I have a SATA->USB bridge that will power 2.5" drives up to 500mA. The problem is that i have drives that run .55A up to 1A that need powering. I tried rigging up my own Y cable but that doesn't seem to be doing it. Can I splice in power from a 5V 4A DC PSU that I have laying around straight into the USB line to power the drive bridge? Will the overcurrent kill anything? Do I need to add a diode so it doesn't try and flow into the USB port on the computer/hub?

Many thanks.

EDIT: In case anyone wants to try something similar

I cut the VCC going to the computer and spliced in the 5V PSU into the VCC on the USB going to the bridge. I connected the data cables (green-green & white-white) and all three GRND wires together. Here is a pic of the setup as it is:

• http://i.imgur.com/64tkzXr.jpg

Make sure to connect the PSU and the USB to the bridge before plugging the other USB end into the computer. It is working so far and the bridge is not complaining about the extra amps, it seems to be using them to power the drive and discarding any unnecessary current.