How do I connect my new HP flash drive to my Mac?
Question by Alonso Aguirre /

Hello!

I know it sounds kind of newbie but my (Mac) computer doesn’t recognize my new flash drive, a HP V225w. I have tried with other Macs and they recognize it, but mine doesn’t. I’ve even change it to a Mac format and still the same. When I connected directly nothing appeared, but if I connected with an adapter, the following message appears:

“A USB device needs more power.

A USB device can’t draw enough power to operate properly. If the device came with a power cord, plug it into an electrical outlet. Otherwise, connect the device to a USB port on your computer.”

I don’t know what to do, can anyone help me please?

Thanks!

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Answers (7)
  • ha14

    buy an AC powered (power adapter) USB hub, the hub plugs into you Mac’s USB port and provides 3 or more powered USB ports.

    reset the System Management Controller (SMC) see if it will help.
    http://support.apple.com/kb/HT3964?viewlocale=en_US

  • Anish Parameshwaran

    Perhaps since this is a new flash drive and your mac may not be as new, this could be an issue arising from USB 3.0 flash drive being inserted into a mac with USB 1.0 slot. However, I suggest that you take your laptop along with the flash drive to the apple store since there may be an issue with your mac.

    • James Bruce

      It’s USB2, checked the model number. It would be helpful to know the Mac model as well though, not sure if older devices have USB2…

  • Jim Chambers

    Perhaps the USB port is damaged and power contact isn’t connecting. Look in port to see if the 4 contacts look the same. Try another USB port on your Mac.

  • Oron Joffe

    The fault is consistent with the error your got. Your Mac is not supplying enough power for your USB drive. This sometimes happens with USB drives that require more than the specification 500ma power (common in USB hard discs), or when the USB port itself produces less than that, but I must admit I’ve never seen this happen on a Mac.
    At any rate, the workaround is to use a powered hub (that is, a USB hub with its own power supply).

    • Alonso Aguirre

      I’ve gone to the system report on my mac and it says that the current on each hub is 500ma so I actually don’t know what to do? That was the reason I proved with other macs so maybe it happens on all of them but, no each mac I tried it on can read perfectly without problems.

    • Oron Joffe

      Hi Alonso, I’m sorry. I think my explanation wasn’t sufficiently clear. Let me try again, though I’m afraid this explanation will be longer.

      First of all, I’m assuming this is a “bus powered” drive (i.e. not powered by mains or battery), and that it is USB 1.1 or 2, not USB 3.0 (though for USB 3.0 the solution wouldl be the same). I’m also assuming that you are using a desktop Mac (though the answer would have to be the same for a laptop).

      The USB specification allows devices to draw up to 500ma at 5V from the USB port. A higher load should trigger a safety mechanism which, on your Mac, results in the error you got.

      Now, engineering being engineering, it is not possible to design the USB ports to reach the PRECISE 500ma limit, there is a tolerance. Let’s say the tolerance is 2%, so a particular USB port may in fact supply anywhere between 490 to 510ma. Your Mac REPORTS 500ma because that’s how it was designed, but those engineering differences exist nonetheless.

      The same applies to the USB drive. It SHOULDN’T require more than 500ma, but if the design sails very close to the wind, it’s possible that an individual specimen may exceed it.

      So let’s say your drive is at the high end and draws 510ma, and your Mac (at least the port you are using) cuts off at 490ma. As you can see, we end up with a “deficit” of 20ma, the Mac would cut off the device and display an error message.

      There is nothing practical you can do to “fix” your Mac, as you would need to replace the Motherboard, and possibly the power supply. There are, however, things you can do to mitigate the effects, or work around the problem:

      1. If this is a Mac, try a different port. (by the way, you are plugging the USB drive to the back of your Mac, not into the keyboard?)

      2. If this failed, get a USB hub with its own power supply, connect it to the Mac and plug the USB drive into it. The USB drive will draw the power from the hub, and with any luck will supply enough “juice” for your drive.

      3. If that fails too, test your Mac with some other USB devices, and once you are convinced that the USB port is OK, get another USB drive.