Method and apparatus for charging a multi-cell battery - Patents.com

Abstract

The invention relates to a method for charging a multi-cell battery 20, in which a battery voltage U0 of the battery 20 is detected before charging begins, a charge-state-dependent charging voltage characteristic curve 10 is determined starting from the detected battery voltage U0, and a charging voltage UL is open-loop and / or closed-loop controlled in a charge-state-dependent manner on the basis of the determined charging voltage characteristic curve 10. Furthermore, the invention relates to a device 1 for charging a multi-cell battery 20.

Description

[Technical field]

[0001] The present invention relates to a method and apparatus for charging a multi-cell battery. [Background technology]

[0002] A lithium-ion cell can only accept a certain charging current depending on the temperature, the time of current application and the state of charge (SOC: State Of Charge) in order not to damage it. Moreover, the limiting current defined thereby changes with the state of health (SOH: State Of Health) of the lithium-ion cell. Moreover, in a battery system, there is the difficulty that several battery cells, which may have different temperatures, states of charge and / or states of health, may be connected in series or parallel. Therefore, it is usually necessary to know the state of charge and state of health of all battery cells in the system, as well as the coldest and hottest points of the battery at any given time. This is accompanied by the need to know the temperature gradient within the battery cells in order to actually know the coldest and hottest points in the entire battery system. These two points, together with the state of charge and state of health of each battery cell, determine the maximum possible charging current at each time. Moreover, the time response of the battery cells to the charging current must be known, since a fully discharged battery cell can accept a current higher than the maximum possible steady-state current for a short time.

[0003] It is known that the maximum possible charging current for a lithium-ion cell can be determined using a three-electrode cell by adjusting the anode potential under load. This is only possible with a three-electrode cell equipped with a reference electrode. Then, as degradation progresses, the system experiences a decrease in the charging current characteristic proportional to the decrease in the capacity or increase in the internal resistance of the cell (see, for example, Non-Patent Document 1 and Patent Document 1).

[0004] It is further known that for a fully discharged battery cell, a maximum pulse current for each state of charge can be determined using a three-electrode cell. This is known, for example, from US Pat. No. 5,399,363, which describes a method for charging a battery. In the method, a number of starting states of charge and a number of ambient temperatures are provided. For each combination of one of the starting states of charge and one of the ambient temperatures, a reference charging current curve for charging the corresponding battery is recorded and stored as a reference charging current characteristic.

[0005] Furthermore, it is known that charging current characteristics that depend on temperature, state of charge, and pulse duration are tested for adverse effects by repeated application to the battery and then applied to the system accordingly. Rather than reacting to degradation of battery cells in the system, it is common to plan for a safety margin on the charging current from the outset.

[0006] Generally, in the initial situation before charging, there is a problem that the state of charge (SOC), state of health (SOH) and temperature of the battery cells in a typical battery are either not known, cannot be accurately determined or must be determined by additional measures. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] German Patent Publication No. 102016007479 [Patent Document 2] German Patent Publication No. 102019003465 [Non-patent literature]

[0008] [Non-Patent Document 1] Sieg et al., Journal of Power Sources 427 (2019) 260-270, doi: https: / / doi.org / 10.1016 / j.jpowsour.2019.04.047 Summary of the Invention [Problem to be solved by the invention]

[0009] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to provide an improved method and apparatus for charging multi-cell batteries. [Means for solving the problem]

[0010] According to the invention, this problem is solved by a method having the features of claim 1 and by a device having the features of claim 7. Advantageous embodiments of the invention emerge from the dependent claims.

[0011] In particular, a method for charging a multi-cell battery is provided in which the battery voltage of the battery is detected before charging begins, a charging voltage characteristic curve dependent on the charge amount is determined starting from the detected battery voltage, and the charging voltage is open-loop controlled and / or closed-loop controlled in a manner dependent on the charge amount based on the determined charging voltage characteristic curve.

[0012] Furthermore, in particular, a device for charging a multi-cell battery is realized, which comprises a control device, the control device being configured to receive a battery voltage of the battery detected before the start of charging, to determine a charging voltage characteristic curve depending on the charge amount starting from the detected battery voltage, and to perform open-loop and / or closed-loop control of the charging voltage depending on the charge amount based on the determined charging voltage characteristic curve.

[0013] The method and the device allow to carry out an open-loop-controlled and / or closed-loop-controlled charging of the battery starting from the battery voltage detected before charging. This is achieved by determining a charge voltage characteristic curve that is dependent on the charge amount starting from the battery voltage detected before charging. Starting from this determined charge voltage characteristic curve, the charge voltage is controlled in an open-loop-controlled and / or closed-loop-controlled manner. In particular, with the aid of this charge voltage characteristic curve, the value of the charge voltage characteristic curve determined starting from the charge amount gives the charge voltage. In this case, the charge amount is in particular the charge amount that is added to charge the battery, i.e. before charging, the value of this charge amount is in particular equal to zero, and at the end of charging, a target charge amount is reached. To this end, the control device in particular receives as input a charge amount that has already been added, starting from this charge amount, determines a value of the charge voltage characteristic curve and uses this value as the respective target value for the charging voltage. This is repeated during charging, so that a target value for the charging voltage is determined continuously. Charging is terminated in particular when a given charge amount or the end value of the charging voltage characteristic curve is reached.

[0014] An advantage of the present method and apparatus is that only a single measurement of the battery voltage needs to be performed, no further measures such as determination of the battery cell voltage, the battery cell temperature and the current state of charge are required.

[0015] The device can be used in a battery system, for example to charge the batteries of the battery system. In particular, the device can be arranged and used in a vehicle, in particular an automobile, for example an electric or hybrid automobile, but the vehicle can also essentially be any other land, rail, water, air or space vehicle, for example a drone or an air taxi.

[0016] The battery cell is in particular a lithium-ion battery cell, and the battery is in particular made up of a plurality of such lithium-ion battery cells.

[0017] Parts of the device, in particular the control device, may be constructed individually or collectively as a combination of hardware and software, for example as program code running on a microcontroller or microprocessor, but it is also possible to provide that the parts are constructed individually or collectively as application specific integrated circuits (ASICs) and / or field programmable gate arrays (FPGAs).

[0018] In one embodiment, it is provided that in order to determine the charging voltage characteristic curve, the detected battery voltage is incorporated as a parameter into a stored charging voltage characteristic curve that is parameterizable with the battery voltage. This minimizes the burden when determining the charging voltage characteristic curve, since it is not necessary to determine the complete charging voltage characteristic curve, but only to parameterize the already determined and stored parameterizable charging voltage characteristic curve. This parameterizable charging voltage characteristic curve can be stored, for example, in a memory of the control device and can be retrieved from this memory when necessary. By incorporating the detected battery voltage, the charging voltage characteristic curve is then, in particular, completely parameterized, so that the relationship between the charge amount and the charging voltage is known for each charge amount or can be determined using the charging voltage characteristic curve parameterized in this way. These charging voltage characteristic curves and the parameterizable charging voltage characteristic curves differ in particular only in the parameter "battery voltage" and are otherwise identical (i.e. the battery voltage is already incorporated in the charging voltage characteristic curve).

[0019] In one embodiment, the charging voltage characteristic curve and / or the parameterizable charging voltage characteristic curve are determined or are provided to have been determined taking into account a given no-load voltage curve of the battery cells, a given limit voltage curve of the battery cells and a topology of the battery cells. This is achieved in such a way that the charging voltage characteristic curve does not assume a value that leads to exceeding the limit voltage of the battery cells at any time during the charging of the battery. In particular, the limit voltage is the voltage above which damage to the battery cells occurs, in particular due to the lithium plating process. On the other hand, the charging voltage determined using the charging voltage characteristic curve should be selected to be greater than the respective no-load voltage of the battery cells. Furthermore, in order to obtain the battery voltage from the observation of the individual battery cells, the topology (series and / or parallel) of the individual battery cells is observed. These limit voltage curves and no-load voltage curves can be determined, for example, based on a series of empirical experiments and / or by simulation using methods known per se, and then applied to the battery cells accordingly.

[0020] In an improved embodiment, the determination of the charging voltage characteristic curve and / or the parameterizable charging voltage characteristic curve is carried out by: For a given final state of charge, a difference between a given limit voltage curve and a given no-load voltage curve is determined or has been determined; Starting from a starting voltage determined for a given starting state of charge using the determined difference and the no-load voltage curve, a progression of the characteristic curve between a given starting state of charge and a given final state of charge is determined or has been determined; Starting from the determined difference, the determined characteristic curve profile and the topology of the battery cells in the battery, a charging voltage characteristic curve and / or a parameterizable charging voltage characteristic curve is determined or has been determined. It is stipulated that:

[0021] This achieves, in particular, that the voltage of the battery cell between a given initial charge state and a given final charge state of the battery cell does not exceed the limit voltage at any time during charging. These given initial charge state and given final charge state are in particular universally given values ​​for all battery cells. The given initial charge state can be, for example, 5% or 20% of the maximum charge of the battery cell. The given final charge state can be, for example, 80% of the maximum charge of the battery cell. In this case, the given initial charge state and the given final charge state are values ​​used to determine the charging voltage characteristic curve and / or the parameterizable charging voltage characteristic curve, which do not have to coincide with the real actual values ​​of the individual battery cells.

[0022] In one embodiment, it is provided that the course of the charging voltage characteristic curve and / or the parameterizable charging voltage characteristic curve is linear and / or that the course of this characteristic curve is determined or has been determined as a linear course. This makes it possible to provide a charging voltage characteristic curve that is particularly easily determined. In particular, the charging voltage characteristic curve can have a course of approximately the following shape: Charge voltage = f(charge amount) = detected battery voltage + determined difference + voltage gradient x charge amount

[0023] This voltage gradient can then be determined, in particular, by adding the determined difference to the respective no-load voltages at the starting state of charge (e.g., 5% or 20%) and at the final state of charge (e.g., 80%) and determining the gradient in terms of charge amount between the resulting values ​​between the starting state of charge and the final state of charge.

[0024] In principle, the course of the charging voltage characteristic curve and / or the parameterized charging voltage characteristic curve can also be configured with other shapes, such as, for example, a quadratic function, a polynomial function, a power function, an exponential function, a logarithmic function, etc.

[0025] In one embodiment, when determining the charging voltage characteristic curve and / or the parameterizable charging voltage characteristic curve, an offset related to the temperature difference of the battery cells connected in series, an offset related to the temperature difference of the battery cells connected in parallel and an offset related to the difference in the state of charge of the battery cells connected in series are taken into account or are provided to have been taken into account, thereby making it possible to take into account a safety margin related to the temperature difference and / or the difference in the state of charge. These offsets are taken into account, in particular, in the form of a pre-exponential factor.

[0026] Further features of the device embodiments will become apparent from the description of the method embodiments, in which case the advantages of the device are the same as those of the method embodiments.

[0027] Furthermore, a battery system is particularly provided which comprises at least one device according to one of the implementations described herein.

[0028] The invention will be explained in more detail below on the basis of preferred embodiments with reference to the drawings. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of an apparatus for charging a multi-cell battery. [Diagram 2] A schematic diagram of an example of a battery and a connection form of the battery and a charging control unit realized using the present device. [Diagram 3] Schematic diagram to clarify the determination form of the charge voltage characteristic curve [Figure 4a] FIG. 1 is a graph showing electrical variables over time when a battery is charged in a simulation for clarifying the present invention. [Figure 4b] FIG. 1 is a graph showing electrical variables over time when a battery is charged in a simulation for clarifying the present invention. [Figure 4c]FIG. 1 is a graph showing electrical variables over time when a battery is charged in a simulation for clarifying the present invention. [Figure 4d] FIG. 1 is a graph showing electrical variables over time when a battery is charged in a simulation for clarifying the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] 1 shows a schematic diagram of one implementation of an apparatus 1 for charging a multi-cell battery 20. In particular, this apparatus 1 can be part of a battery system. This apparatus 1 implements the method described in this disclosure.

[0031] The device 1 comprises a control device 2. The control device 2 comprises, for example, a computing device 3 and a memory 4.

[0032] The control device 2 is configured to receive a detected battery voltage U0 of the battery 20 before the start of charging. For this purpose, the battery voltage U0 is detected at the battery 20, for example by means of a suitable sensor device 22, and transmitted to the control device 2 as a signal.

[0033] Starting from this detected battery voltage U0, the control device 2 determines a charge voltage characteristic curve 10 that depends on the charge level. For this purpose, for example, corresponding program code is executed on the computing device. The control device 2 determines the charge voltage U0 based on the determined charge voltage characteristic curve 10. L The charging voltage U is controlled by open loop or closed loop control depending on the charge amount. L The value of is, for example, the charging voltage U L To this end, in particular, the detected charging current I L It is defined that the additional charge amount Q is detected and / or determined by integrating the charging current I LTo detect this, for example, a current sensor (not shown) configured accordingly can be used in or at the inverter 15 .

[0034] It can be provided that, to determine the charging voltage characteristic curve 10, the detected battery voltage U0 is incorporated as a parameter into a stored charging voltage characteristic curve 11, which is parameterizable with the battery voltage U0. To that end, the computing device 3 retrieves the parameterizable charging voltage characteristic curve 11 from the memory 4 and incorporates the detected or received battery voltage U0 into the parameterizable charging voltage characteristic curve 11, thereby obtaining the charging voltage characteristic curve 10.

[0035] The charging voltage characteristic curve 10 and / or the parameterizable charging voltage characteristic curve 11 are determined based on a given no-load voltage curve OCV of the battery cell 23-x of the battery 20 and a given limit voltage curve U of the battery cell 23-x. max and the connection topology of the battery cells in the battery 20. This will be described in a schematic and exemplary manner with reference to Figs.

[0036] 2 shows a schematic diagram of an example of a battery 20 and a connection form of the charging control unit 30 realized by using the battery 20 and the device 1. The battery 20 includes six battery cells 23-x connected in parallel in pairs, and the parallel-connected battery cells 23-x are connected in series. The charge states and temperatures of the individual battery cells 23-x may differ from each other.

[0037] FIG. 3 shows a schematic diagram with the voltage U on the vertical axis (Y axis) and the state of charge SOC on the horizontal axis (X axis). In this case, an individual battery cell is observed. The no-load voltage curve OCV and the limit voltage curve U max The charging voltage curve 10 and / or the parameterizable charging voltage curve 11 (FIG. 1) are then in particular shown to indicate that the course of the voltage of the individual battery cells at any point during charging falls within the limit voltage curve U maxIn this case, in principle, different suitable curve shapes can be used, as already mentioned above.

[0038] Furthermore, in the improved configuration, in particular for determining the charging voltage characteristic curve 10 (FIG. 1) and / or the parameterizable charging voltage characteristic curve 11 (FIG. 1) for a given final state of charge SOC2, a given limit voltage curve U max and a given no-load voltage curve OCV is determined or can be defined as having been determined as follows: ΔU=U max (SOC2)-OCV(SOC2)

[0039] SOC2 is selected, for example, to be 80% of the full charge of the battery cell. Furthermore, for a given initial state of charge SOC1, the progression of the characteristic curve between a given initial state of charge SOC1 and a given final state of charge SOC2 is determined, starting from the following starting voltage U1, determined using the determined difference ΔU and the no-load voltage curve OCV: U1 = OCV(SOC1) + ΔU This starting state of charge SOC1 is selected, for example, to be 5% or 20% of the total charge of the battery cell. In this case, it is provided in particular that the course of the characteristic curve is determined as a linear course or has been determined. For this purpose, in particular, the slope of the straight line X is determined as follows:

[0040]

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[0041] The charging voltage characteristic curve 10 and / or the parameterizable charging voltage characteristic curve 11 are determined starting from the determined difference ΔU, the determined curve course of the characteristic curves and the topology of the battery cells in the battery.

[0042] Based on the example given above, it can be defined, for example, that the charging voltage characteristic curve 10 has the following shape:

[0043]

number

[0044] In this case, the following equation regarding the additional charge amount Q and the time t is particularly satisfied:

[0045]

number

[0046] If the term ΔU·s+s / p has already been determined, a parameterizable charging voltage characteristic curve 11 can be provided, which can then be stored for retrieval in the memory 4 of the control device 2 and can be retrieved therefrom when necessary and parameterized with the detected battery voltage U0, so that the charging voltage characteristic curve 10 can be generated therefrom. However, it can also be provided that the charging voltage characteristic curve 10 is determined as early as before charging.

[0047] It should be noted that in this case the charging voltage characteristic curve 10 or the parameterizable charging voltage characteristic curve 11 is or can be defined only in the interval 0 to (SOC2-SOC1). In particular, if the charge quantity Q to be topped up reaches the value SOC2-SOC1, the charging process is stopped.

[0048] Basically, one or more of the charging voltage characteristic curve 10, the parameterizable charging voltage characteristic curve 11 and the progression of the characteristic curves can be configured non-linearly or can include such functions, for example as a quadratic function, a polynomial function, a power function, an exponential function or a logarithmic function.

[0049] When determining the charging voltage characteristic curve 10 and / or the parameterizable charging voltage characteristic curve 11, an offset A related to the temperature difference of the battery cells connected in series is T,s , offset A related to the temperature difference of parallel connected battery cells T,p and / or an offset A related to the difference in the state of charge of battery cells connected in series. SOC,s It may be provided that one or more of the following are taken into consideration or have been taken into consideration.

[0050] The charging voltage characteristic curve 10 detailed above then has, in particular, the following shape:

[0051]

number

[0052] The charging voltage characteristic curve 10 represents a limit voltage U max so that the charging voltage U L The purpose of the method and the device 1 is to allow the charging of the battery 20 (FIGS. 1 and 2) in an open-loop and / or closed-loop controlled manner, depending exclusively on the charge amount Q already added. The method and the device 1 allow the charging of the battery 20 to be significantly simplified, since the state of charge, state of health and / or temperature of the individual battery cells no longer need to be known, which in particular allows costs and expenditures to be saved.

[0053] 4a to 4d show schematic diagrams of example temporal progressions of electrical variables when charging a battery 20 with six battery cells 23-x in the topology shown in Fig. 2 in one example state, which has, for example, the following values: Battery cell 23-1: SOC=5%, T=25°C Battery cell 23-2: SOC=5%, T=35°C Battery cell 23-3: SOC=10%, T=35°C Battery cell 23-4: SOC=10%, T=40°C Battery cell 23-5: SOC=15%, T=25°C Battery cell 23-6: SOC=15%, T=40°C

[0054] Starting from this initial situation, a simulation was performed using a battery cell model, in which charging was performed using the method described in this disclosure in the process of controlling the charging voltage depending on the charge amount. In this case, the charging voltage characteristic curve 10 described above, consisting of the following values, was used as the charging voltage characteristic curve 10:

[0055]

number

[0056] In this simulation, the battery voltage before charging is set as follows: U0=10.284V

[0057] The charge amount between 5% (=SOC1) and 80% (=SOC2) of the maximum charge amount is a characteristic of the battery cell or battery.

[0058] FIG. 4a shows the charge voltage U (in volts) after regulation as a function of time t (in seconds). L The graph shows the progression of the charge voltage U0. It can be clearly seen that at the start (approximately at t=0 seconds) the battery voltage U0 is controlled from below to the target value determined using the charging voltage characteristic curve. Subsequently, the voltage rises continuously over time as the charge amount added increases.

[0059] Fig. 4b illustrates the progression of the state of charge SOC (in %) of the individual battery cells 23-x as a function of time t (in seconds). Since the battery cells 23-x have different state of charge SOC and temperatures at the start of charging (t=0), the progression of the state of charge SOC over time t is also different. If one of the battery cells 23-x (battery cell 23-6 in the illustrated example) reaches a state of charge SOC of 80%, the charging is stopped. This is particularly relevant since the charging voltage characteristic curve used to control the charging voltage was determined with reference to a final state of charge of 80%.

[0060] 4c illustrates the progression of the instantaneous charging current I (in amperes) of an individual battery cell 23-x as a function of time t (in seconds) and the halving of the charging current of the battery 20. In this simulation example, there are always two battery cells 23-x connected in parallel (see FIG. 2), which results in a halving of the charging current of the battery 20, since the current is split approximately equally between the respective parallel connected battery cells 23-x.

[0061] FIG. 4d illustrates the progression of the cell voltage (in volts) of an individual battery cell 23-x as a function of its state of charge (in % of the total charge or capacity of the battery cell 23-x). max and the no-load voltage curve OCV are shown. It can be clearly seen that the curves of the individual battery cells 23-x start from different starting points (5%, 10% and 15% SOC) assumed in this example at time t=0. Moreover, none of these curves fall within the limit voltage curve U max It can be clearly seen that the charging process is terminated as soon as one of the battery cells 23-x reaches a charge state of 80%.

[0062] At the end of the charging process (approximately 72-80% SOC, depending on the curve), these curves and the limit voltage curve U max In particular, the remaining interval between offset A T,s ,A T,p ,A SOC,sIf smaller values ​​for these offsets are selected, these curves are treated as limit voltage curves U max can be brought closer to [Explanation of symbols]

[0063] 1 This device 2. Control equipment 3 Computing equipment 4. Memory 10 Charging voltage characteristic curve 11 Parameterizable charging voltage characteristic curve 15 Inverter 20 Battery 22 Sensor Equipment 23-x Battery Cells 30 Charging control unit A T,s Offset (temperature difference, series) A T,p Offset (Temperature difference, parallel) A SOC,s Offset (state of charge difference, series) Q Charge amount I current I L charging current m Slope of the current-voltage curve OCV No-load voltage curve SOC State of Charge SOC1 Starting charge state SOC2 Final state of charge U Voltage U0 Detected battery voltage U L Charging voltage U1 Starting Voltage U max Limiting Voltage Curve ΔU difference X straight line

Claims

1. A method of charging a multi-cell battery (20), comprising: Before the start of charging, the battery voltage (U ０ ) is detected, Detected battery voltage (U ０ ) is used as a starting point to determine the charge voltage characteristic curve (10) depending on the charge amount, Based on the determined charging voltage characteristic curve (10), the charging voltage (U Ｌ ) is open-loop and / or closed-loop controlled in a manner dependent on the charge level.

2. 10. The method of claim 1 , In order to determine the charging voltage characteristic curve (10), the detected battery voltage (U ０ ) is the stored battery voltage (U ０ ) is incorporated as a parameter into a charging voltage characteristic curve (11), which can be parameterized using the

3. The method according to claim 1 or 2, The charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11) are determined based on a given no-load voltage curve (OCV) of the battery cell (23-x), a given limit voltage curve (U ｍａｘ ) and the connection topology of the battery cells (23-x), the method being characterized in that the determination is made or has been made taking into account the connection topology of the battery cells (23-x).

4. 4. The method of claim 3, To determine the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11), For a given final state of charge (SOC2), a given limit voltage curve (U ｍａｘ ) and a given no-load voltage curve (OCV) is determined or has been determined; At a given initial state of charge (SOC1), starting from the determined difference (ΔU) and the charge start voltage (U1) determined using the no-load voltage curve (OCV), a transition of the characteristic curve between the given initial state of charge (SOC1) and a given final state of charge (SOC2) is determined or has been determined; The method according to claim 1, wherein the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11) are determined or have been determined based on the determined difference (ΔU), the determined characteristic curve course and the connection topology of the battery cells (23-x) in the battery (20).

5. The method according to any one of claims 1 to 4, the progression of the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11) is linear; the progression of the characteristic curve is or has been determined as a linear progression.

6. The method according to any one of claims 1 to 5, When determining the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11), an offset (A) related to the temperature difference of the battery cells (23-x) connected in series is Ｔ，ｓ ), an offset (A Ｔ，ｐ ) and an offset (A ＳＯＣ，ｓ ) is taken into consideration or has been taken into consideration.

7. A device (1) for charging a multi-cell battery (20) comprising a control device (2), The control device (2) detects the battery voltage (U ０ ) and receives the detected battery voltage (U ０ ) as a starting point, a charging voltage characteristic curve (10) depending on the charge amount is determined, and the charging voltage (U Ｌ ) in an open-loop and / or closed-loop manner depending on the charge level.

8. 8. The device (1) according to claim 7, The control device (2) furthermore determines the charging voltage characteristic curve (10) by storing the battery voltage (U ０ ) is added to the charging voltage characteristic curve (11), which can be parameterized using the detected battery voltage (U ０ ) as a parameter.

9. 9. The device (1) according to claim 8, The control device (2) further determines a given no-load voltage curve (OCV) of the battery cell (23-x), a given limit voltage curve (U ｍａｘ ) and a connection topology of the battery cells (23-x), the device being configured to perform a determination of a charging voltage characteristic curve (10) and / or a parameterizable charging voltage characteristic curve (11).

10. 10. The device (1) according to claim 9, The control device (2) further comprises, in order to determine the charging voltage characteristic curve (10) and / or the parameterizable charging voltage characteristic curve (11), For a given final state of charge (SOC2), a given limit voltage curve (U ｍａ x) and a given no-load voltage curve (OCV), Starting from a starting voltage (U1) determined using the determined difference (ΔU) and the no-load voltage curve (OCV) at a given starting state of charge (SOC1), a transition of the characteristic curve between a given starting state of charge (SOC1) and a given final state of charge (SOC2) is determined; The device is configured to determine a charging voltage characteristic curve (10) and / or a parameterizable charging voltage characteristic curve (11) based on the determined difference (ΔU), the determined characteristic curve course and the connection topology of the battery cells (23-x) in the battery (20).

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