Before you go buying anything. If this is a new device and it isn't functioning as it should I would contact the seller about a replacement/exchange, or if past their return exchange date, then contact the manufacturer as it should be under warranty.
Yea before getting something I didn't realize you never said how long the battery was lasting before it would die.. OR what you were doing..
IF you were playing a game for example it will die quick.. if all you are doing is browsing the web it should last around 3 hours. but if you play games it can be a LOT less. (this is at around 50% brightness).
I have a higher performing laptop and it only gets around 2 hours of mixed usage for me.
I looked up a few more battery life things for that laptop and basicly IF you just have it on but dont use it.. NO wifi and on min brightness it should last around 12 hours.. IF you do some web stuff then you can go up to 5 hours (light usage and low brightness). at a full load on max brigtness it should last about 1.25 hours.