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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

#111

Post by KaiserPro »

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…

> 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

Ethernet isn't a bus, its point to point. PoE over cat5/6 uses 4 pairs of UTP.

so it might be used to join aggregate things together, but it won't be a bus.

Yes, you can increase the datarate, but ethernet is fundamentally unreliable. So you'll need to either strictly manage the bandwidth requirements of attached devices, or put in flow control(expensive) or use the weird "reliable" Ethernet they made for fibre channel replacment ($lol and you need to pay to make it automotive rated)

48v is logical, and a lot of other people are doing it.

PoE is probably stupid

Ethernet makes kinda sense, but firewire would probably be better, its a bus and rated for life critical use.

Re: Tesla shares 48V architecture with other automakers

#112

Post by thebruce87m »

myself248 wrote: post #52
firebat45 wrote: post #27

Earlier quoted context omitted.

How exactly do you define a negative voltage unless you are using some other voltage as a reference?

It is with respect to ground, the positive pole of the battery is connected to ground. The telegraph system figured this out very quickly. Most water in nature has at least a bit of salt in it, which is present as positive sodium ions and negative chloride ions. By making the outdoor wiring negative with respect to ground, the chloride ions are repelled, and such wires corrode much more slowly than those that're posi…

> that’re

First time I’ve ever seen this typed

Re: Tesla shares 48V architecture with other automakers

#113

Post by KaiserPro »

londons_explore wrote: post #33

Am I right in saying this wasn't shared with the public or other (Chinese) OEM's... Doesn't that raise collusion/anti competitive concerns? Or is Elon relying on the fact no prosecutor will take a case about disadvantaging china?

"shared" in the sense that everyone else was doing it already. In the same way that he's shared the hyperloop, which he got from a 1980s osbourne book of transport.

Re: Tesla shares 48V architecture with other automakers

#114

Post by Filligree »

bluGill wrote: post #59
bryanlarsen wrote: post #38

Earlier quoted context omitted.

Most of the residential snow clearing outfits around me use plows and blowers on Kubota tractors. Probably part of the reason is so that can use PTO hydraulics...

There are pros and cons. Snow plows beat on a the vehicle - which is why plows are the last thing a truck does before you quit using it. Highway departments will use a dump truck mounted plow because the frame of the dump truck can take the beating (that they can put salt on the dump truck is a very useful side effect). Tractors are designed to pull plows through dirt which also beats on them, and so tractors can sta…

You don't use custom-designed vehicles? I'm used to snowplows being these massive, reinforced vehicles that look like they could take on a tank.

Re: Tesla shares 48V architecture with other automakers

#115

Post by hinkley »

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.

Re: Tesla shares 48V architecture with other automakers

#116

Post by smileysteve »

intrepidhero wrote: post #22
jabart wrote: post #15

Earlier quoted context omitted.

Power steering pumps are electric and have one of the largest wires in my truck. With an EV you also have a heat pump, maybe a heater, coolant pumps now that you don't a constant spinning pulley, windows, lights, headlamps, power doors, seats, radio, amplifier, small PC, etc. From the article "Switching to 48V architecture alleviates a huge number of challenges automakers are facing with 12V. The biggest one, though,…

I hadn't connected the dots that all the various pumps (and fans) have to switch from mechanically connected to the engine via the accessory belt to electrically driven. That's a fair point.

It has been optimal to run accessories electrically for ICE already for several reasons. It has been difficult based on some of the loads on a 12v battery (agm has really helped this)

- Start stop is smoother (and more available) without accessories

- Cooling a turbo after the motor is off - true for the engine as well, heat soak on water pump off can go ~20f over the thermostat

- Brake Boosting without a vacuum (Valvetronic or Hybrid)

- Air Conditioning at idle

Re: Tesla shares 48V architecture with other automakers

#117

Post by hinkley »

wongarsu wrote: post #88
SigmundA wrote: post #55

Earlier quoted context omitted.

Remember a fully charged lithium battery with nominal 48v can be close to 60v just like 12v in your car is actually closer to 14v.

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?

Re: Tesla shares 48V architecture with other automakers

#118

Post by myself248 »

SigmundA wrote: post #55
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.

Remember a fully charged lithium battery with nominal 48v can be close to 60v just like 12v in your car is actually closer to 14v.

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 bother me one bit.

Span-powered T1 at 130VDC, on the other hand.... that'll poke ya. That gets little plastic covers over all the terminals, but they have been known to fall off. So there is a meaningful threshold, and 55.2 is solidly below it.

Which suggests to me that there's a good bit of leeway built into the standards, perhaps specifically so they don't have to wheedle about whether a battery system should be measured at its nominal voltage, its float voltage, its absorption voltage, its peak/equalization voltage, its....

Re: Tesla shares 48V architecture with other automakers

#119

Post by myself248 »

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?

It's convenient to build things in multiples and powers of 2 and 3. A nice two-tier or four-tier battery rack full of 2-volt cells just works out nicely.

Re: Tesla shares 48V architecture with other automakers

#120

Post by hinkley »

thebruce87m wrote: post #112
myself248 wrote: post #52

Earlier quoted context omitted.

It is with respect to ground, the positive pole of the battery is connected to ground. The telegraph system figured this out very quickly. Most water in nature has at least a bit of salt in it, which is present as positive sodium ions and negative chloride ions. By making the outdoor wiring negative with respect to ground, the chloride ions are repelled, and such wires corrode much more slowly than those that're posi…

> that’re First time I’ve ever seen this typed

What’re you talking about?
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