Why does my GPS device keep turning itself off?

My TomTom XXL - N14644 device does not seem to hold a charge, when I click on for

destination address, device stays on HOLD & then turns off. However when I click on

Home, no problem, device shows route, etc. and seems OK. Does this seem like a

battery problem, or other problem? Have tried overnight charging - no solution!

Only inherited this tomtom some two weeks ago.