Why my battery draining fast?

[Windows Central Question]

I bought Lumia 730 four days ago. I installed all the updates and apps. i charged the phone fully for 10 hours. at 9 am i unplugged the charger then it was 100%. i just took 1 selfie and turn on the wifi and i found the battery went to 96% in 20 mins. I went my office and at 4pm the battery was near about 40% without any heavy use, just the wifi was on. I unistalled all the apps and just kept hike yesterday but still found to be draining quickly even in the battery saver mode. i just use Whatsapp and wechat in the background nothing else. Still having the draining trouble. what should i do?

 

[someone2639]

Hidden networks drain battery.

 

[Aziz Abdurachman]

Have you checked the usage in Battery Saver app? What app consume more battery?
In WP you don't need to keep apps run in background (just pressing Windows key instead of closing it), if you close it, it will save your battery and still running in background if you allow it to run in bg in battery saver app.