## 1 Introduction  
The massive application of supercapacitors in a variety of applications, as ancillary or even as major power sources, poses a variety of challenges. As a rule, constructors of such power systems try to use the maximum value of supercapacitors declared by the manufacturer, which has been described in a number of papers [1; 2; 3; 4]. Theoretically, supercapacitors are characterized by a very long lifetime, however, they require a very special attitude as the declared values of parameters are to be restrictively approached. It is assumed that the basic parameters for assessing the degradation of supercapacitors are the changes in the capacitance \(C\) and the equivalent series resistance \(R_{ESR}\). As part of the project entitled \"Mechanism of charging/discharging processes at the electrode/electrolyte interface of supercapacitor\", additional methods were developed to support the qualitative assessment of worn out supercapacitors. These methods were based on noise and thermal measurements, which assume the use of existing and developed models of supercapacitors presented in [5; 6; 7; 8]. Figure 1 presents the equivalent electrical circuit of the supercapacitor, using resistive and capacitive elements. It is the basis for other equivalent electric models of supercapacitors, which are presented in [7; 8]. Most of the papers [9; 10; 11; 12; 13] were based on systems consisting of a series of n-consecutive RC branches. The basic model (Figure 1) assumes the existence of two parallel branches of RC and the leakage resistance \(\mathrm{R_{L}}\), representing the leakage current of supercapacitor. The first branch \(R_{ESR}\), \(\mathrm{C_{H}}\) consists of equivalent series resistance (\(R_{ESR}\))--responsible for the main part of losses and the capacity \(\mathrm{C_{H}}\) of the Helmholtz layer, which are available for the rapid charging/discharging phase [14; 15]. The second branch, \(\mathrm{R_{D}}\), \(\mathrm{C_{D}}\), represents the mechanism of charges redistribution occurring in supercapacitors, determining at the same time its velocity (\(\mathrm{R_{D}}\)) and electric capacity of the diffusion mechanism (\(\mathrm{C_{D}}\)) [10; 15]. On the basis of the presented diagram, the criteria for qualitative assessment of supercapacitors are adopted. In classic assessment methods, they are represented by changes in electrical parameters: Capacitance \(C\) measured between the terminals and \(R_{ESR}\). It is assumed that the supercapacitor is completely degraded if the capacity \(C\) decreased by at least 30% or the \(R_{ESR}\) increased by 100% in relation to their initial values. Evaluation studies are carried out by the use of known methods described in [3; 16; 17; 18]. Our paper presents the results of measurements and assessments of supercapacitor quality based on two measurement methods. The first method is focused on the measurement of temperature increments and the second utilizes measurements of noise generated in the tested samples. Reference is made to the experimental results of the proposed methods of the commonly used \(C\) and \(R_{ESR}\) values. The first proposed method is based on the analysis of temperature distributions on the observed surface of the supercapacitor during its intense charging/discharging. The basis of the evaluation presented in the paper are measurements of electromagnetic radiation in the infrared radiation (IR) range. The essentials and principles of thermographic measurements are described in more details, among others, in [19; 20; 21; 22], which illustrate the conditions that should be taken into consideration while performing such type of measurements. The use of non-destructive measurement methods based on the use of the IR measurement technique is presented, inter alia, in [23; 24]. Conducting thermographic tests of supercapacitors requires both proper preparation of the tested samples and consideration of a number of additional factors that may affect the measurement. The factors were presented in [25; 26].