Vehicle access system and controller therefor

A system for accessing a vehicle when the main battery is incapable of supplying sufficient power for actuating the vehicle's power door locks/latches comprises: a power supply in the door or release handle supplying power to the vehicle's power latch; an entry authentication device for receiving one or more inputs for authenticating a user's access to the vehicle, the entry authentication device powered by the rechargeable power supply; and a latch controller powered by the power supply and operatively connected to the power latch and the at least one entry authentication device to receive information from the entry authentication device corresponding to the one or more inputs. The latch controller can authenticate a user's access to the vehicle to place the power latch in an unlocked state so that the door can be opened.