Please do the following

Press and hold the power button then you will get this 4 options to power off and reboot

Now touch n hold the power off n u shall get an option to reboot in safe mode

Reboot the phone in safe mode and observe the battery if it's fine then it's the apps that u have installed if not then you need to visit a service center

Press thank button if helped

Sent from my HTC Desire 816 dual sim using XDA Free mobile app