Most smartphones have either a Lithium Ion battery or a Lithium Polymer battery. Both are Lithium Ion though, and as such, do not have a ''memory'' which means you don't have to fully charge or discharge them at the beginning, and partial charging is fine throughout their life. In fact, these types of batteries suffer from low voltage, so it's actually much better to charge them, even if only a little, whenever you have the chance rather than to fully charge and fully drain them. 1. Use a dark colored background Using a darker wallpaper, saves battery as well as is good for your eyes during night 2. Make apps darker too Use a dark theme inside the app. If on CM ROMs you can try dark themes 3. Get rid of auto-brightness Don't use display auto-brightness. It may sound good, but auto-brightness is usually way brighter than you really need. It's much better to manually set a super low brightness level that is still comfortable, and the...