USB power delivery is...not straightforward. With an old school USB-A/B style port, you may get up to 1.5A @ 5V, but I think that requires both the port and the cable to support it. On a modern computer, you'll more likely get 0.9A @ 5V from USB 3.0/SuperSpeed ports. At least, that's the spec. Lots of gear goes their own way and does something else, and I've run into a pretty new computer that had a "front USB port" header that delivered only the old school 500mA @ 5V.
-- Kelly With USB-C ports and cables, there are a ton of profiles, I don't know what the new Pi's support, but likely something like 3A @ 5V, 9V, or 12V over USB-C On Sun, Sep 15, 2024 at 10:41 PM Jim Klimov via Nut-upsuser < [email protected]> wrote: > At least, the power-hungry RPi5 8GB model did boot and is running for a > few hours now. The USB3-capable ports on the MoBo probably are able to feed > the needed ~5A at 5V? I just pulled the USB-C cable near the fan (large > enough grill) from a connector near the keyboard to the Pi hanging inside > the well-cooled case. > > Also note the PiKVM project (something I thought of but did not adopt > here, more HW needed) or some relative thereof, which may use a PCI card as > a dock for a Pi (maybe Compute Module). Though oddly the ones I've read > about used PCI only for power (and physical containment) but not as e.g. a > way to pose as actual PCI - a video card and other devices, all those > needed separate cabling anyway. > > I suppose an (unmanaged) fan power socket, or one of ATX connectors, could > also be used. At least as an input to a demo PiJuice HAT I had lying around > (documented to accept 4V-10V from external sources), but it is too weak to > boot up an RPi5. Allegedly can run one if booted directly, did not try yet. > > Jim > > > On Sun, Sep 15, 2024 at 6:31 PM Greg Troxel via Nut-upsuser < > [email protected]> wrote: > >> Jim Klimov via Nut-upsuser <[email protected]> writes: >> >> > I am experimenting with a Raspberry Pi, and it is fed from my PC >> > (Debian-ish Linux) that is in turn protected by an UPS - so runs NUT. >> > >> > As far as the Pi is concerned, the bigger computer is its wall power >> > source (provides the USB socket) and being a smart machine with NUT >> > running, it could pose as an UPS itself. That is, if the big computer is >> > going to shut down (including probably rebooting, as I expect the >> > motherboard to power-cycle its USB ports), it should issue FSD on some >> > bare-bone driver *AND* wait for clients (like upsmon running on the Pi) >> to >> > disconnect before proceeding with its own power-off/reboot. >> >> Wow, I never would have guessed that this is a workable approach >> (running the Pi this way not the nut part). Do you have ports that are >> more than 500 mA, and does the Pi (pi0?) really work with 5V 500 mA? >> >> _______________________________________________ >> Nut-upsuser mailing list >> [email protected] >> https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/nut-upsuser >> > _______________________________________________ > Nut-upsuser mailing list > [email protected] > https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/nut-upsuser >
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