Sorry if this problem has been solved before, but nothing came up after a few searches.
I've had my N95 for two days now, but the battery indicator doesn't seem to move from full. After about 6 hours charge out of the box, i took it on a night out and used the camera heavily. The next night the battery died but i had no prior warning. I charged it up fully overnight and today i've been making calls and texting all day, but the charge level is still full.
Any ideas on how to fix this?
No not really, only advice I can give you is to 'bare with it' for a week or two and see if it changes/improves.
My N95 was also behaving somewhat strange regarding the battery indicator in the beginning. It could, as you say, stay on "full" for a looong time then to drop 3-5 steps in no-time.
I can't say it's typical for Li-on batteries but they do tend to require a period of "learning" before it it's able to display battery status more correctly (and it does also improve capacity during this "learning" period). I've seen the same issue with other phones that has Li-on batteries as well.
So, stay put and charge it everyday for a week or two (Li-on does not suffer from memory effect so you can safely charge when ever it suits you).