WHY IS MY BATTERY GOING QUICK??!!!!!?

[Abdul]

I have a Samsung galaxy ace 2 that has a 1500 mah battery but for some reason it acts like as if its a 1300-1400 mah battery. I've had this phone about 4 months and it is not rooted. I only have one widget on the screen and thats it. This started happening for about a week. The apps i don't use can't be deleted from my system because they are already installed into my phone (e.g. Google+ and google messenger).
These are the apps i do use:
Whatsapp
BatteryBot (original name was Battery Indicator)
Dolphin Web Browser
Aptoid
Blackmart
Easy Cache Cleaner
Glovebox
Best Android Market
Dropbox
Adobe Flash Player
Fast Burst Camera
Instagram
Taptu- DJ your news
Advanced Task Killer
ZArchiver
Angry Gran Run
Little Nick The Great Escape
ZombieWood
Pocket Rally
Android weather
Samurai 2: Vengeance

Please do help. Thank you!

[petee p]

Use ds battery saver it stops yr phone using battery when the screen is off.