Thermal runaway detection system, comprising: a venting device with a sealing body (551, 552, 553) disposed in a venting passage in a housing (50, 53) of a battery submodule, a battery module or a battery system enclosing at least one battery cell, the sealing body (551, 552, 553) being configured to close the venting passage in a first position and to open the venting passage in a second position different from the first position, wherein the sealing body (551, 552, 553) is moveable from the first position to the second position in a reversible manner; and a thermal runaway detection circuit configured for monitoring a position of the sealing body (551, 552, 553) and for outputting a signal corresponding to the position, the thermal runaway detection circuit comprising: a first detection node connected to the venting device and a second detection node connected to the venting device, wherein a conductible path between the first detection node and the second detection node is set conductive via the sealing body (551, 552, 553) in one of the first position and the second position, and a controller configured to detect the conductivity of the conductible path and to output the signal corresponding to the conductivity of the conductible path, wherein the thermal runaway detection circuit comprises a first power input connected to a first cell terminal of the at least one battery cell and a second power input connected to a second cell terminal of the at least one battery cell and wherein the first detection node is connected to the first power input and the second detection node connected to the second power input, and wherein the controller is connected to the first power input and to the second power input and is powered via the at least one battery cell. a venting device with a sealing body (551, 552, 553) disposed in a venting passage in a housing (50, 53) of a battery submodule, a battery module or a battery system enclosing at least one battery cell, the sealing body (551, 552, 553) being configured to close the venting passage in a first position and to open the venting passage in a second position different from the first position, wherein the sealing body (551, 552, 553) is moveable from the first position to the second position in a reversible manner; and a thermal runaway detection circuit configured for monitoring a position of the sealing body (551, 552, 553) and for outputting a signal corresponding to the position, the thermal runaway detection circuit comprising: a first detection node connected to the venting device and a second detection node connected to the venting device, wherein a conductible path between the first detection node and the second detection node is set conductive via the sealing body (551, 552, 553) in one of the first position and the second position, and a controller configured to detect the conductivity of the conductible path and to output the signal corresponding to the conductivity of the conductible path, wherein the thermal runaway detection circuit comprises a first power input connected to a first cell terminal of the at least one battery cell and a second power input connected to a second cell terminal of the at least one battery cell and wherein the first detection node is connected to the first power input and the second detection node connected to the second power input, and wherein the controller is connected to the first power input and to the second power input and is powered via the at least one battery cell.