5 ms·

A split 48/12 system makes a lot more sense. Run the heater/heat pump, power steering, coolant pump, etc on 48V and keep entertainment and controls on 12V.

bryanlarsen 3y ago
Computer chips use ~1.5V or so these days. Why go 48V->12V->1.5V when you can go 48V->1.5V directly? If it's more efficient to use an intermediate voltage, you can choose the most efficient intermediate voltage internally rather than using 12V.
- bluGill 3y ago
  There is a lot of off the shelf 12V equipment you can buy. Plus even more that is sitting in garages ready to be installed in the next vehicle. Cars are manufactured in enough quantity that it would only cost $0.01 per vehicle to design it (plus parts costs which are probably the same), but that is still a few million to the bottom line if they use the same 12 volt radio. Add to that that ICE cars everywhere have 12 volt starters, and you can buy 12 volt jump start kits: when (not if!) a battery fails to start the ICE you better be able to jump start it from a 12 volt battery - this is a safety issue. Tesla doesn't have ICEs, so the safety concerns are lost on them. Thus all 48 volt makes some sense. They still need something for all the accessories people have.
- taylodl 3y ago
  Because we already have the 12V infrastructure and part supplies in place. You're disrupting things for no benefit. We've been running split 24V/12V systems for decades now in automotive applications. It's not that big a deal to change that to 48V/12V systems as many European car manufacturers have done.
  - bryanlarsen 3y ago
    No benefit? I've seen estimates of $1000 in reduced cost due to reduced copper wiring, and more importantly the labor required to string that wiring. Modern phones charge on 48V these days, so 48V parts are extremely common & cheap.
    - pgeorgi 3y ago
      I'd fully expect other car makers to move to an exclusive 48V setup at some point. They just do it gradually: For the new model a part is replaced by its next-gen successor that is incompatible anyway? Put it on the 48V bus. Repeat until the 12V system is done away with - or force the issue when there are only a few components left, or downstep the 48V to 12V right in front of them, once that's cheaper than keeping the remaining 12V system.
      - bryanlarsen 3y ago
        It'd be cheaper to delete the 12V bus entirely and add 48V -> 12V converters in front of legacy components, even if they needed several dozen of those converters.
        panick21_ 3y ago
        I expect Tesla to still have a few components like that in the car.
        imp0cat 3y ago
        Isn't that the point of the article though? That they run everything on 48V?
        panick21_ 3y ago
        I think all the wires/communication are but some of the devices attached are lower then 48V, some very low voltage, and some might be 12V. We will see when its taken apart.
    - jabl 3y ago
      > I've seen estimates of $1000 in reduced cost due to reduced copper wiring What about aluminum wiring? Lighter, cheaper, though bulkier than equivalent copper. Aluminum wiring got a bad rep back in the day, but it seems with current electrical aluminum standards it supposedly works pretty well.
deleted 3y ago
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bryanlarsen 3y ago

Computer chips use ~1.5V or so these days. Why go 48V->12V->1.5V when you can go 48V->1.5V directly? If it's more efficient to use an intermediate voltage, you can choose the most efficient intermediate voltage internally rather than using 12V.

bluGill 3y ago
There is a lot of off the shelf 12V equipment you can buy. Plus even more that is sitting in garages ready to be installed in the next vehicle. Cars are manufactured in enough quantity that it would only cost $0.01 per vehicle to design it (plus parts costs which are probably the same), but that is still a few million to the bottom line if they use the same 12 volt radio. Add to that that ICE cars everywhere have 12 volt starters, and you can buy 12 volt jump start kits: when (not if!) a battery fails to start the ICE you better be able to jump start it from a 12 volt battery - this is a safety issue. Tesla doesn't have ICEs, so the safety concerns are lost on them. Thus all 48 volt makes some sense. They still need something for all the accessories people have.
taylodl 3y ago
Because we already have the 12V infrastructure and part supplies in place. You're disrupting things for no benefit. We've been running split 24V/12V systems for decades now in automotive applications. It's not that big a deal to change that to 48V/12V systems as many European car manufacturers have done.
- bryanlarsen 3y ago
  No benefit? I've seen estimates of $1000 in reduced cost due to reduced copper wiring, and more importantly the labor required to string that wiring. Modern phones charge on 48V these days, so 48V parts are extremely common & cheap.
  - pgeorgi 3y ago
    I'd fully expect other car makers to move to an exclusive 48V setup at some point. They just do it gradually: For the new model a part is replaced by its next-gen successor that is incompatible anyway? Put it on the 48V bus. Repeat until the 12V system is done away with - or force the issue when there are only a few components left, or downstep the 48V to 12V right in front of them, once that's cheaper than keeping the remaining 12V system.
    - bryanlarsen 3y ago
      It'd be cheaper to delete the 12V bus entirely and add 48V -> 12V converters in front of legacy components, even if they needed several dozen of those converters.
      - panick21_ 3y ago
        I expect Tesla to still have a few components like that in the car.
        imp0cat 3y ago
        Isn't that the point of the article though? That they run everything on 48V?
        panick21_ 3y ago
        I think all the wires/communication are but some of the devices attached are lower then 48V, some very low voltage, and some might be 12V. We will see when its taken apart.
  - jabl 3y ago
    > I've seen estimates of $1000 in reduced cost due to reduced copper wiring What about aluminum wiring? Lighter, cheaper, though bulkier than equivalent copper. Aluminum wiring got a bad rep back in the day, but it seems with current electrical aluminum standards it supposedly works pretty well.

deleted 3y ago

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