Electrical energy store , in particular for a handheld power tool, having: - a series connection of a number n of energy storage cells (1_1, ..., 1_n), wherein one energy storage cell (1_1) of the energy storage cells (1_1, ..., 1_n) is connected to a reference potential , - a series connection of a number n of measuring resistors (3_1, ..., 3_n), - a number n of measuring switching means (4_1, ..., 4_n), - wherein a first measuring switching means (4_n) of the number n of measuring switching means (4_1, ..., 4_n) is looped in between the series connection of the number n of energy storage cells (1_1, ..., 1_n) and the series connection of the number n of measuring resistors (3_1, ..., 3_n), and - wherein a corresponding measuring switching means (4_1, ..., 4_n-1) is looped in between connection nodes of neighbouring energy storage cells (1_1, ..., 1_n) and connection nodes of neighbouring measuring resistors (3_1, ..., 3_n), - a balancing switching means which is looped in between a measuring resistor (3_1) of the number n of measuring resistors (3_1, ..., 3_n) and the reference potential , - a measuring unit which measures a voltage dropped across a measuring resistor (3_1) of the number n of measuring resistors (3_1, ..., 3_n), characterized by - a control unit which is designed to control the measuring switching means (4_1, ..., 4_n) and the balancing switching means , to ascertain a state of charge of the energy storage cells (1_1, ..., 1_n) depending on a switching state of the measuring switching means (4_1, ..., 4_n) and of the balancing switching means and on the voltage measured by means of the measuring unit , and to monitor the proper functioning of the measuring switching means (4_1, ..., 4_n). - a series connection of a number n of energy storage cells (1_1, ..., 1_n), wherein one energy storage cell (1_1) of the energy storage cells (1_1, ..., 1_n) is connected to a reference potential , - a series connection of a number n of measuring resistors (3_1, ..., 3_n), - a number n of measuring switching means (4_1, ..., 4_n), - wherein a first measuring switching means (4_n) of the number n of measuring switching means (4_1, ..., 4_n) is looped in between the series connection of the number n of energy storage cells (1_1, ..., 1_n) and the series connection of the number n of measuring resistors (3_1, ..., 3_n), and - wherein a corresponding measuring switching means (4_1, ..., 4_n-1) is looped in between connection nodes of neighbouring energy storage cells (1_1, ..., 1_n) and connection nodes of neighbouring measuring resistors (3_1, ..., 3_n), - a balancing switching means which is looped in between a measuring resistor (3_1) of the number n of measuring resistors (3_1, ..., 3_n) and the reference potential , - a measuring unit which measures a voltage dropped across a measuring resistor (3_1) of the number n of measuring resistors (3_1, ..., 3_n), - a control unit which is designed to control the measuring switching means (4_1, ..., 4_n) and the balancing switching means , to ascertain a state of charge of the energy storage cells (1_1, ..., 1_n) depending on a switching state of the measuring switching means (4_1, ..., 4_n) and of the balancing switching means and on the voltage measured by means of the measuring unit , and to monitor the proper functioning of the measuring switching means (4_1, ..., 4_n). <EOS>