An important thing to note, on any Garmin, is that the fastest way to run down the battery is to have the map screen (or any other full screen graphical display, if you are using custom apps/widgets) on all the time. One of the best ways to conserve battery is to just have the main page show minimal statistics (e.g. power, speed, cadence, distance, heart rate) - have everything else on separate pages that you can refer to from time to time.