The purpose of this work is to critically analyze the available procedures to test batteries and to suggest modifications that improve them in the context of the Brazilian Labeling Program (PBE), in order to provide elements to evaluate the performance of Photovoltaic Systems for electric energy generation under different operating conditions. Different types of batteries were used for each of the two testing procedures, from different manufactures. The results were processed using a MATLAB software. The uncertainty of measurement of the measured battery load was used to establish a criterium for qualifications and acceptance of its performance. As a critical point, it is observed that test temperature was a key factor and must be carefully taken into account so that the results be representative of the battery performance. Finally it was concluded that temperature and the discharge current have a larger contribution to measuring its load, and that the qualification and acceptance criterium is not complete if the uncertainty of measurement is not taken into account.