UBERFIX.. you are assuming too much. :-) ( it could not be wrong voltage else different plug ?? says who ? :-)
I blew mine cause i connected it directly to the 12volt line of the battery... I forgot that the cagatte's lighter plug has a converter inside.. :-(
So the way I overcome the issue was to connect o the cables of the internal tomtom battery.. But as an idiot.. I forgot again about the reduction of volts.. so now I think the device is really dead.. :-(