Tired of slow charging in old smartphones? So follow these steps and get fast charging up to 20% Older smartphones do not have a fast charging battery. The phone charges slowly. Sometimes the phone supports fast charging but it does not charge fast. You can eliminate this problem of charging with some settings in the phone. Following this setting will reduce the charging time by up to 20%. Secret setting in the phone The phone connected to the fast charging secretly has some settings. This setting is in the developer option of the phone. It has to be activated first. To apply this setting, first go to Phone Settings and go to About phone. Then tap on Build number at the bottom 7-8 times. Then go to Developer options. This option has a secret setting. Follow these steps When your phone has Developer options open it. This option will appear at the bottom of the settings at the top of About pho...