Joffa,
180mAh rating is quite low. A battery upgrade would be a worthwhile investment provided you can find one that fits the limited available space.
I have upgraded the batteries in 2 of my players (Not Nano Clones) one had a lot of battery space and I was able to use a 850mAh iPod replacement battery and now get around 18 hours on a single charge.
http://www.mympxplayer.org/18-hours-...ge-vt2412.html
The other I used a 650mAh iPod Mini replacement battery and get around 15 hours playtime.
Both players have worked perfectly since the upgrades.