Some users often complain that their battery drains very quickly and the phone gets heated up. There are few basic reasons for this issue discussed as follows:
Turning the screen display on for long time consumes drains battery quickly. Smartphone these days have high resolution large HD display which consumes high battery power if kept on for long duration of time.
It can be managed from display settings of the device. Screen should shut off after few minutes of inactivity.
Frequent use of maps application causes device constantly searching for accurate GPS signal and location. Disable the maps application or any other application which uses GPS service of device even if not required. An application or widget could be installed to could check whether GPS were really turned off. In some occasions, GPS run in the background, after using Google Navigation, without displaying the icon.
A weak 3G connection in poor coverage area may be causing the problem. Mobile phone may be constantly switching between 3G and 2G connection to search strong signal. This could definitely lead the battery to consume quicker than if it had a stable connection and activating the 2G or 3G only option solved the issue. Update the radio firmware as sometimes device switch between E, 3G, H and H+ but without any actual data usage.
Automatic updates should be turned off for the applications as it continuously use data and also drain battery.
Battery usage can be monitored from Settings -> Power Management -> Battery Usage to check applications which are consuming most battery resources. If data seems inaccurate, then third party application could be downloaded from play store to check power usage. In general, top battery consuming apps are Display, Android OS, Cell Standby, Android System, Wifi and Chrome.