I have a 2.5" HDD with two wires, one for USB data and another for USB power. It works perfectly if I connect the USB power cable to the power.

Now, I need to move the raspberry pi and the HDD, so I bought an USB extension cable for the USB power wire of the HDD. But it doesn't work. Why?

Is there any problem with the USB extension cable? Should I buy a new extension cable or should I buy a power USB hub?

  • 1
    what's the HDD model/maker?
    – lenik
    Oct 30, 2013 at 0:06

1 Answer 1


The extra length of the extension cable may drop the voltage enough to cause the failure you are seeing, or you may have a bad cable.Either way power hungry devices such as you HDD should not be powered directly from the Pi for just this reason, even if they seem to work.

You should invest in a powered USB hub. Ideally, one from the verified working peripheral list

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