Batteries are an important source of electrical energy. Due to the growing demand for efficient storage of electricity, the development of batteries, especially in the direction of maximizing energy density, is a major challenge. As a result of its high theoretical specific capacity and low potential lithium metal is a promising anode material for rechargeable Li-based batteries. The growth of lithium dendrites during charging is a major barrier to the development of high-capacity Li-metal-based secondary batteries. For this reason, the attention over the past several decades has been focused on the characterization and analysis of lithium electrodeposition and dendrite formation with the aim to determine the mechanism of dendrite formation, so that dendrites can be predicted and prevented more effectively. Central to these objectives is the development of analytical and non-destructive methods that can be used in situ to operating batteries. In this work, lithium dendrites were monitored in a symmetric Li-Li electrochemical cell indirectly by the 1H MRI method, with a 3D spin-echo sequence. From the images, we determined the volumes of dendrites at different times during the operation of a cell, which we then compared with the calculated theoretical values.