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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

#181

Post by bluGill »

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.

I've never seen that in Minnesota. They are attachments to a dump truck or road grader.

Re: Tesla shares 48V architecture with other automakers

#182

Post by [deleted] »

contingencies wrote: post #84
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.

The great thing about PoE standards is there's so many to choose from. https://en.wikipedia.org/wiki/Power_over_Ethernet#Standards_... Honestly, ethernet introduces a degree of non-determinism with respect to time in the link layer, plus increased bringup times, a potentially more costly core switching fabric, and the need for critical revision of latency assumptions on any potentially safety-related control concerns…

[deleted]

Re: Tesla shares 48V architecture with other automakers

#183

Post by eternityforest »

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?

Aside from modern barrel jack supplies, none of it is actually powers of two, it's like, 13.8v lead acid or a little higher for lithium.

I think we just stay close to the numbers we do, because we just really like multiples of 12 and numbers with lots of divisors. 24 hours in a day, 360 degrees, etc.

Most numbers people really like a lot seem to be on the 7-smooth numbers(https://oeis.org/A002473) list and related/overlapping sets like highly composite numbers.

Which I think is super cool, because it means you can choose one and there's a good chance someone else chose it too for something similar, unless they were using renard numbers or something instead.

Re: Tesla shares 48V architecture with other automakers

#184

Post by Moto7451 »

numpad0 wrote: post #105
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.

Automotive Ethernet is not 8P8C...that's not how they do it at all

Some cars even use optical networking between the front and rear of the car. I think a bit of that has gone away now that you don’t need a DVD full of map data in its own module in the trunk.

Re: Tesla shares 48V architecture with other automakers

#185

Post by jpm_sd »

myself248 wrote: post #136
tootie wrote: post #85

Earlier quoted context omitted.

Is Tesla's design here actually innovative or really just they're the first ones to put together a bunch of stuff that everyone knew and hasn't had the wherewithal to implement?

I haven't seen the document being referred to elsewhere, but I highly doubt that there's anything fundamentally new under the sun. The industry tried this before but got stuck in a first-mover-disadvantage situation, which doesn't affect Tesla as severely because they have relatively few parts in common with other cars in the first place. So put me down in the "wherewithal" column. That's not to discount it at all. T…

Littelfuse makes some nice 58V rated blade fuses.

Re: Tesla shares 48V architecture with other automakers

#186

Post by eternityforest »

hinkley wrote: post #130
myself248 wrote: post #119

Earlier quoted context omitted.

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.

Smaller transformers with whole numbers, right? But why 4 and not 3 or 6?

We seem to stick with 7-smooth numbers, and really extra prefer highly composite numbers (https://en.m.wikipedia.org/wiki/Highly_composite_number) for things we chose before the age of calculators.

3 and 6 were the standard voltages for consumer stuff back in the days of people needing to buy multiple packs of AA cells every year

Re: Tesla shares 48V architecture with other automakers

#187

Post by mrep »

mauvehaus wrote: post #143
Filligree wrote: post #114

Earlier quoted context omitted.

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.

I haven't a clue what you're describing. Do you have a picture? Also: where do you live, and how much snow do you get?!

Not OP, but here in park city UT, we average ~21 feet of snow a season and got an epic 51 feet last season!

I normally see dump salting trucks with plows that plow/salt the roads during snow falls and then we have cat bulldozers that later come pick up the snow and move it into dump trucks to be hauled away.

Video of the cats: https://www.icloud.com/attachment/?u=https%3A%2F%2Fcvws.iclo...

Re: Tesla shares 48V architecture with other automakers

#188

Post by dfox »

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

Telco lines generally are not considered safe voltage. One thing is that ringing voltage is fairly squarely above the threshold and another thing is the whole outside plant thing (ground potential differences, lightning strikes...).

Re: Tesla shares 48V architecture with other automakers

#189

Post by Moto7451 »

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 spins the alternator to keep accessories running.

https://www.autoweek.com/news/a36331077/48-volt-hybrid-syste...

My guess is that handing this out is a very nice thing to do but perhaps irrelevant in a world where 400v and 800v drive systems are the state of the art. Those systems can’t rely on the car body as a common ground for all sources of current and have a lot of inherent safety concerns that force a lot of electrical engineering that my old Camaro didn’t need to have.

Re: Tesla shares 48V architecture with other automakers

#190

Post by IgorPartola »

jacquesm wrote: post #142
kurthr wrote: post #7

Earlier quoted context omitted.

It's a really nice voltage with lots of support for batteries and up/dn conversion hardware. It's also right at the edge of what is human safe. You can burn yourself and blow up cables, but it's very difficult to electrocute yourself (afib or muscle seize) without lots of wet contact. https://incompliancemag.com/article/experiments-of-dc-human-...

Indeed, I'm aware of only one recorded death by electrocution at 48V, iirc it was a Swiss radio amateur that had done a bunch of gardening sat down sweaty in a metallic chair and reached for the one switch of his set. Probably there were other contributory causes as well, I've been zapped multiple times from much higher voltage sources (that could have easily supplied the power required) and lived. I can't find a ref…

I assume if you didn’t live from those zaps you wouldn’t be here making this comment.
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