I'm always looking for ways to save battery and although I'm lucky enough that my current daily driver, the HTC One (M8), behaves properly if I use the classic battery management rules, my good lady wife's LG Nexus 5 doesn't play by these rules. She finds that if she keeps her WiFi on all of the time, it drains the battery. The reason for this is because there's a bug in Android Lollipop‘s WiFi management on her device, which means that if it's search for a WiFi network to connect to, you can watch the battery meter tick down. For best battery life, then, users currently need to enable and disable their WiFi network depending on if they have access to a hotspot. And this is where an application such as WiFi Better Battery can help, which is a location sensing app that can manage the WiFi radio.
WiFi Better Battery uses Google's “always on” WiFi functionality, which is available from Android version 4.3 Jelly Bean and later, in order to determine if it should enable the full on WiFi mode. The WiFi location scanning mode has been designed by Google to help improve location services on our Android devices by keeping the WiFi radio in receive mode and not allowing it to connect to networks. It works because Google's database knows where many WiFi routers are located and so can be used to provide an estimate of where the device is. Checking and looking up the WiFi hotspot location uses much less battery than running the GPS chip for even a few seconds. WiFi Better Battery only enables the WiFi radio in transmit / receive mode if it detects a WiFi radio that the device may connect to.
There's another benefit to WiFi Better Battery, which is that the developer has implemented a MAC checking feature designed to keep our WiFi passwords safe. This is because of a weakness in Android's WiFi security whereby the device broadcasts the WiFi key in a way that may be picked up by a malicious router. MAC checking adds an additional layer of security to our devices and is available free on the Google Play Store, although there is also a premium version available. Meanwhile, having played around with the application on a few of my devices, it does make a small but appreciated difference to battery life.