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Anyone had any luck with USB-C to DC Connectors? (alien.top)

submitted 1 year ago by MagicPracticalFlame@alien.top to c/homelab@selfhosted.forum

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I'm looking at clearing down some of the power bricks that are in my homelab along with plug requirements. There's 3 devices that run off of 12v, so the current idea is to buy something like this:

https://uk.ugreen.com/products/ugreen-nexode-200w-usb-c-gan-charger-6-port-desktop-charge

And then this: https://www.amazon.co.uk/gp/product/B0B9FDZX7P

With the aim of powering:

Beelink Mini-S12
Virgin Media Hub 3 (this is the worst power brick)
asus dsl-ax82u
Raspberry Pi 4 (no converter needed, but will eliminate a plug)

I'm aware this is a single point of failure, it will be plugged into a UPS. I'm just wondering on the viability of it all.

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[–] ThetaDeRaido@alien.top 1 points 1 year ago (2 children)

I’ve found this particular use to be frustrating. USB-PD negotiates how much power each port provides when the device is plugged in, which in practice means whenever you plug or unplug something from the adapter, it cuts off power to every other port while it renegotiates and reallocates the power to each port. This will kill power to the router, miniPC, etc.

If everything is kept plugged in and powered on at all times together—including the Raspberry Pi and the miniPC—then I guess this is one way to eliminate power adapters.

[–] MagicPracticalFlame@alien.top 1 points 1 year ago (1 children)

Yeah just reading up on it. I'm wondering if there's a USB-C device which has zero negotiation time? At the worst case, I may just get a dedicated USB-C charger for the Router as that has the most obnoxiously large power brick.

[–] mosaic_hops@alien.top 1 points 1 year ago

That’s not physically possible, negotiation is required for voltages over 5V. And the voltage may not be within the spec of the device. USB-PD provides higher voltages in order to push more power through a USB cable. Higher voltage means higher wattage for the same amps, meaning less power lost due to cable resistance. You can’t just push 5V 10A through a USB cable or it would melt, but you could push 20V 2.5A, for the same 50W total but with a non-melty cable. So the voltage may not be precise and is usually used to drive a buck converter at the other end to drop it down to a usable voltage again. All this requires expensive components and complex firmware.

What you’re probably looking for is a regular 12V DC power supply. There’s just no need for all the expensive USB-PD negotiation for your use case.

Plus, as others have said, USB-PD chargers will disconnect all devices whenever power requirements change. This can happen at any time even without the devices being unplugged-re-plugged, it happens whenever the power needs dictate a switch to a new USB-PD mode.