilverBirch wrote: post #147
rnk wrote: post #18

Earlier quoted context omitted.

We humans are all terrible on some level (except my mom, she was a saint), but if you have enormous power, you can help or hurt a lot of people based on your actions. Musk has a lot of power. He must be a terribly lonely person, not knowing if he can trust anyone or they just want something from him.

Hi, excuse me. Just want to say, don't appreciate you rounding me up with the anti-semites. "We humans". No - those anti-semites, and us reasonable people. Wouldn't like to mix with them thanks. You can make whatever excuses you want for him, but that's what they are, excuses.

This is silly, don't stand on some high horse. If you don't think you have the capability to be unreasonable, you are delusional. Every single person on this planet is capable of evil, but majority luckily see that as a path that ends badly.

Re: Tesla shares 48V architecture with other automakers

#228

Post by noughtme »

jrockway wrote: post #179
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 cybertru…

Didn’t read the article, but Musk mentioned in an interview yesterday they are specifically not using CAN and are using Ethernet. He didn’t explicitly say, but it seems likely they are using PoE, saving a lot of wiring as you can daisy chain a higher bandwidth connection and you don’t need separate power cables.

https://youtube.com/watch?v=ky1Z2klPalw

Re: Tesla shares 48V architecture with other automakers

#229

Post by dreamcompiler »

Turskarama wrote: post #221
_ea1k wrote: post #161

Earlier quoted context omitted.

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.

The mechanical backup for a drive-by-wire system is different to all those other things in that it's a critical safety issue. If _anything at all_ happens to the electronics while driving then it's important that you can stop the vehicle safely. That mandates manual brakes and steering, even if they're barely effective at all without power it's a lot better than nothing.

The cybertruck has two separate steering motors for redundancy. Passenger jets have been doing "x-by-wire" for decades. Properly engineered it's as reliable as mechanical linkage.

Re: Tesla shares 48V architecture with other automakers

#230

Post by dreamcompiler »

DennisP wrote: post #205
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.

Sure, people have been talking about 48 volts for the past 30 years. Somehow most automakers didn't actually manage to do it though. Sandy Munro just did an interview with Musk, who said they hadn't done anything revolutionary, they just built the car up to general 21st century standards.

https://youtube.com/watch?v=ky1Z2klPalw
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