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> That would force all power adapters to support a fixed maximum current No, we would just start to have both 20VDC sockets on all the walls in the world in ad

by dheera 3y ago

> That would force all power adapters to support a fixed maximum current No, we would just start to have both 20VDC sockets on all the walls in the world in addition to 120VAC/240VAC, and people would stop needing to lug around power adapters. Yes there would be a maximum current per socket, maybe 5A or 10A, that's not much different from the 15A limit on most AC sockets. The conversion to 20VDC could be be wired into buildings as standard. Before then people can lug around a 20VDC adapter that supplies enough current for their own devices. If they have a laptop they might need a 10A adapter, if it's just a phone they could get by with 1A.

lxgr 3y ago
So you're suggesting we re-wire every single building with these "simple" 20V DC plugs? We'd better get both the voltage and maximum current exactly right, because the last time we picked standards for this, they lasted for several centuries! And if we do get it wrong, do we change the mechanical plug shape if we decide that no, actually 40V (or 15V, or 32.945V) would have been better so that no unsafe connections become possible?
- dheera 3y ago
  AC outlets have been the same on a per-country basis for decades and will be for several more decades. USB, on the other hand, is "hey I have a new plug" every 5 years. We'll have USB-D in 2030 and everyone will have to buy new cables and adapters. Anyone who needs 40V should just design it to use 120V/240V instead.
  - lxgr 3y ago
    Sure, but what makes 20V the perfect voltage for almost everything, so important that we should go through the effort of rewiring entire buildings? It's way too much to charge small accessories (without an internal step-down converter [1]), yet it's probably not enough to sustain (let alone charge) beefy laptops. > "hey I have a new plug" You do realize that this is exactly your pitch for these 20V "standardized" plugs/outlets, right? :) [1] A big reason why USB's 5V is so popular is that it's just the right voltage to charge lithium ion batteries and run simple circuits without expensive (in terms of parts) active voltage converters.
    - dheera 3y ago
      > it's just the right voltage to charge lithium ion batteries No, it's not. Lithium is nominally 3.7 volts per cell and charging voltage goes up to about 4.2 volts max, maybe 4.3. Definitely never 5V. A 5V->4.2V buck converter isn't particularly different than a 20V->4.2V buck converter. In fact it's probably a bit easier to make a 20V->4.2V converter since you don't have to worry about parasitic losses as much. > You do realize that this is exactly your pitch for these 20V "standardized" plugs/outlets, right? :) Not exactly, (a) I'd use an existing connector, maybe a Lenovo 20V connector (b) USB keeps having to switch things because they weren't a charging standard to begin with, they were abused as a power plug and then had to keep evolving with that while maintaining backward compatibility and continually keeping up with Moore's law in bandwidth requirements. A 20VDC plug would just be that -- a low-voltage socket for <100W appliances. Anything higher, just use 120V/240V and get upto 1800W.

by dheera 3y ago

lxgr 3y ago

So you're suggesting we re-wire every single building with these "simple" 20V DC plugs? We'd better get both the voltage and maximum current exactly right, because the last time we picked standards for this, they lasted for several centuries! And if we do get it wrong, do we change the mechanical plug shape if we decide that no, actually 40V (or 15V, or 32.945V) would have been better so that no unsafe connections become possible?

dheera 3y ago
AC outlets have been the same on a per-country basis for decades and will be for several more decades. USB, on the other hand, is "hey I have a new plug" every 5 years. We'll have USB-D in 2030 and everyone will have to buy new cables and adapters. Anyone who needs 40V should just design it to use 120V/240V instead.
- lxgr 3y ago
  Sure, but what makes 20V the perfect voltage for almost everything, so important that we should go through the effort of rewiring entire buildings? It's way too much to charge small accessories (without an internal step-down converter [1]), yet it's probably not enough to sustain (let alone charge) beefy laptops. > "hey I have a new plug" You do realize that this is exactly your pitch for these 20V "standardized" plugs/outlets, right? :) [1] A big reason why USB's 5V is so popular is that it's just the right voltage to charge lithium ion batteries and run simple circuits without expensive (in terms of parts) active voltage converters.
  - dheera 3y ago
    > it's just the right voltage to charge lithium ion batteries No, it's not. Lithium is nominally 3.7 volts per cell and charging voltage goes up to about 4.2 volts max, maybe 4.3. Definitely never 5V. A 5V->4.2V buck converter isn't particularly different than a 20V->4.2V buck converter. In fact it's probably a bit easier to make a 20V->4.2V converter since you don't have to worry about parasitic losses as much. > You do realize that this is exactly your pitch for these 20V "standardized" plugs/outlets, right? :) Not exactly, (a) I'd use an existing connector, maybe a Lenovo 20V connector (b) USB keeps having to switch things because they weren't a charging standard to begin with, they were abused as a power plug and then had to keep evolving with that while maintaining backward compatibility and continually keeping up with Moore's law in bandwidth requirements. A 20VDC plug would just be that -- a low-voltage socket for <100W appliances. Anything higher, just use 120V/240V and get upto 1800W.