DE102020126879A1 - Method and device for determining an amount of energy in an electrical energy store - Google Patents

Abstract

The invention relates to a method for determining the amount of electrical energy contained in an electrical energy store (2) for the electrical supply of at least one electrical load (3, 4, 5) during its intended operation, in which the amount of electrical energy contained in the energy store (2) during intended operation amount of energy is calculated by means of at least one predetermined energy consumption variable when the consumer (3, 4, 5) is activated during operation, corresponding to the energy consumption caused by the consumer (3, 4, 5) when it is actually activated. The invention also relates to a device (1) for Determination of an amount of electrical energy contained in an electrical energy store (2) for the electrical supply of at least one electrical consumer (3, 4, 5) during its intended operation.

Description

The invention relates to a method and a device for determining an amount of energy in an electrical energy store, in particular for determining an amount of electrical energy contained in the electrical energy store (e.g. battery or accumulator) for the electrical supply of at least one electrical consumer during its intended operation.

Conventionally, batteries or accumulators with which an electrical consumer is fed are continuously monitored by measurement technology in order to determine the amount of energy contained in the battery or accumulator at any time. For this purpose, for example, the removal of energy is continuously measured, e.g. B. by means of load current measurement, and thus closed on the remaining capacity of the battery / rechargeable battery, as is common with smartphones, for example.

Another conventional method for detecting the amount of energy in the energy store is to determine the remaining capacity of the energy store itself by measuring the electrical voltage on the energy store. However, this metrological method is difficult to carry out with lithium batteries and cannot be carried out with lithium batteries due to their structure.

The metrological methods described above for determining the remaining capacity of an energy storage device also require part of the electrical energy provided by the energy storage device, so that these methods are preferably only carried out at specific time intervals. The methods also presuppose that the proportion of energy required for the measurement is significantly lower than the energy consumption of an electrical consumer fed by the energy store. In addition, with intermittent recording, it must be ensured that there is no change in the energy consumption by the consumer(s) in the periods without measurement, since the entire energy consumption must be interpolated.

Against this background, the invention is based on the object of providing an improved, alternative method and a device for determining an amount of energy in an electrical energy store for supplying an electrical consumer, which overcomes the disadvantages of the prior art explained above. In particular, the determination of the amount of energy in the energy store should be reliable and precise and, in addition, in comparison to the above-mentioned measurement methods, it should require essentially no or a negligibly small fraction of electrical energy.

This object is achieved by a method having the features of claim 1 and by a device having the features of claim 9. Further, particularly advantageous configurations of the invention are disclosed in the respective dependent claims.

It should be pointed out that the features listed individually in the claims can be combined with one another in any technically sensible way (even across category boundaries, for example between method and device) and show further refinements of the invention. The description additionally characterizes and specifies the invention, in particular in connection with the figures.

It should also be pointed out that an “and/or” used herein, standing between two features and linking them to one another, must always be interpreted in such a way that in a first embodiment of the subject matter according to the invention only the first feature can be present, in a second embodiment only the second feature may be present and in a third embodiment both the first and the second feature may be present.

In a method according to the invention for determining in an electrical energy store, z. B. rechargeable battery or non-rechargeable battery (also referred to as primary cell), which is used to supply electricity to at least one electrical consumer during its intended operation, the amount of electrical energy contained in the energy store is during intended operation by means of at least one during normal operation activation of the consumer predetermined energy consumption variable determined by calculation according to an actual activation of the consumer caused by this energy consumption.

For the purposes of the invention, the activated state of the load after its activation is to be understood as meaning a state in which the load draws electrical energy from the energy store in order to carry out its intended operation and preferably to carry out a function. In contrast to this, an idle state of the consumer is a state in which the operation of the consumer is essentially or actually completely stopped and it does not carry out its intended function and accordingly essentially no or only a ver takes negligibly small amount of electrical energy from the energy store. It should be understood here that the consumer can switch between its idle state and its activated state at will, so that both states can be assumed by the consumer for a certain limited period of time. The change can be event-controlled (automatically), for example, in response to the occurrence of a predetermined event (e.g. reaching a predetermined limit/threshold value of a process variable such as a fill level, limit level, viscosity, density, pressure, etc. of a medium) , whereby the length of the consumer's individual periods of rest need not be known in advance and may vary accordingly. Alternatively or additionally, the change can also take place according to a predetermined time pattern, with the consumer then being activated periodically at fixed time intervals and (automatically) changing back to the idle state after its intended function has been carried out.

The method according to the invention now provides that the energy consumption variable characteristic of the operational activation of the consumer is determined in advance, preferably (e.g. once) before the intended use of the consumer. This can, for example, be precisely determined by measurement in a laboratory before the first intended operation. The energy consumption quantity can, for example, be an electrical power consumption (=amount of energy per unit of time) of the consumer when it is performing a function as intended during its activation. However, the power consumption amount is not limited to power consumption. For example, the energy consumption variable of the consumer that characterizes the activation state can also specify a total energy consumption for carrying out the intended function of the consumer when the consumer is activated (for example once). In this case, each activation of the consumer leads to the total energy consumption defined by the energy consumption variable.

Irrespective of the specific type of energy consumption variable describing the consumer, the amount of energy contained in the energy store is always only calculated in the method according to the invention, but not determined by measurement. It goes without saying that the output energy quantity in the energy storage device must be known at least once before the (e.g. first-time) activation of the consumer (e.g. in the form of a specified nominal capacity of the energy storage device or as the result of a one-off measurement-related preliminary determination) in order to to be able to calculate the energy consumption caused by the activation of the consumer using the predetermined energy consumption variable by subtracting the amount of energy consumed by the consumer as a result of its activation from the initial amount of energy in the energy store. The result represents the new initial amount of energy in the energy store for a subsequent activation of the consumer, with the above calculation being repeated in this way each time the consumer is activated again. Thus, the amount of energy present in the energy store can always be determined over the entire intended operation of the consumer, depending on the activations actually taking place, without having to continuously measure an electrical voltage that can (still) be provided by the energy store and/or an electrical current flowing to the consumer.

Since only a calculation of the amount of energy contained in the energy store is carried out instead of a metrological determination, the energy input to be used for the additional calculation steps is only a fraction of this if the calculation steps are carried out, for example, by means of an electronic computing/control unit (e.g. microcontroller). , which conventional metrological methods require for the same task. Nevertheless, the method according to the invention is able to deliver reliable and accurate results with regard to the amount of energy still available in the energy store during the entire intended operation of the consumer.

According to an energy-saving embodiment of the invention that is easy to implement, the energy consumption variable represents an absolute energy consumption of the consumer per (single) activation. This type of energy consumption variable that characterizes the consumer can then be used advantageously when the consumer, as a result of its activation, performs a function as intended that always leads to the same electrical energy consumption. The sum of all activations of the consumer then results in the total energy consumption and, based on the very first starting/initial amount of energy in the energy store, the remaining amount of energy that is currently still stored in the energy store. For example, the temporary activation of a sensor (= electrical consumer) to determine a process variable (e.g. a fill level, limit level, viscosity, density, pressure and the like of a solid, liquid or gaseous medium) can cause an always constant energy consumption per activation, which can advantageously be mapped as explained above.

In an alternative embodiment of the invention, the energy consumption variable represents an energy consumption of the consumer per unit of time (e.g. a power consumption). In this case, the energy consumption caused by the load when it is activated is calculated according to a time period measured during its activation in connection with the corresponding power consumption (energy consumption variable). Accordingly, in addition to the actual activation of the consumer, the activation duration is also recorded, which can be implemented without great effort, for example, by means of an electronic computing and control unit (eg microcontroller). For example, the required activation time of a data transmission device (= electrical consumer) for wireless or wired data transmission (e.g. measurement data determined by a sensor such as filling level, limit level, pressure, density, viscosity, etc.) can be due to sporadically occurring transmission errors and the associated errors Retransmissions vary so that the total energy consumed by the consumer during an activation can be calculated more accurately and reliably over the actual activation duration.

It is to be understood that a suitable energy consumption variable can be defined according to the energy consumption to be expected, depending on the function profile to be carried out by the consumer, as has already been explained above.

According to a further advantageous embodiment of the invention, the consumer is assigned a number of energy consumption variables which are dependent on its operating temperature. These characterize different levels of energy consumption by the consumer, which depend on its operating temperature. For example, some sensors can have a temperature-dependent energy consumption that is not negligible for an even more precise and reliable determination of the amount of energy in the energy store. According to this embodiment, when the consumer is activated, the energy consumption caused by it is calculated according to an operating temperature measured before and/or during and/or after its activation and the energy consumption variable assigned in each case. The temperature can be determined using a temperature sensor on the consumer directly or preferably at least in the immediate vicinity of the consumer. The temperature sensor can also be fed from the energy store.

For example, the operating temperature can be measured once at the beginning of each activation or once after the end of each activation. It can also be determined once before activation and once after activation in order to approximately determine an average temperature during the entire activation. These measurements can only be made once per activation. However, the temperature determination can also be carried out repeatedly at different times during activation of the consumer in order to obtain an even more precise operating temperature profile and to use the corresponding energy consumption variable for calculating the amount of energy drawn from the energy store.

The mathematical determination of the amount of energy contained in the energy store and the activation of the at least one consumer can particularly preferably be carried out using an electronic computing and control unit, e.g. B. microprocessor, microcontroller and the like, are performed. Since the arithmetic and control unit controls the activation of the consumer itself, it is always ensured that each energy consumption of the consumer is recorded and the result of the calculation with regard to the amount of energy remaining in the energy store is very precise. Furthermore, the arithmetic and control unit preferably also has an electronic storage unit, e.g. B. RAM, ROM, Flash and the like, in which the predetermined power consumption sizes are stored. In this way, a highly reliable determination of the remaining capacity of the energy store can be provided in a compact manner. It should be pointed out that the arithmetic and control unit itself can represent an electrical consumer that is fed from the energy store and accordingly calculates its own energy consumption for the respective activation period in the event of external and/or self-activation.

According to yet another advantageous embodiment of the invention, at least two electrical consumers are supplied from the energy store, one consumer being a sensor for determining a process variable, e.g. B. a radar, ultrasonic, infrared, capacitance, vibration sensor and the like. For detecting, for example, a fill level, limit level, viscosity, density or pressure of a solid, liquid or gaseous medium, and the other consumer a data transmission device for Remote transmission is at least the process variable determined by the sensor. The long-distance data transmission can preferably take place wirelessly, although wired data transmission should not be ruled out.

At least one primary cell, in particular a lithium battery, can preferably be used as the electrical energy store. as a primary cell is to be understood herein as a galvanic cell which cannot be recharged after discharge, e.g. B. the aforementioned lithium battery. However, other battery types can also be used. In addition, the use of a rechargeable battery such. B. lithium-ion battery, not excluded from the present invention.

According to yet another advantageous embodiment of the invention, the activation of the load has a number of activation stages. These are each defined by a different, predetermined energy consumption variable. For example, a data transmission device in a first activation stage, a network connection with a first energy consumption and in a second activation stage data transmission with a second, z. B. perform higher (or lower) energy intake. In this case, the activation of the consumer runs through the previously defined different activation stages. In this case, the energy consumption caused by the load when it is activated is calculated according to the respective energy consumption variable of the activation stages passed through when it was activated, in order to make the calculation result with regard to the residual energy remaining in the energy store even more reliable and accurate.

According to a further aspect of the invention, a device for determining an amount of electrical energy contained in an electrical energy store for the electrical supply of at least one electrical consumer during its intended operation according to the invention has an arithmetic and control unit, z. B. microprocessor, microcontroller and the like, for selectively activating the consumer. The arithmetic and control unit is set up here to carry out a method according to one of the configurations described herein.

In other words, the arithmetic and control unit calculates the amount of energy contained in the energy store during normal operation by means of at least one energy consumption quantity predetermined when the consumer is activated according to an energy consumption caused by the consumer when the consumer is actually activated.

Since the arithmetic and control unit controls the activation of the consumer itself, it is always ensured that every energy consumption by the consumer is recorded and the result of the calculation with regard to the amount of energy remaining in the energy store is extremely accurate and reliable. Furthermore, the arithmetic and control unit preferably also has an electronic storage unit, e.g. B. RAM, ROM, Flash and the like, in which the predetermined power consumption amount (s) is / are stored. The arithmetic and control unit is preferably also fed from the energy store and thus also represents an electrical consumer whose energy consumption during its activation period is taken into account in the manner described herein for determining the amount of energy present in the energy store.

Since the electrical energy required by the arithmetic and control unit for the calculation is only a tiny fraction compared to a conventional metrological determination of the energy content in the energy storage device, the device enables particularly energy-saving operation and ensures reliable and precise determination of the amount of energy contained in the energy storage device at all times What is particularly important for energy storage, e.g. B. lithium batteries, which do not allow metrological determination of the remaining capacity in a conventional metrological manner, is a particularly great advantage.

It should be noted that with regard to device-related definitions of terms and the effects and advantages of device-specific features, reference is made in full to the disclosure of analogous definitions, effects and advantages of the method according to the invention. Accordingly, disclosures herein regarding the device according to the invention can be used analogously to define the method according to the invention, unless this is expressly excluded. Disclosures herein with regard to the method according to the invention can also be used analogously to define the device according to the invention. In this respect, a repetition of explanations of the same features, their effects and advantages of the device according to the invention and the method according to the invention can be dispensed with in favor of a more compact description, without such omissions having to be interpreted as a restriction.

According to a particularly preferred embodiment of the subject matter according to the invention, the energy store has at least one primary cell, for example a lithium battery. In addition, at least two electrical loads are provided, of which one load is a sensor for determining a process variable, e.g. B. a radar, ultrasonic, infrared, capacitance, vibration sensor and the like. For detecting, for example, a filling level, limit level, viscosity, density or pressure of a solid, liquid or gaseous medium, and the other consumer is a data transmission device for long-distance transmission of at least the process variable determined by the sensor. The long-distance data transmission can preferably take place wirelessly, although wired data transmission should not be ruled out. In this way, a compact and simple construction, energy-saving and self-sufficient device can be provided, which has a long service life and can promptly and reliably cause the necessary maintenance work to change the almost discharged energy store (e.g. by means of appropriate remote data transmission).

• 1 ein Funktionsblockdiagramm eines Ausführungsbeispiels einer Vorrichtung zur Bestimmung einer Energiemenge in einem elektrischen Energie-speicher gemäß der Erfindung,
• 2 ein Stromaufnahmediagramm zur Erläuterung eines Ausführungsbeispiels eines erfindungsgemäßen Verfahrens zur Bestimmung einer Energiemenge in einem elektrischen Energiespeicher und
• 3 ein weiteres Ausführungsbeispiel eines Verfahrens zur Bestimmung einer Energiemenge in einem elektrischen Energiespeicher gemäß der Erfindung.

Further features and advantages of the invention result from the following description of exemplary embodiments of the invention, which are not to be understood as limiting, which are explained in more detail below with reference to the drawing. In this drawing show schematically:

• 1 a functional block diagram of an embodiment of a device for determining an amount of energy in an electrical energy store according to the invention,
• 2 a current consumption diagram to explain an exemplary embodiment of a method according to the invention for determining an amount of energy in an electrical energy store and
• 3 a further exemplary embodiment of a method for determining an amount of energy in an electrical energy store according to the invention.

In the different figures, parts that are equivalent in terms of their function are always provided with the same reference symbols, so that they are usually only described once.

1 shows a function block diagram of an embodiment of a device 1 for determining an amount of energy in an electrical energy store 2 according to the invention. Other battery types are also conceivable.

As 1 It can be seen that the energy store 2 is used to supply electricity to a number of electrical consumers, in the present example a sensor 3 for determining a process variable, e.g. B. a radar, ultrasonic, infrared, capacitance, vibration sensor and the like. For detecting, for example, a fill level, limit level, viscosity, density or pressure of a solid, liquid or gaseous medium (not shown), and also a Data transmission device 4 for remote transmission of at least the process variable determined by sensor 3 to an in 1 also not shown data receiving device (z. B. a central data server and the like.).

Furthermore, the in 1 Device 1 shown an electronic computing and control unit 5, z. B. microprocessor, microcontroller and the like, with an electronic memory unit, z. B. RAM, ROM, Flash and the like on. The arithmetic and control unit 5 is set up to control the connected electrical loads 3 and 4, that is to say, for example, to activate the sensor 3 (preferably only temporarily) when a measured value is to be recorded, and to switch on the data transmission device (preferably only temporarily). activate in order to transmit the recorded measured value to a central data acquisition device (not shown), for example.

At least one temperature sensor 6 for determining an operating temperature of the device 1 or the electrical consumers 3 and/or 4 (possibly also 5) can also be present, as in 1 is indicated. The at least one temperature sensor 6 can be arranged in the vicinity of the loads 3 and 4 . Several temperature sensors 6 can also be provided (not shown), in which case one temperature sensor 6 can be assigned to one of the consumers 3, 4 (possibly also 5) and attached to it. The temperature sensor 6 can be supplied with electricity, for example, via the arithmetic and control unit 5 .

Data and control lines between the arithmetic and control unit 5 and the consumers 3 and 4 are in 1 indicated by double arrows, energy supply lines between the energy store 2 and the consumers 3, 4 and 5 by means of dashed directional arrows.

The components 2, 3, 4 and 5 (if present also the temperature sensor(s) 6) are in the in 1 case shown in a common housing 7 of the device. Overall, the in 1 Device 1 shown can be referred to as a compact, battery-supplied, self-sufficient and controlled by means of the computing and control unit 5 measuring device for determining a process variable. The measuring device can be used, for example, to determine a fill level, limit level, viscosity, density or pressure and the like of a solid, liquid or gaseous medium. In this case, the measuring device can be used in an industrial environment, for example on vessels, containers and the like holding the medium, but also in a natural environment, for example in a body of water such as a river or canal for detecting a water level. or at a weather/climate station for recording air pressure, temperature, amount of rain, etc.

The arithmetic and control unit 5 in 1 In addition to the control tasks described above, the device 1 shown as an example is also set up so that, during the intended operation of the device 1, the amount of energy contained in the energy store 2 depends on the activations of the electrical consumers 3, 4 that are actually taking place and are initiated by the computing and control unit 5 and the here to be determined arithmetically by the energy consumption caused in each case. Before the device 1 is actually used as intended, for example in a laboratory using conventional metrological methods, the energy consumption values corresponding to their operational activation are determined once for each consumer 3, 4 (optionally also 5) and preferably in the memory unit of the computing and control unit 5 saved. The energy consumption variable can be, for example, a power consumption of the consumer, so that a total energy consumption by the consumer during this activation can be calculated from a time period of the respective activation to be recorded. The energy consumption variable can also already indicate a total energy consumption by the consumer, provided that each activation of the consumer essentially always results in the same energy consumption. In this case, a time recording of the activation can be omitted.

It can also be provided, before the device 1 is actually used as intended, for example in a laboratory using conventional metrological methods, once for each consumer 3, 4 (optionally also 5) and for previously specified operating temperatures of the respective consumer, the corresponding energy consumption variables for their activation determine and preferably store in the memory unit of the arithmetic and control unit 5. In this case, the current operating temperature or ambient temperature can be detected by means of the at least one temperature sensor 6 during the intended operation of the device 1 for each activation of the consumer 3, 5 (possibly also 5) and, depending on the detected operating temperature, the corresponding energy consumption variable for calculating the Amount of energy contained in the energy store can be used. The operating/ambient temperature can be measured before and/or during and/or after the respective activation of the load.

2 shows a current consumption diagram to explain an exemplary embodiment of a method according to the invention for determining an amount of energy in an electrical energy store, for example the energy store 2 of the device 1 1 , dar. About the power consumption I and the consumer here supplied electrical voltage, present z. B. 3.3 V, the amount of energy consumption can be determined directly.

In 2 is an example of a current consumption I (in milliamperes) of a data transmission device, e.g. B. the data transmission device 4 of the device 1 from 1 , plotted against time t (in seconds) during an activation process. It can be seen that the activation has a total of several different activation stages S1, S2, S3, S4, each activation stage being characterized by a different current or energy consumption (= different energy consumption variables). For example, in stage S1 the data transmission device 4 takes during setup of a network connection, e.g. B. a NB-IoT network connection (Narrow Band IoT), a total energy of 130 mJ. In stage S2, the implementation of a data transmission with several repetitions is undertaken, for which purpose e.g. B. a total of 530 mJ are expended. Since the data transmission ultimately fails in stage S2, the transmission power of the data transmission device 4 is increased in stage S3 and the data transmission is finally carried out successfully in stage S3 with an energy consumption of 260 mJ. In stage S4, the network connection is terminated properly, which requires 80 mJ of energy. According to the activation stage S1, D2, S3 and S4 that is passed through during the overall activation of the consumer, the associated energy consumption variable is used to calculate the energy consumption. At least the stages S2 and S3 can vary in their duration depending on the number of attempted data transmission repetitions, so that the energy consumption variable for these two stages is a power specification (=energy consumption per time) of the consumer. The energy consumption variables for the network setup (stage S1) and network dismantling (stage S4) can also represent an absolute energy consumption of the consumer due to an essentially fixed period of time, e.g. B. 130 mJ for level S1 and 80 mJ for level S4, but not necessarily limited to this. The actual duration of the activation stages S1 and S4 can also be recorded and converted to a respective energy consumption using a power specification from the consumer in the corresponding stages.

3 provides another embodiment of a method for determining an amount of energy in an electrical energy store, z. B. Energy store 2 of the device 1 , according to the invention.

The method starts with step S100. In the following step S110, a time measurement for a network setup, e.g. B. for an NB-IoT network connection, which is the first activation stage (similar to stage S1 in 2 ) of a data transmission device (e.g. data transmission device 4 of the device 1 1 ) can be viewed. The network connection is established in step S120. In step S130, it is checked whether the network setup is complete. As long as this is not completed, the process returns to step S120. Otherwise, the time measurement for setting up the network connection is ended in step S140 and the energy required for setting up the network is calculated in step S150 from the energy consumption variable predetermined for setting up the network and the previously measured duration.

In the subsequent step S160, based on a previously known initial amount of energy in the energy storage device, the remaining amount of energy remaining in the energy storage device after the previously determined energy consumption has been removed by the consumer is determined by calculation.

In step S170, a time measurement is started for a second activation stage of the consumer, which is similar to stage S2 or S3 in 2 has remote data transmission, which is carried out in step S180. In step S190, it is checked whether the data transfer is completed. As long as this is not the case, the method returns to step S180. Otherwise, the time measurement is ended in step S200, in step S210 the energy used for the data transmission is calculated from the time period and the energy consumption size and in step S220 the residual energy remaining in the energy store after deduction of the previously calculated energy consumption for the data transmission is calculated. This in 3 The method presented as an example is initially ended in step S230.

It is to be understood that the method steps S100-S230 are carried out again each time the data transmission device is activated. The energy consumption of other electrical consumers, e.g. B. des in 1 Sensor 3 shown can be carried out in a manner adapted to the respective consumer.

The device disclosed herein for determining an amount of energy in an electrical energy store and the method disclosed herein for determining an amount of energy in an electrical energy store are not limited to the specific embodiments disclosed herein, but also include other embodiments that have the same effect and are derived from technically meaningful further combinations of the features of the device and of the method described herein result. In particular, the features and feature combinations mentioned above in the general description and the description of the figures and/or shown alone in the figures can be used not only in the combinations explicitly stated herein, but also in other combinations or on their own, without going beyond the scope of the present invention leaving.

In a preferred embodiment, the method according to the invention for determining an amount of energy in an electrical energy storage device, in particular an energy storage device (e.g. lithium battery) having at least one primary cell, which has at least one or more electrical loads, preferably e.g. B. a sensor for determining a process variable (e.g. filling level, limit level, viscosity, density, pressure and the like of a solid, liquid or gaseous medium) and, if necessary, also a data transmission device for remote transmission of the process variable determined by the sensor .

Reference List

1

contraption

2

energy storage

3

sensor

4

data transmission facility

5

Computing, storage and control unit

6

temperature sensor

7

Housing

I

electricity

S1-S4

Different activation levels

t

time

Claims (10)

Method for determining an amount of electrical energy contained in an electrical energy store (2) for the electrical supply of at least one electrical load (3, 4, 5) during its intended operation, in which during the intended operation the amount of energy contained in the energy store (2) is determined by means of at least one upon operational activation of the consumer (3, 4, 5) predetermined energy consumption size corresponding to an actual activation of the Ver consumer (3, 4, 5) is calculated by this effected energy consumption. procedure according to claim 1 , characterized in that the energy consumption variable represents an absolute energy consumption of the consumer (3, 4, 5) per activation. Procedure () according to claim 1 , characterized in that the energy consumption variable represents an energy consumption of the consumer (3, 4, 5) per unit of time, wherein the energy consumption caused by the consumer (3, 4, 5) when it is activated corresponds to a time period (t) measured during its activation and the energy consumption quantity is calculated. Method according to one of the preceding claims, characterized in that the consumer (3, 4, 5) are assigned a plurality of energy consumption variables dependent on its operating temperature, the energy consumption caused by this when the consumer (3, 4, 5) is activated corresponding to a and/or the operating temperature measured during and/or after its activation and the respectively associated energy consumption variable is calculated. Method according to one of the preceding claims, characterized in that the computational determination of the amount of energy contained in the energy store (2) and the activation of the at least one consumer (3, 4, 5) is carried out by means of an electronic computing and control unit (5). Method according to one of the preceding claims, characterized in that at least two electrical consumers (3, 4, 5) are supplied from the energy store (2), one consumer being a sensor (3) for determining a process variable and the other consumer being a Data transmission device (4) for remote transmission of at least the process variable determined by the sensor (3). Method according to one of the preceding claims, characterized in that at least one primary cell, in particular a lithium battery, is used as the electrical energy store (2). Method according to one of the preceding claims, characterized in that the activation of the consumer (3, 4, 5) has a plurality of activation stages (S1, S2, S3, S4), which are each defined by a different energy consumption variable, the activation of the Consumer (3, 4, 5) caused by this energy consumption is calculated according to the respective energy consumption size of the activation stages (S1, S2, S3, S4) passed through when it is activated. Device (1) for determining an amount of electrical energy contained in an electrical energy store (2) for the electrical supply of at least one electrical consumer (3, 4, 5) during its intended operation, having an arithmetic and control unit (5) for selectively activating the consumer (3, 4), wherein the arithmetic and control unit (5) is set up to carry out a method according to one of the preceding claims. Device (1) according to the preceding claim, characterized in that the energy store (2) has at least one primary cell and at least two electrical consumers are provided, of which one consumer is a sensor (3) for determining a process variable and the other consumer is a Data transmission device (4) for remote transmission of at least the process variable determined by the sensor (3).

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