The possibility of using the effect of full energy absorption in a light scintillator when an electron beam passes through it to determine the energy characteristics of a low and medium energy beam (the "absorbed energy" method) is experimentally presented. The energy calibration of the quasi-monochromatic electron beam of the Pakhra accelerator of the P. N. Lebedev Physical Institute of the Russian Academy of Sciences using scintillation detectors with a thickness of 14.5, 20, 23.5 and 51.2 cm was performed. For electron beam energies up to ~100 MeV and scintillation detector thicknesses from 5 to 20 cm the accuracy of electron beam energy determination was 10 to 20%, respectively.