Issue 1 -> Power Supply
Issue 2 -> Usb Power
Issue 3 -> Wi-Fi power saving
Issue 1: Power Supply
Get a decent power supply from the start the one sold by the SWAG shop is reliable get it here
http://swag.raspberrypi.org/collections ... wer-supply
Issue 2: USB Power
Sadly this change alone did not fix my problem I constantly suffered brownouts and found that when I initiated high levels of wi-fi traffic the pi became totally unresponsive.
You can solve the problem with a powered usb hub however this did not suit me and the SWAG power supply already outputted a good 2Amps so I already had the power available...
After a lot of reading of schematics and other peoples attempts I decided to jump straight from the power supply to usb port. You just need two bits of insulated wire and some very careful soldering. Be careful not to overheat the components and to keep the exposed wire to a minimum as its easy to short across nearby contacts. I bridged the usb power connectors with solder to provide a better connection to the wire though it probably does not make a real difference.
This is what I have done and its worked fine, however I do not take any responsibility for damages caused to your pi in copying this method.
right click open in new tab to see larger image I have been told the ground wire is theoretically doing nothing however on testing I noticed a voltage drop when disconnected of about 0.3 volts. My theory is that the ground trace is too long or thin and has a higher resistance than it should. This may be unique to my pi but please if you try this mod post your voltage readings before and after!
Issue 3: Wi-Fi power saving
With this mod I no longer got the brownouts when under load but after 12-24hrs wifi disconnected again. A bit of a search revealed that power saving mode was the issue, when enabled it can cause the wifi adapter to stop working and never reconnect.
To disable wi-fi power saving
open the config in your favourite editor (I will be using vim you can use nano)
move the cursor down below "auto lo"
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sudo vim /etc/network/interfaces
hit the O key to insert a new line below
add this text
press :w to save and :q to quit vim
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reboot the pi and you should now have stable wi-fi