Sometimes applications installed on the iPhone behave incorrectly and as a result, very quickly "drain" the battery charge, even while working in the background. This application can be one of the built-in programs, such as Calendar, Siri, or Mail.

This can happen because the application tries to connect to a certain server, can not do it, tries again and again, because of what the battery charge is consumed.

In this case, to extend the battery life of the iPhone, you need to reconnect all the accounts that are used on the smartphone. This can be an Apple ID, an account in an email, in any social network, etc..

If reauthorization does not fix the problem of fast battery drain, you may have to reset all settings of your iPhone.

To do this, go to Settings, select the item "Basic" and "Reset all settings". In the pop-up window, click on the "Reset".

If after the reboot the problem does not resolve, you may have to erase all the data, and start the iPhone as a new one. Remember that before starting the procedure, you need to copy all the important data to iCloud.

To track which of the applications consume the most battery charge, you can in the settings. To do this, go to Settings, select "Battery" and wait for the system to make calculations.