A dynamic battery emulator for replacing and mimicking the characteristics of a battery in a portable electronic device when the device is located in or on a vehicle can include a power control module capable of varying its output voltage to adapt to the voltage requirements of an attached portable electronic device; an input for conveying electrical power from the vehicle's electrical system to the power control module; an output for providing electrical power to the portable electronic device; an output for communicating a control signal from the power adaptor to the portable electronic device to selectively turn on and off the portable electronic device; a battery replacement module configured to replace the battery in a portable electronic device and including battery replacement circuitry for transferring electrical power from the power control module to the portable electronic device via the output for providing electrical power; an ignition sense controller for determining the power state of the vehicle's electrical system; and in communication with the ignition sense controller, at least one timer and switch for reducing the conveyance of electrical power from the vehicle's electrical system to the portable electronic device at a predetermined time after the vehicle's ignition or electrical system is turned off.