There's a menu option on most modern iPhone models which will extend your battery life hugely - adding about four hours to the time it lasts.
‘Low Power Mode’ disables non-essential tasks such as visual effects – and stops your phone’s screen switching on when you get a message.
The mode, standard in all devices running iOS 9, can extend battery life by up to four hours, according to Boy Genius Report.
You just have to ensure it's switched on - as it's usually switched off unless your phone's battery is about to conk out.
By default, you’re offered an option to switch it on when your phone’s battery hits 20% – but you CAN have it on all the time, if you need your phone for the long haul.
Just go to Settings > Battery > Low Power Mode – or if you’re feeling flashy, ask Siri to enable Low Power Mode.
If your phone is charging, it turns off automatically at 80% – but you are offered an option to Enable Again (pictured above). Do it!