An accessory for transportation and storage of an autonomous cardiac implant, in particular of the leadless capsule type, before implantation, the accessory comprising an external source of electrical energy for the temporary storage of an electrical energy during the transportation and storage of the implant, the external source being physically separated from the implant, and a temporary electrical coupling link (66, 68, 78, 80, 84, 86) from the external source to the implant, wherein the implant comprises a tubular body which houses: - an energy harvesting module adapted to convert external stresses applied to the implant into electrical energy, by means of an inertial pendular unit comprising an elastically deformable element coupled to an inertial mass; and - a rechargeable battery adapted to be recharged by the energy harvesting module, the battery being previously charged at an initial charge level, the electrical coupling link (66, 68, 78, 80, 84, 86) is a link to the implant rechargeable battery, in such a way as to ensure a power supply of the rechargeable battery by the external source and hence to maintain, during the whole transportation and storage duration before implantation, a charge level of the battery higher than a minimum predetermined level; and the accessory further comprises: - a protection support for receiving and wedging the implant with respect to the accessory in a configuration ensuring the electrical coupling of the implant to the external source, wherein the protection support comprises a shock-absorbing and vibration-filtering structure comprising a texture of elastically deformable strands or slats wrapping and wedging the implant in position inside the protection support. the accessory comprising an external source of electrical energy for the temporary storage of an electrical energy during the transportation and storage of the implant, the external source being physically separated from the implant, and a temporary electrical coupling link (66, 68, 78, 80, 84, 86) from the external source to the implant, wherein the implant comprises a tubular body which houses: - an energy harvesting module adapted to convert external stresses applied to the implant into electrical energy, by means of an inertial pendular unit comprising an elastically deformable element coupled to an inertial mass; and - a rechargeable battery adapted to be recharged by the energy harvesting module, the battery being previously charged at an initial charge level, - an energy harvesting module adapted to convert external stresses applied to the implant into electrical energy, by means of an inertial pendular unit comprising an elastically deformable element coupled to an inertial mass; and - a rechargeable battery adapted to be recharged by the energy harvesting module, the battery being previously charged at an initial charge level, the electrical coupling link (66, 68, 78, 80, 84, 86) is a link to the implant rechargeable battery, in such a way as to ensure a power supply of the rechargeable battery by the external source and hence to maintain, during the whole transportation and storage duration before implantation, a charge level of the battery higher than a minimum predetermined level; and the accessory further comprises: - a protection support for receiving and wedging the implant with respect to the accessory in a configuration ensuring the electrical coupling of the implant to the external source, wherein the protection support comprises a shock-absorbing and vibration-filtering structure comprising a texture of elastically deformable strands or slats wrapping and wedging the implant in position inside the protection support. - a protection support for receiving and wedging the implant with respect to the accessory in a configuration ensuring the electrical coupling of the implant to the external source, wherein the protection support comprises a shock-absorbing and vibration-filtering structure comprising a texture of elastically deformable strands or slats wrapping and wedging the implant in position inside the protection support.