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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

#251

Post by somedudetbh »

dmix wrote: post #222
eqvinox wrote: post #202

Earlier quoted context omitted.

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?

ebikes, phantom power in audio equipment...

Re: Tesla shares 48V architecture with other automakers

#252

Post by Kirby64 »

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.

12V isn't a 'standard' USB-PD voltage, so pretty much none of them. Tons of phones charge at 9V, though. And some use 15V.

The regulators/buck converters you speak of are inside the phones these days. They want a higher voltage even if the battery itself is 3-4.2V, so losses from cabling are lower and you don't need a special 5A cable to handle charging at the fastest rate.

Re: Tesla shares 48V architecture with other automakers

#253

Post by hatsunearu »

mmaunder wrote: post #246

Many comments here seem to be confusing the accessories circuit voltage with the electrical vehicle motor and drive system. The vehicle motors have a combined power output of 450KW which requires a high voltage 800V system or the wiring would be so heavy it would not be feasible. This spec appears to be the accessories circuit with Tesla pushing for a new 48V standard. That’s super smart because it immediately means…

A lot of commercial trucks use 24V systems also.

Re: Tesla shares 48V architecture with other automakers

#254

Post by maxerickson »

mmaunder wrote: post #246

Many comments here seem to be confusing the accessories circuit voltage with the electrical vehicle motor and drive system. The vehicle motors have a combined power output of 450KW which requires a high voltage 800V system or the wiring would be so heavy it would not be feasible. This spec appears to be the accessories circuit with Tesla pushing for a new 48V standard. That’s super smart because it immediately means…

Stuff like buses have used 24 volt for ages. Basically anywhere with larger accessory loads.

48 volt has been 'on the radar' in automotive spaces for a couple decades.

Re: Tesla shares 48V architecture with other automakers

#255

Post by Kirby64 »

Turskarama wrote: post #218
gleenn wrote: post #212

Earlier quoted context omitted.

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.

They're getting mixed up, the 400-800V systems are _only_ for the motors, everything else in the car still uses low voltage. In fact, afaik every single electric car has two separate systems. There's a high voltage system (the main battery and motor(s)) and the low voltage (almost always 12v) system, usually with a traditional lead-acid 12v battery that is charged via a DC-DC converter connected to the high voltage b…

Not true in most EVs regarding 'only the motors'. The AC/heat pump compressor is run off the HVDC, typically. Since it runs for long periods of time and consumes kilowatts, you want to run it straight off the main HV battery. Also, any vehicle that still uses resistive heating (older EVs tended to do this, Tesla included) use the HVDC for that.

Re: Tesla shares 48V architecture with other automakers

#256

Post by bigdict »

mmaunder wrote: post #246

Many comments here seem to be confusing the accessories circuit voltage with the electrical vehicle motor and drive system. The vehicle motors have a combined power output of 450KW which requires a high voltage 800V system or the wiring would be so heavy it would not be feasible. This spec appears to be the accessories circuit with Tesla pushing for a new 48V standard. That’s super smart because it immediately means…

Dumb question but why does deciding to run at a higher voltage decrease the amount of wiring necessary? And why not increase it even further then?

Re: Tesla shares 48V architecture with other automakers

#257

Post by dreamcompiler »

bluGill wrote: post #64
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.

You would need larger wires to account for the losses at a house scale. Since nothing runs are 48 volts you still have the bad power supply in every LED bulb.

12 gauge wire would work fine for 48v lighting loads; probably 14 gauge too for many of them. Small DC constant-current sources are commodity items now and they're very efficient.

Re: Tesla shares 48V architecture with other automakers

#258

Post by Kirby64 »

dreamcompiler wrote: post #235
gleenn wrote: post #212

Earlier quoted context omitted.

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.

Tesla uses 800v only to run the Cybertruck's drive motors. Every other electric load in the truck uses 48v. Both of these are much higher in the Cybertruck than all other Tesla models. All other Tesla models use 400v [IIRC] for the drive motors and 12v for everything else.

Pretty sure the AC/heat pump on the Cybertruck runs off the 800V pack. Since it consumes so much power for long periods of time, it makes little sense to run it off the 48V. Existing other Tesla's use the main pack voltage for AC/heat pump.

Re: Tesla shares 48V architecture with other automakers

#259

Post by kalleboo »

bigdict wrote: post #256
mmaunder wrote: post #246

Many comments here seem to be confusing the accessories circuit voltage with the electrical vehicle motor and drive system. The vehicle motors have a combined power output of 450KW which requires a high voltage 800V system or the wiring would be so heavy it would not be feasible. This spec appears to be the accessories circuit with Tesla pushing for a new 48V standard. That’s super smart because it immediately means…

Dumb question but why does deciding to run at a higher voltage decrease the amount of wiring necessary? And why not increase it even further then?

Watts = Amps * Volts (or, more scientifically, P = I * V)

If something draws 48 Watts of power, you can either supply it with 4 Amps @ 12 Volt, or 1 Amp @ 48 Volt.

It's the amps that determine how thick the wiring needs to be, so by lowering the amperage, you lower the amount of wiring needed.

I believe the only reason cars are 12 V is because that's a practical voltage to build lead-acid batteries at (which is actually closer to 14 V in practice). Early car electric systems were only 6 V back when the only accessories were the front lights and the horn, but as more stuff was added on cars moved to 12 V.

Re: Tesla shares 48V architecture with other automakers

#260

Post by maxerickson »

grecy wrote: post #223
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 e…

Realistically, using 12 volt and 48 volt for accessory systems are pretty similar. 48 volts just reduces your current, and you have to design everything for ~56 volts instead of ~14. But it's not really a different exercise.
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