Autonomous mobile power supply with task or user tracking

An electric power supply comprising:

• an energy store module;
• a power coupling module connected with the energy store module to transfer electric energy from the energy store module to an electric power tool to power the power tool or to a power tool power pack to charge the power tool power pack;
• a power supply communication module to communicate with the one or more power tools;
• a motorized cart having the energy store module, the power coupling module, the power supply communication module mounted thereon for locomotion of the electric power supply;
• and
• a control module carried by the motorized cart, the control module being connected with the power supply communication module to accomplish data and command transmissions, to process information, and connected with the motorized cart so that the electric power supply accomplishes autonomous movement to maintain a predetermined distance to the power tool or to a communication device.