quite heavy use.... I managed to use this phone for almost 2 days...

Enable Battery Saving Mode:

1. On the home screen, swipe the “Status” bar down using two fingers
2. Tap the “Battery Saver” tile to enable the feature
3. For additional Battery Saver options, open “Settings”
4. Then, tap “Battery” > “Battery saver”
5. Tap “Turn on automatically” and select a battery percentage at which the mode enables automatically

Turn Off Unused Connectivity Features:

NOTE: By turning off connectivity options when unused, including Wi-Fi, Bluetooth, and Hotspot, you can improve battery life in the long run.

1. Swipe the “Status” bar down on the home screen using two fingers
2. Open “Settings”
3. Under “Wireless & networks” tap “More”
4. Enable “Airplane mode”
5. To turn off Wi-Fi, tap the “Wi-Fi” switch OFF
6. To disable Hotspot, first tap “Tethering & portable hotspot” and set the switch OFF
7. To turn off Bluetooth, go to “Settings” and disable “Bluetooth” by tapping the switch

Change GPS Settings:

1. Open “Settings”
2. Scroll to and tap “Location”
3. Tap the Location switch to OFF

Forget Wi-Fi Networks:

NOTE: By forgetting saved Wi-Fi networks that are no longer in use (particularly networks using hidden SSID) you might improve battery life in the long run.

1. Go to “Settings”
2. Tap “Wi-Fi” and make sure the feature is enabled
3. Tap “Menu”
4. Go to “Saved networks”
5. Select the desired network and tap “Forget”