I have just purchased a nuvi 270 and I have an old Motorola phone charger with the same mini usb connection and correct output for Nuvi (5v). When I connect the charger to the Nuvi, the Nuvi shows a PC icon on screen - is this the usual symbol for charging via mains ?
Probably not. I have a nuvi250. I use the supplied charging cable (cigar plug on one end) It does not show a PC symbol. I had to buy a further cable to connect the nuvi to a PC (for updating it) Why are you not using the supplied cable for charging?
The unit can be used on foot as well as in the car, with the obvious effect of eventually draining the batteries. I would not want to leave the unit in the car to recharge if it, when you can use a mains charger instead.