5 ms·

Standards are meant to be broken, especially when they’re based on outdated assumptions. I’m glad that Tesla is trying to do that with the 48V auxiliary (non-t

by 1-6 2y ago

Standards are meant to be broken, especially when they’re based on outdated assumptions. I’m glad that Tesla is trying to do that with the 48V auxiliary (non-traction) battery. 48V is just below the Low Voltage threshold for human safety (NEC, NFPA). It’s also 4X the 12V std and still a number cleanly divisible by 3V. Sometimes first principles design outshines industry standards especially when there are newer reasons.

klysm 2y ago
Why does divisibility by 3 matter?
- spamizbad 2y ago
  If I had to guess: common multiple of nominal voltage of a single battery cell (which is 1.5 to 3V)
- m463 2y ago
  Might be for transformers windings in vs windings out? I think transformers are pretty efficient, but convert voltage in multiples. I'm not an EE though and don't know if that is how electrical conversion is actually handled in cars.
  - kogepathic 2y ago
    > transformers windings in vs windings out Transformers only apply to AC, where there is a fluctuating magnetic field. A transformer in a DC circuit is just a physically large (very low resistance) resistor. The standard practice to convert DC voltage (at least for these voltages) would be a buck converter, which is an active circuit. [1] [1] https://en.wikipedia.org/wiki/Buck_converter https://en.wikipedia.org/wiki/Buck_converter
  - klysm 2y ago
    Even if it was AC, the ratio of the number of turns is what matters. I don’t see why 3 would matter there.
lttlrck 2y ago
Tesla didn't spearhead that though, in fact they were very late. It was initiated by German manufacturers in the early 2010's. https://en.m.wikipedia.org/wiki/48-volt_electrical_system https://en.m.wikipedia.org/wiki/48-volt_electrical_system
- 93po 2y ago
  Audi has sold less than 10k cars total with a 48v system since 2018 and isn't even double digit percent of their total US sales. MB does better with a few hundred thousand since 2018. Tesla will be shipping a couple million per year. I think it's still fair to say Tesla is spearheading the actual production of these cars, whenever it starts to happen for them.
  - jwnin 2y ago
    Has Tesla moved to 48V in any platform beyond the Cybertruck? Last I read, they have delivered ~4000 of them, and I don't know that they've updated the manufacturing of the existing lines to 48V yet.
    - 93po 2y ago
      Tesla has said they're moving to 48v for "all future vehicles". So my assumption is whenever their existing models get a big change-up, 48v will be part of that change-up. I doubt they're going to switch e.g. Model 3 to 48v starting next year or anything unless there's some compelling cost cutting reason to do so. They're also using it for their humanoid robot
voxadam 2y ago
> Standards are meant to be broken, especially when they’re based on outdated assumptions. A standard I'd love to be modernized would be wider availability of 240 volt outlets in North America. I'd love to have the option of a 240 V electric kettle on my countertop or a 240 V toaster/pizza oven.
- fragmede 2y ago
  for your kettle, the Japanese ones cheat by just keeping it hot all the time. as far as a pizza oven, unless you want to import one from Europe and have an electrician wire you up 240V, the new induction ones are cool (well, hot).
  - voxadam 2y ago
    > for your kettle, the Japanese ones cheat by just keeping it hot all the time Sure, but that's not what I'd call terribly energy efficient. I'd rather boil on demand seeing as my wife, the primary user of the kettle, doesn't drink tea while she's sleeping or at the office. As far as the pizza oven goes I'll probably end up going with an propane Ooni, Roccbox, or the like on my patio. I'm just saying that I'd like to option to dump 240V @ 13A into a small appliance in my kitchen. As it stands now I'm limited to a paltry 1500 watts compared to a peek that's more than double that in the UK.
- jimbobthrowawy 2y ago
  Think you'd go with NEMA 240V sockets, or prefer a different standard of outlet?
  - jen20 2y ago
    The Type G connector serves perfectly well, and is vastly safer than the standard US outlets!
    - ars 2y ago
      The Type G is way too big! They only reason it's that big is leftover baggage from ring circuits requiring fuses in the plugs. And while it might be safer on paper, in practice there is little difference in injury rates US vs UK.
sebazzz 2y ago
Newer Tesla Model 3 (2022+?) already have a 16V internal system (Li-ion) instead of 12V lead-acid.

by 1-6 2y ago

klysm 2y ago

Why does divisibility by 3 matter?

spamizbad 2y ago
If I had to guess: common multiple of nominal voltage of a single battery cell (which is 1.5 to 3V)
m463 2y ago
Might be for transformers windings in vs windings out? I think transformers are pretty efficient, but convert voltage in multiples. I'm not an EE though and don't know if that is how electrical conversion is actually handled in cars.
- kogepathic 2y ago
  > transformers windings in vs windings out Transformers only apply to AC, where there is a fluctuating magnetic field. A transformer in a DC circuit is just a physically large (very low resistance) resistor. The standard practice to convert DC voltage (at least for these voltages) would be a buck converter, which is an active circuit. [1] [1] https://en.wikipedia.org/wiki/Buck_converter https://en.wikipedia.org/wiki/Buck_converter
- klysm 2y ago
  Even if it was AC, the ratio of the number of turns is what matters. I don’t see why 3 would matter there.

lttlrck 2y ago

Tesla didn't spearhead that though, in fact they were very late. It was initiated by German manufacturers in the early 2010's. https://en.m.wikipedia.org/wiki/48-volt_electrical_system https://en.m.wikipedia.org/wiki/48-volt_electrical_system

93po 2y ago
Audi has sold less than 10k cars total with a 48v system since 2018 and isn't even double digit percent of their total US sales. MB does better with a few hundred thousand since 2018. Tesla will be shipping a couple million per year. I think it's still fair to say Tesla is spearheading the actual production of these cars, whenever it starts to happen for them.
- jwnin 2y ago
  Has Tesla moved to 48V in any platform beyond the Cybertruck? Last I read, they have delivered ~4000 of them, and I don't know that they've updated the manufacturing of the existing lines to 48V yet.
  - 93po 2y ago
    Tesla has said they're moving to 48v for "all future vehicles". So my assumption is whenever their existing models get a big change-up, 48v will be part of that change-up. I doubt they're going to switch e.g. Model 3 to 48v starting next year or anything unless there's some compelling cost cutting reason to do so. They're also using it for their humanoid robot

voxadam 2y ago

> Standards are meant to be broken, especially when they’re based on outdated assumptions. A standard I'd love to be modernized would be wider availability of 240 volt outlets in North America. I'd love to have the option of a 240 V electric kettle on my countertop or a 240 V toaster/pizza oven.

fragmede 2y ago
for your kettle, the Japanese ones cheat by just keeping it hot all the time. as far as a pizza oven, unless you want to import one from Europe and have an electrician wire you up 240V, the new induction ones are cool (well, hot).
- voxadam 2y ago
  > for your kettle, the Japanese ones cheat by just keeping it hot all the time Sure, but that's not what I'd call terribly energy efficient. I'd rather boil on demand seeing as my wife, the primary user of the kettle, doesn't drink tea while she's sleeping or at the office. As far as the pizza oven goes I'll probably end up going with an propane Ooni, Roccbox, or the like on my patio. I'm just saying that I'd like to option to dump 240V @ 13A into a small appliance in my kitchen. As it stands now I'm limited to a paltry 1500 watts compared to a peek that's more than double that in the UK.
jimbobthrowawy 2y ago
Think you'd go with NEMA 240V sockets, or prefer a different standard of outlet?
- jen20 2y ago
  The Type G connector serves perfectly well, and is vastly safer than the standard US outlets!
  - ars 2y ago
    The Type G is way too big! They only reason it's that big is leftover baggage from ring circuits requiring fuses in the plugs. And while it might be safer on paper, in practice there is little difference in injury rates US vs UK.

sebazzz 2y ago

Newer Tesla Model 3 (2022+?) already have a 16V internal system (Li-ion) instead of 12V lead-acid.