Researchers from the United States and Sweden have launched free iOS and Android smartphone/tablet software that singles out which apps take the biggest toll on your device batteries and also illustrates fragmentation of Apple and Android mobile OSes.The NODES research group at the University of Helsinki’s Department of Computer Science has joined forced with the University of California at Berkeley to deliver the Carat app and has published live stats based on some 2 terabytes of data extracted from Carat, which has been downloaded by about 750,000 users who employ more than 300,000 apps.