The present invention provides a battery charger for cell phones which operates off the cigarette lighter receptacle of a vehicle. The battery charger includes a visual indication that is activated by electromagnetic induction from the ringing current that is generated when the cell phone receives an incoming call. An incoming call sensing circuit operates to receive the electromagnetic signal that includes the incoming call signal to the user's cell phone. The electromagnetic signal is filtered and rectified by a conditioning and activation circuit such that only an incoming call signal remains thereafter the incoming call signal is transmitted to a visual indicator circuit having at least one light source for causing the at least one light source to illuminate such that the user is alerted to the incoming call.