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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

#301

Post by owengee »

jeffparsons wrote: post #298

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…

For batteries it tends to be multiple of the battery cell voltages. So 48v is probably so you could wire 4x12v batteries in series but that is a guess. With tool voltages this tends to be a multiple of the nominal battery voltage (rounded for marketing).

Re: Tesla shares 48V architecture with other automakers

#302

Post by ianlevesque »

elif wrote: post #287
bigdict wrote: post #256

Earlier quoted context omitted.

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?

The reason to not keep going higher is purely practicality because stepping down bigger voltage gaps for lower voltage applications begins to become less efficient/more waste heat. If you design 100v computers, monitor, headlights, seat adjustment motors, window/windshield motors, pumps, etc. you could cut these 48v wires in half again but if you end up stepping everything down anyway it loses its utility. The safety…

Just don't try that with wet hands.

Re: Tesla shares 48V architecture with other automakers

#303

Post by grepfru_it »

kalleboo wrote: post #259
bigdict wrote: post #256

Earlier quoted context omitted.

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 actua…

Car electrical systems typically run at 13.8-14.4V while the alternator is charging and drops slightly after the battery is topped off. When the engine is off the battery regulates a 12v output

Re: Tesla shares 48V architecture with other automakers

#304

Post by grepfru_it »

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.

I actually run Poe in my car to power a mini pc in the trunk. I guess I’m ahead of the game :)

Re: Tesla shares 48V architecture with other automakers

#305

Post by injb »

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?

As an analogy, if you have a hose squirting out water at a certain rate, and you increase the pressure, then all other things being equal you'll get a higher rate of water. But then that means you could now reduce the size of the hose, keeping the new higher pressure, and achieve the original rate of water delivery with a smaller, cheaper, lighter hose.

It's very similar with electricy: water pressure is voltage and the rate of water delivery is power.

Re: Tesla shares 48V architecture with other automakers

#306

Post by p1mrx »

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?

240W USB-C uses 48V, so that should eventually become common for stuff like gaming laptops.

Re: Tesla shares 48V architecture with other automakers

#308

Post by CodeWriter23 »

arcticbull wrote: post #194
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…

Most automotive parts are 12V so that just means due to economy of scale, 48V parts are more expensive. They are trying to reduce their cost basis by getting everyone to move over to a common, more efficient voltage spec. This is good industry advocacy.

There's a crossover where ROI results in lower wiring costs.

Re: Tesla shares 48V architecture with other automakers

#309

Post by justapassenger »

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…

[dead]

Re: Tesla shares 48V architecture with other automakers

#310

Post by accrual »

1970-01-01 wrote: post #192
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…

>potentially improves overall electrical efficiency Looks like he understood it the entire time :)

I wasn't sure, so I asked:

> Higher voltage systems experience lower power losses over the same distance compared to lower voltage systems. This is due to the fact that power loss in a conductor is proportional to the square of the current. By using higher voltage, you can transmit the same amount of power with less current, reducing resistive losses in the wires.

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