it won't reach it's full capacity until you have charged it from close-to-empty a few times. also, the player will last longer if you use its native format (ATRAC3 or plus) instead of mp3 - but you have to ask if you can be bothered converting your mp3s for a few extra hours listening, as not only will it take time to convert them, take up space on ur computers hd, but will invariably decrease the quality of the music, as it will have been compressed twice.
I've just bought a a Sony HD3, and i'm not hitting anywhere near 20-30hrs. After a full charge, I listened for 8hrs 50 mins and the battery gauge is showing 25% capacity left!!
I'd guess of the music i was listening to; 60% was atrac3+ 64kps and 40% was mp3 128-192kps. I haven't taken the vol. limiter off, and i had the vol. set to about 40-60%.
Thing is i bought it off ebay, and i'm thinking i've maybe bought a shagged out player! But then again its not been out long, so how could the battery be worn out? and its still gotta be under warranty.
The troubleshooter in the manual, offers this answer to the query of low battery life: "You have not used the player for a prolonged period. Efficiency of the battery will be improved by repeatedly charging and discharging"
Also, don't believe what the charge meter is showing. It may seem low at one point, and then if you don't use the unit for a few hours and then come back to it, the meter will show more charge available.