Android only: When your phone is scanning for potential Wi-Fi connections, it’s using battery power it doesn’t need to. Free app Y5 Battery Saver periodically checks your location, without GPS, and turns on Wi-Fi if you’re home or at another previous connection.
Y5 watches as you connect to Wi-Fi spots from your phone, then memorises their rough location. As you get away from those Wi-Fi locations and Y5 notices through mobile signal triangulation, it turns off Wi-Fi, saving you power and those lightly annoying “Wi-Fi Networks Available” messages. When you’re close to your trusted Wi-Fi again, Y5 turns your Wi-Fi back on.