Cell phones, tablets, and other mobile devices can be very useful during winter storms and emergency situations -- the Indiana Department of Homeland Security reminds Hoosiers that you can be ready if a situation arises by fully charging your devices beforehand. Plug devices into a surge protector power strip to charge them. Charge devices to the full battery capacity. To conserve energy and battery power, close out of smartphone apps after using them. Consider turning off other capabilities such as Bluetooth, that drain batteries faster. If you must drive, use a car charger to charge devices that you may need, like cell phones and GPS devices.