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USB PD chargers have protocols they follow, and most fast charging protocols operate at higher than 5V, which the Pi does not support. The default for 5V is typically 3A (15W). The Pi 5B supports 5V at 5A, which is in the PD spec, but uncommonly used or supported by 3rd parties.
So it's very likely that your 45W PD charger outputs less than the official 27W Pi5 PSU.
You'd be surprised how many "certified" USB3 drives are out of spec, and the introduction of USB-C has complicated things because it's often assumed USB-C can supply at least 3A at 5V (15W) so that 900mA spec doesn't apply to USB-C drives.
However, I would think that your Pi5 could reliably power a single drive, and you say it can't. Your 45W charger is the most likely culprit. It's probably trying to negotiate for a higher power mode the Pi doesn't support and defaulting to a "safe" low power mode (<3A).
Could be other things as well, such as the USB cables connecting the drives or the PSU to the Pi. Hard to say, but your best bet would be to try the official 27W Pi5 power supply.
No, that's not the way it works.Even at 12w Peak for a Pi5, that should still leave 33w for everything else, no?
USB PD chargers have protocols they follow, and most fast charging protocols operate at higher than 5V, which the Pi does not support. The default for 5V is typically 3A (15W). The Pi 5B supports 5V at 5A, which is in the PD spec, but uncommonly used or supported by 3rd parties.
So it's very likely that your 45W PD charger outputs less than the official 27W Pi5 PSU.
Wish it was that simple (but it's not).USB 3.0 and 3.1 allow 5V at 900 mA (4.5W) and the drive is "certified" which means it should only draw max 4.5W??
You'd be surprised how many "certified" USB3 drives are out of spec, and the introduction of USB-C has complicated things because it's often assumed USB-C can supply at least 3A at 5V (15W) so that 900mA spec doesn't apply to USB-C drives.
However, I would think that your Pi5 could reliably power a single drive, and you say it can't. Your 45W charger is the most likely culprit. It's probably trying to negotiate for a higher power mode the Pi doesn't support and defaulting to a "safe" low power mode (<3A).
Could be other things as well, such as the USB cables connecting the drives or the PSU to the Pi. Hard to say, but your best bet would be to try the official 27W Pi5 power supply.
Statistics: Posted by HawaiianPi — Wed Jan 24, 2024 11:03 pm