Land maintenance system, in particular for turfgrasses or gardens or agricultural land, said system comprising: - at least one mobile device electrically powered by an on-board battery and comprising at least one payload configured to carry out maintenance operations, in particular grass cutting operations, within a working area, a complete execution of maintenance operations within the working area defining a working cycle of the mobile device, and - at least one control unit operatively connected to said mobile device and configured for: • receiving in input, and/or defining, a reference parameter representative of a spatial extent of the working area and/or a reference time duration expressed as a time necessary to complete the maintenance operations within the working area, • determining, during said working cycle with temporal continuity or with temporal periodicity according to which two consecutive determinations are spaced apart by a predetermined time interval, said predetermined time interval being between 100 milliseconds and 600 seconds, a work completion parameter representative of a fraction of the working cycle whose corresponding maintenance operations have been completed and/or a remaining work parameter representative of a fraction of the working cycle in which the maintenance operations have not been completed yet, • estimating a charge level representative of a remaining charge of said on-board battery, • determining, as a function of the reference parameter, the work completion parameter and the estimated charge level or as a function of the remaining work parameter and the estimated charge level, at least one piece of information concerning if the estimated charge level is sufficient to complete the working cycle. - at least one mobile device electrically powered by an on-board battery and comprising at least one payload configured to carry out maintenance operations, in particular grass cutting operations, within a working area, a complete execution of maintenance operations within the working area defining a working cycle of the mobile device, and - at least one control unit operatively connected to said mobile device and configured for: • receiving in input, and/or defining, a reference parameter representative of a spatial extent of the working area and/or a reference time duration expressed as a time necessary to complete the maintenance operations within the working area, • determining, during said working cycle with temporal continuity or with temporal periodicity according to which two consecutive determinations are spaced apart by a predetermined time interval, said predetermined time interval being between 100 milliseconds and 600 seconds, a work completion parameter representative of a fraction of the working cycle whose corresponding maintenance operations have been completed and/or a remaining work parameter representative of a fraction of the working cycle in which the maintenance operations have not been completed yet, • estimating a charge level representative of a remaining charge of said on-board battery, • determining, as a function of the reference parameter, the work completion parameter and the estimated charge level or as a function of the remaining work parameter and the estimated charge level, at least one piece of information concerning if the estimated charge level is sufficient to complete the working cycle. • receiving in input, and/or defining, a reference parameter representative of a spatial extent of the working area and/or a reference time duration expressed as a time necessary to complete the maintenance operations within the working area, • determining, during said working cycle with temporal continuity or with temporal periodicity according to which two consecutive determinations are spaced apart by a predetermined time interval, said predetermined time interval being between 100 milliseconds and 600 seconds, a work completion parameter representative of a fraction of the working cycle whose corresponding maintenance operations have been completed and/or a remaining work parameter representative of a fraction of the working cycle in which the maintenance operations have not been completed yet, • estimating a charge level representative of a remaining charge of said on-board battery, • determining, as a function of the reference parameter, the work completion parameter and the estimated charge level or as a function of the remaining work parameter and the estimated charge level, at least one piece of information concerning if the estimated charge level is sufficient to complete the working cycle.