Battery Life

[Fenclare]

I have just taken delivery of the above MP4 player, but am having trouble. The battery was fully charged from my PC (the mains charger supplied appears not to work) I have added about 200 tracks, no problem.
However the unit's battery seems to last under 2 hours, goes from 1/2 charge to low battery in a matter of minutes. The display shows 'low battery' and then switches off.
I cannot believe this is right - what is the battery life?

[AFF]

Generally speaking, you should get 4 to 5 hours from a full charge.

This could be due to a faulty battery or an irregular file type.