Cell connector for a battery system

The cell connector (3) has several battery cells (2) which are electrically conductively connected with each other through a pole (6) of adjacent battery cell. An insulation-piercing terminal (7) is provided for tapping the electric voltage. The insulation-piercing terminal is partially coated with the specific material having nickel and copper. The insulation piercing connector is soldered, ultrasonically welded and is pressed into the cell connector main portion. A measuring conduit (4) is inserted into insulation piercing connector. An independent claim is included for battery system.