Battery Draining Fast Issue

[Ble_uu]

Hi, 

I'm using Xperia C5 and it's been fee weeks back I experienced the battery Draining in flash, even I have charge it fully to 100% and its like only last for less than an hour. It drops so fast.

Once I saw the indicator showing 75% but when i open whatsapp it's shutting down immediately.

Please help, the it suffers me alot.

Thanks.