WO2011083062A1

WO2011083062A1 - Method for detecting the ability to start

Info

Publication number: WO2011083062A1
Application number: PCT/EP2010/070768
Authority: WO
Inventors: G Yuvarajan; Falco Sengebusch; John Alex Dcruz
Original assignee: Robert Bosch Gmbh
Priority date: 2010-01-05
Filing date: 2010-12-28
Publication date: 2011-07-14
Also published as: CN102687034B; EP2521923A1; DE102010000679A1; CN102687034A; WO2011083108A1

Abstract

The invention relates to a method for detecting the ability to start of a starter battery, in conjunction with a start-stop controller for an internal combustion engine, wherein various operating modes of the internal combustion engine are considered in order to determine the charge state of the battery, wherein voltages are analyzed and no current measurement is necessary. The battery state is thereby determined with the aid of an analysis method running according to three different methods in three different operating states. The different methods are performed during the starting process, during the driving state, and during a stoppage of the internal combustion engine.

Description

Description title

Method for detecting startability State of the art

The invention relates to a method for detecting the starting capability of a starter battery, in particular in connection with a start-stop control for a start-stop operating mode of an internal combustion engine in a motor vehicle. The internal combustion engine is thereby started with the aid of a starting device fed by an electrical energy source, for example a starter battery. The invention also relates to a start-stop control with a switching logic for a start-stop operating mode of an internal combustion engine in a motor vehicle, wherein the internal combustion engine is startable with a starting device fed by a starter battery. The invention further relates to a computer program product for

Implementation of the method according to the invention.

To detect a starting ability, it is necessary to detect the state of charge of the starter battery and deduce whether it is still sufficient for a safe startup. For determining the battery state, in particular the battery state of charge, there are already a large number of methods. With the aid of special battery condition detection algorithms, errors, in particular false shutdowns, which prevent a successful restart of an internal combustion engine in a start-stop system, can be avoided. Such errors in

Restart can be caused, for example, by poor battery charge.

In conventional systems for battery state detection usually the voltage is measured and the battery supplied current or from the Battery removed current as well as the temperature. From these variables, the battery status is then determined. But there are also simpler ones

Battery condition detectors that operate without a current sensor. Such a battery state detection is described in DE 102 58 034 AI. This battery condition detection requires only a voltage measurement in addition to the temperature measurement. For this purpose, the system current pulses are fed, the reaction leads to voltage pulses, which in turn are measured and evaluated. Depending on the information thus obtained, the battery state of charge is determined.

Advantages of the invention

The inventive method for detecting the starting ability of a starter battery and for determining or determining the battery state has the advantage that no current measurement is required and thus no current sensor is needed and that nevertheless a very accurate statement about the

Battery state, in particular the battery state of charge is possible. This advantage is achieved by a method having the features of claim 1.

The battery state detection algorithm or methods for battery state detection on which the invention is based assist the start-stop system for an internal combustion engine driving a vehicle by indicating whether or not the battery is charged well enough for a successful restart of the internal combustion engine.

The battery state detection algorithm according to the invention is a concept with which the requirements for a low-cost start-stop system can be met. The required input variables for the battery state detection or for the algorithm for battery state detection are the battery voltage, the voltage at the starter terminal and, in an advantageous embodiment, the temperature. As a result of the battery condition detection algorithm, information about the battery condition is given. This information

differs in a particularly advantageous manner only between two states "HIGH" for good battery condition and thus good or safe new or Restart capability and "LOW" for poor battery condition and thus low or insecure restart or restart capability.

The inventive device for battery state detection advantageously has only two different states at its output, "HIGH" or "Low". In an advantageous embodiment, the states "HIGH" or "Low" can be specified so that the state "HIGH" is output for the following battery states: The battery state is good enough to ensure that a successful restart or restart under all conditions , In particular, critical conditions of the internal combustion engine can be done. The LOW state is issued in a battery condition that states that the battery condition is not good enough to successfully reboot or restart under all conditions.

In a start-stop system, the information outputted by the battery condition detection is considered to be turning off the current one

Internal combustion engine, if desired, to allow ("stop enable") and Neubzw. Restart the internal combustion engine at a corresponding

Start request.

description

The embodiments or correlations, signal curves and flow diagrams required for the understanding of the invention are illustrated in the figures of the drawing and are explained in more detail in the description.

In detail, Figure 1 shows an embodiment in which the measurement points are entered for the voltages required in the evaluation.

In Figure 2, the bases for the implementation of the

Battery state algorithm shown in various operating state phases.

A typical course of the battery voltage U ß _a fl- during the starting phase is shown in Fig. 3. FIG. 4 shows the circuit of the starter motor.

The various battery characteristics at different temperatures and states of charge SOC are shown in FIG. FIG. 6 shows a flow diagram for the start phase according to strategy 1.

FIG. 7 shows a flowchart for the starting phase according to strategy 2.

FIG. 8 shows a flow chart for the driving operation. FIG. 9 shows a flowchart for the standstill phase C.

FIG. 10 shows a block diagram of the starter motor solinoid.

FIG. 11 shows the course of the starter motor solinoid voltage proportional to the battery state of charge for a known temperature.

FIG. 12 plots the time course of the solinoid threshold voltage over time.

Figure 13 shows the relationship between battery voltage and electrical load for a given state of charge and a given temperature.

FIG. 14 shows battery model data relating to these threshold values.

Figure 15 shows the relationship between the voltage dip Udip and the duty factor during idling.

FIG. 16 shows the battery voltage to be evaluated before the electrical load during an idling phase.

Input signals for the battery state detection algorithm

FIG. 1 shows an exemplary embodiment in which the measuring points for the voltages required in the evaluation method are entered. Specifically, the battery 10 with the negative terminal 11 and the positive terminal 12 and starter 13 with terminal T30. The battery voltage is designated Ußatt and the voltage at terminal T30 is Uj3Q.

In The battery condition detection algorithm uses the following

Total System Voltage Information: The battery voltage U β _a fl as the voltage measured between the plus and minus terminals of the battery 10. And the terminal voltage Uj3Q, so the voltage measured between the terminal T30 of the starter and the negative terminal 11 of the battery 10. For a basic concept, the battery voltage U ß _a fl- alone is sufficient to carry out the algorithm. The extended concept also requires the T30 terminal voltage as input. Fig. 1 shows the interconnection of battery 10 and starter 11 and the associated

Measuring points for the input voltage of the battery detection algorithm.

In addition, in the battery state detection algorithm, the following information for detecting the battery state may be taken into account: the voltage at the starter relay terminal T50, which assumes the state on / off and the speed of the internal combustion engine or the

Combustion engine. These two additional information are in

Engine control unit in any case before and can be used as input signals for various other control or regulating systems, and for the battery state detection.

The battery state detection is, for example, an evaluation logic, a processor or a control unit to which the required information is supplied, which carries out the necessary evaluation or calculation processes and which outputs output signals which represent the determined variables, in this case the determined battery charge state.

Battery Status Detection Algorithm (Battery State Detection Algorithm (BSD)

The BSD algorithm operates in three phases of a vehicle operating cycle:

Phase A: Starting phase Phase B: Driving

Phase C: standstill phase

The algorithm begins with the start phase A. The phase B, driving operation follows and the shutdown of the internal combustion engine follows the stoppage phase C. With the subsequent restart of the internal combustion engine and the algorithm is restarted. Fig. 2 shows the three phases of the BSD algorithm. In this case, voltages U are plotted over the time t. The various indications of voltages or periods of the phase durations can be regarded as examples of a possible application variant.

Start phase A

The conditions during the starting phase A are determined at terminal 50, which can also be referred to as connection 50, with the starting relay switched on. The starting phase is the phase during which the internal combustion engine or the internal combustion engine is started with the aid of the starter motor. If the

Internal combustion engine or the internal combustion engine is started, occurs

Voltage drop on, because the current drawn by the starter motor is very high and leads to this voltage drop.

A typical course of the battery voltage U ß _a fl- during the starting phase is shown in Fig. 3. To determine the battery condition of the

Voltage dip U ^ jp evaluated during startup. U ^ jp is the voltage that occurs at the short-circuit current of the starter. From the

During the starting phase, two types of strategies can be derived with the aid of which the battery state during the starting phase can be detected or determined. One of the two strategies listed below can be selected:

Strategy 1: The information on the battery status is determined from the resistance of the battery and determined from the voltage drop U ^ jp. Both input information is used, the battery voltage Ußatt and the voltage Uj3Q at terminal T30. Strategy 2: The battery condition detection is only based on the

Voltage drop U ^ jp determined. It is used to only one input signal, the battery voltage Uß _a fl-. Figure 4 shows the circuit of the starter motor with the required for understanding the two strategies

Sizes. These are the line resistance Rc of the line 14, the

Internal resistance Ri of the battery 10 and the resistance Rm of the starter motor 13.

Strategy 1: Calculation of the internal battery resistance Ri from U ^ j

By connecting the starter motor to the battery before it begins to rotate, the maximum short-circuit current through the starter motor and the connections between it and the battery will flow. This

Short-circuit current is referred to as l _sc , it is composed of: lsc = Ußatt / (R, ⁺ R _c ⁺ R _m )

This short-circuit current causes a deep voltage dip at the battery voltage U ß _a fl-. The battery voltage at the occurrence of the

Short-circuit current occurs, is referred to as dip voltage U ^ jp. The internal resistance Ri of the battery can thus be calculated from the dip voltage U ^ jp according to the equation:

^R i = ( ^u Battl ^"u dip) / 'sc

The voltage U ß ^ i is the battery voltage U ß _a fl- before switching on the starter. The short-circuit current l _sc is calculated from the voltage U 730 according to the relationship 'sc = ( ^u dip ^{' u} T30dip) / ^R T30

The voltage U J30dip is the maximum dip voltage measured at the T30 terminal of the starter. The resistor Rj3o is the resistance of the cable between the positive terminal 12 of the battery 10 and the terminal or terminal T30 on the starter motor 13. The resistor R 730 is called

application dependent parameter in the

Battery state detection algorithm entered. Temperature model for T30 cable

The resistance of the T30 cable, so the cable between the battery 10 and the starter motor 13 is variable depending on the temperature. A constant value of the resistance can not be assumed in all operating conditions of the vehicle, since the temperature of the internal combustion engine or the environment in a wide range of, for example - 5 ° C to + 80 ° C varies. The temperature of the T30 cable during vehicle operation is predicted using a temperature model. The temperature model uses the engine temperature and the intake air temperature as reference values. The temperature of the cable is predicted from these reference values, which are normally available to an engine control unit anyway. Based on the temperature of the cable predicted using the temperature model, an appropriate correction of the R 730 value is possible.

Calculation of the permissible internal resistance Rj _{a of} the battery 10

The value of the internal resistance Rj of the battery 10 is compared with the maximum allowable value Rj _a . This value Rj _a is obtained from the maximum permissible internal resistance of the battery with which the starter motor can be accelerated to a speed required for a successful start, whereby the internal combustion engine can be driven so far that a successful starting capability is present.

The value of the permissible internal resistance is selected taking into account the fact that the battery resistance increases when the ambient temperature drops. The ambient temperature is especially the temperature that prevails while the vehicle is parked.

The value for the permissible internal resistance Rj _a is not a constant parameter. He will change when the temperature of the battery. This means that it is a dynamic value that is set during the starting phase taking into account the battery temperature. The value of the permissible internal resistance Rj _{a of} the battery 10 can be determined from the following variables:

Tc: minimum temperature at which engine starting capability is required, in ° C, Rimax: internal battery resistance required to obtain startability at the minimum temperature Tc, in milliohms,

Smin: state of charge SOC of the battery corresponding to the maximum

Internal resistance of the battery at Tc, in percent,

Tßatt ^: temperature of the battery, in ° C,

Ria: allowed internal resistance of the battery according to the state of charge SOC at the present battery temperature.

The values for the battery internal resistance, which correspond to the minimum charge state Smin in percent of the charge state SOC at different temperatures, are fed to the algorithm as input variables. The temperature of the battery Τβ ₃ ^ is calculated with the help of the

Temperature Models. The battery temperature model uses the

Intake air temperature and the engine temperature as reference values for the calculation of the battery temperature. These values are optionally supplied by the control unit of the internal combustion engine.

In the following an example is given for the selection of the limit value for the maximum permissible internal resistance Rimax and the permitted ones

Internal resistance Ria. For this purpose, the following values are assumed: The minimum temperature at which the startability of the internal combustion engine must be present is -5 ° C. The internal battery resistance Rimax, which is required for starting ability, is 5.0 milliohms. It can be seen from the battery characteristics or characteristic curve that the SOC of the battery, which corresponds to 5.0 milliohms at -5 ° Celsius, is 60 percent. This means that the battery must be at least 60 percent for a starting capability that is permissible under the given conditions.

The various battery characteristics at different temperatures and states of charge SOC are shown in FIG. The internal resistance of the battery is applied over the state of charge SOC. In the upper part of the state of charge is not good.

From Fig. 5 it can be seen that, for example, in a

Battery temperature of 50 ° C, the maximum expected temperature corresponds to a value for the allowed internal resistance Ria of 4.2 milliohms is obtained. If the value of the internal resistance is lower, ie better than the permissible value of the internal resistance Ria, the battery state is referred to as "HIGH". The "HIGH" condition indicated by the battery condition detection means that the battery charge level is sufficient for the next successful restart. This means that the start-stop system can switch off the internal combustion engine if all other conditions for switching off the internal combustion engine are met.

If the value of the internal resistance Ri is higher than a permissible value for the internal resistance Ria, the battery condition is displayed as "LOW". A "LOW" condition indicated by the battery condition detection means that the battery charge level is not high enough for the next successful restart. If the battery condition during the startup phase is indicated as "LOW", the battery condition will continue to be maintained as "LOW", at least for a period of minimum charge time Tmc.

This means that no further shutdowns of the internal combustion engine may be made by the start-stop system, if this time has not expired. The calculation of the charging time Tc starts, if the

Engine speed during the driving phase is greater than the

Idle speed.

In general, the meaning of a "LOW" condition in the start-stop system is defined as follows: When the battery condition detection outputs a signal indicative of a "LOW" condition, the engine is not shut down, although all other conditions to shut off the

Internal combustion engine are met. This avoids errors in the new re-start, which could occur due to the low battery state of charge. Similarly, during start-stop system standstill, a start of the engine is initiated when the engine stops

Battery status detection indicates the status "LOW". At a standstill, the internal combustion engine is usually switched off and the battery supplies electrical energy to the various consumers. Restarting will avoid a fault for the next reboot, which could be due to further battery discharge. If the start-stop system, a signal "HIGH" supplied, there is a high battery state of charge and it is a shutdown of the engine allowed unless the other conditions require a shutdown. A restart is certainly possible because the battery condition is sufficient for a successful restart. Similarly, during the

Standstill phase left the engine off as long as the battery state of charge is "HIGH".

FIG. 6 shows a flow diagram for the start phase according to strategy 1.

The individual steps mean:

Step S1: Measurement of U ^ jp and U J30dip.

Step S2: Calculation of the battery internal resistance Rj

Step S3: Check if Rj is smaller than the allowable resistance Rj _a . If this comparison shows that the internal resistance is smaller than the permissible internal resistance, the status "LOW" is set for a defined period of time in step S4. If the step S3 indicates that the internal resistance is smaller than the permissible internal resistance, the status "HIGH" is set to the step S5.

Strategy 2: Battery state information from the voltage dip U ^ jp

In this method is for the voltage dip U ^ jp as allowed

Limit voltage U ^ jp] assumed. If U ^ jp is less than the voltage Udipl, the battery status is set to "LOW" for a minimum charging time. If U ^ jp is greater than U ^ jp! the battery status is set to "HIGH". The limit for U ^ jp! corresponds to the value of U ^ jp, which is obtained when there is a minimum battery condition of SOCSmin during the starting phase of the internal combustion engine.

FIG. 7 shows a flowchart for the starting phase according to strategy 2. In this case, the voltage U ^ jp and the voltage U J30dip is measured in step S6. In step S7 it is checked whether U ^ jp is greater than a threshold value U ^ jp]. If this is not true, in step S 8 for a defined period of time Status "LOW" set. If step S7 results in U ^ jp> being the threshold value ^u dipl _> ^, the status "HIGH" is set ⁱⁿ step S9.

Phase B, driving

Condition for driving is that the speed of the internal combustion engine is greater than or equal to the idle speed, the idle speed is an applicable value. If the internal combustion engine or the

Internal combustion engine is running, the value for the charging time Tnc is continuously updated. The charging time Tnc is calculated by integrating weighted time periods Tc for which the battery voltage is greater than a charging limit voltage. The same applies to the period of time Tdc during which the battery voltage is less than the limit voltage. Even then will

integrated. The context applies:

Tnc = int (ne x Tc) - int (Tdc)

The factor ne is introduced as an efficiency factor. It is needed because some energy is lost in the form of heat during charging. This efficiency factor describes the effect. The factor can be dependent on the battery type, the battery charge state and / or the battery temperature. When the battery condition detection detects a battery state "LOW" during the

Start phase indicates, it is set in a state "HIGH" when the value of the charging period Tnc is greater than a predetermined period of time that can be applied. The status is set to "LOW" when the value of the charging period Tnc is smaller than the predetermined period.

Possible application values for phase B, driving operation are:

13.5V is the threshold voltage above which the battery is charged during driving under all conditions.

13.0V is the threshold voltage below which the battery will not charge while driving.

Between 13.0V and 13.5V is a band in which it can not be said with certainty whether the battery is charged or discharged. The specified voltage values may differ for different applications, in particular depending on the electrical system of the vehicle.

FIG. 8 shows a flow chart for the driving operation (phase B). In this case, the battery voltage Uß _a fl- is measured in step S10. In step Sil, the charging time Tc is calculated. In step S12 it is checked whether the charging time Tc is above a predefinable value. If this is not the case, the status "LOW" is set in step S13. If the charging time Tc is greater than the predefinable value, the status "HIGH" is set in step S14.

Standstill phase C

Condition for the stoppage phase is that the speed of the

Internal combustion engine is equal to 0. The stoppage phase refers to the phase during which the internal combustion engine is switched off, for example because of a corresponding shutdown signal from a starl / stop system. The generator drivable by the internal combustion engine provides no electrical energy and the energy supplied by the battery is supplied only to the electrical consumers that are needed during this time. Since the battery supplies charge to these consumers, the voltage drops during the standstill phase. When the battery voltage reaches a special limit Ul, the battery status is set to "LOW".

The start-stop system initiates a vehicle start request when the battery condition detection indicates the "LOW" status in the standstill phase. The vehicle, on the other hand, remains in the standstill phase when the battery status remains "HIGH".

If the stoppage phase is greater than, for example, five minutes, the battery condition detection will set the status to "LOW", even if the

Battery voltage is higher than the limit Ul. If the discharge current is smaller than a predetermined value of, for example, 5 amperes, no noticeable drop in the battery voltage will occur even if the discharge takes place for a longer time. Under these conditions, the battery will lose its charge without significantly changing the battery terminal or battery terminal voltage. To include this condition will be during the Standstill phase given a time limit of five minutes. As time limit, another suitable value can be selected.

It defines a limit voltage Ul, which is formed taking into account the following quantities:

Tc in ° C: minimum temperature at which the startability of the internal combustion engine is required,

Rimax in mOhm: internal battery resistance required to make a

Startability to reach, Smin in% State of charge of the battery at its maximum internal resistance

Rimax at the minimum temperature Tc (cold start condition)

T ^" Batt: temperature of the battery.

Y in Amps: Medium electrical load while the vehicle is at a standstill. Ul: The limit voltage is defined as the battery voltage at the

Condition that the battery is charged with Y amperes, in the state of charge Smin in% of the battery at its maximum internal resistance Rimax at the minimum temperature Tc.

The value of the limit voltage Ul depends on the temperature of the battery. FIG. 9 shows a flow chart for the procedure in the standstill phase

C.

In detail, it is shown in FIG. 9 that the battery voltage Ußatt is measured in step S15. In step S16, the battery voltage is compared with a threshold voltage Ul. This comparison shows that the

Battery voltage U ß _a fl- is not greater than the limit voltage is in step

S17 the state "LOW" set. If the comparison in step S16 reveals that the battery voltage U β ^ is greater than the voltage U1, the state "HIGH" is set in step S18. Supplementary and further measures for battery condition detection:

Current through the magnet coil of the starter as an indicator of the battery condition

In another battery state detection algorithm, the

Battery condition determined when a defined electrical load is switched to the battery. The battery voltage breaks depending on the battery condition and the electrical resistance. The battery terminal voltage U ^ jp is proportional to the battery state, this applies in each case for a defined load. Thus, the battery state of charge SOC for a known temperature can be determined by the battery voltage drop is measured when a defined electrical load. In this concept, the defined electrical load is the starter motor. It could also be evaluated the connection of another electrical load, which leads to a significant voltage dip, for example, a window heating, glow plugs, fuel heaters, fans, driving lights, etc.

Operation of the starter motor

The starter motor is switched on and off by means of a starter relay. The starter relay includes a special solenoid. This solenoid usually has two windings, a turn-on winding EW and a

Holding winding HW. When the starter motor starts, the windings of the coils are turned on for a short time to close the starter motor contact. When the starter motor starts, only the holding winding is the

Magnetic coil supplied with voltage.

FIG. 10 shows schematically a block diagram of the starter motor with the starter relay. In this case, the starter motor is denoted by 13, 10 is the battery. 18 denotes the ignition switch and 15 the starter relay with the pull-in winding 16 and the holding winding 17th

FIG. 11 shows the profile of the voltage dip U.sub.Dip of the voltage across the starter motor for various states of charge of the battery. The top curve stands for a full battery and the bottom one for one

Battery charge of 65%, each for a specific temperature. The battery condition can be seen from FIG. 11, for a known one Battery temperature can be determined by the starter motor with the starter relay is regarded as a defined electrical load and the voltage drop is evaluated when switching on this electrical load.

Functionality of the concept

For a successful restart of the internal combustion engine, a minimum battery state of charge for a given temperature is defined. The voltage applied to the starter relay is the voltage Udipl. During the starting phase, the combustion engine is started by the starter motor. The resulting dip voltage U ^ jp is measured. This measured voltage is compared with the threshold value Udipl. Depending on

Comparison result is detected whether the battery state can be set as "HIGH" or "LOW". "High" again means that the

Battery condition is good for the next successful reboot or restart. Similarly, the battery state is set to "LOW" when the battery is low

Battery condition is not good enough for a successful restart.

FIG. 12 shows the time profile of the voltage across the starter motor for various states of charge of the battery in accordance with a section of the curve according to FIG. 11 over time. The voltage dip Udip is the minimum value. If the voltage is lower than the threshold value Udipl, the battery state "LOW" is set.

State of charge prediction for the standstill phase C

In the stoppage phase of the vehicle, the voltage drop is on

Battery terminal or at the battery terminal 12 for a known temperature and a known battery state of charge SOC proportional to the electrical load current IL. FIG. 13 shows, in the relationship between battery voltage Ußatt and electrical load IL for a given state of charge SOC and a given temperature.

To decide on the present battery condition during the

Standstill phase, a threshold voltage must be defined. In FIG. 14, battery model data are indicated with respect to the threshold voltage. The state of charge SOC applies to a battery voltage threshold of 11.9 UBattl Volt. As shown in this table, the lower the discharge current, the lower the state of charge limit can be set. The higher the discharge current, the higher the charge state limit must be set. This results in a broad selection of the state of charge limit

Tolerance band of 18%.

In order to reduce this wide tolerance band for the state of charge SOC of the battery 10, the voltage limit UBattl is set proportional to the load current. However, since the load current is unknown, the electric load current is adaptively predicted according to the following concept.

First method for this is the evaluation of the "DFM signal", thus the

Duty cycle of the exciter current:

If the feature "DFM signal output from the generator" is available in the vehicle or in the control unit of the vehicle, the duty cycle factor is proportional to the load current and can be evaluated to this effect. The "DFM signal" can be detected at idle speed or idle speed or at another defined speed or speed before switching off the internal combustion engine. Thus, the threshold value of the voltage drop U ^ jp] can be set depending on the duty factor for the switched on electrical load in the standstill phase or idle. This reduces the tolerance band for the

Charge state to a smaller value.

In FIG. 15, the fall in the battery voltage Uß ^ djp is above

load factor DF or the duty cycle of the exciting current during idling for a state of charge SOC of 65% "shown.

Second method is the evaluation of a voltage level:

This concept can be used in cases where a "DFM signal" is not available. In this case, the voltage level on the battery can be monitored, for example, at idle speed. If the electrical load current at idle is greater than the generator output current, a voltage dip will occur. This voltage dip is approximately proportional to the electrical load that exceeds the generator current. In order to allows monitoring of the battery voltage Uß _a fl- at idle speed before switching off the engine, the corresponding load

estimate and the associated limit U ßattdipl be selected. This method also reduces the tolerance band for battery status estimation. When the electrical load is less than that available from the generator

Current can not be used this method, the associated area is called "blind area", since the voltage remains the same and at a charge level.

In FIG. 16, the course of the battery voltage U.sub.bet.s to be evaluated over the electrical load factor during an idling phase for one

Battery charge state SOC of 65% shown. On the left of the dashed line is the so-called "blind area", to the right of which, ie at higher load, an evaluation is possible.

Claims

claims

1. A method for detecting the starting ability, in particular a starter battery for a start-stop control of an internal combustion engine in one

Motor vehicle, wherein the internal combustion engine is started with the starter battery powered starting device and means for detecting the battery condition are present, in which proceed the method, characterized in that the operating condition of the internal combustion engine is taken into account and this in at least three different phases (A, B , C) and for each of the three phases (A, B, C) runs its own battery state detection method.

2. The method according to claim 1, characterized in that the

Battery state detection method runs as an algorithm.

3. The method according to claim 1 or 2, characterized in that the

Battery state detection method as information about the

Battery state either the state "HIGH" or the state "LOW" outputs, with the state "HIGH" safe new or Widerstartfähigkeit and the state "LOW" uncertain new or Widerstartfähigkeit means.

4. The method of claim 1, 2 or 3, characterized in that for each of the three phases (A, B, C) performed

Battery state detection method is set a status representing the state "HIGH" or the state "LOW".

5. The method of claim 1, 2, 3 or 4, characterized in that the three different phases (A; B; C), the actual starting phase (A), the driving state (B) and a stoppage phase (C).

6. The method according to any one of the preceding claims, characterized

characterized in that in the first phase (A), a voltage evaluation is performed so that the depth of the voltage drop (U ^ jp) is evaluated when switching on the starter (13).

7. The method according to claim 6, characterized in that the

Battery state detection by determining the internal resistance (Ri) of the battery (10) and this in addition to the depth of the voltage dip (Udjp) nor the battery voltage (U ß ^) and the voltage (UJ3Q) is considered at the starter terminal (T30).

8. The method according to claim 7, characterized in that in addition a temperature is taken into account.

9. The method according to any one of the preceding claims, characterized

characterized in that in the second phase (B) is a time-dependent

Integration is carried out in which the supplied charge is positive and the discharged charge is considered negative.

10. The method according to claim 9, characterized in that a

Load period (Tc) is defined, and if the charging period (Tc) is greater than a predetermined period of time, the output status is set to "HIGH" and otherwise to "LOW".

11. The method according to any one of the preceding claims, characterized

characterized in that in the third phase (C), which represents a stoppage phase which is limited to a predefinable period of time, a

Voltage evaluation is carried out to the effect that by a load current (I L) resulting voltage drop within this phase (C) is determined.

12. The method according to any one of the preceding claims, characterized

characterized in that the decision on the present

Battery state in the third phase (C) taking into account a threshold voltage, which is determined from a battery model, taking into account the state of charge (SOC), the temperature (T) and the expected charging or discharging current.

13. Apparatus for carrying out a method according to one of

preceding claims, characterized in that the device comprises at least input means for supplying signals, a processor or a computer and storage means and output means for outputting a battery state indicating output signal.

14. An apparatus for start / stop control, characterized in that the battery state indicating output signal according to claim 13 is used as a criterion for preventing a stop request.