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I'm a bit lost in electricity stuff, but I want an USB hub to power supply my Raspberry Pi and my hard drive.

I know that there are lists of USB hubs for Raspberry Pi that works perfectly, but I want to know how can I choose a good USB hub in the store? What features have to be considered?

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2 Answers 2

up vote 4 down vote accepted

I reformulate:

  • You want an USB Hub that will be self-powered.
  • You want it to backfeed (power) your RPi by connecting the Hub and RPi through the mini-USB connector
  • You want to plug an HDD to your RPi through this USB Hub

You should first read this about backfeeding. I cannot recommend you to backfeed your RPi with your hub, it may not be safe and may lead to failures.

To choose your hub, you should consider the max power per port that can be delivered by the hub:

  • RPi needs 5V/1000mA (see this)
  • Your hard drive needs X V / Y mA (see hard drive user manual)

This should give you the required power per port for your hub.

You should also prefer a well known hub manufacturer than a cheap one.

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While preferring a "well known manufacturer" is good advice, beware that the USB 2.0 specification limits each port to 500 mA, and that if the hub is of a quality such that it meets the spec in all respects, each individual port will be limited to that! However, my understanding is that most low or mid-priced hubs don't regulate each port, and therefore you can draw up to the total amperage of the hub from any of them -- which is what you will need to power the pi itself... –  goldilocks Feb 12 at 16:05
    
...so don't buy the most expensive, highest quality hub you can find. You probably won't be able to find out by looking the box or online (but if it helps, I have a cheap Belkin and it's unregulated, so works for the pi). See also: elinux.org/RPi_Powered_USB_Hubs –  goldilocks Feb 12 at 16:08

A powered hub uses the power provided by a Wall wart to power USB devices instead of the computers power. In the case of the Raspberry Pi, a powered hub is necessary to power many devices such as hard drives, CD drives, etc. because powering all these devices would leave the Raspberry Pi under powered, leading to shorter component life and even a non functioning Pi. When looking for a good powered hub you want to look for the following:

Durability: You want to look at the construction of the hub itself, if you can see imperfections such as a warped side, or chips DON'T GET IT. If it already has these imperfections and is still brand new, this shows poor quality control. Which will later lead to more problems.

Number of Ports: The number of ports does matter, depending on the number of devices you want to power. You will want to get a hub that has enough ports to support all your devices.

Power Source: Many USB hubs will have a USB cable with 2 USB A ends on it. You DO NOT want this. These kinds of powered hubs get their power from the computer, not the wall. When looking for hubs You want to make sure that the wall wart is included.

Here is a list of the five Best USB Hubs, although I recommend the first two for you application.

Here is the one I use, It is a Raspberry Pi themed hub that works great and is VERY durable.

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