Leaving Bluetooth and Wifi On
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Even when they aren't synced up to a specific device, Bluetooth and Wifi are colossal power drains, as devices regularly cast about for a suitable connection, flooding their surroundings with radio waves. Toggling these features off when they aren't in use will extend the capacity of batteries dramatically, and lengthen their overall life. It's not an obscure, menu-diving operation, either – click on the Bluetooth or Wifi icon at the top of your computer screen, or swipe to your settings from nearly any screen on an Android or iOS device, and tap the features off.