Method for monitoring an electrochemical cell system

Abstract

The invention relates to a method for monitoring an electrochemical cell system, the electrochemical cell system comprising at least one electrochemical unit (1) which has at least two electrochemical cells (2a - 2d), preferably battery cells, connected in series, wherein the potential of the electrochemical cells (2a - 2d) is tapped at least at a first measurement point (5a - 5e), at a second measurement point (5a - 5e) and at a third measurement point (5a - 5e) via leads (6a - 6e) and a first voltage (UV1 - UV4) between the first and second measurement points (5a - 5e) is measured and a second voltage (UV1 - UV4) between the second measurement point (5a - 5e) and the third measurement point (5a - 5e) is measured, characterized in that a first sum resistance and a second sum resistance are chosen to have different magnitude and the presence of an incorrect connection between components of the electrochemical cell system is evaluated on the basis of the measured voltages (UV1 - UV4).

Description

[0001] Method for monitoring an electrochemical cell system

[0002] The invention relates to a method for monitoring an electrochemical cell system, wherein the electrochemical cell system comprises at least one electrochemical unit which has at least two electrochemical cells, preferably battery cells, connected in series, wherein the potential is taken from the electrochemical cells at least at a first measuring point, at a second measuring point and at a third measuring point via leads and the measuring points are each electrically connected to at least one pole of the at least two electrochemical cells, wherein the measuring points are each electrically connected to different poles and a first voltage is measured between the first and the second measuring point and a second voltage is measured between the second measuring point and the third measuring point, wherein a first total resistance,which results from a circuit between the first measuring point and the second measuring point and a second total resistance, which results from a circuit between the second measuring point and the third measuring point, are selected to be of different sizes and the presence of a misconnection between components of the electrochemical cell system is assessed based on the measured voltages.

[0003] It also relates to an electrochemical cell system comprising at least one electrochemical unit, wherein the electrochemical unit comprises at least two electrochemical cells, preferably battery cells, which are connected in series, wherein the electrochemical cell system has at least one voltage measuring unit which is or can be electrically connected to a first measuring point, a second measuring point and a third measuring point via leads, and the measuring points are each connected to at least one pole of the at least two electrochemical cells, wherein the measuring points are each electrically connected to different poles and wherein the voltage measuring unit is configured toto measure a first voltage between the first and second measuring points and a second voltage between the second measuring point and the third measuring point, and wherein the voltage measuring unit is connected to an evaluation unit for supplying the measurement data, wherein a first total resistance, which results from a circuit between the first measuring point and the second measuring point, and a second total resistance, which results from a circuit between the second measuring point and the third measuring point, are of different sizes, and that the evaluation unit is configured to assess the presence of a faulty connection between components of the electrochemical cell system based on the measured voltages.

[0004] Electrochemical cells in an electrochemical cell system are often monitored by measuring their voltage. The measured voltage can be used to determine the charge state of the electrochemical unit or to detect malfunctions. The electrochemical cell system can in particular be a battery system or a fuel cell system. The electrochemical unit can in particular comprise several battery cells connected in series or a fuel cell stack, or particularly preferably be a fuel cell stack. The electrochemical cell can preferably be a battery cell or a fuel cell. Due to the large number of electrochemical cells connected in series, usually only one derivative of the potential is applied between two electrochemical cells, which is then used to measure the voltage of both adjacent electrochemical cells.

[0005] If there is a misconnection between the components, such as faulty transmission through a downstream conductor, this misconnection is often not detectable because the total voltage of the two adjacent electrochemical cells is distributed essentially evenly between the two voltage measurements.

[0006] US 2017 / 0266050 A1 discloses a battery system in which resistors can be connected in parallel to the voltage measuring unit by means of a switch. The system is configured to activate the corresponding switch upon detection of a malfunction in an electrochemical cell, thus discharging the affected subunit via the corresponding resistor. However, this embodiment does not support the detection of faulty connections, which often go undetected.

[0007] US 62555826 B1, JP 2007010580 A, and CN 112748367 A disclose cell systems that have resistor elements of different sizes connected between the measuring points to enable fault detection in the event of a contact fault through the resulting voltage difference. However, these resistors make the circuit more complex and increase the space requirement.

[0008] The object of the invention is to provide a method for monitoring an electrochemical cell system and an electrochemical cell system that enables improved detection of faulty connections at the lowest possible cost and space requirements. This object is achieved according to the invention by selecting different internal resistances for the first voltmeter and the second voltmeter.

[0009] It is also solved by the fact that the internal resistance of the first and the second voltmeter are different.

[0010] The different total resistances ensure that, in the event of a faulty connection, the voltage distribution between the first and third measuring points is not even. This makes faulty connections easy to detect.

[0011] The components of the electrochemical cell system can be, for example, the electrochemical cells, the derivatives or other functional components.

[0012] It is particularly advantageous if the faulty connection is localized based on the measured voltages. This is because the voltages can also provide information about the location of the faulty connection. Localization refers to the limitation of the faulty connection to a specific area of ​​the electrical circuit in which the faulty connection is located, or preferably the determination of the components between which the faulty connection exists. In this sense, it is also advantageous if the evaluation unit is configured to localize the faulty connection based on the measured voltages.

[0013] The measuring points are each electrically connected to at least one pole of at least one electrochemical cell. Thus, the potential of the measuring point corresponds to that of the corresponding pole(s). The measuring points are each connected to different poles, for example, the first measuring point to a positive pole of a first electrochemical cell, the second measuring point to a negative pole of the first and a positive pole of a second electrochemical cell, and the third measuring point to the negative pole of the second electrochemical cell. The three measuring points thus measure the potentials at three different locations in the series circuit of the electrochemical cells.

[0014] "Connected" or "switched" shall hereinafter mean "electrically connected" or "electrically switched" unless expressly defined otherwise.

[0015] Particularly when more than two electrochemical cells are planned, more than three measuring points may be provided. In this case, the voltages between different measuring points can be compared. A measuring point can be used as either the second measuring point or the first measuring point for a measurement, depending on which areas of the electrochemical cell system are to be tested.

[0016] Preferably, the potential along the series circuit of electrochemical cells is measured at least at a first measuring point, a second measuring point, and a third measuring point. In other words, the first measuring point, the second measuring point, and the third measuring point are preferably arranged along the series circuit. This means that along the series circuit, the second measuring point lies between the first and third measuring points.

[0017] The circuits are each connected in parallel to at least one electrochemical cell. A circuit is an electrical circuit which, during normal operation, is connected in parallel to the electrochemical cell or cells connected between the respective measuring points. Normal operation means that no incorrect connections occur. This is because a circuit can be inadvertently disconnected from a measuring point due to an incorrect connection. The circuit usually has a voltmeter, which is used to measure the voltage between the two measuring points. It can also include other elements such as resistors, low-pass filters, or similar.

[0018] For the purposes of this invention, resistance means electrical resistance and preferably ohmic resistance, unless explicitly stated otherwise.

[0019] Accordingly, the total resistance refers to the electrical resistance resulting from the circuit connected in parallel to at least one electrochemical cell between the respective measuring points. If the circuit only has a voltmeter, the total resistance is simply the internal resistance of the voltmeter. If an adapter resistor is connected in parallel to a voltmeter, the total resistance is the product of the adapter resistance and the internal resistance, divided by the sum of the adapter resistance and the internal resistance.

[0020] Incorrect connections within the meaning of the invention are faulty electrical connections between components. During manufacture or use of the electrochemical cell system, an electrical connection can be mistakenly not established or broken. Such incorrect connections can lead to faulty function or even inoperability of the electrochemical cell system. The first and second voltages do not necessarily have to be measured simultaneously. It can be provided that one voltage is measured first and then the other. In any case, however, it is advantageous if the measurements are carried out as quickly as possible one after the other in order to prevent misinterpretations caused by interim changes in the charge state of the electrochemical cells.

[0021] Preferably, all electrochemical cells are designed identically and / or all electrochemical cells have the same output voltage. Preferably, each electrochemical cell has at least one, particularly preferably exactly one, battery cell. The electrochemical cells can also comprise multiple battery cells, one battery module, or multiple battery modules. Alternatively, each electrochemical cell can also have at least one, particularly preferably exactly one, fuel cell.

[0022] A series or parallel circuit refers to an electrical circuit. For example, in a series circuit of two electrochemical cells, the negative pole of a first electrochemical cell is connected to the positive pole of a second electrochemical cell.

[0023] Particularly when more than two electrochemical cells are provided, it may be advantageous to provide at least one additional measuring point that is electrically connected to at least one pole of at least one electrochemical cell, with the measuring points each being electrically connected to different poles. The voltage measurements as described for the first and second voltages, as well as their evaluation, can then be carried out analogously between the available plurality of measuring points, for example, between the third and the additional measuring point or between the additional measuring points.

[0024] Preferably, the first voltage and the second voltage are compared with each other, and the presence of a faulty connection between components is assessed based on the comparison of the voltages. In this sense, the evaluation unit can be configured to compare the first voltage and the second voltage with each other and to assess the presence of a faulty connection between components based on the comparison of the voltages. For example, the absolute voltage difference can be used for the assessment.

[0025] It is also particularly advantageous if a first threshold value is specified for the difference between the first voltage and the second voltage, that the difference between the first voltage and the second voltage is compared with the first threshold value and the presence of a faulty connection is assessed as positive if the difference is on a first side, in particular above, the first threshold value, and is assessed as negative if the difference is on a second side, in particular below, the first threshold value.

[0026] In this sense, it may also be advantageous if it is provided that the evaluation unit is set up to compare the difference between the first voltage and the second voltage with a predetermined first threshold value and to assess the presence of a faulty connection as positive if the difference is on a first side, in particular above, the first threshold value, and to assess it as negative if the difference is on a second side, in particular below, the first threshold value.

[0027] It can also be provided that a second threshold value is specified for a value of the first voltage and / or the second voltage, that the first voltage and / or the second voltage is compared with the second threshold value and the presence of a faulty connection is assessed as positive if the first voltage and / or the second voltage is on a first side, in particular above, the second threshold value, and is assessed as negative if the first voltage and / or the second voltage is on a second side, in particular below, the threshold value.

[0028] For example, the second threshold may be above the maximum voltage of the respective electrochemical cell or cells. If this threshold is exceeded, it is clear that the measured voltage is not only the actual voltage of the respective electrochemical cell or cells, but that a faulty connection is causing a voltage measurement that does not correspond to the actual voltage at the respective electrochemical cell or cells.

[0029] In this sense, it may also be advantageous if the evaluation unit is set up to compare the first voltage and / or the second voltage with a predetermined second threshold value and to assess the presence of a faulty connection as positive if the first voltage and / or the second voltage is on a first side, in particular above, the second threshold value, and to assess it as negative if the first voltage and / or the second voltage is on a second side, in particular below, the threshold value.

[0030] It can be provided that the first, second and third measuring points are electrically connected to poles of two electrochemical cells connected directly one after the other in series. In this sense, it can also be provided that the first, second and third measuring points are electrically connected to poles of two electrochemical cells connected directly one after the other in series. This means that no third electrochemical cell is connected between them. Thus, the first measuring point is preferably connected to a positive pole of a first electrochemical cell, the second measuring point to the negative pole of the first and the positive pole of a second electrochemical cell, and the third measuring point to the negative pole of the second electrochemical cell.

[0031] In a preferred embodiment, the presence of a faulty connection of leads for taking the potentials from the measuring points is assessed based on the measured voltages. Lead here refers to the electrical connection between the measuring point and the voltage-measuring unit, usually the voltage measuring unit. The lead is usually an electrical line such as a cable or a conductor. If a measuring point is connected to two poles of different electrochemical cells - for example because they are connected directly in series, the measuring point can be used to take the potential of both poles. Since usually only one lead is provided per measuring point, the potential of neither pole can be identified if the lead is faulty.The connection of the lead to the measuring point, the lead itself, or even its connection to the voltage measuring unit may be faulty, for example, disconnected. The different total resistances according to the invention make a faulty lead easily identifiable. In this sense, it is also advantageous if the evaluation unit is configured to assess the presence of a faulty connection of leads for measuring the potentials from the measuring points based on the measured voltages.

[0032] In a preferred embodiment, the first voltage is measured by a first voltmeter and the second voltage is measured by a second voltmeter. In this sense, it is also advantageous if the voltage measuring unit has a first voltmeter connected between the first measuring point and the second measuring point, and a second voltmeter connected between the second measuring point and the third measuring point. Voltmeter refers to any type of voltage measuring device that can directly or indirectly determine the voltage between two measuring points.

[0033] According to the invention, the internal resistance of the first voltmeter and the internal resistance of the second voltmeter are selected to be different. Accordingly, it is also advantageous for the internal resistance of the first and second voltmeters to be different. Even in simple circuits consisting only of the voltmeter, this ensures that the total resistances are different.

[0034] It can also be provided that, in order to adjust the first and / or second total resistance, at least one adapter resistor is connected between the first measuring point and the second measuring point and / or the second measuring point and the third measuring point. In this sense, it can also be provided that at least one adapter resistor is connected between the first measuring point and the second measuring point and / or between the second measuring point and the third measuring point. In this case, "between the respective measuring points" preferably means a parallel connection of the resistor to the voltage measuring unit, but a series connection can also be provided. Preferably, one pole of the resistor is connected directly to one measuring point and another pole of the resistor is connected directly to the other measuring point, i.e. preferably no other electrical component is arranged in between.

[0035] Preferably, the adapter resistor is arranged in the area of ​​the voltage measuring unit and, particularly preferably, connected in parallel to the voltage measuring unit. Furthermore, the adapter resistor can be part of the voltage measuring unit. This ensures that the connection to the adapter resistor is not also severed in the event of faulty discharge.

[0036] It is particularly advantageous if, to adjust the first and second total resistances, at least one first adapter resistor is connected in parallel to the first measuring point and the second measuring point, and at least one second adapter resistor is connected in parallel to the second measuring point and the third measuring point, and that the first and second adapter resistors are selected to be different values. In this sense, it can also be provided that at least one adapter resistor is connected between the first measuring point and the second measuring point, and between the second measuring point and the third measuring point, and that the adapter resistors are different.

[0037] It is particularly advantageous if at least one adapter resistor is permanently connected between the first measuring point and the second measuring point and / or between the second measuring point and the third measuring point. Permanently connected means that it cannot be disconnected by, for example, a relay or other switching element. This simplifies the design and ensures that the adapter resistor is always available for a voltage measurement and adjusts the total resistances accordingly.

[0038] Furthermore, it is particularly advantageous if the electrochemical unit has at least three electrochemical cells, preferably battery cells, connected in series, and that the potentials are taken at measuring points of the end poles of the electrochemical unit and at measuring points of the electrically connected poles of neighboring electrochemical cells, and the voltages are measured at the measuring points that are electrically connected to the two poles of an electrochemical cell, and that the total resistances resulting from a circuit between these measuring points are selected to be different from the total resistances between the measuring points that are electrically connected to the poles of their neighboring electrochemical cell or electrochemical cells, and that the presence of a faulty connection between components of the electrochemical cell system is assessed based on the measured voltages.This allows the individual electrochemical cells to be monitored particularly well.

[0039] In particular, at least one adapter resistor has an ohmic resistance of at least 1,000 kΩ, preferably at least 5,000 kΩ, and particularly preferably at least 10,000 kΩ. Such high resistances do not significantly discharge the battery cells, but they do change the ratio of the total resistances sufficiently to enable detection of faulty connections.

[0040] The invention will now be described in more detail with reference to a non-limiting embodiment of the invention, illustrated in the figures.

[0041] Fig. 1 is a circuit diagram of an electrochemical cell system according to the invention for use in the method according to the invention during normal operation; Fig. 2 is a circuit diagram of an electrochemical cell system according to the invention for use in the method according to the invention in the event of a faulty connection;

[0042] Fig. 3 is a diagram showing the actual voltage of the battery cells of the embodiment compared to the measured voltages during the faulty connection according to Fig. 2.

[0043] Fig. 1 shows a schematic circuit diagram of an electrochemical cell system comprising an electrochemical unit 1 having a total of four electrochemical cells 2. In the illustrated embodiment, each electrochemical cell 2a-2d is designed as an individual battery cell, which has, for example, a nominal output voltage U1-U4 of 3 V. Alternatively, the electrochemical cells 2a-2d can also be designed, for example, as a battery module, battery pack, or fuel cell. The electrochemical cell system also has a voltage measuring unit 3, which has a voltmeter 4a-4d for each electrochemical cell 2. Schematically, each voltmeter 4a-4d is shown as an ideal voltmeter 4a"-4d" (i.e., with infinitely high ohmic resistance) and a real internal resistance 4a'-4d' connected in parallel.

[0044] The positive pole of the first electrochemical cell 2a is electrically connected to a measuring point 5a. This positive pole represents one output pole of the electrochemical unit 1. The negative pole of the last electrochemical cell 2d is electrically connected to a measuring point 5e. This negative pole represents the other output pole of the electrochemical unit 1.

[0045] The remaining poles of the electrochemical cells 2a - 2d are each electrically connected in series with the oppositely polarized pole of the adjacent electrochemical cell 2a - 2d. A measuring point 5b - 5d is also electrically connected to each of these pole pairs.

[0046] Each measuring point 5a - 5e is electrically connected to a lead 6a - 6e. Each voltmeter 4a - 4d is electrically connected by its two poles to two adjacent leads 6a - 6e, thus forming a series circuit of the voltmeters 4a - 4d.

[0047] Adapter resistors 7a, 7b are each connected in parallel to the first or third voltmeter 4a, 4c. This results in an adapter resistor 7a, 7b being connected between measuring point 5a and measuring point 5b, and between measuring point 5c and measuring point 5d, if the contact is intact. The adapter resistors 7a, 7b are connected in close proximity to the respective voltmeter 4a, 4c, so that their parallel connection to the voltmeter 4a, 4c is exposed to a low risk of incorrect contact. This wiring results in a first circuit 8a between measuring point 5a and measuring point 5b, which is connected in parallel to the first electrochemical cell 2a and consists of the first voltmeter 4a and the first adapter resistor 7a connected in parallel. The first total resistance of the first circuit 8a results from the parallel connection of the first adapter resistor 7a and the internal resistance 4a' of the first voltmeter 4a.

[0048] Between measuring point 5b and measuring point 5c, a second circuit 8b is formed, which is connected in parallel to the second electrochemical cell 2b and consists only of the second voltmeter 4b. The second total resistance of the second circuit 8b is thus determined by the internal resistance 4b' of the second voltmeter 4b.

[0049] Analogous to the first circuit 8a, the third circuit 8c, between measuring point 5c and measuring point 5d, which is connected in parallel to the third electrochemical cell 2c, consists of the third voltmeter 4c and the second adapter resistor 7b connected in parallel. The third total resistance of the third circuit 8c results from the parallel connection of the second adapter resistor 7b and the internal resistance 4c' of the third voltmeter 4c. As a rule, all voltmeters 4a - 4d have essentially the same internal resistances 4a' - 4d'.

[0050] Analogous to the second circuit 8b, the fourth circuit 8d, which is connected in parallel to the fourth electrochemical cell 2d, consists only of the fourth voltmeter 4d. The fourth total resistance of the fourth circuit 8d is thus determined by the internal resistance 4d' of the fourth voltmeter 4d.

[0051] Circuits 8a-8d are all connected in series. For clarity, circuits 8a-8d are highlighted in Fig. 2.

[0052] During normal operation, as shown in Fig. 1, the voltmeters 4a - 4d can be used to monitor the voltages Ul - U4 of the individual electrochemical cells 2a - 2d. For this purpose, the voltages UV1 - UV4 dropped across the individual voltmeters 4a - 4d can be measured. Since all leads 6a - 6e are intact, the voltages Ul - U4 of the electrochemical cells 2a - 2d correspond to the measured voltages UV1 - UV4.

[0053] The voltmeters 4a - 4d are connected via data lines to an evaluation unit 9, which receives and evaluates the measured voltages UV1 - UV4 of the voltmeters 4a - 4d.

[0054] Fig. 2 shows the same embodiment when one lead, in this case the third lead 6c, is faulty. Here, it is completely interrupted. Thus, if the potential is supposedly measured from measuring point 5c via lead 6c according to the invention, this is not done correctly because lead 6c is defective.

[0055] Thus, the total voltage U2 + U3 from the second and third electrochemical cells 2b, 2c is distributed between the second and third circuits 8b, 8c depending on their two ohmic total resistances. The second adapter resistor 7b reduces the total resistance of the third circuit 8c. The resulting different total resistances create a voltage difference between the measured voltages UV2 and UV3.

[0056] If measuring point 5b is used as the first measuring point, measuring point 5c as the second measuring point and measuring point 5d as the third measuring point, voltage UV2 represents a first voltage and voltage UV3 a second voltage, which have a significant voltage difference.

[0057] This voltage difference is visible in Fig. 3. While the measured voltage UV1 is essentially identical to the actual voltage Ul at the first electrochemical cell 2a, the measured voltage UV2 is significantly higher, while UV3 is significantly lower. This voltage difference is preferably compared by the evaluation unit with a first threshold value, which is preferably selected to be below the measured voltage difference. This allows the evaluation unit to detect a faulty connection.

[0058] If measuring point 5a is used as the first measuring point, measuring point 5b as the second measuring point, and measuring point 5c as the third measuring point, voltage UV1 represents the first voltage and voltage UV2 the second voltage. Here, too, a voltage difference is visible, but this is lower than the voltage difference between UV2 and UV3 and preferably lower than the first threshold. This can also be used to assess the presence of a faulty connection, particularly in locating the faulty connection. Accordingly, measuring point 5c can also be used as the first measuring point, measuring point 5d as the second measuring point, and measuring point 5e as the third measuring point.

[0059] UV2 exceeds a specified second threshold value 10. Thus, the evaluation unit can determine that the third derivative 6c is defective.

[0060] Difference values ​​between UV1 and UV2, between UV2 and UV3, and between UV3 and UV4 can also be calculated and compared with a first threshold value. The first threshold value is preferably set such that the difference between UV2 and UV3 lies above it, but the other differences do not. In this way, the evaluation unit, which can calculate these differences, can also determine that a faulty connection exists and locate it, namely in this case at the third derivative 6c.

Claims

P A T E N T A N S P R Ü C H E 1. A method for monitoring an electrochemical cell system, wherein the electrochemical cell system comprises at least one electrochemical unit (1) which has at least two electrochemical cells (2a - 2d) connected in series, preferably battery cells, wherein the potential of the electrochemical cells (2a - 2d) is measured via leads (6a - 6e) at least at a first measuring point (5a - 5e), at a second measuring point (5a - 5e) and at a third measuring point (5a - 5e), and the measuring points (5a - 5e) are each electrically connected to at least one pole of the at least two electrochemical cells (2a - 2d), wherein the measuring points (5a - 5e) are each electrically connected to different poles and a first voltage (UV1 - UV4) is measured between the first and the second measuring point (5a - 5e) and a second voltage (UV1 - UV4) is measured between the second measuring point (5a - 5e) and the third measuring point (5a - 5e) is measured,wherein a first total resistance, which results from a circuit (8a - 8d) between the first measuring point (5a - 5e) and the second measuring point (5a - 5e), and a second total resistance, which results from a circuit (8a - 8d) between the second measuring point (5a - 5e) and the third measuring point (5a - 5e), are selected to be different, and the presence of a faulty connection between components of the electrochemical cell system is assessed based on the measured voltages (UV1 - UV4), characterized in that the internal resistance (4a' - 4d') of the first voltmeter (4a - 4d) and the internal resistance (4a' - 4d') of the second voltmeter (4a - 4d) are selected to be different.

2. Method according to claim 1, characterized in that the first voltage (UV1 - UV4) and the second voltage (UV1 - UV4) are compared with each other and the presence of a faulty connection between Components are assessed based on the comparison of the stresses (UV1 - UV4).

3. Method according to claim 2, characterized in that a first threshold value for the difference between the first voltage (UV1 - UV4) and the second voltage (UV1 - UV4) is specified, that the difference between the first voltage (UV1 - UV4) and the second voltage (UV1 - UV4) is compared with the first threshold value and the presence of a faulty connection is assessed as positive if the difference is on a first side, in particular above, the first threshold value, and is assessed as negative if the difference is on a second side, in particular below, the first threshold value.

4. Method according to one of claims 1 to 3, characterized in that a second threshold value (10) is specified for a value of the first voltage (UV1 - UV4) and / or the second voltage (UV1 - UV4), that the first voltage (UV1 - UV4) and / or the second voltage (UV1 - UV4) is compared with the second threshold value and the presence of a faulty connection is assessed as positive if the first voltage (UV1 - UV4) and / or the second voltage (UV1 - UV4) is on a first side, in particular above, the second threshold value, and is assessed as negative if the first voltage (UV1 - UV4) and / or the second voltage (UV1 - UV4) is on a second side, in particular below, the threshold value.

5. Method according to one of claims 1 to 4, characterized in that the first, second and third measuring points (5a - 5e) are electrically connected to poles of two electrochemical cells (2a - 2d) connected directly one after the other in series.

6. Method according to one of claims 1 to 5, characterized in that the presence of a faulty connection of at least one derivation (6a - 6e) for taking the potentials from the measuring points (5a - 5e) is assessed based on the measured voltages (UV1 - UV4).

7. Method according to one of claims 1 to 6, characterized in that the first voltage (UV1 - UV4) is measured by means of a first voltmeter (4a - 4d), and the second voltage (UV1 - UV4) is measured by means of a second voltmeter (4a - 4d). -. Method according to one of claims 1 to 7, characterized in that for setting the first and / or second total resistance at least one adapter resistor (7a, 7b) is connected in parallel to the first measuring point (5a - 5e) and the second measuring point (5a - 5e) and / or the second measuring point (5a - 5e) and the third measuring point (5a - 5e).

9. The method according to claim 8, characterized in that for setting the first and second total resistances at least one first adapter resistor (7a) is connected in parallel to the first measuring point (5a - 5e) and the second measuring point (5a - 5e) and at least one second adapter resistor (7b) is connected in parallel to the second measuring point (5a - 5e) and the third measuring point (5a - 5e) and that the first and second adapter resistors (7a, 7b) are selected to be of different sizes.

10. The method according to one of claims 1 to 9, characterized in that the electrochemical unit has at least three electrochemical cells (2a - 2d) connected in series, preferably battery cells, and that the potentials are taken at measuring points (5a - 5e) of the end poles of the electrochemical unit and at measuring points (5a - 5e) of the electrically connected poles of neighboring electrochemical cells (2a - 2d) and the voltages (UV1 - UV4) are measured at the measuring points which are electrically connected to the two poles of an electrochemical cell (2a - 2d) and that the total resistances which result from a circuit (8a - 8d) between these measuring points (5a - 5e) are compared with the total resistances between the measuring points (5a - 5e) which are connected to the poles of their neighboring electrochemical cell (2a - 2d) or electrochemical cells (2a - 2d) are electrically connected,be chosen to be of different sizes and that the presence of a misconnection between components of the electrochemical cell system is assessed based on the measured voltages (UV1 - UV4).

11. An electrochemical cell system comprising at least one electrochemical unit, wherein the electrochemical unit comprises at least two electrochemical cells (2a - 2d), preferably battery cells, which are connected in series, wherein the electrochemical cell system has at least one voltage measuring unit (3) which is or can be electrically connected to a first measuring point (5a - 5e), a second measuring point (5a - 5e) and a third measuring point (5a - 5e) via leads (6a - 6e), and the measuring points (5a - 5e) are each connected to at least one pole of the at least two electrochemical cells (2a - 2d), wherein the measuring points (5a - 5e) are each electrically connected to different poles, and wherein the voltage measuring unit (3) is configured to first voltage (UV1 - UV4) between the first and the second measuring point (5a - 5e) and a second voltage (UV1 - UV4) between the second measuring point (5a - 5e) and the third measuring point (5a - 5e), and wherein the voltage measuring unit (3) is connected to an evaluation unit for supplying the measurement data, wherein a first total resistance, which results from a circuit (8a - 8d) between the first measuring point (5a - 5e) and the second measuring point (5a - 5e), and a second total resistance, which results from a circuit (8a - 8d) between the second measuring point (5a - 5e) and the third measuring point (5a - 5e), are of different sizes, and that the evaluation unit (9) is configured to detect the presence of a faulty connection between components of the electrochemical cell system based on the measured voltages (UV1 - UV4), characterized in thatthat the internal resistance (4a' - 4d') of the first and second voltmeters (4a - 4d) are different., 12. Electrochemical cell system according to claim 11, characterized in that the voltage measuring unit (3) has a first voltmeter (4a - 4d) which is connected between the first measuring point (5a - 5e) and the second measuring point (5a - 5e) and a second voltmeter (4a - 4d) which is connected between the second measuring point (5a - 5e) and the third measuring point (5a - 5e).

13. Electrochemical cell system according to one of claims 11 or 12, characterized in that at least one adapter resistor (7a, 7b) is connected between the first measuring point (5a - 5e) and the second measuring point (5a - 5e) and / or between the second measuring point (5a - 5e) and the third measuring point (5a - 5e).

14. Electrochemical cell system according to claim 13, characterized in that at least one adapter resistor (7a, 7b) is connected between the first measuring point (5a - 5e) and the second measuring point (5a - 5e) and between the second measuring point (5a - 5e) and the third measuring point (5a - 5e), and in that the adapter resistors (7a, 7b) are different.

15. Electrochemical cell system according to claim 13 or 14, characterized in that at least one adapter resistor (7a, 7b) is permanently connected between the first measuring point (5a - 5e) and the second measuring point (5a - 5e) and / or between the second measuring point (5a - 5e) and the third measuring point (5a - 5e). 2024 11 20 MT / IV

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