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How to work around power limitations of the USB ports on the Pi4?

Posted: Sat Jan 18, 2020 8:27 pm
by Pxtl
Hey all,

I've got a Pi4 with the official power supply running Lakka (LibELEC+RetroArch) and 3 wireless USB dongle-based game controllers and a 512GB USB HDD (no power-port on that one to augment that way). When the drive gets accessed, the controllers flake out - elongation, delay, cutting out, etc. I'm pretty sure it's a power problem (amperage, not voltage - no voltage lightning bolt complaint). This even occurs on the USB2 port, so I assume it's a power issue and not that it's starving the controllers of bandwidth.

So, 2 questions:

1) Is there any way to diagnose/log USB power problems?
2) Ideas on best way to get more power? I can see three avenues:
- Powered USB hub.
- Some way to get more power on the USB ports - beefier power supply?
- Switch to an external storage that doesn't draw so much power.

I'd hate to have a rats'-nest of cables to power this thing, with a power-supply for the USB hub and another supply for the Pi4 itself, but I assume that's the only realistic option.

Thoughts?

Re: How to work around power limitations of the USB ports on the Pi4?

Posted: Sat Jan 18, 2020 10:03 pm
by dustnbone
Pretty much, yes, a powered hub is your only option without some serious hardware hacking. The limitiation isn't the power supply itself, but a regulator on the board that limits total USB power output to 1.2A. This power is shared across all 4 USB ports.

Re: How to work around power limitations of the USB ports on the Pi4?

Posted: Sat Jan 18, 2020 10:18 pm
by LTolledo
There were some who did board hacks (that though will void warranty) and were successful

Powered USB hubs is, as already mentioned, your next best bet
do note that there are some USB3.0 hubs that dont work well with the RPi.
I've yet to see a good list of known powered USB 3.0 hubs that work well with RPi4B, maybe someone generous can open a new topic and post it there.
if HDD access speed is not that critical, using a powered USB2.0 hub for that may be better.

Re: How to work around power limitations of the USB ports on the Pi4?

Posted: Sat Jan 18, 2020 11:30 pm
by W. H. Heydt
Another alternative would be to swap the HDD for an SSD, carefully picking one with low power specs.

Re: How to work around power limitations of the USB ports on the Pi4?

Posted: Sat Jan 18, 2020 11:39 pm
by LTolledo
W. H. Heydt wrote: Another alternative would be to swap the HDD for an SSD, carefully picking one with low power specs.
definitely the above change to SSD recommendation is much better than what I posted. go for this! :D

Re: How to work around power limitations of the USB ports on the Pi4?

Posted: Sun Jan 19, 2020 4:53 pm
by rjbook51
W. H. Heydt wrote:
Sat Jan 18, 2020 11:30 pm
Another alternative would be to swap the HDD for an SSD, carefully picking one with low power specs.
Depending on the size of the SSD you're looking at way more money that what the Pi is worth! :|

I have not found a usb 3 powered hub, with 5V power supply that will work with the Pi 4 and power a usb powered HDD or SSD!

What I have found that works, is any 12V HDD enclosure that I own,, or desktop external drive, USB2 or 3 and 3.5 inch drives.
I have also found that 12V USB 2 and 3 Docks work without fail. I own 2 thermaltake docskscand one nextar...no problem.

So any of the 12V enclosures or docks will not backfeed on the Pi. If they did, I expect they would fry the board.
They work, but not exactly portable, and I am not happy about it. :evil:

Re: How to work around power limitations of the USB ports on the Pi4?

Posted: Sun Jan 19, 2020 4:58 pm
by croft
hi
please look at croft for ansers to this question

a powered usb 3 hub may work

or a cable modified and 5 volt psu

thanks
croft

Re: How to work around power limitations of the USB ports on the Pi4?

Posted: Mon Jan 20, 2020 3:22 am
by dustnbone
rjbook51 wrote:
Sun Jan 19, 2020 4:53 pm

I have not found a usb 3 powered hub, with 5V power supply that will work with the Pi 4 and power a usb powered HDD or SSD!
i have one of these and I've tested it with an SSD and a 2.5" HDD and both seemed fine. Only issue I had was it backpowering the Pi4 and not allowing it to restart, but new firmware seems to have fixed that.

https://www.aliexpress.com/item/32691812366.html

Aliexpress says it's not available but I got mine at my local computer store, no brand markings at all that I can see.

Re: How to work around power limitations of the USB ports on the Pi4?

Posted: Mon Jan 20, 2020 5:31 am
by chipace
Rather than pay $20 for a new powered USB 3.0 hub, you could put the money towards a new powered USB HDD. Don't know if you need more than 512GB, but 8TB drives are a little over $100 these days. Lots of space to grow into.

Re: How to work around power limitations of the USB ports on the Pi4?

Posted: Mon Jan 20, 2020 7:11 am
by BeauSlim
Are you seeing a low-power warning? I bet it is the USB3 ports interfering with 2.4 GHz.
See https://www.intel.ca/content/www/ca/en/ ... paper.html
I get the same thing with wireless keyboard dongles. Using an extension cable with the dongle eliminates the problem.