Reply by: PowerExpert
They dont usually draw the full 3a unless youre really pushing them. Under normal load expect around 1.5-2a per pi. For 8 pi's i'd get a 60-80 watt usb power supply with multiple ports just to be safe. Make sure its a quality one though, cheap power supplies can cause instability. Anker makes good ones. Or you could use a atx power supply with usb adapters if you have one lying around.

Username: ClusterBuilder
Posted: 3 days ago
Building a cluster of 8 raspberry pi 4's for kubernetes learning. What kind of power supply do i need? Each pi needs 3a at 5v according to specs but do they actually draw that much under normal load? Trying to figure out if i can use a single power supply or need multiple.