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Your best bet is to 'work out the battery'. Drain it completely, plug it into a wall, let it charge completely, and then see how it does.

I haven't charged my phone in nearly 2 days (43 hours and counting) and I have 27% battery left. I couldn't be happier! Wayyyyy better than my 3G.
 
Did you completely charge it the first time? Before using it? You didn't let it finish charging last night, so I'm curious.

ETA: ummm... Ok.
 
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