I have buy recently BV6000S,number of version 20170605,and i am not happy with battery life. I have only installed few apps like facebook,viber,whatssup,nothing else,and i am not all day connected to internet or wifi,and yesterday battery was charged full,second day i have only like now 18%

Before i was using BV5000 and there battery life was great,but unfortunately i have broken the display,and guys when they try to repair it,they have made some internal damage as well.
And i have all day long battery on power save mode,but doesnt help much,is there any trick that i can try,or update maybe?
Thanks!