There was a thread on this a few weeks back if it helps any....i bought one of the £5 ones from amazon and have been using it as a backup for when i'm away from home (a lot with work)...i don't use it often, or all the way to empty but just until i can recharge the original (so bought a desktop charge for £3 from ebay)...it works perfectly for me this way.

http://talk.maemo.org/showthread.php...heap+batteries