http://www.amazon.co.uk/gp/product/B006STOKTO/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Battery Overview

at £12.24 this is a bargin, and after fully charging it, configuring linux to disable usb, webcap, ethernet adapter and a whole bunch of other stuff i don't use to browse the net, I now have over three hours of battery life to browse the net with.

Testing the Battery

current up time; up 45 min (whilst debbuging the machine), with an estimated 2hr 20mins left :)

a couple of these work great instead of an official one for £70+