Hi... question in the title. I have an old Magsafe charger from 2009 which was used for a Macbook and Macbook Pro. I bought the Magsafe 2 converter to use this old charger... does this mean I can safely use this as a spare charger for my 2012 MBA 11 inch? I believe the MBA's standard charger is a lower voltage due to the smaler battery so just wondering if this will be okay. I am confused if the "converter" is to convert current too or just convert charger format to the new size.