Navi 1450 shutting off
After driving four hours my 1450 began to shut off saying external power disconnected and then said low battery. hit thee leave on button and all is well for awhile then it will happen agin. This went on for four days but always got us to where we wanted to go. When I got home plugged it into AC and let it charge for three hours then tried it and the same thing happened with it plugged into AC, Aney suggestions on what may be wrong. Is it reached it sell by date and should I look for another unit. I never use it on battery only always have it plugged into the auto. Does the battery need to be changed, would a bad battery cause this problem?