Method for carrying out a deep discharge of at least one battery by means of a deep discharge device, computer program product, computer-readable storage medium, and deep discharge device

Abstract

The invention relates to a method for carrying out a deep discharge (30) of a battery (12), having the steps of: providing at least one battery (12); applying a first discharge current (I1) to the battery (12) for a first specified duration (t1) up to a first voltage value (V1) of the battery (12); relaxing (R) the battery (12) by interrupting (U) the first discharge current (I1); determining a power loss of the battery (12) during the relaxation (R); determining a second discharge current (I2) and a second duration (t2) up to a second voltage value (V2) for the battery (12) on the basis of the determined power loss; and applying the second discharge current (I2) to the battery (12) for the second duration (t2). The invention also relates to a computer program product, to a computer-readable storage medium and to a deep discharge device (10).

Description

[0001] Description

[0002] Method for deep discharging at least one battery using a

[0003] Deep discharge device, computer program product, computer-readable storage medium and deep discharge device

[0004] The following invention relates to a method for deep discharging at least one battery by means of a deep discharge device according to claim 1. The invention further relates to a computer program product, a computer-readable storage medium and a deep discharge device.

[0005] The safe and efficient recycling of batteries is a topic of growing importance given the steadily increasing use of battery-powered devices and the growing number of electric cars. Among the various steps of the recycling process, deep discharge prior to the actual recovery process plays a crucial role for two reasons. Firstly, lithium-ion batteries pose a risk if handled improperly. Typically, the first step in recycling involves a mechanical processing step in which the batteries are shredded. This releases the energy still stored in the battery all at once, thus creating a safety hazard. Removing the cells from the battery requires a multi-stage disassembly process, which, like the transport of the cells within the factory, is largely carried out manually. Therefore, any risk to human employees must be absolutely eliminated.

[0006] Furthermore, even if the battery no longer offers sufficient power for second-life operation, it may still retain residual charge. By selectively discharging this residual energy, it can, for example, be fed back into the building's electrical system and the wider power grid, or used in the DC link for process applications; for instance, the battery charge can be used for analytical measurements.

[0007] Deep discharge involves the controlled and safe removal of the remaining energy from batteries (which can be considered as individual batteries, battery modules, or battery systems). This process ensures that the batteries are in a stable and safe condition before further processing. It reduces the risk of uncontrolled energy discharges during transport or storage, thus protecting the employees and equipment responsible for recycling from potential hazards. The deep discharge process should be as fast as possible to enable high throughput. However, it is crucial that not too much energy is converted into heat during discharge, as this could cause the battery to overheat and potentially catch fire.

[0008] It is known from the prior art that, in order to carry out deep discharge as quickly and safely as possible, the maximum discharge rate, i.e., the maximum specified continuous current, from the datasheet of the respective battery is used. Alternatively, higher currents can also be used, but this can lead to higher temperatures and potential hazards. In particular, the battery is discharged with a constant current, specifically the discharge current.

[0009] Discharging the battery through an external resistor is also possible and results in a discharge current that depends on the battery voltage. Depending on the choice of external resistor, this can also lead to dangerous temperature increases.

[0010] The object of the present invention is to provide a method, a computer program product, a computer-readable storage medium and a deep discharge device by means of which an efficient discharge process of a battery, in particular an efficient deep discharge process of a battery, can be realized.

[0011] This problem is solved by a method, a computer program product, a computer-readable storage medium, and a deep discharge device according to the independent claims. Advantageous embodiments are specified in the dependent claims.

[0012] One aspect of the invention relates to a method for deep discharging at least one battery using a deep discharge device. The battery is provided. A first discharge current is then applied to the battery for a first predetermined period until a first voltage value is reached, using an electronic processing unit of the deep discharge device. The battery is then relaxed by interrupting the first discharge current using the electronic processing unit. The power loss of the battery during relaxation is then determined using the electronic processing unit. In particular, the power loss that occurred during the discharge step is determined. This is determined primarily based on the voltage profile during relaxation.A second discharge current and a second time period until a second voltage value for the battery are then determined depending on the specified power loss by means of the electronic computing device, and the second discharge current is applied to the battery for the second time period by means of the electronic computing device.

[0013] In particular, this allows for the fastest possible deep discharge without exceeding a predetermined maximum power loss. The deep discharge process can be adjusted accordingly. Unlike discharge with a relatively constant current, the proposed method interrupts the discharge at specific intervals and variably adjusts the current in each interval.

[0014] During the interruptions themselves, no discharge current flows from the battery, allowing the voltage to drop to its current resting voltage value. This drop-off behavior results in the momentary overvoltage of the battery.

[0015] In particular, by interrupting the discharge process, the voltage approaches the open-circuit voltage at specific intervals. The current is interrupted at these intervals, and the current intensity can be adjusted depending on the measured power loss. On average, this allows for higher current intensities than with state-of-the-art methods, thus accelerating the deep discharge process and making it more efficient.

[0016] In particular, the proposed method allows the battery to be discharged with a significantly higher average current than with current-rate methods. This accelerates the process, thereby increasing the system's throughput. The use of higher currents and the intervening pauses presented here enable more economical / efficient operation of the system.

[0017] In particular, the current values ​​specified in the datasheet, if available, are usually significantly lower than the current values ​​usable during deep discharge, as they serve to prevent damage to the battery. Since the battery is no longer directly usable after deep discharge, such damage can be accepted as long as the battery poses no hazard. Other discharge methods currently in the art either use insufficient current values ​​or risk dangerous overheating of the battery.

[0018] As shown, these dangers can be avoided by limiting the maximum power loss. Measuring this power loss allows the current to be adjusted during the process to ensure the fastest possible yet safest process.

[0019] Specifically, it is intended that, for example, the battery is provided in a virtually discharged state, such as with a state of charge (SoC) of 0 percent or slightly higher. It is also possible, for example, to discharge the battery from a 100% state of charge, including intermediate values, down to 0 percent, and then perform a deep discharge. In other words, during deep discharge, the battery is outside the essentially applicable state of charge range of 0 percent to 100 percent. The deep discharge ensures that the battery is essentially completely discharged.

[0020] For example, a lithium-ion battery can essentially be considered discharged at a voltage between 2V and 3.2 volts. At this point, the deep discharge process begins, which can essentially discharge the battery to 0 volts.

[0021] In particular, it may be possible to apply further deep discharge cycles. In other words, after the second discharge current and duration, a third discharge current with a third duration, and further discharge currents with additional durations, can be applied. Depending on the type of battery and its state of aging or charge, multiple cycles can be applied to the battery, thus achieving deep discharge. Specifically, analogous to the first discharge step, further discharge steps are carried out until the battery is completely depleted of residual energy.

[0022] According to an advantageous embodiment, the power loss is determined as a function of a specific overvoltage during relaxation. In particular, the difference between the instantaneous voltage before the current interruption and the open-circuit voltage to which the battery would decay during the interruption can yield the instantaneous overvoltage. From the determined overvoltage Q and the current,

[0023] Before the discharge is interrupted, the instantaneous power loss Pveriust is calculated according to:

[0024] P Loss — QXI ( 1 ) ■

[0025] The usable electrical power drawn from the battery is given by Pusable = (Vo - n) x I = ximm x I, where Vo is the open-circuit voltage and Vi is the terminal voltage. The power loss, on the other hand, is converted into heat and can be limited based on various criteria. Thus, the power loss can be determined in detail.

[0026] It is also advantageous to determine the overvoltage by extrapolating the relaxation. This allows the overvoltage to be extrapolated using appropriate fits of a standard model, enabling a reliable determination of the power loss. This, in particular, allows for rapid deep discharge.

[0027] It is also advantageous to use an overvoltage model that takes into account battery diffusion effects to perform the extrapolation. In other words, an extrapolation is performed during the interruption to accurately determine the overvoltage. This extrapolation usually results from fitting a standard model, which typically describes diffusion effects, to the corresponding measurement data. The current is therefore interrupted only until such a fit can be achieved with sufficient accuracy, which can often be accomplished within a few seconds.

[0028] Another advantageous configuration involves applying a first discharge current of a different value and a second discharge current that differs from the first. In particular, the duration between the first and second discharges can also differ accordingly. However, it is also possible for these durations to be essentially the same, for example, if optimal deep discharge is already achievable with the first discharge current.

[0029] Another advantageous embodiment involves repeating the process until the battery has a resting voltage of 0 volts. For example, even after the 0-volt threshold has been crossed during deep discharge, a negative voltage can be generated in the battery so that, at least after relaxation, the battery has a resting voltage of 0 volts. This allows a battery to be safely deep discharged and, for example, safely recycled after the deep discharge process.

[0030] It has also proven advantageous to predict the battery's temperature change during deep discharge and, based on this temperature change, to determine at least the second discharge current and duration. In particular, critical temperature values ​​for the battery can be specified, which can be found, for example, in the battery's datasheet. The temperature change can then be predicted based on the power loss. It is advantageous to adjust the corresponding discharge currents and durations so that the battery does not exceed a desired temperature and thus prevents overheating. This ensures a safe deep discharge process.

[0031] Furthermore, it has proven advantageous to predict temperature changes using a thermal model of the battery and / or to predict temperature changes based on the battery's heat capacity. In particular, discharge and the heat generated by the loss, especially depending on the battery's heat capacity and heat transfer properties, lead to an increase in temperature. If the temperature exceeds a critical value, the battery can, for example, catch fire. To prevent this, the heat generated by the power loss must not exceed the maximum heat dissipation capacity of the battery. For this purpose, thermal models or empirical data from the battery in question, which describe heat transfer, can be used, if available.Alternatively or additionally, the battery's heat capacity C can be estimated based on its weight and approximate material composition. Using Pveriust = C x dT / dt, the instantaneous temperature rise of the battery can then be calculated. Similarly, the temperature rise during a specific phase of the discharge process can be determined.

[0032] At is involved n the duration of the respective process segment before the nth interruption, which occurs at time t n This occurs. T(t n ) and Pveriust (t nThe temperatures and power losses determined at the time of the nth interruption are shown, where T(to) is the battery temperature at the beginning of the process. Due to heat dissipation to the environment, the actual battery temperature will be lower than the values ​​determined here. By limiting the temperature during the deep discharge process—possibly also depending on the currently reached open-circuit voltage T(t)—the temperature can be reduced. n ) < T Max (v0(t n This prevents the battery from overheating, provided the heat distribution within the battery is sufficiently rapid. The maximum permissible power loss during an interruption can then be successively calculated from the equation shown above:

[0033] It is further advantageous if, while at least one battery is relaxing, another battery is deep-discharged using the same method. In particular, since no discharge current is supplied during the relaxation phase, another battery can be discharged during this time. This increases the throughput of batteries in the deep-discharge device, resulting in time savings when deep-discharging a large number of batteries.

[0034] It has also proven advantageous to store usable battery power in a storage device and use the stored energy to perform at least one process step. In particular, the battery's residual energy can be used, for example, to provide the discharge current. Furthermore, corresponding computational or analytical tasks for the electronic computing device can also be performed using the stored energy. Alternatively, the usable power can be converted into electrical energy and fed into a building network or power grid, for example. Thus, the battery's residual energy during deep discharge can be used effectively.

[0035] Furthermore, it has proven advantageous if at least the second discharge current is limited depending on the power usable by the deep discharge device. For example, if the deep discharge device only requires a certain amount of electrical power to perform calculations, the discharge current can be adjusted accordingly. This may result in a longer deep discharge time, but it improves the utilization of the remaining energy. It is also advantageous if the first current value and duration are specified based on a battery datasheet, particularly the battery's discharge rate. The discharge rate can be described, in particular, as the factor C. This factor describes how much current can be drawn from the battery in a given time.For example, the factor 1C describes the fact that the battery's entire charge capacity is drawn in one hour. In particular, it has proven advantageous to discharge at a rate or current of 0.5C to 2C, especially at 1C. This helps prevent the battery from overheating.

[0036] The presented method is, in particular, a computer-implemented method. Therefore, a further aspect of the invention relates to a computer program product with program code means which, when the program code means are executed by the electronic computing device, cause a method according to the preceding aspect to be carried out.

[0037] The invention also relates to a computer-readable storage medium containing the computer program product.

[0038] A further aspect of the invention relates to a deep discharge device for deep discharging at least one battery, comprising at least one electronic computing unit, wherein the deep discharge device is configured to carry out a method according to the preceding aspect. In particular, the method is carried out by means of the deep discharge device. Specifically, the electronic computing unit can, for example, generate control signals for the power electronics, which then apply the actual discharge current to the battery and physically perform the deep discharge process.

[0039] In addition to the electronic computing device, the deep discharge device can also include, for example, appropriate contact devices for the battery, such as power electronics, as well as appropriate measuring devices for measuring current or voltage.

[0040] Advantageous embodiments of the process are to be regarded as advantageous embodiments of the computer program product, the computer-readable storage medium, and the deep discharge device. The deep discharge device possesses specific features to enable the corresponding process steps to be carried out.

[0041] A computing unit / electronic computing device can be understood, in particular, as a data processing device containing a processing circuit. The computing unit can therefore process data to perform arithmetic operations. This may also include operations to perform indexed access to a data structure, such as a lookup table (LUT).

[0042] The computing unit may, in particular, contain one or more computers, one or more microcontrollers, and / or one or more integrated circuits, for example, one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), and / or one or more systems on a chip (SoCs). The computing unit may also contain one or more processors, for example, one or more microprocessors, one or more central processing units (CPUs), one or more graphics processing units (GPUs), and / or one or more signal processors, in particular one or more digital signal processors (DSPs). The computing unit may also include a physical or virtual array of computers or other units of the aforementioned type.

[0043] In various embodiments, the computing unit includes one or more hardware and / or software interfaces and / or one or more storage units.

[0044] A storage unit can be volatile data storage, for example as dynamic random access memory (DRAM) or static random access memory (SRAM), or as non-volatile data storage, for example as read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory or flash EEPROM, ferroelectric random access memory (FRAM), or magnetoresistive random access memory.It can be designed as MRAM (magnetoresistive random access memory) or as phase-change random access memory, PCRAM (phase-change random access memory).

[0045] For use cases or application situations that may arise in a method according to the invention and that are not explicitly described herein, it may be provided that, according to the method, an error message and / or a request for user feedback is issued and / or a default setting and / or a predetermined initial state is set.

[0046] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

[0047] Further features and combinations of features of the invention will become apparent from the figures and their descriptions, as well as from the claims. In particular, further embodiments of the invention need not necessarily include all features of any one of the claims. Further embodiments of the invention may have features or combinations of features that are not mentioned in the claims.

[0048] This shows:

[0049] Fig. 1 shows a schematic block diagram according to an embodiment of a deep discharge device;

[0050] Fig. 2 shows a schematic time-voltage diagram; and

[0051] Fig. 3 is a schematic time-flow diagram.

[0052] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0053] Fig. 1 shows a schematic block diagram according to an embodiment of a deep discharge device 10 for deep discharging a battery 12. The deep discharge device 10 comprises an electronic computing unit 14 and, in the present case,

[0054] An exemplary embodiment includes a power electronics unit 16 with, for example, a current measuring device 18 and a voltage measuring device 20. Measured values ​​22 can be transmitted from the power electronics unit 16 to the electronic computing unit 14. The electronic computing unit 14 can, in turn, transmit specifications 24 to the power electronics unit 16. Furthermore, framework conditions 26, such as a maximum temperature, a maximum power dissipation, or thermal data for the battery 12, can be supplied to the electronic computing unit 14.

[0055] The electronic computing unit 14 can be physically integrated into the existing power electronics 16 or connected to it as a separate device. The power electronics 16 functions as in the prior art. It applies a defined current I to the battery 12 and measures its voltage V. In the present method, the current I and the duration At for which it is applied are determined by the electronic computing unit 14 and can be recalculated for each of the described interruptions. The current and voltage profiles measured by the power electronics 16 are transmitted to the electronic computing unit 14. Furthermore, a user, for example, stores specifications 24 in the electronic computing unit 14, which define the framework conditions 26 of the method based on the criteria described later.From this data, the electronic computing unit 14 then determines the specifications for the current strengths I and the duration of the next process step, which are transmitted to the power electronics 16, in the manner described below.

[0056] Fig. 2 shows a schematic time-voltage V-diagram. In particular, a voltage curve 28 during a deep discharge 30 is shown. Specifically, a starting voltage Vstart and an open-circuit voltage Vs0c=0 are shown. Furthermore, a 0-volt line V=0 is shown.

[0057] Figure 3 shows essentially the same time course as Figure 2; however, in Figure 3, the time t and the current I are shown schematically. In particular, a datasheet current value ID is shown.

[0058] Fig. 3 shows in particular six discharge cycles to deep discharge the battery 12 accordingly.

[0059] The figures show, in particular, that battery 12 is being provided accordingly.

[0060] This can be provided, for example, with the open-circuit voltage Vs0c=0 or with a starting voltage Vstart. A first discharge current h is then applied to the battery 12 for a first predetermined time ti until a first voltage value Vi of the battery 12 is reached by means of the electronic computing unit 14. The relaxation R of the battery 12 then occurs by interrupting U of the first discharge current h by means of the electronic computing unit 14. The power loss of the battery 12 during relaxation R is then determined by means of the electronic computing unit 14.A second discharge current I2 and a second time duration t2 are then determined for the battery 12 up to a second voltage value V2, depending on the determined power loss, by means of the electronic computing device 14, and the second discharge current I2 is applied or specified to the battery 12 for the second time duration t2 by means of the electronic computing device 14. The discharge currents are applied physically, in particular via the power electronics 16.

[0061] In the present embodiment, further discharge / deep discharge cycles are shown, which are demonstrated over further current intensities I3 to le and over further time durations t3 to te. Furthermore, corresponding additional voltages V3 - Ve are shown in the voltage diagram, whereby the sixth voltage Ve corresponds to a voltage of 0 volts, and the deep discharge process can be terminated at this point.

[0062] In particular, it can be provided that the power loss is determined as a function of a specific overvoltage R during relaxation. Furthermore, the overvoltage can be determined by extrapolating the relaxation R. Alternatively, an overvoltage model taking into account diffusion effects of battery 12 can also be used to perform the extrapolation.

[0063] In particular, it may be provided that a first current value h is applied as the first discharge current and a second current value I2, which differs from the first, is applied as the second discharge current. The time durations ti to te may also differ accordingly. However, depending on the specific type of battery 12 or its state of aging, it is also possible in one configuration that the discharge currents h to le and the time durations ti to te are essentially the same.

[0064] Furthermore, it may be provided that a temperature change of the battery 12 during the deep discharge 30 is predicted and, depending on the temperature change, at least the second discharge current I2 and at least the second time duration t2 as well as the further discharge currents I3 to le and the further time durations t3 to te are determined.

[0065] In particular, the temperature change can be predicted using a thermal model of the battery 12 and / or the temperature change can be predicted depending on a heat capacity of the battery 12.

[0066] Furthermore, it can be provided that during the relaxation R of at least one battery 12, another battery is deep-discharged using the method. Likewise, usable power can also be stored in a storage device 32 and used to carry out at least one process step of the method.

[0067] It may also be provided that at least the second discharge current I2 is limited depending on the power usable by the deep discharge device 10.

[0068] Furthermore, the first current value and the first time duration ti can also be specified depending on a data sheet of the battery 12, in particular depending on a given charging rate of the battery 12.

[0069] The method thus proposes the fastest possible deep discharge 30, while ensuring that a predetermined maximum power loss is not exceeded. The deep discharge process is adjusted accordingly. Unlike a discharge with a (relatively) constant current according to the prior art, the proposed method interrupts the discharge at specific intervals and adjusts the current variably in the respective sections.

[0070] During the interruptions U, no current flows from battery 12, allowing the voltage to drop to its current open-circuit voltage. This drop-off behavior results in the instantaneous overvoltage of battery 12.

[0071] By interrupting the current at specific intervals and adjusting the current intensity based on the measured power loss, higher average current intensities are achieved compared to state-of-the-art methods, thus accelerating the deep discharge process. The difference between the instantaneous voltage V before the current interruption and the open-circuit voltage VO, to which battery 12 would decay during the interruption U, yields the instantaneous overvoltage. Extrapolation is usually obtained by fitting a standard model (which typically describes diffusion effects) to the measured data. Therefore, the current interruption U only needs to last until such a fit is possible with sufficient accuracy; this is usually a few seconds.

[0072] From the determined overvoltage ri and the current I before the interruption U of the discharge, the instantaneous power loss Pveriust is calculated according to:

[0073] (1) Pveriust — 0 XI

[0074] The usable electrical power drawn from the battery is accordingly PNusable = (Vo - rQ x i. The power loss, on the other hand, is converted into heat and can now be limited based on various criteria, for example with regard to the topics mentioned below.

[0075] The heat generated by losses leads to an increase in temperature, depending on the heat capacity and heat transfer properties of battery 12. If the temperature exceeds a critical value, battery 12 can catch fire. To prevent this, the heat generated by the power losses must not exceed the maximum heat dissipation capacity of battery 12. Thermal models or empirical data for the specific battery 12, which describe heat transfer, can be used for this purpose, if available. Alternatively, the heat capacity C of battery 12 can be estimated based on its weight and approximate material composition. Using Pveriust = C x dT / dt, the (instantaneous and averaged) temperature rise of battery 12 can be calculated. Similarly, the temperature rise during a section of the discharge process can be determined using:

[0076] In this case, A t nthe duration of the respective process segment before the nth interruption U, which occurs at time t n This occurs. T(t) and P Ve riust (Ai) are the determined temperatures and power losses at the time of the nth interruption U, where T(t0) is the temperature of battery 12 at the beginning of the process. Due to heat dissipation to the environment, the actual temperature of battery 12 will be below the values ​​determined here. By limiting the temperature during the deep discharge process – possibly also depending on the currently reached open-circuit voltage, T(t0) < T0 Max (70(tn)) - thus, overheating of battery 12 can be prevented, provided that the heat distribution within battery 12 functions sufficiently quickly. From (2), the maximum permissible power loss at each interruption U can then be successively calculated:

[0077] If the energy of battery 12 is to be utilized, the power loss must not exceed a certain value in order to operate the deep discharge device 10 effectively. For this purpose, an absolute value for the maximum power loss can be assumed, or the permissible ratio between power loss and usable power can be limited.

[0078] The deep discharge process is now controlled as follows: If the measured power loss is below the permissible value Ploss.max (one of the previously described criteria), the current after the interruption U is chosen to be higher than before, in order to accelerate the process. However, if the power loss is higher than permissible, the current must be chosen to be lower. The exact value by which the current can be adjusted results from the following condition:

[0079] (3) 0(l) XI < Ploss.max

[0080] In general, rt(l) exhibits a complex dependence on the current due to the superposition of ohmic behavior, diffusion, and charge transfer, which changes with the state of charge and the temperature of battery 12. For sufficiently small changes in current, a linear dependence can be assumed: ri(l) = R x |, where the effective resistance R is derived from the currently measured overvoltage and current. From (3) it then follows accordingly: With each interruption U, the power loss or overvoltage and / or resistance can be recalculated to adjust the current for the next process step. By using a sufficient number of interruptions U and repeatedly readjusting the current, the duration of the deep discharge 30 can be optimized. With sufficiently long interruptions U, the paused channels could also be used for other purposes during the interruption period, for example, to discharge another battery until it experiences its own interruption U. This would further increase the overall throughput of the deep discharge device 10.

[0081] Reference symbol list

[0082] 10 Deep discharge device

[0083] 12 batteries

[0084] 14 electronic computing equipment

[0085] 16 Power Electronics

[0086] 18 current meter

[0087] 20 Voltage measuring device

[0088] 22 measured values

[0089] 24 specifications

[0090] 26 Framework conditions

[0091] 28 Voltage curve

[0092] 30 Deep discharge

[0093] 32 Storage device

[0094] V voltage t time

[0095] I discharge current

[0096] R Relax

[0097] U interruption

Claims

Patent claims 1. Method for deep discharging (30) at least one battery (12) using a deep discharge device (10), comprising the steps: - Providing at least one battery (12); - Applying an initial discharge current (h) to the battery (12) for a first predetermined time period (h) up to a first voltage value (Vi) of the battery (12) using the deep discharge device (10); - Relaxation (R) of the battery (12) by interruption (U) of the first discharge current (h) using the deep discharge device (10); - Determining the power loss of the battery (12) during relaxation (R) using an electronic computing device (14) of the deep discharge device (10); - Determining a second discharge current (I2) and a second time duration (t2) until a second voltage value (V2) for the battery (12) as a function of the determined power loss using the electronic computing device (14); and - Applying the second discharge current (I2) to the battery (12) for the second time period (t2) using a deep discharge device (10).

2. Method according to claim 1, characterized in that the power loss is determined as a function of a certain overvoltage during relaxation (R).

3. Method according to claim 2, characterized in that the overvoltage is determined by extrapolation of the relaxation (R).

4. Method according to claim 3, characterized in that an overvoltage model taking into account diffusion effects of the battery (12) is used to perform the extrapolation.

5. Method according to one of the preceding claims, characterized in that a first current value is applied as the first discharge current (h) and a second current value different from the first discharge current (h) is applied as the second discharge current (I2).

6. Method according to one of the preceding claims, characterized in that the method is repeated until the battery (12) has a resting voltage of 0 volts.

7. Method according to one of the preceding claims, characterized in that a temperature change of the battery (12) during deep discharge (30) is additionally predicted and, in addition, at least the second discharge current (I2) and at least the second time duration (t2) are determined as a function of the temperature change.

8. Method according to claim 7, characterized in that the temperature change is predicted by means of a thermal model of the battery (12) and / or the temperature change is predicted as a function of a heat capacity of the battery (12).

9. Method according to one of the preceding claims, characterized in that during the relaxation (R) of the at least one battery (12) a further battery is deep discharged by means of the method.

10. Method according to one of the preceding claims, characterized in that a usable power of the battery 12 is stored in a storage device (32) and is used to carry out at least one process step of the method.

11. Method according to one of the preceding claims, characterized in that at least the second discharge current (I2) is limited depending on a power usable by the deep discharge device (10).

12. Method according to one of the preceding claims, characterized in that a first current value for the first discharge current (h) and the first time duration (ti) is specified depending on a data sheet of the battery (12), in particular depending on a predetermined discharge rate of the battery (12).

13. Computer program product comprising program code means which cause an electronic computing device (14) to perform a method according to one of claims 1 to 12 when the program code means are executed by the electronic computing device (14).

14. Computer-readable storage medium comprising at least one computer program product according to claim 13.

15. Deep discharge device (10) for deep discharging (30) at least one battery (12), with at least one electronic computing device (14), wherein the deep discharge device (10) is configured to carry out a method according to one of claims 1 to 12.

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