ipod shuffle battery backup is not satisfactory

Hello I bought an ipod shuffle 4G 2/3 months ago from Singapore Apple Store. So there is no chance of the device of being faulty. While the shuffle was supposed to give me back up of 8-10 hours but in my case when i hear songs like for 30-40 minutes then it suddenly says "battery low" and turns off automatically. When i on the shuffle once again after few minutes it says battery is 75%. And the problem continues. So far I haven't got any idea of the actual battery backup of the device. There is no physical support available in the country I am in right now. What can I do get rid off the problem?

PS: The device OS and iTuens OS is completely up to date.