The invention provides a device and a method for testing a vehicle battery (40) in a state in which it is removed from a vehicle, by means of a testing device (30) which is designed to test the vehicle battery (40) installed in the vehicle, by means of an on-board diagnosis interface of the vehicle. The device comprises: an interface (12) to which a plug (32) of the testing device (30) can be connected, which plug (32) is designed for connection to the on-board diagnosis interface of the vehicle; an electric connecting device (13) by means of which at least one electric vehicle battery terminal (44, 45, 46, 47) of the vehicle battery (40) can be connected to the device (10); and an adapter device (18) by means of which signals, which can be received by the at least one electric vehicle battery terminal (44, 45, 46, 47) of the vehicle battery (40) via the connecting device (13), can be conducted to the interface (12) in such a way that the signals can be tested at the interface (12) for the testing device (30) by means of the plug (32) in accordance with a configuration of the on-board diagnosis interface of the vehicle.