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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

#161

Post by _ea1k »

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.

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.

Re: Tesla shares 48V architecture with other automakers

#162

Post by tzs »

myself248 wrote: post #118
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.

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'd be surprised if the wired phone system is not allowed to do a lot of things that would not be allowed under current codes and standards. By 1920 about 35% of US households had a phone. Upgrading all of that to keep up with evolving safety standards would probably have been way too expensive, and so I would expect that there was a lot of grandfathering.

Re: Tesla shares 48V architecture with other automakers

#163

Post by [deleted] »

londons_explore wrote: post #20
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.…

Some devices in a car are still pretty power hungry. Eg. The blower motor for the fan (typically 800 watts = 70 amps @12v). Heated rear screen (240 watts = 20 amps). Window motors are pretty powerful too. End result is you need a lot of fairly chunky cables to power those things. And the price of copper has been steadily climbing since 1960 - unlike other commodities which have been getting easier and easier to extra…

[deleted]

Re: Tesla shares 48V architecture with other automakers

#164

Post by myself248 »

jabl wrote: post #69
bryanlarsen wrote: post #63

Earlier quoted context omitted.

No benefit? I've seen estimates of $1000 in reduced cost due to reduced copper wiring, and more importantly the labor required to string that wiring. Modern phones charge on 48V these days, so 48V parts are extremely common & cheap.

> I've seen estimates of $1000 in reduced cost due to reduced copper wiring What about aluminum wiring? Lighter, cheaper, though bulkier than equivalent copper. Aluminum wiring got a bad rep back in the day, but it seems with current electrical aluminum standards it supposedly works pretty well.

Aluminum is hell to terminate. It basically requires ultrasonic welding; every trade-show has folks hawking various crimp terminals that're meant to break through the surface oxides during the crimp cycle, but not a single automaker has been swayed enough to use it on normal wiring.

The reliability concerns really add up with flexing fatigue, too. It's one thing to put aluminum wiring in a house where its only flex is due to thermal expansion, and it has a hard enough time coping with that it's still a special category in home insurance, to say nothing of a vehicle that's going to spend the next ten-plus years bouncing over the road.

Furthermore, you basically can't modify aluminum wiring. In-line splices and solders are virtually impossible. While that's irrelevant for manufacturing, it hits the aftermarket pretty hard, including dealer mods, and of course, dealer repairs. That can be worked around but it would require communication between branches who don't normally talk, and it just adds friction to any possible aluminum migration.

I've seen aluminum in a single very-heavy-gauge battery cable for a car that put the battery in the back, with ultrasonic-welded terminals on both ends, and that's it. Everything else in that car was copper.

Re: Tesla shares 48V architecture with other automakers

#165

Post by teruakohatu »

ianburrell wrote: post #99
epx wrote: post #29

It would be great to have 48VDC in homes, for lightning, light appliances, etc. to centralize the whole power factor control in a single big power supply instead of doing it (poorly, or not at all) at every LED bulb.

The DC power for LED varies based on the bulb and most are less than 48V. Which means you end up with DC-DC converter in each one. DC-DC is slightly more efficient than DC-AC but not enough to make worth converting. The same is true of electronics, you are replacing AC-DC charger with DC-DC charger. The other big problem is that lots of appliances require more power than feasible with 48V. People are fine with the lo…

> Are you going to have two kinds of outlets everywhere?

People already do, with usb sockets sitting next to mains sockets.

Of course if you standardise on usb-c you are still doing dc to dc (and all sorts of extra things) so not much point as you pointed out.

Re: Tesla shares 48V architecture with other automakers

#166

Post by [deleted] »

Filligree wrote: post #114
bluGill wrote: post #59

Earlier quoted context omitted.

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.

[deleted]

Re: Tesla shares 48V architecture with other automakers

#167

Post by p_l »

_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.

What everyone was waiting for was for Italians to make the huge casting press so that castings could be done in mass production at automaker margins.

Re: Tesla shares 48V architecture with other automakers

#168

Post by myself248 »

Tuna-Fish wrote: post #108
myself248 wrote: post #60

Earlier quoted context omitted.

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…

And to explain why this hadn't been done before/how we got here: Nothing in a car actually wants 12V DC. Most of the low voltage stuff will run better at 5V or below, while a lot of the higher voltage stuff would benefit from going as high as possible. 12V exists because DC-DC conversion used to be expensive, and you had to make a compromise about the voltage based on losses, wire thickness, and picking a low enough…

12v exists because 6v was too low; wires were impractically thick for even the early accessories being added in the 1950s. The 6v-12v transition happened in 1955/56 for many cars. Some stuff like lightbulbs could be reused by putting two 6v bulbs in series in a 12v car, so it was a very cheap and relatively straightforward transition.

If they'd just had some foresight and gone 48v in 1955, we would've saved 50 million tons of copper in the years since. It's no harder to make 48v motors or lightbulbs or relays or anything else (and in fact, the telephone network contains plenty of exactly those things, and has, in staggering numbers, for over a century), but the automotive industry isn't exactly known for being forward-thinking.

Re: Tesla shares 48V architecture with other automakers

#169

Post by turtlebits »

smileysteve wrote: post #124
Kirby64 wrote: post #100

Earlier quoted context omitted.

What modern phone charges at 48V? I'm not aware of any that charge at even 20V, outside of a couple of gimmick devices. No Samsung or Apple phone charges at anywhere close to that, that's for sure.

What modern phone charges at 12v? Most phones charge at 5v. Modern USB-C chargers can charge between 5v and 20v based on configuration. Buck converts and regulators are cheap and small these days.

Samsung phones can fast charge at 15v/3a (45W).

Re: Tesla shares 48V architecture with other automakers

#170

Post by vampiresdoexist »

jmrm wrote: post #141

>48V architecture also potentially improves overall electrical efficiency for reasons that I am not sufficiently qualified to explain beyond a kindergarten level This is double bad in a green energy and EV website: On one hand, they admit they don't now why that happens, but on the other hand, they also didn't research just a bit more on that, and that's bad journalism. Most of the comment threads in this HN post are…

I mean… it’s definitely more of a blog than a strict journalism outlet in the vein of say Bloomberg and whoever is on the EV beat.

The writer isn’t publishing false information, and it’s good that the comments are able to add more value! It’s a casual style that has humility and a touch of personality. That’s ok!

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