[sdiy] USB power (slightly off-topic)

[dh at atoav.com]

I am only going to comment on plan C as I did this before:

You can get yourself a beefy enough 5V PSU¹ and directly power the Raspi 
(per USB or by soldering two wires to the right pads. Then you connect 
your externals in parallel to the beefy power supply using thick enough 
wire (one for GND one for 5V).

Then for the USB data connection you connect anything, except for the 5V 
which comes already from the PSU directly. So: GND, Data+, Data- are 
connected, but no 5V.

For this you can just cut an USB-cable, strip the isolation and cut the 
5V wire and frankenstein everything back together. Alternatively you can 
get USB-powerblockers that do this for you. Make sure GND (0V) is still 
connected tho: GND is mostly for the shielding to protect your precious 
Data from stray EMF interference.

This way the current for the SSDs will be not running through the Raspi, 
but comes directly from the PSU and because the PSU-GND and the 
Raspi-GND is shared there should be no (harmful) voltage differential 
between the external 5V and Raspi 5V.

Note that with isolated PSUs this should even work with multiple such 
supplies as long as their secondary GNDs are connected.


Cheers,
David/atoav

---
¹ If you get a PSU that has connectors that go to mains power, please 
don't do this yourself unless you _really_ know what you are doing (e.g. 
you have been trained to do this). Mains voltage can kill you even hours 
after you had the very painful experience. By being smart this can be 
avoided from the start.

On 08/11/2022 19:28, Rutger Vlek wrote:
> Plan C, that just came to mind, is that I might be able to find a beefy 
> USB PSU with multiple ports, that I can use to feed the Pi from, as well 
> as the drives via Y-cable. The Y-cable would then be combining the power 
> from Pi's USB output with the direct output of the same PSU. Would that 
> work?