Gilbert Laporte, Ola Jabali, and e-VRO’s Aurélien Froger and Jorge E. Mendoza just published a new paper on the electric vehicle routing problem with nonlinear charging function (E-VRP-NL). The problem was introduced a couple of years ago (by e-VRO’s researchers) to account for the more realistic nonlinear relationship between the time spent charging and the amount of energy charged. In this new paper Froger et al. propose two new formulations for the E-VRP-NL. They first develop an arc-based tracking of the time and the state of charge which, according to their experiments, outperforms the classical node-based tracking of these values. To avoid replicating the charging stations nodes, as done for both node and arc based formulations, they also introduce a path-based model. They develop an algorithm to generate a tractable number of these paths. This path-based model outperforms the classical models. They also propose a new model, a heuristic, and an exact labeling algorithm for the problem of finding the optimal charging decisions for a given route. Extensive computational results show that charging decisions considerably impact the quality of the E-VRP-NL solutions. Indeed, they improve 23 out of 120 best known E-VRP-NL solutions by solely revising the charging decisions. You can access the paper here.