I would like to connect two external 2.5 HDDs a Pi 4. Can the Pi 4 power two of them at once?
This is the model I have in mind: WD 2TB Elements
Raspberry Pi Stack Exchange is a question and answer site for users and developers of hardware and software for Raspberry Pi. It only takes a minute to sign up.Sign up to join this community
Not without voiding your warranty. An RPi4 can deliver a maximum of 1.2 A to all the USB ports together. This is done to protect the USB-C connector which is rated for 3A maximum.
The disks you have in mind consume up to 1 A each. Without touching to the Pi, you'll need to use a powered USB hub or a bigger-capacity single disk. If you don't care about the warranty of your Raspberry and you're powering it externally, you can bypass the current limitation by connecting the 5V GPIO pin to the Ubat pin of USB directly (check out the semi-translucent copper wire):