Systems and processes are provided to detect an improper external power supply including a battery having a battery current output, a power supply for receiving an external voltage and an external current from an external power supply and for generating a control signal in response to receiving the external voltage, a processor operative to determine a first polarity of the battery current output at a first time in response to the control signal, to generate an error indicator in response to the first polarity being indicative of a discharging battery, and a display operative to display a user warning indicative of an improper external power supply in response to the error indicator.