1. A computer-implemented method for estimating a remaining useful life of an observed battery asset, comprising the steps of: obtaining exemplar degradation data from at least one exemplar battery asset; transforming the exemplar degradation data into functional approximations to obtain a plurality of exemplar degradation paths; acquiring observed battery asset degradation data from an observed battery asset; transforming the observed battery asset degradation data into a functional approximation to obtain an observed battery asset degradation path; classifying the observed battery asset degradation data by determining a plurality of similarities each quantifying a degree of similarity of the observed battery asset degradation path to at least one of the plurality of exemplar degradation paths; and estimating, with a computer, a remaining useful life of the observed battery asset using the determined plurality of similarities each quantifying the degree of similarity of the observed battery asset degradation path to at least one of the plurality of exemplar degradation paths.