Abstract: Physical and performance characteristics of power sourcesincluding batteries, fuel cells and solar cells frommanufacturers' data are collated and a database is built using advanced selectionsoftware. A method is subsequently developed for selecting portable powersources based on matching their physical and performance characteristics,such as weight, volume, capacity, voltage and cost, to the requirements ofa given task. This allows the construction of performance maps in terms ofvoltage, maximum current, mass energy density, volume energy density andcost, with a systematic comparison of different kinds of power sources.The use of the method as a preliminary design tool is demonstrated in a casestudy on the selection of batteries for mobile phones.