Power supply for Model B

[sherif]

Hello, I was looking at elinux wiki about powering up a RPI Model B 256Mb of ram, As I did read it can handle up to 1200mA, I got a Nokia charger with output of 5.0V and 1200mA dose this hurt the RPI ? most users recommends the 1000mA , any advice if the 1200mA can burn up the RPI or not ?

Thank You

[jamesh]

That should be fine (in fact I'm been using a Nokia charger myself today). Although it can produce more current it will only do so if needed. Otherwise the Raspi just uses what it needs.

[Mobius]

The polyfuse on the input is supposed to blow if the current drain exceeds 1000ma. It's actually better to have reserve current capability on the power supply because they sometimes go down in voltage as they reach the maximum current output. In addition, the polyfuse has an internal resistance so it decreases the effective board voltage as the current drain increases. That won't damage the Pi but it's not guaranteed to run properly on less than 4.75 volts of input.

[sherif]

Thanks also I am planning to connect a wireless micro USB along with Keyboard + mouse wireless connected via single dongle Thx for the support.

Sherif

[ScottBouch]

Your Power Supply will provide 5V and up to 1.2A (1200mA)

The Pi, keyboard, mouse and any other gizmo's will only draw the current they need to draw. I have a 5V 10A (10,000mA) Power supply in my shed which I'm going to be using with the Pi. It will not hurt it, it just means the power supply has got the current available if called for by the loading devices (pi, kb, mouse, hdd, memory stick, wifi dongle, etc....

As Mobius points out, you should always use a PSU (Power Supply Unit) with higher current capability than the load requires. You may find that your Nokia 1.2A supply may struggle a bit depending on the USB devices you use. I think the lowest power way to use the Pi is to remote-desktop to it! That way you don't need a Keyboard or Mouse! I don;t know how much current your wireless dongle consumes for kb/mouse.

I mostly run my Pi in conjunction with a 2A powered USB hub. The USB hub provides power for the Pi and all USB devices. This 2A supply has struggled when running two External Hard Drives, but has been great for everything else.

I have struggled with some 1A PSU's on just Pi, keyboard and mouse, but I have a 1A car cigarette lighter PSU that works fine! (See my in-car video: http://youtu.be/F9FwQRZsdEE Some PSU's won't actually deliver what it says on the label, or the voltage may get "ripply" or "noisy" at high current loads which can mess with the pi's brain. I have however had the Pi working ok down to 4v and discussion: http://www.raspberrypi.org/phpBB3/viewt ... 28&t=11047.

You may not be able to use an external USB Hard Drive with the 1.2A supply.

Basically, add the power requirements of all USB devices togehther, add these to the Pi's power needs, and you'll have your total figure of what you Pi setup will need. Make sure you use a PSU with a capability greater than this total need.

Good Luck, Scott.

[ScottBouch]

Forgot to add, one clear way to recognise if you have PSU's issues, is that when typing (with conventional USB keyboard), your last keypress will get repeated...

eg: "hello" will appear as:

"hhhhhhhhhhhhhhhhhhhhheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeellllllllllllllllllllllllllllllllllllloooooooooooooooooooooooooooooooo" and on and on.....

Cheers, Scott.