The invention relates to a test apparatus for checking a battery control device or for checking a battery having at least one cell, comprising a battery simulator (18) for simulating a voltage of at least one cell of a simulated battery for specification on the battery control device, wherein the battery control device or the battery is connected to an evaluation module (14) via a rail designed as a central bus in order to process and check the voltage of a selected cell, wherein the selected cell of the battery simulator for the battery control device or the selected cell of the battery can be selected via a separation module (24). In this way, a test apparatus for checking a battery control device or for checking a battery can be provided, which has a simple construction and can check all of the cells of a simulated or actual battery in a simple manner.