garmin goes dead after a few weeks...normal or no

[steveo3002]

recently got a garmin sat nav , battery went dead after 3 weeks or so , sent it away for replacement and the new does the same

is it normal that the unit goes dead until recharged ? our old one worked after months in a drawer

[daydotz]

Pretty sure the Garmin's + TomTom we have looses charge while its not plugged