The subject matter of the invention is a battery forming unit, being used at the final stage of a production line, where the batteries are electrochemically formed. It is characterized in that the tank (1) on/in its side walls (4) has water ducts (5) containing water level regulators (6), with outlets over the cooler (7), installed in the area under the tank (1) over the liquid reservoir (8); moreover the tank (1) has air ducts (10) located on/in its side walls (4), with inlets over the area of the cooler (7) and the outlet in the area of the suction collector (11).