hi all, need help

my N3 have charging problem.
after using original S-view cover, face extreme slow charging speed.

i do some test on my phone, before turn on charging i restart my phone 1st.
screen show 9% battery available.
only with wifi turn on. result i get after 20 min just increase to 13% 
use original charger.

i remove the cover and battery, then instantly assemble back i got 16% shown on screen...
something goes wrong...

after that continue charging found the charging speed back to normal already.
10min increase to 26%.

to get normal charging speed every time i have to remove cover and battery and assemble back....
or else it will very slow... i experience worst 4 hours only 60%.

before i use s view cover, do not have this issue with N3 phone cover.
when i change back to ori phone cover, can easily charge full not more than 2 hours...

do any one face same issue, any advice what is going wrong???
battery problem? s view cover problem? or phone problem???

help please.