Mobile beverage dispensing machine comprising: a liquid tank having an insulated tank body for receiving and storing a liquid used for preparing a beverage, a beverage preparation unit for preparing a beverage using the liquid and dispensing the prepared beverage, a fluid circuit for delivering the liquid from the tank to the beverage preparation unit, heating means for heating the liquid in the tank, and at least one main power supply connector (9, 80) connectable to an external power source and at least one mobile power source (7, 51), and, at least one control unit (50, 8) configured to: - control and operate at least part of the heating means by external power to heat up the liquid in the tank when the machine is supplied in electrical power by the main power supply connector connected to an external power source, and - control and operate at least part of the heating means by power of the mobile power source (7, 51) to keep heating liquid in the tank when the machine is no longer supplied in electrical power from the at least one main power supply connector (9, 80), characterized in that: - the fluid circuit comprises a first fluid path (12, 13, 55, 57, 63) fluidly connecting the tank with the beverage preparation unit, and the fluid circuit further comprises an air pump; at least one control unit being configured for actuating the air pump to fill air inside the tank; and - it comprises a first control valve activated by the control unit to fluidly connect the air pump to a first portion (13, 55) of the first fluid path. a liquid tank having an insulated tank body for receiving and storing a liquid used for preparing a beverage, a beverage preparation unit for preparing a beverage using the liquid and dispensing the prepared beverage, a fluid circuit for delivering the liquid from the tank to the beverage preparation unit, heating means for heating the liquid in the tank, and at least one main power supply connector (9, 80) connectable to an external power source and at least one mobile power source (7, 51), and, at least one control unit (50, 8) configured to: - control and operate at least part of the heating means by external power to heat up the liquid in the tank when the machine is supplied in electrical power by the main power supply connector connected to an external power source, and - control and operate at least part of the heating means by power of the mobile power source (7, 51) to keep heating liquid in the tank when the machine is no longer supplied in electrical power from the at least one main power supply connector (9, 80), characterized in that: - the fluid circuit comprises a first fluid path (12, 13, 55, 57, 63) fluidly connecting the tank with the beverage preparation unit, and the fluid circuit further comprises an air pump; at least one control unit being configured for actuating the air pump to fill air inside the tank; and - it comprises a first control valve activated by the control unit to fluidly connect the air pump to a first portion (13, 55) of the first fluid path. - control and operate at least part of the heating means by external power to heat up the liquid in the tank when the machine is supplied in electrical power by the main power supply connector connected to an external power source, and - control and operate at least part of the heating means by power of the mobile power source (7, 51) to keep heating liquid in the tank when the machine is no longer supplied in electrical power from the at least one main power supply connector (9, 80), - the fluid circuit comprises a first fluid path (12, 13, 55, 57, 63) fluidly connecting the tank with the beverage preparation unit, and the fluid circuit further comprises an air pump; at least one control unit being configured for actuating the air pump to fill air inside the tank; and - it comprises a first control valve activated by the control unit to fluidly connect the air pump to a first portion (13, 55) of the first fluid path.