For testing the connections (13) of batteries (8) that are connected in a battery module (5) to several bus bars (6, 7) that are electrically in parallel with their battery electrodes (10, 11) by a resistance measurer (16) comprising a pair of contact pins (17, 18), during a measurement a first batten’ electrode (10) is contacted by a first contact pin (17) and a point on the conductor arrangement (13, 6, 13, 10) connected to the first battery electrode (10) is contacted by the second contact pin.