I had this phone 7 months and then started losing power, reinstalled FnC 6 (my fave) and ran loads of tests. Got a replacement battery for £10 and was happy again a few months. I always always got good power retension up until changing the battery and then after fitting the new one, up until it started again. I put the Micro SD and the 02 card in another non Android phone and decided to use that until I had enough for a new phone. I decided against another new battery, but really hated the fact that I could no longer use this phone, I love it to bits.
The non Android phone went flat overnight and was turned off when I awoke, yet it started with 100% power and I knew this phone normally lasted 5 days+. Straight away I suspected one of the cards, 02 or Micro SD. It turned out it was the Micro SD Card, so I copied the contents, formatted the card in the phone, replaced the contents, started the phone and ran Titanium Backup. Overnight the phone only lost 1% where normally even when I was happy with the power usage it lost 8% overnight. Two days in with slight use I still have 80% power left and I am well happy at this and the prospect of continuing to use the phone I love to bits. The Micro SD Card is a cheap 16gig Adata one and though a more expensive one may have helped people will fit their purchases to their budget. So this is a post to inform others that it's not always the end of the world with power issues and it's not always the most obvious of causes and/or replacements.
Just a FYI and hope it helps someone......
*** Just remember, any ROM change, Kernel change or any other type of change you do is at your own risk. Someone helping you is not responsible for any risks you decide to take. It works for many but their are situations, events and errors outside of the control of a third party that may cause a bricked phone. Think before you start. I took the chance and thankfully it worked for me. Had it not then only I would have been to blame. ***