Even if supercapacitors present a reduced energy density, they enable to store a significant amount of energy, which leads to a significant autonomy for applications with reduced energy needs. The main advantage of supercapacitors is there to compensate a limited autonomy by frequent and fast charge processes. This contribution presents some considerations on the fast charge of supercapacitors, in the general frame of a low voltage application. The losses have been estimated using loss models of all elements of the conversion chain. Some results of an experimental validation are proposed.