Ac adapter and also USB Hub

[Redux]

Hello everyone, this is my first post and I just received my pi today! I won't be using it just yet, I'm waiting on a wireless usb adapter and a usb hub.

My question is this: My pi came with an power adapter (canakit included it) to power the pi. Will it be safe to hook up this power and use my powered usb hub also powered? According to amazon, several people ordered the same hub as mine and used it with their pi, and were also able to power their pi with it. Would it be a good idea to just use the adapter that comes with the pi? Or should I power it with the USB hub? I wasn't sure if I should power both the pi with the adapter it comes with and the usb hub itself. I'm worried about giving too much power to the pi.

Thank you.. and here's the USB hub in question:
http://www.amazon.com/gp/product/B00552 ... UTF8&psc=1

[johndough]

Hi

The power adapter that came with the Pi is the one to use with the Pi.

The powered hub is for your accessories, and inevitably they are going to have a common USB cable between them.

I do not see any voltage/current specifications for the powered hub so it is difficult to assess.

If you have more details please post them.

[Sheila]

That power supply only gives 500mA per port and the RPi needs 700mA. It seems other people have been using it, but perhaps the things they are doing are not using much power. You could find it crashing and doing odd things as the logic levels drop below what it needs due to the current being inadequate.

Also, note that if a powered USB hub puts power into the RPi and you also have a separate power going to the RPi power port they can interfere with each other. One or the other is likely to die or go bang.

Somewhere there is a list of compatible powered USB hubs but I got mine from the Pi Hut which has one specifically for the RPi.

Another thing to bear in mind is that if you get a unregulated power supply the voltage will drop at higher currents. My present one is one of these, it is supposedly 5V 1A but actually only gives 4.93V by itself (not connected). Once I connect it to the RPi that's dropping to 4.79V when connected to the RPi. Works fine until I tried grounding pin 5 on the GPIO and then the camera refuses to work, probably because the power has dropped too low.