Method, Apparatus for Emergency Power Supply and Device Associated Thereto

An apparatus comprises a transformer coupled to a mains power, a backup power source comprising a first battery, a first power supply line switch configured to switch the power source between the backup power source and the mains power, a connecting interface coupling the power source to an external electronic device comprising a second battery which is rechargeable and a second power supply line switch which is configured such that the external electronic device is able to be powered by either the power source or a second battery, and a charging detector configured to detect the availability of the mains power, wherein the first power supply line switch is further configured to couple the backup power source to the external electronic device via the connecting interface when the mains power is not available such that the first battery is able to deliver power to the external electronic device.