4 ms·

It seems there are more alternatives. Use the USB-PD supply for the laptop and another one for you 5 devices. It's a bad laptop design. An iPad or Android phon

by 323 4y ago

It seems there are more alternatives. Use the USB-PD supply for the laptop and another one for you 5 devices. It's a bad laptop design. An iPad or Android phone/tablet can fast charge with a good supply or slow charge with a cheap one. The laptop should do the same, accept whatever the supply can deliver. Also, what's the problem with the user using 5 individual small USB chargers versus a big one? The efficiency of all USB chargers is about the same, so it doesn't matter how you split them up. In fact, a small USB charger working at maximum output is more efficient than a large one working at 20% load. You are correct that ideally the USB-PD supply should monitor the actual usage and route power accordingly, but I'm not sure it's such a problem in practice.

sowbug 4y ago
what's the problem with the user using 5 individual small USB chargers versus a big one? :) This thread started with iamchp asking about "single multi-port USB-C PD converters." The laptop should [...] accept whatever the supply can deliver. And both sides should renegotiate when available/needed power changes. If a laptop could say "I could use 240W but I can deal with 18W," a supply said "I can give you only 18W, but I'll let you know when I can give you 240W," and the laptop later said "you know what? Now I really need only 36W," then I think USB-PD would be good. My experience is the negotiation happens once, possibly days earlier, when the device is first plugged in. (By the way, it's not always the right product decision to include boosting circuitry from lower-voltage supplies. While a MacBook will charge from a 5-volt supply, you'll be sad when it dies during a critical work presentation even though it's charging, because the presentation needed more than 15 watts. It's a defensible product decision to require a minimum wattage, and thus effectively a minimum voltage, or refuse to charge.)
- vel0city 4y ago
  It would be pretty neat to have some kind of refresh interval, where both devices list their current capabilities and have it renegotiate to some optimal level. As for the refusing to charge, my ThinkPad on Windows will alert me when the dock or power source isn't putting out enough power for it to maintain the current power usage trend.

by 323 4y ago

sowbug 4y ago

what's the problem with the user using 5 individual small USB chargers versus a big one? :) This thread started with iamchp asking about "single multi-port USB-C PD converters." The laptop should [...] accept whatever the supply can deliver. And both sides should renegotiate when available/needed power changes. If a laptop could say "I could use 240W but I can deal with 18W," a supply said "I can give you only 18W, but I'll let you know when I can give you 240W," and the laptop later said "you know what? Now I really need only 36W," then I think USB-PD would be good. My experience is the negotiation happens once, possibly days earlier, when the device is first plugged in. (By the way, it's not always the right product decision to include boosting circuitry from lower-voltage supplies. While a MacBook will charge from a 5-volt supply, you'll be sad when it dies during a critical work presentation even though it's charging, because the presentation needed more than 15 watts. It's a defensible product decision to require a minimum wattage, and thus effectively a minimum voltage, or refuse to charge.)

vel0city 4y ago
It would be pretty neat to have some kind of refresh interval, where both devices list their current capabilities and have it renegotiate to some optimal level. As for the refusing to charge, my ThinkPad on Windows will alert me when the dock or power source isn't putting out enough power for it to maintain the current power usage trend.