Even if supercapacitors present a reduced energy density, they allow 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 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 identification of the losses is operated from a primary energy source via a DC/DC converter to a single supercapacitive cell of reduced capacitance. Some experimental results are proposed.