Hi!
I use this K551LN.
So far the battery is alright, nothing fantastic.
But the remarkable thing about the K551LN is not the battery.
I bought this notebook in late May, and it broke down THREE times already!!
I have went to the service centre FOUR times for the same problem, and each time the technician claim to solve a different issue.
IMO, the technician don't even know what is wrong with the notebook to begin solving the problem.
PLEASE THINK CAREFULLY BEFORE BUYING THIS NOTEBOOK, or you will have to visit 8, burn Road very often like me!!