So I'm on a trip last week and have two 550s with me and both of them go dead - low battery. I checked the voltage to charging cradle at the motel one night and it was getting 12 volts, so I figured that the charging cradle was bad. Both GPSs did charge when hooked to a USB cord to the computer or a wall outlet. I got home (using turn by turn written directions to get my last few TOH sites) and replaced the cradle with a new one. So now one GPS does charge the battery in the cradle, but one does not. hmmmm Fred W told me of a diagnostic I can use to look at GPS parameters and it does show the battery charging, but another diagnostic says battery "suspended"?? Don't know what that is. I have three batteries which all seem to charge ok in both GPSs when hooked to the USB cable but only one GPS charges the batteries in the cradle. I haven't had any luck posting in the Zumo forum, but will call Garmin and talk to them. Anyone every experienced their Zumo not charging in a supposedly good cradle, but with a USB cable?