System for controlling the temperature of at least one battery in a vehicle; said system comprising: - at least one battery configured for outputting electric power; - a thermal regulation circuit configured for being run through by a liquid and comprising an operative tract in thermal exchange relation with said battery, so as to control the temperature thereof; said system being characterized in that it further comprises: - a refrigeration circuit configured for being run through by a fluid that can be subjected to a refrigeration cycle in a non-reversible manner; said refrigeration circuit in turn comprising a condenser in thermal exchange relation with a heating tract of said thermal regulation circuit; and an evaporator in thermal exchange relation with a cooling tract of said thermal regulation circuit; and - a valve assembly associated with the thermal regulation circuit and configured for selectively taking a heating configuration, in which said valve assembly defines, in the thermal regulation circuit, a closed heating path for the liquid between the operative tract and the heating tract; a cooling configuration, in which said valve assembly defines, in the thermal regulation circuit, a closed cooling path for the liquid between the operative tract and the cooling tract said system being characterised in that said valve assembly comprises - a heating valve situated between the heating tract and the operative tract; - a cooling valve situated between the cooling tract and the operative tract; and - a return switching valve situated downstream of the operative tract and upstream of the heating tract and of the cooling tract. - at least one battery configured for outputting electric power; - a thermal regulation circuit configured for being run through by a liquid and comprising an operative tract in thermal exchange relation with said battery, so as to control the temperature thereof; - a refrigeration circuit configured for being run through by a fluid that can be subjected to a refrigeration cycle in a non-reversible manner; said refrigeration circuit in turn comprising a condenser in thermal exchange relation with a heating tract of said thermal regulation circuit; and an evaporator in thermal exchange relation with a cooling tract of said thermal regulation circuit; and a condenser in thermal exchange relation with a heating tract of said thermal regulation circuit; and an evaporator in thermal exchange relation with a cooling tract of said thermal regulation circuit; and - a valve assembly associated with the thermal regulation circuit and configured for selectively taking a heating configuration, in which said valve assembly defines, in the thermal regulation circuit, a closed heating path for the liquid between the operative tract and the heating tract; a cooling configuration, in which said valve assembly defines, in the thermal regulation circuit, a closed cooling path for the liquid between the operative tract and the cooling tract said system being characterised in that said valve assembly comprises a heating configuration, in which said valve assembly defines, in the thermal regulation circuit, a closed heating path for the liquid between the operative tract and the heating tract; a cooling configuration, in which said valve assembly defines, in the thermal regulation circuit, a closed cooling path for the liquid between the operative tract and the cooling tract said system being characterised in that said valve assembly comprises - a heating valve situated between the heating tract and the operative tract; - a cooling valve situated between the cooling tract and the operative tract; and - a return switching valve situated downstream of the operative tract and upstream of the heating tract and of the cooling tract.