I ordered a few Raspberry Pi 4s, still under way, each with their own power supply, and I plan to get more, but when I have been previously able to power RPis with USB-hub, there's apparently no USB-C-hubs, beyond few expensive 2 usb-c-port-hubs, in the existance:
https://superuser.com/questions/1381139/why-cant-i-find-a-usb-c-hub-with-multiple-usb-c-ports
So is the only option hoping to find some slim enough 5V/3A/15W USB-C charger for each RPi4 and plugging those into extension cords?
The official Power Requirements of the Pi 4B is 5v, 3.0A - I.e. a total of 15W maximum power requirement from each of the Pis, so a 60W USB power supply, or larger, would be ideal. This is a maximum, as they acknowledge with:
We recommend a 2.5A (2500mA) power supply, from a reputable retailer, that will provide you with enough power to run your Raspberry Pi for most applications, including use of the 4 USB ports.
This month, I have built a 4 board Hadoop/Spark cluster following this guide.
I looked at the possibility of buying a PC Power Supply but for a 4-Pi cluster, that seemed like overkill and would generate a clunky solution.
To power it, I bought an Anker 63W 5-port USB Charger and 30cm USB to USB-C cables. There's no need for a USB-C hub and, as you point out, they don't exist in any case.
It's true, that only two of the sockets are rated at 3.0A, the others are described as 2.4A, but even with the draw from the fans that came as part of the cluster case (5V 0.2A) the cluster works perfectly well. I am running them headless and won't be having any external peripherals so I don't foresee any power issues with this setup.
Los Alamos labs looked at powering a huge cluster of RPi to cheaply simulate their supercomputer cluster . Out of that came the Bitscope blades which will mount 4 Rpi per blade and host IIRC ten blades in a single rack.
It might be worth a look. Each blade is capable of delivering up to 4A current and is compatible with DC power sources ranging from 9V to 48V.
Here is what you can do. Open a casing of a desktop PC. You will find a PSU. That PSU is called SMPS. Now go to a store and find that PSU. Grab it(of course after buying) and come home. Short the green line with black and power the SMPS. Find the 5 volt line with 5V-15A power and split that line into many USB type-C cable.
Buy a 5 volt 15 A power source
Or use 3 or 4 ,5V-3A BEC with 12 volt LiPo battery to power your boards.
Buy a USB hub for charging (Anker, Belkin, etc.) and use that. No need to go all the way to the wall for multiple PIs.
This guy built an interesting stack including a USB powered network hub. https://makezine.com/projects/build-a-compact-4-node-raspberry-pi-cluster/
I use a power strip like this to power my raspberry pi stack https://amzn.to/30M8ggt
The manager node in the black case is using an official pi power supply since it has a SSD for its drive. Stay away from "smart" USB ports for power
I bought 2 of these, 2 usbc 18W port, it works well but it's kinda bulky https://www.amazon.com/AmazonBasics-Two-Port-Charger-Tablets-Delivery/dp/B087MDRFWW
