Default Problem With battery of LG l9 2

Hi, sorry for writing in The wrong section But there's no Place for LG d605. I noticed that battery falls down by 2% in 2% or 3% in 3%. For example When It is charged At 100% i unplug It And It stands at 100% for lots of minutes, than Fall down to 99% for few seconds And immediately at 98%for Very little time And than 97%, where It stands for minutes during The use of The device.
Why does it happen? Thanks for answere
Sent from my LG-D605 using xda app-developers app