[sdiy] USB power (slightly off-topic)

[cheater cheater]

If you want a lot of USB ports, save yourself the trouble and buy one
of those. they're extremely reliable. I use the 16 port version
myself. The wallwart is beefy.

https://de.aliexpress.com/item/1005003391622141.html

https://de.aliexpress.com/item/4000249543061.html

https://de.aliexpress.com/item/4001241352721.html

https://de.aliexpress.com/item/1005003707226040.html

https://de.aliexpress.com/item/32895214936.html

https://de.aliexpress.com/item/1005003935717973.html

https://de.aliexpress.com/item/1005003395173402.html

https://www.amazon.com/Splitter-Adapter-Individual-Switches-Computer/dp/B07G8S324L

https://www.amazon.com/Powered-USB-Hub-Individual-Switches/dp/B07JM9ZFFV

https://www.amazon.com/Charging-Individual-Switches-Computer-More%EF%BC%88Purple%EF%BC%89/dp/B089NTKX14

They come in various different brands, I have Acasis and I-Tec,
they're both very reliable. All that's different is the name silk
screened on the face plate, and possibly the chassis color is either
metallic blue or black. Just search whatever store front for "acasis
hub" or "16 port usb hub" and you'll find one that looks exactly like
that, then find the version with the right amount of ports for you.
Budget two ports for each SSD you need.

When buying the Y cables, buy ones that are USB 3 or 3.1 - otherwise
you will get terrible speeds. I assume your SSDs have USB C on them.
You can use this cable, which says it's USB 3.1:

https://www.amazon.com/USB-C-Extra-Power-Cable-Phone/dp/B01LAV03KE

However, if you don't need it immediately, I'd first try hooking up
the drives via a normal A to C cable (with a single A connector), and
see how they work. USB hubs often have power budgets that are shared
across all the ports. You might well be able to get that extra power
from a single port, even though officially these hubs only support
1.3A per port.

Of course, if you hadn't already purchased the SSD's, I'd have told
you not to use USB for data storage, and instead get a SAS controller
card and use SATA drives with it. Ultimately not just cheaper but way
more reliable, but it requires a pc with at least a pcie x1 slot.

On Tue, Nov 8, 2022 at 8:33 PM Rutger Vlek via Synth-diy
<synth-diy at synth-diy.org> wrote:
>
> Dear list,
>
> I hope you don't mind me tapping into our collective list wisdom for something slightly non-synth related. The case is as follows:
>
> I'm building a NAS at home from a Raspberry Pi 4B and a couple of SSDs. The SSDs are connected to the Pi via a SATA-to-USB converter. They work, but stop working when used intensively. Not to my surprise, because the power requirement of the drive is 1.7A at 5V each. The Pi USB ports can only deliver 1.2A at most (and shared between 2 ports). So I need a more beefy supply. My initial idea was to buy a couple of these USB Y-cables that have two USB-A connectors on one side, allowing the user to provide the paralleled power of two USB ports. However, even on a single port, the Pi already reaches it's limits. So I thought, why not plug the second USB-A plug of the Y-cable into a USB-charge, so that it can provide all the current needed by the drives. However, I have a bad feeling about this...
>
> I don't have a clue about the internals of a typical USB Y-cable, and have not been able to find any datasheets on them. In the worst case, power from the Pi's USB port would just be connected directly to the power output of the USB-charger, and that does not sound like a good idea. They might not be at the exact same voltage, and I since both of them are SMPS's, I don't know if they'll somehow start interfering with each other. If only there would be some series diodes internally present in the Y-cable, but I have no clue if there are... Does anyone know (or can measure)?
>
> Plan B was to buy a powered USB hub, but I struggle to find one that can deliver the required 1.7A at 5V on multiple of its ports at the same time.
>
> 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?
>
> Plan D would be to make my own power distribution board, where USB connectors pass data between the Pi and the disks (but no power), and power is injected from a DC barrel plug (and some filtering)
>
> What do you think would be the best approach?
>
> Rutger
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