DE102019217376A1 - Procedure for testing a battery sensor and battery sensor - Google Patents

Abstract

The invention relates to a method for testing a battery sensor (10), the battery sensor (10) having at least one detection device (50, 30, 62) for a battery parameter, an evaluation circuit (92) for the at least one recorded battery parameter and a power supply (20) for the battery sensor (10), a supply line for the operating current (11) of the power supply (20) having an electronic component (28) for which a dependency ratio between voltage and current and temperature is stored in a controller of the battery sensor, with the following Steps: a) in a first state in which only the operating current (11) flows through the electronic component (28), determination of a first voltage drop (U1) between a first contact point (32) in front of the diode (28) and a second contact point ( 46) behind the electronic component (28), b) then in a second state in which a defined additional measuring current (Is) over he flows the electronic component (28), determination of a second voltage drop (U2) between the first contact point (32) in front of the diode (32) and the second contact point (46) behind the electronic component (28), c) determination of the electronic component (28) flowing operating current (11) from the detected first voltage drop (U1), the detected second voltage drop (U2) and the known measurement current (Is), d) determining at least one sensor parameter from the determined operating current, e) comparing the at least a sensor parameter with at least one limit value; f) output of an error signal if the sensor parameter exceeds and / or falls below at least one limit value.

Description

The invention relates to a method for testing a battery sensor, the battery sensor having at least one detection device for a battery parameter, an evaluation circuit for the at least one detected battery parameter and a power supply for the battery sensor. The invention also relates to such a battery sensor.

Battery sensors are used in vehicles to record battery parameters in order to assess the state of the vehicle battery, in particular the state of charge of the vehicle battery. For this purpose, the battery sensor has detection devices, for example for the battery voltage, the battery current or the battery temperature. The battery sensor must be able to determine the battery parameters with a very high level of reliability. For this it is necessary that the battery sensor has diagnostic functions in order to be able to check its own function, in particular at regular intervals.

The object of the invention is to provide a method for testing a battery sensor and a battery sensor which enable the battery sensor to be tested reliably.

1. a) In einem ersten Zustand in dem ausschließlich der Betriebsstrom über das elektronische Bauteil fließt, Ermittlung eines ersten Spannungsabfalls zwischen einem ersten Kontaktpunkt vor dem elektronischen Bauteil und einem zweiten Kontaktpunkt hinter dem elektronischen Bauteil,
2. b) anschließend in einem zweiten Zustand, in dem ein definierter zusätzlicher Messstrom über das elektronische Bauteil fließt, Ermittlung eines zweiten Spannungsabfalls zwischen dem ersten Kontaktpunkt vor dem elektronischen Bauteil und dem zweiten Kontaktpunkt hinter dem elektronischen Bauteil,
3. c) Ermittlung des über das elektronische Bauteil fließenden Betriebsstroms aus dem erfassten ersten Spannungsabfall, dem erfassten zweiten Spannungsabfall sowie dem bekannten Messstrom,
4. d) Ermittlung zumindest eines Sensorparameters aus dem ermittelten Betriebsstrom,
5. e) Vergleich des zumindest einen Sensorparameters mit zumindest einem Grenzwert;
6. f) Ausgabe eines Fehlersignals, wenn der Sensorparameter zumindest einen Grenzwert überschreitet und/oder unterschreitet.

To achieve the object, a method for testing a battery sensor is provided, the battery sensor having at least one detection device for a battery parameter, an evaluation circuit for the at least one detected battery parameter and a power supply for the battery sensor, with a feed line for the operating current of the power supply being an electronic component has, for which a dependency ratio between voltage, current and temperature is stored in a controller of the battery sensor, in particular in the form of a family of characteristics. The procedure consists of the following steps:

1. a) In a first state in which only the operating current flows through the electronic component, determination of a first voltage drop between a first contact point in front of the electronic component and a second contact point behind the electronic component,
2. b) then in a second state in which a defined additional measuring current flows through the electronic component, determination of a second voltage drop between the first contact point in front of the electronic component and the second contact point behind the electronic component,
3. c) Determination of the operating current flowing through the electronic component from the recorded first voltage drop, the recorded second voltage drop and the known measurement current,
4. d) determination of at least one sensor parameter from the determined operating current,
5. e) comparison of the at least one sensor parameter with at least one limit value;
6. f) Output of an error signal if the sensor parameter exceeds and / or falls below at least one limit value.

The electronic component is, for example, a diode and the relationship between voltage, current and temperature is represented by a diode map.

The advantages of the method described above are described below by way of example for a diode as an electronic component, it being possible to use any other electronic component for which a relationship between voltage, current and temperature is known, in particular in the form of a family of characteristics, instead of the diode.

Usually, the power supply of the battery sensor is preceded by a diode as reverse polarity protection, which is intended to keep negative supply voltages away from the battery sensor, in particular from the electrical circuits of the battery sensor. The entire operating current that is consumed by the battery sensor flows through this diode.

A so-called diode map is usually available for such a diode. In the case of a diode, the voltage drop across the diode changes with temperature, the ratio of the temperature change to the change in the voltage drop being directly proportional. A diode map shows the relationship between the current and the voltage drop for different temperatures. That is, a characteristic curve of the characteristic curve field defines the ratio between the current flowing across the diode and the voltage drop across the diode for a specific temperature. The current is usually plotted against the voltage on a logarithmic scale, which means that the characteristics are approximately linear and parallel to one another in a relevant operating range.

In order to determine the operating current of the battery sensor, the current flowing through the diode can be determined.

$${10}^{a\ast \left(U2-U1\right)}={10}^{{\text{log}}_{10}\left(I2\right)-{\text{log}}_{10}\left(I1\right)}$$

$$=\frac{I2}{I1}=1+\frac{Is}{I1}$$

$$I1=\frac{Is}{{10}^{a\ast \left(U2-U1\right)}-1}$$

To this end, in the first state in which only the - unknown - operating current 11 flows through the diode, the voltage drop U1 across the diode is measured by measuring a voltage in front of and behind the diode. Then the In the second state, a measuring current Is additionally passed through the diode, so that a total current 12 = 11 + Is flows through the diode, and the voltage drop U2 is measured. Two pairs of values are obtained from the two measurements ( 11 , U1) and (11 + Is; U2). With these two pairs of values, the slope a of the diode characteristic in the relevant operating range can be calculated in the diode map. The operating current can then, for example, using the equations listed below 11 be calculated. $$a\ast \left(U2-U1\right)={\text{log}}_{10}\left(\mathrm{I.}2\right)-{\text{log}}_{10}\left(\mathrm{I.}1\right)$$

$${10}^{a\ast \left(U2-U1\right)}={10}^{{\text{log}}_{10}\left(\mathrm{I.}2\right)-{\text{log}}_{10}\left(\mathrm{I.}1\right)}$$

$$=\frac{\mathrm{I.}2}{\mathrm{I.}1}=1+\frac{\mathrm{I.}s}{\mathrm{I.}1}$$

$$\mathrm{I.}1=\frac{\mathrm{I.}s}{{10}^{a\ast \left(U2-U1\right)}-1}$$

With the calculated operating current, various parameters of the battery sensor can be checked.

With the method described above, the operating current of the battery sensor can be determined in a simple manner without, for example, having to know the exact electrical resistance of the electronic component. All that is required is the detection of a voltage drop across the electronic component and the application of a known additional measuring current.

The at least one sensor parameter can be, for example, the internal power consumption of the battery sensor and a first limit value is a maximum power consumption of the power supply. The method described above can therefore be used to check whether the battery sensor consumes too much electricity. If this is the case, a malfunction or a defect in the battery sensor is assumed and an error signal is output.

Since there is a characteristic curve, especially a diode characteristic curve, for different temperatures in the stored relationship between voltage, current and temperature, in particular in the stored diode characteristic map, it is also possible to determine the temperature of the electronic component from the measured values and the operating current determined , in particular the diode, by determining the corresponding characteristic, in particular the diode characteristic, on which the two pairs of values lie. Since the electronic component is located on the circuit board of the battery sensor, this temperature essentially corresponds to the temperature of the battery sensor. The at least one sensor parameter can therefore be a first battery sensor temperature, which is determined from the determined voltages, the determined current and the relationship between voltage, current and temperature of the electronic component. This temperature can be compared with a limit value.

As an alternative or in addition, the battery sensor can have an internal temperature sensor with which a second battery sensor temperature is determined, which is compared with the battery sensor temperature. In this embodiment, the at least one limit value is defined as a maximum deviation of the battery sensor temperature and the second temperature.

A sensor parameter can be the lead resistance of the power supply. In a state in which the battery voltage is essentially constant, the voltage in front of the electronic component can be detected in both states. The difference in the measured voltages is proportional to the connected measuring current Is and the lead resistance. Since the measurement current Is is known, the lead resistance can be calculated and compared with a specified maximum value. If the measured lead resistance is too high, an error signal is also generated.

To detect the voltage drop across the electronic component, voltage detection before and after the electronic component is required. This can be done in a number of ways. For example, the battery sensor can have a voltage detection device which is connected alternately to the first contact point and the second contact point in order to detect the first voltage drop and the second voltage drop. In this way, for example, system-related errors in the measurement, for example an offset error in the voltage detection devices, can be compensated, since these occur to the same extent in both measurements and are thus eliminated when the voltage drops are differentiated.

Alternatively, the battery sensor can have a first voltage detection device and a second voltage detection device, the first voltage detection device being connected to the first contact point and the second voltage detection device being connected to the second contact point, the voltages at the first contact point and the second contact point being detected simultaneously. The use of two voltage detection devices has the advantage that the voltages can be measured simultaneously at both contact points, so that the measurement of the voltage drops is essentially independent of voltage fluctuations during the measurement.

The first voltage detection device can detect the battery voltage, for example. Since the first voltage detection device is arranged in front of the electronic component and is thus connected to one of the battery poles, it can also detect the battery voltage. In particular, a voltage divider is provided in front of the first voltage detection device and / or the second voltage detection device in order to reduce the voltage to be measured at the first voltage detection device and / or the second voltage detection device. Furthermore, a filter, in particular a low-pass filter, can be provided in front of the first voltage detection device and / or the second voltage detection device.

The second voltage measuring device can alternately be connected to the second contact point and a temperature sensor. The battery sensor usually has a temperature sensor, the values of which are recorded with a recording device. However, since the battery sensor temperature changes only slowly, the detection device of the temperature sensor can also be used temporarily to detect other values, in particular the voltages at the second contact point. For this purpose, a changeover switch is preferably provided which can alternately connect the detection devices to the second contact point and the temperature sensor.

Optionally, a relative error of the first voltage detection device and the second voltage detection device can be determined from the voltages determined in the second state at the first contact point and the second contact point.

The second state is established, for example, by establishing an electrical connection between the energy supply and the negative pole of the battery, at least one resistor with a known electrical resistance being arranged in series between the energy supply and the battery. In this way, an additional measuring current of known magnitude can be passed across the diode in a simple manner. A switch is preferably provided to establish the electrical connection.

Optionally, the battery sensor has a current detection device with a measuring resistor and a detection device for detecting a voltage drop across the measuring resistor, which is contacted with a first contact in front of the measuring resistor and a second contact behind the measuring resistor, the electrical connection with the first and the second Contact is connected, and an error message is output if the voltage drop in the second state exceeds a limit value. The detection device for the voltage drop across the measuring resistor detects the difference in voltages between the two contacts of the measuring resistor. If the measuring current is also applied to the contacts, this leads to a voltage change at both contacts, which altogether only leads to a very small change in the measured voltage drop across the measuring resistor. If, on the other hand, the connection of one of the contacts to the detection devices for the voltage drop is interrupted, the additional measuring current only leads to a change in the measured voltage at the respective other contact, so that the detected voltage drop changes when the measuring current is applied. A change in the voltage drop across the measuring resistor in the second state or when changing from the first state to the second state can therefore indicate an error in the current detection device and an error signal can be output.

To achieve the object, a battery sensor for detecting at least one battery parameter is also provided, which has at least one detection device for a battery parameter, an evaluation circuit for the at least one detected battery parameter and a power supply for the battery sensor, with a supply line for the operating current of the power supply being an electronic one Component for which a relationship between voltage, current and temperature is known, in particular a diode as polarity reversal protection, the battery sensor having a device for producing a second state in which an additional measuring current flows through the electronic component, as well as at least one Detection device for detecting a voltage drop between a first contact point in front of the electronic component and a second contact point behind the electronic component. Furthermore, a control is provided for carrying out at least one of the methods described above. The dependency ratio between voltage, current and temperature of the electronic component, in particular a diode characteristic map for the diode, which has several diode characteristic curves for different temperatures, is preferably stored in the control.

The battery sensor can have an internal temperature sensor with which a second battery sensor temperature is determined, wherein the controller compares the second battery sensor temperature with the first battery sensor temperature and a Can output error signal when a limit value is exceeded, which defines a maximum deviation of the battery sensor temperature and the second temperature.

The battery sensor has, for example, a voltage detection device which can be alternately connected to the first contact point and the second contact point in order to detect the first voltage drop and the second voltage drop. In particular, a switch is provided in order to alternately connect the voltage detection devices to the first contact point and the second contact point

Alternatively, the battery sensor can have a first voltage detection device and a second voltage detection device, wherein the first voltage detection device is connected to the first contact and the second voltage detection device is connected to the second contact.

The first voltage detection device can also detect the battery voltage.

The second voltage measuring device can alternately be connected to the second contact and a temperature sensor, in particular to a changeover switch.

In order to conduct the measurement current via the electronic component, an electrical connection can be established between the energy supply and the negative pole of the vehicle battery, at least one resistor with a known electrical resistance being arranged in series between the energy supply and the battery. A switch is preferably provided in order to close or open the electrical connection.

The battery sensor has, for example, a current detection device with a measuring resistor and a detection device for detecting a voltage drop across the measuring resistor, which is contacted with a first contact in front of the measuring resistor and a second contact behind the measuring resistor.

• 1 eine schematische Darstellung eines erfindungsgemäßen Batteriesensors;
• 2 eine beispielhafte Darstellung eines Diodenkennfeldes für eine Diode;
• 3 eine Darstellung des erfindungsgemäßen Verfahrens zur Prüfung des Batteriesensors

Further advantages and features emerge from the following description in conjunction with the accompanying drawings. In this show:

• 1 a schematic representation of a battery sensor according to the invention;
• 2 an exemplary representation of a diode map for a diode;
• 3rd an illustration of the method according to the invention for testing the battery sensor

In 1 is a battery sensor 10 for the acquisition of battery parameters of a vehicle battery 12th shown. The battery sensor 10 is with a pole clamp on a first battery pole 14th the vehicle battery 12th attached and electrically contacted with these. Furthermore is the battery sensor 10 about consumers 16 or a generator 22nd of the vehicle with the second battery pole 18th electrically connected so that the load current of the vehicle battery 12th via the battery sensor 10 flows.

The battery sensor 10 has a power supply 20th for the operating current 11 of the battery sensor 10 that has a supply line 24 with the second battery pole 18th is contacted. The power supply 20th supplies the entire battery sensor 10 , in particular a controller or an evaluation unit of the battery sensor 10 with the operating current 11 . In the supply line 24 is a lead resistance 26th and an electronic component designed as a diode 28 intended. The diode has the function of a polarity reversal protection of the circuits of the battery sensor 10 to protect against negative voltages.

The one from the battery sensor 10 The battery parameters to be monitored in this embodiment are the battery current 25th , i.e. the load current, the battery voltage and the battery temperature.

The battery voltage is measured with a first voltage detection device 30th captured that with a first point of contact 32 in front of the electronic component 28 connected is. The first voltage detector 30th has a toggle switch 34 as well as a registration unit 36 with an analog-to-digital converter. Between the first point of contact 32 and the first voltage detection means 30th is a voltage divider 38 consisting of two resistors 40 , 42 intended.

There is also a second voltage detection device 44 provided with a second contact point 46 behind the electronic component 28 can be connected. The second voltage sensing device 44 has a toggle switch 48 as well as a registration unit 50 with an analog-to-digital converter. At the switch 48 is also a temperature sensor 52 connected. Via the switch 48 can thus optionally be the contact point 46 or the temperature sensor 52 with the registration unit and the analog-to-digital converter 50 get connected. Between the second contact point 46 and the switch 48 is analogous to the first voltage detection device 30th a voltage divider consisting of two resistors 54 , 56 arranged.

In addition, both between the contact point 32 and the first Voltage detection device 30th as well as between the second contact point 46 and the second voltage detecting means 44 a filter, in particular a low-pass filter, can be provided, which is formed, for example, by a resistor and a capacitance.

The current detection device 58 has a measuring resistor arranged in the current path 60 on as well as a detection device 62 that have a differential amplifier 64 with two contacts 66 , 68 in front of and behind the measuring resistor 60 connected and a voltage drop between the two contacts 66 , 68 can capture. Between the detection device 62 and the contacts 66 , 68 is always a resistor 70 , 72 provided, the resistors 70 , 72 in particular have the same electrical resistance.

The electrical resistance of the measuring resistor 60 is known, so that from the detected voltage drop across the measuring resistor 60 as well as the electrical resistance of the measuring resistor 60 about Ohm's law of about the measuring resistance 60 flowing current, i.e. the battery current 25th , can be calculated.

The battery sensor also has an electrical connection 74 between the power supply 20th and the first battery pole 14th on that via a switch 76 can be opened or closed.

The electrical connection 74 has a first branch that has a resistor 78 and a resistor 80 with the contact 66 connected, being between the resistors 78 and 80 a line 82 branches that have a resistor 84 with the first contact 66 , i.e. one input of the differential amplifier 64 , connected is. The resistances 78 , 80 form a voltage divider, with the divided voltage across the line 82 and the resistance 84 to one input of the differential amplifier 64 is created.

Similarly, a second branch is provided, one of the resistors 86 , 88 having formed voltage divider, wherein across the resistors 86 , 88 a connection to the second contact 68 is established and another resistor 90 with the second contact 68 , i.e. the second input of the differential amplifier 64 .

Furthermore, the battery sensor 10 a microcontroller 92 on the one controller for the battery sensor 10 as well as an evaluation circuit for the values of the detection devices, as well as a connection 94 for vehicle electronics.

In the microcontroller 92 a dependency relationship between voltage, current and temperature is also stored for the electronic component, in particular in the form of a family of characteristics. For the diode 28 this dependency relationship is stored in the form of a diode map. In the case of a diode, the voltage drop across the diode changes with temperature, the ratio of the temperature change to the change in the voltage drop being directly proportional. A diode map shows the relationship between the current and the voltage drop for different temperatures. This means that a characteristic curve of the characteristic curve field defines the ratio between the current flowing through the diode and the voltage drop across the diode for a specific temperature. Such a dependency relationship or such a family of characteristics can also be used for any other electronic component 28 and save in the control system for which a relationship between voltage, current and temperature is known.

The current is usually plotted against the voltage on a logarithmic scale, which means that the characteristics are approximately linear and parallel to one another in a relevant operating range (see 2 ).

Is the switch 76 open, flows over the connection 74 no electricity, so over the lead 24 only the operating current 22nd flows. Will the switch 76 closed, flows over the connection and thus also over the supply line 24 an additional measuring current Is, which depends on the electrical resistance of the resistors 60 , 70 , 72 , 78 , 80 , 84 , 86 , 88 , 90 . The electrical resistances of the resistors 60 , 70 , 72 , 78 , 80 , 84 , 86 , 88 , 90 are known so that the measuring current is known.

The structure of the battery sensor described above 10 enables the testing of various functions of the battery sensor or various sensor parameters.

A first sensor parameter can, for example, be the operating current 11 be the one across the diode 28 flows.

This is done in a first state in which the switch 76 is open, so the connection 74 is interrupted, the voltage drop between the contact points 32 , 46 , i.e. the voltage drop U1 across the electronic component 28 , measured by using the first voltage detection device 30th the voltage at the first contact point 32 and with the second voltage detection means 44 the voltage at the second contact point 46 is measured.

A second state is then established by applying an additional measuring current Is via the electronic component 28 flows by the switch 76 is closed. The one in the second state via the electronic component 28 flowing stream 12th is therefore composed of the operating current and the measuring current Is (12 = 11 + Is). In this second state, there is a second voltage drop U2 between the contact points 32 , 46 measured.

$$\begin{array}{l}{10}^{a\ast \left(U2-U1\right)}={10}^{{\text{log}}_{10}\left(I2\right)-{\text{log}}_{10}\left(I1\right)}\\ =\frac{I2}{I1}=\text{1}+\frac{Is}{I1}\end{array}$$

$$I1=\frac{Is}{{10}^{a\ast \left(U2-U1\right)}-1}$$

Two pairs of values are obtained from the two measurements ( 11 , U1) and (11 + Is; U2). These two pairs of values can be used in the diode map (see 2 ) calculate the slope a of the diode characteristic in the relevant operating range. Then, since the size of the measuring current Is and the voltage drops U1 and U2 are known, the operating current can 11 can be calculated, for example using the equations listed below: $$a\ast \left(U2-U1\right)={\text{log}}_{10}\left(\mathrm{I.}2\right)-{\text{log}}_{10}\left(\mathrm{I.}1\right)$$

$$\begin{array}{l}{10}^{a\ast \left(U2-U1\right)}={10}^{{\text{log}}_{10}\left(\mathrm{I.}2\right)-{\text{log}}_{10}\left(\mathrm{I.}1\right)}\\ =\frac{\mathrm{I.}2}{\mathrm{I.}1}=\text{1}+\frac{\mathrm{I.}s}{\mathrm{I.}1}\end{array}$$

$$\mathrm{I.}1=\frac{\mathrm{I.}s}{{10}^{a\ast \left(U2-U1\right)}-1}$$

In the control are for the operating current 11 Limit values are stored that correspond to the regular power consumption of the battery sensor. Exceeds or falls below the battery current 11 the stored limit values for the battery current, a malfunction of the power supply or the battery sensor is assumed and an error signal is output.

A further sensor parameter can be a first battery sensor temperature of the battery sensor 10 be. The temperature of the electronic component 28 essentially corresponds to the temperature of the battery sensor 10 . As stated above, the resistance of the electronic component or the voltage drop of the electronic component is 28 at a defined current depending on the temperature of the electronic component 28 .

Is the operating current 11 as well as the voltage drop U1 is known, the corresponding characteristic curve can be identified in the diode map and, above it, the temperature of the electronic component, i.e. the diode 28 , which corresponds to a first battery sensor temperature.

The determined battery sensor temperature can also be compared with a limit value, this limit value being either a defined temperature or the deviation from a second determined battery sensor temperature. For example, with the temperature sensor 52 determines a second battery sensor temperature, which is compared with the determined first battery sensor temperature.

If a limit value is exceeded, an error signal is output.

A third sensor parameter can be the lead resistance 26th of the battery sensor. In a state in which the battery voltage is substantially constant, the voltage at the first contact point 32 in front of the electronic component 28 can be detected in both states, i.e. with the switch open and closed. The difference in the measured voltages is proportional to the connected measuring current Is and the lead resistance. Since the measurement current Is is known, the lead resistance can be calculated and compared with a specified maximum value. If the measured lead resistance is too high, an error signal is also generated.

In the embodiment of the battery sensor shown here 10 the measuring current Is is via the electrical connection 74 and the resistances 78 , 80 , 84 , 86 , 88 , 90 and the contacts 66 , 68 on both sides of the measuring resistor 60 created. Since the measuring current is thus on both sides of the measuring resistor 60 is applied, the measuring current only leads to a voltage change, but this only leads to a very small change in the measured voltage drop between the contacts 66 , 68 so over the measuring resistor 60 , leads.

Will connect one of the contacts 66 , 68 to the detection device for the voltage drop, i.e. to the differential amplifier 64 , interrupted, the additional measuring current is only applied to the other contact 66 , 68 to a change in the measured voltage. In this case, when the measuring current Is is applied, there is a significant change in the voltage drop between the contacts measured with the differential amplifier 66 , 68 . A change in the voltage drop between the contacts 66 , 68 when the measuring current Is is applied, a malfunction of the current detection device can thus be identified. Via a change in the voltage drop across the measuring resistor 60 in the second state or when changing from the first state to the second state, an error in the current detection device can thus be inferred and an error signal can be output.

With the battery sensor described above 10 can therefore have several functions of the battery sensor 10 be checked, thereby reducing the reliability of the battery sensor 10 and its measurements are increased.

The structure of the battery sensor 10 can also be changed if only some of the functions or battery parameters listed above are to be checked.

In the embodiment shown here, the measurement current Is is set by closing the switch 76 and thus the establishment of the electrical connection 74 about the resistors 60 , 70 , 72 , 78 , 80 , 84 , 86 , 88 , 90 generated. However, it is only necessary to apply a measurement current Is of known magnitude to the electronic component 28 to put on. This can also be generated in any other way and transferred to the electronic component 28 be created.

For example, at least some of the resistors can be used 78 , 80 , 84 , 86 , 88 , 90 can be omitted if the current detection device is not checked 64 is desired. It's just an electrical connection 74 through which the measuring current Is can flow.

As an alternative to the two voltage detection devices 44 , 30th can the battery sensor 10 also have only one voltage detection device, which is alternately connected to the first contact point and the second contact point in order to detect the first voltage drop and the second voltage drop. In this way, for example, system-related errors in the measurement, for example an offset error in the voltage detection devices, can be compensated, since these occur to the same extent in both measurements and are thus eliminated when the voltage drops are differentiated.

Claims (21)

Method for testing a battery sensor (10), wherein the battery sensor (10) has at least one detection device (50, 30, 62) for a battery parameter, an evaluation circuit (92) for the at least one recorded battery parameter and a power supply (20) for the battery sensor ( 10), a supply line for the operating current (11) of the power supply (20) having an electronic component (28) for which a dependency ratio between voltage and current and temperature is stored in a controller of the battery sensor, with the following steps: a) in a first state in which only the operating current (11) flows through the electronic component (28), determination of a first voltage drop (U1) between a first contact point (32) in front of the electronic component (28) and a second contact point ( 46) behind the electronic component (28), b) then in a second state in which a defined additional measuring current (Is) flows through the electronic component (28), determination of a second voltage drop (U2) between the first contact point (32) in front of the electronic component (28) and the second Contact point (46) behind the electronic component (28), c) Determination of the operating current (11) flowing through the electronic component (28) from the recorded first voltage drop (U1), the recorded second voltage drop (U2) and the known measurement current (Is), d) determination of at least one sensor parameter from the determined operating current, e) comparison of the at least one sensor parameter with at least one limit value; f) Output of an error signal if the sensor parameter exceeds and / or falls below at least one limit value. Procedure according to Claim 1 , characterized in that the at least one sensor parameter is the internal power consumption of the battery sensor (10) and the at least one limit value is a maximum power consumption of the power supply (20). Method according to one of the Claims 1 and 2 , characterized in that the at least one sensor parameter is a first battery sensor temperature, which is determined from the determined voltages, the determined current and the relationship between voltage and current and temperature of the electronic component (28). Procedure according to Claim 3 , characterized in that the battery sensor (10) has an internal temperature sensor (52) with which a second battery sensor temperature is determined, which is compared with the first battery sensor temperature, wherein the at least one limit value defines a maximum deviation of the first battery sensor temperature and the second battery sensor temperature . Method according to one of the preceding claims, characterized in that a sensor parameter is the lead resistance (26) of the power supply (20). Method according to one of the preceding claims, characterized in that the battery sensor (10) has a voltage detection device which is alternately connected to the first contact point (32) and the second contact (46) to detect the first voltage drop and the second voltage drop. Method according to one of the Claims 1 to 5 , characterized in that the battery sensor (10) has a first voltage detection device (30) and a second voltage detection device (44), the first voltage detection device (30) being connected to the first contact point (32) and the second voltage detection device (44) being connected to the first Contact point (32) and at the second contact point (46) are detected simultaneously. Procedure according to Claim 7 , characterized in that the first voltage detection device (30) detects the battery voltage. Method according to one of the Claims 7 and 8th , characterized in that the second voltage measuring device (46) is alternately connected to the second contact point (46) and a temperature sensor (52). Method according to one of the Claims 7 to 9 , characterized in that a relative error of the first voltage detection device (30) and the second voltage detection device (46) is determined from the first voltages and second voltages determined in the second state. Method according to one of the preceding claims, characterized in that the second state is established by establishing an electrical connection (74) between the power supply (20) and the vehicle battery (12), wherein at least one resistor (78, 80, 84, 86, 88, 90) with known electrical resistance is arranged in series between the power supply (20) and the vehicle battery (12). Procedure according to Claim 11 , characterized in that the battery sensor (10) has a current detection device (62) with a measuring resistor (60) and a detection device (64) for detecting a voltage drop across the measuring resistor (60), which is connected to a first contact (66) before the Measuring resistor (60) and a second contact point (68) behind the measuring resistor (60) is contacted, an error message being output if the voltage drop in the second state exceeds a limit value. Method according to one of the preceding claims, characterized in that the electronic component (28) is a diode, and the relationship between voltage and current and temperature of the electronic component (28) is a diode map. Battery sensor for detecting at least one battery parameter, which has at least one detection device for a battery parameter, an evaluation circuit for the at least one detected battery parameter and a power supply for the battery sensor, wherein a supply line for the operating current of the power supply has a diode, the battery sensor having a device for producing of the second state, in which an additional measuring current (Is) flows through the diode, and at least one detection device (30, 44) for detecting a voltage drop between a first contact point (32) in front of the diode (28) and a second contact point (46 ) behind the diode (28) and a controller (92) for performing a method according to one of the preceding claims. Battery sensor Claim 14 , characterized in that the battery sensor has an internal temperature sensor (52) with which a second battery sensor temperature is determined, wherein the controller (92) can compare the second battery sensor temperature with the first battery sensor temperature and can output an error signal if there is a maximum deviation from the first battery sensor temperature to the second battery sensor temperature is exceeded. Battery sensor according to one of the Claims 14 and 15th , characterized in that the battery sensor (10) has a voltage detection device which can be alternately connected to the first contact point (32) and the second contact (46) to detect the first voltage drop and the second voltage drop. Battery sensor according to one of the Claims 14 to 16 , characterized in that the battery sensor (10) has a first voltage detection device (30) and a second voltage detection device (44), wherein the first voltage detection device (30) with the first contact point (32) and the second voltage detection device (44) with the second contact point (46) is connected. Battery sensor according to one of the Claims 14 to 17th , characterized in that the first voltage detection device (30) detects the battery voltage. Battery sensor according to one of the Claims 14 to 18th , characterized in that the second voltage detection device (44) can be alternately connected to the second contact point (46) and a temperature sensor (52), in particular to a changeover switch (48). Battery sensor according to one of the Claims 14 to 19th , characterized in that an electrical connection (74) is established between the power supply (20) and the vehicle battery (12) can be, wherein at least one resistor (78, 80, 84, 86, 88, 90) with known electrical resistance is arranged in series between the power supply (20) and the vehicle battery (12). Battery sensor according to one of the Claims 14 to 20th , characterized in that the battery sensor (10) has a current detection device (62) with a measuring resistor (60) and a detection device (64) for detecting a voltage drop across the measuring resistor (60), which is connected to a first contact (66) before the Contact is made with measuring resistor (60) and a second contact (68) behind the measuring resistor (60).

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