Abstract: A filling head assembly for filling a battery cell with a liquid electrolyte includes a filling head. The filling head includes a first and a second fluid channel and a valve. The inlet of the first fluid channel is connected to a pump. The inlet of the second fluid channel is connected to a vacuum pump. The outlet of the first fluid channel engages with a filling opening of the battery cell. The valve determines whether the outlet of the first fluid channel is connected to the inlet of the first fluid channel. The apparatus includes the filling head, to a production line comprising the apparatus and to a method for filling a battery cell with liquid electrolyte using the apparatus.