Originally Posted by DrIsotope

My 520 is around 2 years old, and has dropped from ~15 hours of battery life when new to ~7.5 hours now. But it's also been charged at least 250 times. It's just what lithium batteries do. Even with the backlight switched off, I have to charge it every 2-3 rides. Time of ownership is not necessarily a telling metric-- my wife's Garmin 500 still has fantastic battery life, and we've had it for over 3 years... but it also logs about 1,200 miles a year, less than 100 hours of use per year.