fixed
Now then guys, i realiwe this is a bit of a dead thread but thought this might be useful to others with the problem. The problem is caused by a dodgy micro usb socket. First thing to try is cleaning the socket. I used isopropyl alcohol on a toothbrush. If that doesnt work (didnt for me) and you dont mind losing the dock function completely you can use nodock from play store. You need root, but this deactivates the function at kernel level. Ive gone from losing20% battery per hour and being woken up by the incessant charging not charging beeps to perfect functionality and a battery consumption of 1.5 - 2% per hour. For information i was quoted 35 quid for engineer to replace the socket.
Hope this helps someone!
Tomo