I recently bought a raspberry pi 2 B and I was planning using an external HDD with it (this one: http://www.newegg.com/Product/Product.aspx?Item=N82E16822236569) and I'm wondering if this PSU will work with it: https://i.stack.imgur.com/uwXbR.jpg 5.35v and 2A Will I turn into any issues with this? Thanks! :)

  • The Pi2 has a 2 amp fuse at the microUSB so there is no point in a larger power supply (if you are powering the Pi conventionally).
    – joan
    Aug 31, 2015 at 13:16
  • My question is if I will be able to run it with an external HDD that takes all its power from the PI2
    – Morish
    Aug 31, 2015 at 13:22
  • How much power does your external HDD need?
    – joan
    Aug 31, 2015 at 13:29
  • I'm not sure I haven't decided if I should buy a 2,5" or 3.5", I'm pretty new to this so I don't really know if this is possible, I've been reading around and some people say I need an USB hub to power a 2.5" hdd since they don't usually have any external power. Is this still necesary with a Raspi 2 model B? and also I read that the power for my Pi should be 5v 2A, but my PSU will be 5.35v, can this kill my pi?
    – Morish
    Aug 31, 2015 at 16:56
  • 5.35V will be fine for the Pi (for the Pi >5.9V is the real killer). USB devices should be fed between 4.75 and 5.25 volts, but I'd have no qualms with 5.35V. It's your kit, your risk. 2.5" drives would normally work from a USB socket. 3.5" drives normally would not.
    – joan
    Aug 31, 2015 at 17:20

1 Answer 1


Had a similar problem using the 314GB WD PiDrive and an additional WiFi dongle. The default setting of the Raspberry limits available current for the USB ports, so using both devices did not work at first. Setting max_usb_current=1 in /boot/config.txt fixed the issue.

So now i successfully use an USB HDD and a Wifi dongle together, using an 2 Amps power supply. In the end it will depend on how much current your devices draw from the USB ports. From what i have read, max_usb_current=1 will raise the limit to 1,2 Amps. However, i would not try this without an 2 Amp power supply as the Raspi will get unstable when there is not enough current available.

See also https://www.raspberrypi.org/forums/viewtopic.php?f=46&t=102634

  • Using a powered USB hub would be a safer option, opposed to forcing as much current through the USB ports as possible.
    – Darth Vader
    May 8, 2016 at 8:08
  • That is of course correct - yet since the PiDrive claimed to be designed for use with the Raspi i had the impression it should be possible to use this device without an USB hub. And being a lazy guy i did not want to start another shopping tour while being impatient to get this thing working... maybe not the best strategy. May 8, 2016 at 15:10
  • BTW i am quite happy i did not grill my Arduino yet, done worse things with that one. May 8, 2016 at 15:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.