System comprising: • at least one unit, • a support configured to receive the at least one unit removably at least in one first position, wherein the at least one unit is secured to the support, - an elastically deformable device configured to be elastically deformed in the first position, so as to exert a thrust force on the at least one unit relative to the support, - a retaining device comprising at least one fuse element having a melting point, the retaining device being configured to oppose the thrust force so as to maintain the at least one unit in the first position when the temperature of the fuse element is below the melting point, and to not oppose the thrust force when the temperature of the fuse element crosses the melting point such that the thrust force moves the at least one unit to a second position different from the first position, the system being characterised: - in that the at least one unit is an electrical energy storage unit and is provided with a first electrical connecting element and a second electrical connecting element, the system comprising an electrical connecting device, capable of electrically connecting by contact, the first element and the second element to the support in the first position, - and in that the contact between the first electrical connecting element and the second electrical connecting element and the support is a pressure contact only. • at least one unit, • a support configured to receive the at least one unit removably at least in one first position, wherein the at least one unit is secured to the support, - an elastically deformable device configured to be elastically deformed in the first position, so as to exert a thrust force on the at least one unit relative to the support, - a retaining device comprising at least one fuse element having a melting point, the retaining device being configured to oppose the thrust force so as to maintain the at least one unit in the first position when the temperature of the fuse element is below the melting point, and to not oppose the thrust force when the temperature of the fuse element crosses the melting point such that the thrust force moves the at least one unit to a second position different from the first position, the system being characterised: - in that the at least one unit is an electrical energy storage unit and is provided with a first electrical connecting element and a second electrical connecting element, the system comprising an electrical connecting device, capable of electrically connecting by contact, the first element and the second element to the support in the first position, - and in that the contact between the first electrical connecting element and the second electrical connecting element and the support is a pressure contact only. - in that the at least one unit is an electrical energy storage unit and is provided with a first electrical connecting element and a second electrical connecting element, the system comprising an electrical connecting device, capable of electrically connecting by contact, the first element and the second element to the support in the first position, - and in that the contact between the first electrical connecting element and the second electrical connecting element and the support is a pressure contact only.