I have a few questions to ask. I have referred to many other similar questions, but couldn't get a straight forward answer to my questions.

Current situation: I just recently bought a Canakit Raspberry Pi 2 Kit. I want to use it as a media server and a file server (I am using one hard disk for each purpose). I have set up everything except that my hard disks are not getting enough power.

  1. What is the maximum safe power (current and voltage) that I can provide my raspberry pi using a power adapter?
  2. What is the power output by the USB ports on RPi and how to increase it. (I'm unable to power my hard disks through it. I want to connect 2 Hard disks)
  3. What is the required power/current adapter for my requirements? (Simply said, what adapter should I use for this)
  • You WILL need a powered USB hub unless the hard-drives have their own Power Supplies - although the later models including the 2 B have an option to increase the power available through the USB ports - I have a hard time believing it would be enough fornot just one but two HDDs!
    – SlySven
    Jan 3, 2016 at 0:40

1 Answer 1


The short answer is to use a powered USB hub to connect the drives to the Pi.


The Pi needs a 5 volt power supply. The Pi will only draw as much current as it needs so something between 1 and 2.5 amps should be fine. The one that came with your kit should be fine.

To change the amount of power supplied by the USB ports:

edit the /boot/config.txt set the max_usb_current=1

This will set the available current over USB to 1.2A (default is 600mA). For additional details see this question.

Also please note that shopping recommendations are off-topic per the site FAQ.

  • The max_usb_current=1 setting also seems to fail. Hard disk makes a sound indicating lack of current. So there is no way other than using a powered usb hub ?
    – Harish R
    Jan 2, 2016 at 15:40
  • 3
    @HarishR There are only so many ways of saying you need a powered hub for your drives.
    – joan
    Jan 2, 2016 at 16:07

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.