ENERGY STORAGE WITH PREDICTION CONTROL

Description

[0001] The present invention relates to a method for operating an energy storage device for a power tool by measuring or determining a one-dimensional or multi-dimensional state vector of the energy storage device and measuring or determining a consumption value with respect to the power output of the energy storage device. Furthermore, the present invention relates to an energy management system for an energy storage device of a power tool, comprising a measuring device for measuring a one-dimensional or multi-dimensional state vector of the energy storage device and for measuring a consumption value with respect to the power output of the energy storage device. The present invention also relates to a power tool with such an energy storage device.

[0002] Here, "power tools" refers specifically to battery-operated handheld devices such as cordless screwdrivers, cordless drills, circular saws, and the like. Furthermore, the term "power tools" is also intended to include cleaning equipment, household appliances, and garden tools.

[0003] Energy storage devices are batteries or accumulators (or simply accumulators) that enable cordless operation of power tools. Power tools typically have replaceable battery packs. Such a battery pack usually comprises several battery cells. Both a battery pack and a single battery cell can be considered energy storage devices.

[0004] Battery packs, for example those based on lithium-ion batteries, typically have a limited lifespan, which also depends heavily on the usage patterns of the individual user. Many users are completely unaware of this dependence on usage.

[0005] Factors influencing the lifespan of a battery pack include storage temperature, voltage during storage, cycle depth, charging speed at a given temperature, stress during discharge, vibration, shock, and similar factors. Due to the complex interplay of various influencing factors on battery pack lifespan, it is difficult, if not impossible, for users to understand how their own behavior contributes to reducing or extending the lifespan of their battery packs.

[0006] Up to now, battery management systems integrated into smart battery packs have often taken the approach of abruptly disconnecting consumers from the battery or battery pack as soon as critical current, voltage, or temperature limits are exceeded. This can mean that the user has to stop machining with a tool still in the workpiece. This can sometimes be a rather inconvenient situation.

[0007] For example, US patent 2003 / 0096158 A1 discloses a battery pack and a cordless power tool that uses the battery pack as its power source. When the battery voltage is above a first threshold and below a second threshold, the rotation of the power tool's motor is abruptly slowed. This signals to the operator that the battery needs to be charged.

[0008] Furthermore, US patent 7,990,109 B2 describes a temperature-dependent or polarization-dependent voltage compensation system. For the battery pack of a power tool, the duration for which current is drawn from the battery is determined. A cutoff voltage is set based on a voltage measurement of the battery, the measured current, and the current draw duration. A discharge control module limits the power to the load based on the set cutoff voltage.

[0009] The publication EP 2 351 182 B1 discloses an energy consumption output device for displaying the remaining usable capacity of an electrical consumer connected to an energy storage device. Using a power setting device, the user can specify the remaining usable capacity, so that the optimal operating mode of the consumer is set based on the power consumption in the current operating mode and the remaining capacity of the electrical energy storage device.

[0010] Furthermore, the publication DE 10 2013 213 267 A1 discloses a method for battery management, wherein an amount of current that can be provided by the battery in a prediction period is determined from an available amount of a state variable predicted in the prediction period, wherein the predicted available amount of the state variable is determined by means of a difference between a permissible amount of the state variable determined with respect to a first reference period and an amount of the state variable withdrawn with respect to the first reference period.

[0011] German patent application DE 10 2016 104 956 A1 discloses a method for operating a household appliance. A control unit detects the state of charge of an energy storage device. An operating time is determined based on the state of charge and a selected power level. If the operating time is less than a target operating time, the power is reduced. This patent application discloses the preamble of claim 1.

[0012] In this document, the word "measure" is also used as a synonym for measuring or determining.

[0013] The object of the present invention is to enable the more reliable operation of a power tool with an energy storage device.

[0014] According to the invention, this problem is solved by a method, an energy management system, and a power tool according to one of the independent claims. Advantageous embodiments of the invention are described in the dependent claims.

[0015] Accordingly, a method for operating an energy storage device for a power tool is provided. As mentioned at the outset, the energy storage device is understood to be, in particular, a battery or rechargeable battery pack. The term "power tool" encompasses, in particular, the aforementioned electrical devices, especially cordless screwdrivers, cordless drills, cordless circular saws, but also cordless garden tools such as cordless pruning saws and the like.

[0016] The method involves measuring a one-dimensional or multi-dimensional state vector of the energy storage device. In the simplest case of a one-dimensional state vector, a single state value is measured. Examples of such a state value include the current flowing, the voltage, or the temperature of the energy storage device or battery pack. However, multiple state values ​​of the energy storage device can also be measured (simultaneously). For example, the remaining voltage and the temperature of the battery pack can be determined at the same time. This results in a two-dimensional state vector from these two values, representing the state of the energy storage device. Optionally, several other state values, such as internal pressure, internal resistance, or a specific electrode potential, may also be measured.All these state values ​​result in a multidimensional state vector that quite clearly represents the current state of the energy storage device.

[0017] Furthermore, in the operating method according to the invention, a consumption value relating to the power output of the energy storage device is measured. Such a consumption value is, for example, the power output from the energy storage device or the current currently flowing. Therefore, it is not necessary to determine the actual power output of the energy storage device; instead, corresponding partial quantities such as currents and voltages can also be determined. If necessary, the current currently flowing (or another quantity) can also be measured as a state value, and the consumption value (e.g., the power) can be determined from this.

[0018] Furthermore, in the method according to the invention, a predictive value for the power tool is determined from the state vector and the consumption value using a model. A mathematical model is thus used to predict or estimate a value for controlling or regulating the power tool. This predictive value does not relate to the past or present, but rather to the future operation of the energy storage device or power tool. For example, based on the current consumption value and a current temperature value, a future temperature value is predicted. This means that, for example, the temperature of the battery pack in the next few seconds can be predicted based on the current consumption value.

[0019] Finally, the power tool or energy storage device is controlled or regulated based on the predicted value. This means that the power tool or energy storage device is influenced with or without feedback. While control involves no feedback, regulation, according to system theory, is a closed-loop process in which the controlled variable continuously influences itself within the control loop. Not only the energy storage device itself, but also the tool can be controlled or regulated. This means that the power output of the energy storage device can be influenced directly by the device itself or indirectly by the power tool. Control or regulation is based on the predicted value.For example, if it is predicted that the battery pack temperature will exceed an impermissible threshold within a few seconds due to current power consumption, the power draw can be reduced at the present time, i.e., before the threshold is actually exceeded. The operation of the energy storage device or power tool is therefore not (only) influenced based on a current state value, but rather on an estimated future value or value trend. In this way, for example, it can be prevented that a battery-powered circular saw stops mid-cut due to very high power consumption, resulting in a rough cut edge at the point of interruption when cutting is resumed with a newly charged battery pack.

[0020] The system is designed so that the predicted value includes a remaining runtime, which determines the end of the remaining runtime, and includes the control (here, as well as in the following, representing rules) of a reduction in the energy storage system's power output as soon as the time difference between a current time and the end of the remaining runtime falls below a predefined threshold. The remaining runtime represents the period during which the energy storage system can still supply power according to the measured consumption value, or during which the power tool can still draw power according to the measured consumption value. Thus, the remaining runtime is understood as the remaining operating time. When using the remaining runtime, a distinction can be made between whether it is uninterrupted or potentially interrupted.Once the remaining operating time has been determined, it, or a value used as the basis for calculating it, may exceed the predefined threshold. At this point, a reduction in the energy storage system's power output is not yet necessary. In this case, the remaining operating time can be used to determine an actual end point or end time. A new calculation of the remaining operating time is then unnecessary, as the end of the originally calculated remaining operating time can now be used for control. If the time difference between the current point in time and the end of the remaining operating time falls below the predefined threshold, the energy storage system's power output should be reduced. Therefore, it is not necessary to constantly recalculate the remaining operating time.Rather, it is sufficient if, at the beginning of a power output of the energy storage system, a remaining operating time and, if necessary, a corresponding end time of the remaining operating time are used for regulating or controlling.

[0021] In a specific configuration, the state vector describing the state of the energy storage device can include a state value relating to an electrical voltage across the energy storage device or an electrical current into or out of the energy storage device. Specifically, the electrical voltage can be the total voltage across a battery pack. Alternatively, the electrical voltage can also be the voltage of a single battery cell. The state vector can optionally contain a multitude of individual voltages, each relating to a single cell within a battery pack. These voltage values ​​ensure that the cell chemistry is not damaged during operation of the energy storage device. In particular, a cell should not be operated below a defined voltage to prevent irreversible damage, especially to the energy storage device's capacity.

[0022] Furthermore, the state vector can include a state value relating to the temperature of the energy storage device. This temperature can refer to an entire battery pack or to a single cell within a battery pack. Maintaining a temperature limit is essential for the lifespan of an energy storage device, such as a lithium-ion battery. Above a defined temperature limit, significantly faster aging typically occurs. At very high temperatures, spontaneous destruction can occur. In some cases, the energy storage device may even catch fire or explode. If the current temperature is low, the control system, for example, can intervene later in reducing the energy storage device's operating temperature compared to when the initial temperature is higher.If the energy storage temperature is very low, no intervention will occur in the next few seconds of operation, while if the current temperature is already high, intervention may occur immediately.

[0023] Furthermore, the state vector can include a state value relating to the internal pressure of the energy storage device. The internal pressure of the energy storage device is also a significant parameter for assessing its overall state of health. If the internal pressure of the energy storage device is very high, there is a risk that its structure will change and potentially lead to a short circuit. Conversely, excessively high pressure can also cause chemicals to leak from the energy storage device, creating corresponding hazards.

[0024] According to another embodiment, the state vector can include a state value relating to the internal electrical resistance or impedance spectrum of the energy storage device. Typically, the internal resistance increases with the age of the energy storage device. However, the internal resistance is largely responsible for the heat input during current flow. Therefore, the internal resistance is an important parameter when, for example, the temperature of the energy storage device is to be predicted. If the power output from the energy storage device is not constant and exhibits steep power peaks, the discharge current will contain corresponding alternating components. Consequently, the impedance spectrum of the energy storage device is also important if its temperature is to be predicted with a certain degree of accuracy. The impedance spectrum can refer to two or more discrete frequency values.

[0025] Alternatively or additionally, the state vector can include a state value that relates to one or more electrode potentials, particularly relative to a Li / Li+ reference potential. By relating the electrode potentials to the Li / Li+ reference potential, the state of the energy storage device, especially a lithium-ion battery, can be assessed particularly accurately. Specifically, the Li / Li+ reference potential allows for a more precise determination of both the anode and cathode states, especially compared to determining only the total voltage between the anode and cathode.

[0026] In a preferred embodiment of the method according to the invention, the consumption value is a current value or a power value. Typically, the current in an energy storage device is measured by the battery management system. This can then be used directly to determine the predictive value, in particular the future temperature or future total voltage. Often, the voltage of the energy storage device is also measured using appropriate sensors in the battery management system. From both values, a corresponding power value can then be determined, which in turn can be used to obtain the predictive value. As a rule, the power value is more meaningful for assessing the power output than a corresponding estimate using the current value.

[0027] According to a further development of the inventive method, at least some of the process steps described above can be repeated. If necessary, the process steps can be repeated at certain predetermined time intervals (e.g., 1 ms). Under certain circumstances, the repetition can also be carried out continuously. This means that, for example, when controlling or regulating the energy storage device, the predicted value is constantly recalculated. Depending on the computational effort, the predicted value is then updated at correspondingly short intervals. The entire process may be carried out multiple times. Thus, reliable operation can be ensured even with changing operating modes of the energy storage device or power tool.

[0028] The predicted value can be part of a prediction curve that is determined and used as a basis for control or regulation. This prediction curve can represent the time course of an electric current or voltage, a state of charge, a temperature, an electrode potential, an internal resistance, or an internal pressure of the energy storage device. The prediction curve is then used, for example, to determine the remaining operating time of the energy storage device or the power tool by comparing it to a threshold value.

[0029] In a specific embodiment of the method, the prediction value can be determined in such a way that a predetermined minimum voltage of the energy storage device is not undershot and / or a maximum temperature or internal pressure of the energy storage device is not exceeded. This means that when determining the prediction value, not just one physical quantity is monitored, but several. It is quite conceivable, for example, that the remaining operating time, as a prediction value for maintaining the minimum voltage, has a different value than for maintaining the temperature or internal pressure. If the corresponding results are combined, the remaining operating time can be determined in such a way that each of the conditions can be met. The same, of course, applies to prediction values ​​other than the remaining operating time.In principle, a predictive value can also relate to the total voltage of a battery pack, the cell voltage of an individual cell of the energy storage device, a temperature, an internal pressure, an internal resistance, defined parameters of an impedance spectrum, a specific electrode potential, especially against a Li / Li+ reference potential, or the like. In this document, the word "relates" means that the respective value can be the corresponding physical quantity directly or at least describe it indirectly.

[0030] In a specific configuration, when the energy storage device reduces its power output, the output voltage or current can be reduced by the energy storage device's own energy management system. This energy management system (also called a battery management system) thus controls and regulates the energy storage device independently. Alternatively, the power tool can have its own energy management system, which then indirectly controls and regulates the energy storage device. If the energy storage device has its own energy management system, any power tool, even one without its own energy management system, can benefit from it. Alternatively, a power controller or switching actuator (e.g., a FET) in the power tool can be used by the energy storage device's energy management system for power regulation.

[0031] In a specific implementation, the predicted end time of the remaining runtime can be transmitted to the power tool, and the reduction of the energy storage system's power output is controlled by the power tool itself by reducing its power input. In this case, the predicted value is transmitted to the power tool, which then uses this value to control the power tool, including the energy storage system, as desired. This means that not only the remaining runtime but also other predicted values ​​can be transmitted from the energy storage system to the power tool for its control purposes. Alternatively, only the raw data can be measured in the energy storage system and transmitted to the power tool with little or no preprocessing.There, the prediction value can be determined from the raw data, which may only be slightly pre-processed, for the control of the power tool.

[0032] The above-mentioned problem is also solved according to the invention by an energy management system for an energy storage device of a power tool, with a measuring device for measuring or determining a one-dimensional or multi-dimensional state vector of the energy storage device and for measuring or determining a consumption value with respect to a power output of the energy storage device, a computing device for determining a prediction value for the power tool or the energy storage device from the state vector and the consumption value by means of a model, and a control device for controlling or regulating the power tool or energy storage device as a function of the prediction value, wherein the prediction value includes a remaining operating time with which an end of the remaining operating time is determined, and the control device is configured to reduce the power output of the energy storage device (1) when controlling (S5) as soon as a time difference from a current time to the end of the remaining operating time falls below a predetermined threshold.

[0033] The measuring device therefore usually has at least one sensor, but generally at least two. Firstly, at least one state value of the energy storage device must be measured or determined for the state vector, and secondly, at least the specified consumption value must be measured. Suitable sensors must be provided for both measurements, which measure the corresponding physical values. Preferably, more than two sensors are provided, which can record more current state values ​​(multidimensional state vector) and, if necessary, also several consumption values.

[0034] The computing unit can include one or more processors to determine the predicted value as an output value based on the state vector and the consumption value as input values. The aforementioned model is implemented in this computing unit, enabling the desired function of determining the predicted value from the input values. The computing unit can also include artificial intelligence, and in particular a neural network or similar, which may have been individually trained prior to the commissioning of the energy storage system.

[0035] The advantages and variations described above in connection with the method according to the invention can also be implemented as functional features in the energy management system according to the invention using appropriate means.

[0036] Specifically, an energy storage system with an energy management system of the type just mentioned can also be provided. In particular, this energy storage system can be an intelligent battery pack. This would then, for example, contain not only storage or energy cells (preferably lithium-ion cells) within a single housing, but also the energy management system.

[0037] Furthermore, according to the invention, a power tool can also be provided with an energy storage device of the above design. In particular, the energy storage device can be detachably attached to the power tool as a battery pack. This allows the energy storage device according to the invention to be used together with different power tools.

[0038] The present invention will now be explained in more detail with reference to the accompanying drawings, which show: Fig. 1 a schematic block diagram of an embodiment of a method according to the invention; and Fig. 2 a basic sketch of an energy storage device according to the invention.

[0039] The exemplary embodiments described in more detail below represent preferred embodiments of the present invention.

[0040] Power tools, such as battery-powered circular saws, should be able to be operated more reliably and / or more comfortably. This will be achieved accordingly. Fig. 1An exemplary embodiment of a method for operating an energy storage device of a power tool is provided. In step S1, a first state value of the energy storage device is measured or recorded. In an optional second step S2, a second state value of the energy storage device is measured or recorded. Optionally, further state values ​​of the energy storage device are measured. Each state value is typically measured or recorded with its own sensor (in this document, "measure" also means "record," where a state value may only be recorded electronically). A single state value results in a one-dimensional state vector. Multiple state values ​​result in a multi-dimensional state vector. Typically, the state values ​​relate to a charging or discharging current, a voltage, or a temperature.These quantities can refer to either a single cell or a pack of multiple cells. Thus, the current, voltage, or temperature of a single cell can be measured. Alternatively or additionally, the current, voltage, or temperature of a cell pack (also called a battery pack) can be measured. Accordingly, the term "energy storage device" refers to either the individual cell or the cell pack.

[0041] Alternatively or additionally, other physical quantities of the energy storage device can be measured for the state vector. These include, for example, the internal pressure, the internal electrical resistance, the impedance spectrum, one or more electrode potentials, or similar parameters. If necessary, the temperature of an electronic component (e.g., a power semiconductor) can also be recorded as a state value. All the measured state values ​​of the state vector can be used as inputs for the subsequent process.

[0042] In addition to measuring or determining the one- or multi-dimensional state vector according to steps S1 and S2, step S3 involves measuring or determining a consumption value related to the power output of the energy storage device. This consumption value can be, for example, the current and, if applicable, also the voltage of the energy storage device. The power output can be estimated from the current. The power output can be calculated from the current and voltage by multiplication.

[0043] In a subsequent step S4, a predictive value for the power tool or energy storage device is determined. This predictive value is derived from the values ​​measured, recorded, or determined in steps S1 to S3. Specifically, the predictive value is determined from the state vector and the consumption value using a model. This means that the current state of the energy storage device, as well as the instantaneous power consumption, is taken into account when predicting the operation of the power tool or energy storage device. Based on these parameters, the state of the energy storage device, or one or more physical properties of the energy storage device, can be predicted.

[0044] The predicted value could, for example, be the remaining operating time, which is calculated, among other things, from the current power output. If the energy storage device still has a certain charge, the current power output can be used to calculate how long this power output can continue until a certain limit (e.g., the discharge cut-off voltage or a maximum temperature) is exceeded or fallen below. From this time period, a specific point in time can then be calculated, starting from the current time. If the calculated time period, i.e., the remaining operating time, is less than 5 seconds, this can be indicated to the operator haptically by a temporary reduction in the energy storage device's power output, or even a reduction that lasts for the entire remaining operating time.This means that in step S5, the power tool or energy storage device is controlled or regulated depending on the prediction value determined in step S4.

[0045] Instead of the remaining operating time, another physical value, such as the temperature inside a cell, cell voltage, anode potential, cathode potential, internal cell pressure, or similar parameters, can be determined using a model. If an equilibrium of certain energy storage parameters is reached during the current power output, a corresponding equilibrium value can represent the predicted value. For example, if the energy storage reaches a specific cell temperature at equilibrium during a certain power output, the predicted value can be this (maximum) cell temperature. A similar principle applies to the internal cell pressure.

[0046] Alternatively, the predicted value can also be part of a prediction curve. The prediction curve represents a multitude of predicted values ​​over time. In one embodiment, for example, the cell voltage curve can be determined as a predicted curve at the current power output. From the cell voltage curve, it is then possible to deduce, for example, the remaining operating time at a constant power output. If the predicted cell voltage falls below the discharge cut-off voltage, the end of the remaining operating time would be reached. Similar principles apply, for example, to the internal pressure, cell temperature, anode potential, and cathode potential of the energy storage device. The model for determining the predicted value or the prediction curve can be based on artificial intelligence.In particular, a neural network can be used to determine the predicted value or predicted profile from multiple input variables, namely one or more state values ​​(state vector) and one or more consumption values. The neural network can be trained with numerous datasets. The advantage of using a neural network is that it can be precisely adapted to a specific type of energy storage device without significant effort. It then consistently delivers optimal predicted values ​​for that type of energy storage device.

[0047] Optionally, not just a single consumption value, but a time series of consumption values ​​(load profile) for the energy storage system's power output can be measured. A prediction in the form of a predicted value or predicted trend can also be determined from such a load profile, particularly using a neural network. In this way, fluctuations in power output can also be taken into account for the prediction.

[0048] Controlling or regulating the power tool or energy storage device depending on the prediction value or prediction curve involves reducing the power output.

[0049] If necessary, the charging or discharging current can also be completely interrupted. In one embodiment, the power output can also be regulated depending on, for example, the feed rate of a circular saw or a hammer drill.

[0050] In Fig. 2An energy storage device 1 is shown schematically. This energy storage device 1 could, for example, be a replaceable battery pack for a power tool. Here, the energy storage device 1 symbolically has four storage cells 2. In this example, the storage cells 2 are connected in parallel pairs, representing any other circuits, with the parallel circuits connected in series. This allows, for example, current measurements in all branches for each individual storage cell 2. The energy storage device 1 also has an energy management system 3. This system is used to control and regulate the energy storage device 1. The energy management system 3 has numerous functions, particularly those related to... Fig. 1These have been explained. The individual functions can be optional. Specifically, the energy management system 3 can control or regulate the power output of the energy storage system 1. For example, temperature, pressure, and / or current can be measured at one or more, or at each, of the storage cells. Furthermore, a partial voltage can be measured at each of the parallel connection of the storage cells, and a total voltage of the energy storage system can be measured at the series connection of the parallel connection.

[0051] The energy management system 3 includes a computing unit 4 and a control unit 5. Furthermore, the energy management system 3 includes a measuring unit 6 for measuring at least one state value and at least one consumption value. For example, the measuring unit 6 includes a current sensor 7 for measuring the current flowing into or out of the storage cells 2. In addition, the measuring unit 6 may also include, for example, a voltage sensor 8 to measure the total voltage of several storage cells 2 or the voltage of a single storage cell 2. Furthermore, the measuring unit may also include, for example, a temperature sensor 9 to measure the temperature in the housing of the energy storage device 1, at a storage cell 2, or within a storage cell 2. Numerous other sensors for recording physical quantities as state values ​​or consumption values ​​may be provided in the measuring unit 6.The sensors 7, 8, 9 of the measuring device 6 deliver corresponding measured values ​​to the computing device 4.

[0052] The computing unit 4 has a mathematical model or algorithm (e.g. based on a neural network) with which a prediction value or prediction curve is determined from the input variables (state value(s) and consumption value(s)).

[0053] The predicted value or prediction curve is transmitted to the control unit 5. In one embodiment, the control unit 5 controls or regulates the energy storage device 1 itself based on the predicted value. Specifically, the control unit 5 can reduce, (briefly) interrupt, and so on, the power output at an output 10 of the control unit 5 or the energy storage device 1.

[0054] In another embodiment, the control unit 5 generates a control signal at output 10 from the prediction value of the computing unit 4, for example, to control or regulate the power tool. It is conceivable that the power tool, based on the control signal, requests less power from the energy storage device 1. Alternatively, the control unit 5 may simply transmit the prediction value of the computing unit 4 to the power tool unchanged. In this case, the control unit possesses not (only) a control function, but (also) an interface function for data transmission.

[0055] Optionally, the control unit 5 can have an input 11, which, like the output 10, can be configured for power and / or data signals. For example, the control unit 5 controls the charging current for the energy storage device 1 via input 11. This control preferably occurs based on the prediction value of the computing unit 4. However, input 11 can also be used to receive a control signal from the power tool and to influence the charging or discharging process of the energy storage device 1 based on this control signal. In this way, the control unit 5 can, for example, control or regulate the discharge current depending on the type of power tool and the detection value.

[0056] According to the invention, improved control can thus be implemented, particularly in or near-limit situations, to reduce the output voltage of the battery pack in accordance with the power limit. Specifically, a time-resolved caloric control mechanism can be provided, which computationally considers the actual load situation within the cells at any given time. If the cells, for example, approach their power limit, it is possible under such conditions to adapt the power output of the pack to the load situation within the cells by selectively reducing the output voltage at the pack contacts. The reduced pack voltage also typically reduces the current draw in the power tools operated with it. This naturally leads to a drop in power at the tool, but allows work to continue.A power tool controlled in this way provides the user with haptic feedback (e.g., a decrease in speed) and allows them to adjust the required power, for example by reducing the contact pressure, while still continuing the work process without interruption. This is particularly important when, for example, continuous cuts need to be made without interruption, as the cut quality can suffer if the work process is interrupted.

[0057] The technical implementation of voltage adjustment can be achieved, for example, through pulse-width modulation. A linear regulator or similar device can also be used. Alternatively, the motor control unit of the power tool can be used to reduce power consumption by drawing less current. In this case, appropriate communication between the energy storage device and the load is necessary. REFERENCE MARK LIST:

[0058] 1 Energy storage 2 Storage cell 3 Energy management system 4 Computing unit 5 Control unit 6 Measuring unit 7 Sensor 8 Sensor 9 Sensor 10 Output 11 Input S1 First step S2 Second step S3 Third step S4 Fourth step S5 Fifth step

Claims

1. A method for operating an energy storage (1) for an electric tool by - measuring or ascertaining (S1, S2) a one-dimensional or multi-dimensional state vector of the energy storage (1), - measuring or ascertaining (S3) a consumption value with respect to a power output of the energy storage (1), - determining (S4) a prediction value for the electric tool or the energy storage (1) from the state vector and the consumption value by means of a model, and - controlling or regulating (S5) the electric tool or energy storage (1) depending on the prediction value; characterized in that - the prediction value includes an end of a remaining runtime, and controlling (S5) includes reducing the power output of the energy storage (1) as soon as a time difference from a current time up to the end of the remaining runtime falls below a preset threshold value.

2. The method according to claim 1, characterized in that the state vector includes a state value, which relates to an electrical voltage on the energy storage (1) or an electrical current into the or from the energy storage (1).

3. The method according to any one of the preceding claims, characterized in that the state vector includes a state value, which relates to a temperature of the energy storage (1).

4. The method according to any one of the preceding claims, characterized in that the state vector includes a state value, which relates to an internal pressure of the energy storage (1).

5. The method according to any one of the preceding claims, characterized in that the state vector includes a state value, which relates to an electrical internal resistance or an impedance spectrum of the energy storage (1).

6. The method according to any one of the preceding claims, characterized in that the state vector includes a state value, which relates to one or more electrode potentials in particular against a Li / Li+ reference potential.

7. The method according to any one of the preceding claims, characterized in that the consumption value is a current strength value or a power value.

8. The method according to any one of the preceding claims characterized in that at least some of the method steps (S1 to S5) are repeatedly performed.

9. The method according to any one of the preceding claims, characterized in that the prediction value is part of a prediction course, which is determined and is effected depending on controlling or regulating (S5), and the prediction course represents a temporal course of an electrical voltage, a state of charge, a temperature, an electrode potential, an internal resistance or an internal pressure of the energy storage (1).

10. The method according to any one of the preceding claims, characterized in that in reducing the power output of the energy storage (1), the output voltage or the output current strength of the energy storage is reduced by an energy management system (3) of the energy storage (1) itself.

11. The method according to any one of claims 1 to 9, characterized in that the determined end of the remaining runtime is transferred to the electric tool and reducing the power output of the energy storage (1) is achieved controlled by the electric tool by means of reducing a power input of the electric tool.

12. An energy management system (3) for an energy storage (1) of an electric tool, comprising - a measuring device (6) for measuring a one-dimensional or multi-dimensional state vector of the energy storage (1) and for measuring a consumption value with respect to a power output of the energy storage (1), a computing device (4) for determining a prediction value for the electric tool or the energy storage (1) from the state vector and the consumption value by means of a model, and - a control device (5) for controlling or regulating the electric tool or energy storage (1) depending on the prediction value, characterized in that - the prediction value includes an end of a remaining runtime, and - the control device is formed to reduce the power output of the energy storage (1) in controlling (S5) as soon as a time difference from a current time up to an end of the remaining runtime falls below a preset threshold value.

13. An energy storage (1) with an energy management system (3) according to claim 12.

14. An electric tool with an energy storage (1) according to claim 13.