RE: rhino 520 gps
The battery life will completely vary, and depend solely on how you use it. On my unit I like to adjust the settings frequently, and caneasily get well over 16 hours of battery life. Settings like WAAS, Electronic Compass, Radio, GPS, Battery Save Mode, Backlight, etc,are all features which will vary your battery life. If you use your unit sensibly, battery life is very good, considering you have both a GPS and Radio in your hand.