Abstract: An accumulator, in particular as a releasable energy source for a power tool, containing at least one energy storage cell. The accumulator contains at least a first and second interface device, wherein the at least first and second interface devices are configured both to charge the at least one energy storage cell with electrical energy and to discharge electrical energy from the at least one energy storage cell. System containing a power tool and at least one accumulator, which is able to be connected to the power tool.

Abstract: A method includes adjusting a rechargeable battery from a first state of charge to a second state of charge; creating a first current intensity value after a first predetermined time duration has elapsed, after a predetermined temperature value has been reached, after a predetermined current intensity value has been reached, or if the difference between a first and a second ascertained current intensity value reaches a predetermined threshold value; ascertaining a first voltage value after the first current intensity value has been reached; adjusting a second current intensity value after a second predetermined time duration has elapsed; ascertaining a second voltage value after the second current intensity value has been reached; and determining a first impedance value of the rechargeable battery from the quotient of the difference between the first and second current intensity values and the difference between the first and second voltage values. Rechargeable battery and charger for carrying out the method.

Abstract: In a method for charging a rechargeable battery of a mobile power tool, wherein the rechargeable battery has an electrolyte that is liquid at room temperature, charging is carried out at least temporarily at a core temperature (TK) of at least 60° C. and at a charging rate of at least 3 C. A charging apparatus is also provided.

Abstract: A method for open-loop and closed-loop control of a rechargeable battery having at least one energy storage cell, at least one temperature sensor for detecting at least one temperature value of the rechargeable battery, a current measuring device, a voltage measuring device and also a rechargeable battery control device having at least one rechargeable battery storage device. The method involves the method steps of setting a first charging current value for charging the rechargeable battery; charging the rechargeable battery with the first charging current value until a first temperature value is reached; setting a second charging current value for charging the rechargeable battery for maintaining the first temperature value for a first predetermined time duration; setting a third charging current value for charging the rechargeable battery after a second predetermined time duration has elapsed; and setting a first voltage value after the second predetermined time duration has elapsed.