RDT series battery pack DC impedance tester is used to detect the whole set of DC impedance and the DC impedance of single series battery in the group state of battery module or battery box. The device can accurately and quickly test the corresponding DC impedance, that is, the transformation of battery state and connection state, which provides a strong basis for judging the health status of battery module and battery box, and eliminates the potential safety hazard due to the increased connection impedance.