The “energy saving” mode reduces the amount of energy used by your mobile phone and therefore extends its autonomy by reducing the brightness, disabling automatic application updates, geolocation or automatic rotation of the screen. As soon as the battery drops below 20%, your phone prompts you to activate it. But it is also possible to put it at any time. To activate it on an Android phone, you have to go to the settings, select “battery and performance” and choose “battery saver”. To put it on an iPhone, you have to go to the settings, select “battery”, then “energy saving mode