A portable self-contained electric power tool assembly such as for example pruning shears, chainsaw, fruit collecting tool, string lawn trimmers, pneumatic drill or similar, including at least three distinct functional sub-assemblies, namely a first sub-assembly forming an electrical actuator and generating the mechanical action of the tool, a second sub-assembly portable by the user, forming an electrical energy source and including essentially a rechargeable electrochemical battery, and a third sub-assembly forming a charger able to carry out the controlled recharging of the battery, characterized in that: the second sub-assembly is constituted, on the one hand, by a lithium-ion or lithium polymer electrochemical battery formed by association of more than four cells in series, each cell being composed of one or several elements in parallel and, on the other hand, by a control and command module for the battery, ensuring over time and in a controlled manner a maximum capacity of the battery and an optimum use of the tool; the first sub-assembly is subjected during its operation to a control by a system of current limitation adapted to preserve the lithium-ion or lithium polymer electrochemical battery from which it draws energy; the third sub-assembly consists at least in a source of electrical supply whose voltage and current are suitable for recharging the lithium-ion or lithium polymer battery, the electronic control and command module of the battery of the second sub-assembly being present in the form of an electronic card and including at least one digital processing unit, associated with a memory, and with annexed circuits able together to fulfil at least certain, and preferably all of the tasks of the following group of tasks formed by: management of the charge, management of the discharge, balancing the charge of each cell, evaluation and display of the capacity of the battery, protection in discharge of the battery as to overcurrent during use of the tool, management of the tool during storage phases, management of the alarms, management and transmission of collected information, management of the diagnostics. the second sub-assembly is constituted, on the one hand, by a lithium-ion or lithium polymer electrochemical battery formed by association of more than four cells in series, each cell being composed of one or several elements in parallel and, on the other hand, by a control and command module for the battery, ensuring over time and in a controlled manner a maximum capacity of the battery and an optimum use of the tool; the first sub-assembly is subjected during its operation to a control by a system of current limitation adapted to preserve the lithium-ion or lithium polymer electrochemical battery from which it draws energy; the third sub-assembly consists at least in a source of electrical supply whose voltage and current are suitable for recharging the lithium-ion or lithium polymer battery, the electronic control and command module of the battery of the second sub-assembly being present in the form of an electronic card and including at least one digital processing unit, associated with a memory, and with annexed circuits able together to fulfil at least certain, and preferably all of the tasks of the following group of tasks formed by: management of the charge, management of the discharge, balancing the charge of each cell, evaluation and display of the capacity of the battery, protection in discharge of the battery as to overcurrent during use of the tool, management of the tool during storage phases, management of the alarms, management and transmission of collected information, management of the diagnostics. management of the charge, management of the discharge, balancing the charge of each cell, evaluation and display of the capacity of the battery, protection in discharge of the battery as to overcurrent during use of the tool, management of the tool during storage phases, management of the alarms, management and transmission of collected information, management of the diagnostics.