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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

#291

Post by inferiorhuman »

gleenn wrote: post #212
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…

My understanding was that nearly every production vehicle on the road is 12V and that Tesla and perhaps Audi as you mentioned are doing things differently. Who is using 400-800V systems? That sounds extremely dangerous.

Mercedes introduced their 48V hybrid in 2016. Kia in 2018. Peugeot just introduced theirs this year.

Jalopnik was talking about the "48V revolution" in 2017:

https://jalopnik.com/everything-you-need-to-know-about-the-u...

Re: Tesla shares 48V architecture with other automakers

#292

Post by _ea1k »

CharlesW wrote: post #172
_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.

> Everyone knew castings were the way to go… The jury's still out on whether gigacasting is courageous, or just moves costs from production (which will not be passed to consumers) to repairs (which will). > Everyone knew that 48V would be a big benefit, but noone did it. Audi did in 2016 with the SQ7 TDI, no?

TBH, the repairability concerns seem to be overstated so far. There are still conventional crash structures in front of and behind them. It takes a lot to damage the casting beyond repair.

You are right, though. The jury is still out in that they haven't really been used in the real world for long.

> Audi did in 2016 with the SQ7 TDI, no?

I didn't know about that one, but it was still a dual architecture. Going full 48V is a bit different, assuming Tesla really did that.

Re: Tesla shares 48V architecture with other automakers

#293

Post by [deleted] »

Trex_Egg wrote: post #243
klysm wrote: post #240

Earlier quoted context omitted.

Wouldn’t it be PoC instead of PoE?

Power over Ethernet (PoE) is a technique for delivering DC power to devices over copper Ethernet cabling, eliminating the need for separate power supplies and outlets. Source: https://www.google.com/url?q=https://www.cisco.com/c/en/us/s...

[deleted]

Re: Tesla shares 48V architecture with other automakers

#294

Post by _ea1k »

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.

I tend to agree, TBH. People bring up fly-by-wire, but even that is simpler. AFAIK, those systems aren't variable ratio the way CT is. CT literally will have different steering ratios depending on the speed, so one steering wheel angle will have different effects on the actual steering angle depending upon the speed.

How will that work in the real world? Could there be bugs? Will people get used to it or will it lead to mistakes?

I'm looking forward to getting a chance to try it, TBH.

Re: Tesla shares 48V architecture with other automakers

#295

Post by networkchad »

Turskarama wrote: post #264
dreamcompiler wrote: post #229

Earlier quoted context omitted.

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.

Two motors is great and all, but that only provides motor redundancy and won't help if something happens to the electrical system. Planes are fly by wire but that's because they literally have to be, no amount of gym time will let you move the rudder on a 737 by hand.

[dead]

Re: Tesla shares 48V architecture with other automakers

#296

Post by stephen_g »

tgsovlerkhgsel wrote: post #199
mcguire wrote: post #81

Earlier quoted context omitted.

The rumor I heard was that the higher voltage resulted in lower switch lifetimes. Any truth to that?

Would there actually be switches switching 12 or 48V in a modern car, especially a Tesla? I'd expect the switches to only switch signal voltage/current, and power electronics (MOSFET? no idea, not an electrical engineer) switching the actual loads.

That's right, the switching concern was in older cars where they were switching the 12V straight up, so that is a reasonable point for why they never switched to higher voltages, but yes, in most modern cars (and basically all EVs) buttons and switches would mostly all just be signalling electronic units to do the actual switching.

Re: Tesla shares 48V architecture with other automakers

#297

Post by phire »

sbierwagen wrote: post #275
phire wrote: post #269

Earlier quoted context omitted.

No. For safety, hybrids and electric vehicles physically disconnect the high-voltage battery from everything when it's off with massive relays. So you can end up in the somewhat stupid situation where your high-voltage battery is fully charged, but you can't do anything because the tiny 12v motorcycle battery is flat. Starting simply requires enough 12v current to close a relay, the amps going though the "jumper pins…

That describes the situation where the 12V battery is flat but the HV battery is charged. But what happens if the HV battery is flat on a non-plug in hybrid? Can it be charged from 12V?

Yeah, I started wondering the same thing as I was writing that response, as I do actually own a Lexus with the Prius drive chain.

For starters, it would be pretty hard to get into that state in the first place. My understanding is they actually report a 10% or 20% charged battery as "completely empty". And the it's completely disconnected, so it shouldn't discharge much.

Looking though the service manual, there doesn't even seem to be an error code for "HV battery low", nor any mention of the DC-DC converter being able to charge the HV battery from 12v, it only goes from HV to 12v.

So I really suspect if you do happen to end up with a flat HV battery that's too flat to start the engine, it's just going to flash the "Replace HV battery" error code. Theoretically, someone with the right tools could disassemble the battery and charge the individual modules.

And the only speculation I can find on google is that "flat HV batteries are very rare" and probably only happen when the HV battery has other issues and needs replacement.

Edit: After more googling, apparently Toyota dealers have a special charger called the THS that can charge the HV battery in non-plugin hybrids.

Re: Tesla shares 48V architecture with other automakers

#298

Post by jeffparsons »

I'm ignorant and curious: why 48V specifically? Why not 40V? Why not 50V? Is there some ideal ratio that makes DC-DC conversions more efficient or something?

For comparison, Makita (and I think some other power tool makers) have augmented their 12V lineup with a newer 40V platform for tools that need a bit more oomph. I guess there's no need for them to interoperate with other DC voltages, so maybe that explains the "messy" number?

USB, on the other hand, recently grew support for a handful of pleasantly neat voltages:

> Increased power levels from existing USB standards up to 240W. New 28V, 36V, and 48V fixed voltages enable up to 140W, 180W and 240W power levels, respectively.

Does anybody know how these decisions are made?

Re: Tesla shares 48V architecture with other automakers

#299

Post by phire »

ace2358 wrote: post #289
sbierwagen wrote: post #275

Earlier quoted context omitted.

That describes the situation where the 12V battery is flat but the HV battery is charged. But what happens if the HV battery is flat on a non-plug in hybrid? Can it be charged from 12V?

Wouldn’t you just start the car if the HV was flat and the LV was charged? If they’re both flat I agree, I’m curious what you do.

There is no 12v starter motor, it always just uses one of the large motor-generator units to start the engine, and in the Prius drive chain, they require 600v (boosted from 200v from the HV battery).

So if the HV battery is flat, you can't start the engine to charge it.

Re: Tesla shares 48V architecture with other automakers

#300

Post by stephen_g »

tootie wrote: post #85
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…

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've been in the telco/digital communications space for years and all this stuff has run from 48V for decades. So basically plenty of electronic parts are already available with margins suited to 48V already since it's extremely common in other industries like the one I'm in.

Automotive just tends to be a pretty slowly changing industry, but everything is ready for them to adopt 48V that other industries have been using for a long time, someone just needed to take the plunge I guess.

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