SE536552C2 - Diagnostics of starter motor - Google Patents

Abstract

An electric starter motor (110) is arranged to start an internal combustion engine (120). The function of the starter motor (110) is diagnosed via measuring means (130, 140) which measure a supply voltage (U) of the starter motor and a speed (RPM) of the internal combustion engine. Based on the measured quantities (U, RPM), a processor (160) determines a status indicator (S), which indicates a quality measure of the performance of the starter motor (110). A storage means (170) stores a respective value of the status indicator (S) at a number activations of the electric starter motor (110) in a data series (M). The processor (160) analyzes the data series (M) and, on the basis thereof, assesses whether the function of the electric starter motor (110) is acceptable, and if the function is not judged to be acceptable, generates an error code (E). (Fig. 1)

Description

20 25 30 536 552 the function of an electric starter motor, for example in a motor vehicle. However, there is no solution for checking the functional status of an electric starter motor in a simple and reliable manner during normal operation of the machine in which the starter motor is included.

SUMMARY OF THE INVENTION The object of the present invention is therefore to provide a solution to the above problems which enables an automatic and efficient diagnosis of an electric starter motor, where neither the starter motor nor the machine in which it is part needs to be transported to a workshop.

According to one aspect of the invention, the object is achieved by the system initially described, the system comprising a storage means configured to store a respective value of the status indicator upon a number of activations of the electric starter motor in a data series. The processor is configured to analyze the data series and on that basis assess whether the operation of the electric starter motor is acceptable. If the function is not judged to be acceptable, the processor is configured to generate an error code, which in turn is stored and / or gives rise to an alarm, for example.

This system is advantageous because the error code does not need to be generated at a predetermined level of the status indicator. Instead, the system can react adaptively to a trend, which indicates an unfavorable development for the starter motor's performance. In this way, unnecessary alarms and subsequent workshop visits can be avoided, for example. The alarm is conveniently generated when the starter motor is so worn that it needs to be replaced relatively soon, which is why it is recommended to plan a workshop visit in response to an alarm.

According to an embodiment of this aspect of the invention, said number of activations of the electric starter motor which the data series comprises are assumed to be consecutive. Either each activation is linked to a respective time indication, or only one sequence number is given for each activation. In any case, a consecutive sequence of starter activations provides a good basis for analyzing the function of the starter.

According to another embodiment of this aspect of the invention, the processor is configured to analyze the data series by examining a rate at which the status indicator changes over time. The error code is generated either if an absolute amount of the rate exceeds a first predetermined limit value, or if the status indicator decreases at a rate which is faster than a second predetermined limit value. The limit values in turn depend on whether the data series includes information on time or not. In any case, this makes adequate criteria possible for ascertaining a possible defect in the starter motor.

According to a further embodiment of this aspect of the invention, the processor is configured to analyze the data series by calculating an average value of the status indicator over a subset of the values in the data series, such as within a scrolling measurement window. The processor is further configured to generate the error code if the average value is below a third predetermined limit value.

This effectively avoids the generation of the error code as a result of a temporary deviation in the development of the status indicator over time.

According to another embodiment of this aspect of the invention, the processor is configured to consider at least one parameter describing the conditions under which the status indicator has been generated. If the status indicator is judged to have been generated under a first type of condition, the processor is configured to control storage of the status indicator to a first data series. If instead the status indicator is judged to have been generated under at least one second type of conditions, the processor is configured to control storage of the status indicator to at least a second data series. The processor is further configured to analyze the respective first and at least a second data series individually, and on the basis thereof assess whether the function of the electric starter motor is acceptable. Thus, the decision to generate a possible error code can be made on adequate grounds (such as in similar conditions regarding ambient temperature, battery voltage, cold, half-warm or hot start), so that the reliability of a possible error code can made relatively high.

According to an embodiment of this aspect of the invention, the system comprises means for generating, on the basis of the error code: an acoustic signal suitable for being perceived by an operator, a visual signal suitable for being perceived by an operator, storing an error code for a minute. nose unit, a signal arranged to be transmitted to a monitoring equipment connected to the system and / or a wireless signal arranged to be transmitted via at least one communication network to a monitoring node. This gives great flexibility in the handling of the error code.

According to yet another embodiment of this aspect of the invention, the system comprises at least one temperature measuring means configured to measure at least one temperature related to the electric starter motor. The processor is here configured to determine the status indicator on a further basis of the at least one measured temperature. Such consideration of the temperature is advantageous, since thus environmental changes (for example due to seasonal changes and / or geographical conditions) can be weighed into the diagnostic method in a natural and adequate way.

The viscosity of the oil in the internal combustion engine varies considerably with the temperature, which in turn is reflected in the measured speed.

According to a further embodiment of this aspect of the invention, the processor is configured to assign the status indicator a special value representing that the function of the starter motor cannot be determined if the measured supply voltage is below a voltage threshold. If the supply voltage is too low, no conclusion can be drawn as to whether the fact that the internal combustion engine does not start depends on whether the starter motor is faulty, or if the fault is due to something else, such as insufficient battery voltage. According to a further embodiment of this aspect of the invention, the measuring means are configured to measure the supply voltage and the speed during a measuring range, and the processor is configured to average the supply voltage and the speed over the measuring range. The processor is also configured to determine the status indicator on the basis of an average value of the supply voltage to the starter motor during the measuring interval and an average value of the speed of the internal combustion engine during the measuring interval. Advantageously, the temperature measuring means is also configured to measure the at least one temperature during a measuring interval and the processor is configured to average the measured temperature over the measuring interval. The processor is configured here to use the averaged temperature when determining the status indicator. Such consideration of averages is advantageous, since the instantaneous values of supply voltage, speed and temperature may be temporarily misleading for the actual conditions. It may also be advantageous to consider other parameters, such as a minimum measured supply voltage to the starter motor during a compression cycle. of the electric starter motor is stored in a storage means in the form of a data series. The data series is analyzed and, on the basis of said analysis, it is judged whether or not the function of the electric starter motor is acceptable. If the function is not judged to be acceptable, an error code is generated. The advantages of this method, as well as of the preferred embodiments thereof, are apparent from the discussion above with reference to the proposed system.

According to a further aspect of the invention, the object is achieved through a computer program directly downloadable to the internal memory of a computer, comprising software for controlling the steps according to the method proposed above when said program is run on a computer. The computer may in turn be represented by a control unit in the system, a diagnostic unit connected thereto, a tablet, a smartphone, etc.

According to yet another aspect of the invention, the object is achieved by a computer-readable medium having a program stored thereon, the program being adapted to cause a computer to control the steps according to the method proposed above.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be explained in more detail by means of embodiments, which are described by way of example, and with reference to the accompanying drawings.

Figure 1 shows a schematic view of a proposed system, Figures 2a-b show graphs of examples of how the status indicator can change over time, and Figure 3 shows a flow chart which illustrates the general method according to the invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION We first refer to Figure 1 which shows a schematic view of a system according to the invention for diagnosing an electric starter 110. The electric starter 110 is arranged to start an internal combustion engine 120, and can thus be included in a motor vehicle. . However, the proposed system may just as well be integrated in a stationary machine, such as a power generator or a stone crushing machine. In any case, the electric starter 110 is powered by a battery 135.

The proposed system comprises measuring means 130 and 140, a processor 160 and a storage means 170. It is also advantageous if at least one temperature measuring means (not shown) is included in the system.

The measuring means 130 and 140 are configured to measure a supply voltage U to the starter motor 110 and an RPM speed of the internal combustion engine 120, respectively. In the following description, the RPM speed of the internal combustion engine 120 is discussed throughout.

When the starter motor 110 and the internal combustion engine 120 are connected (for example via a so-called Bendix connection), there is of course a connection between the speed of the internal combustion engine 120 and the speed of the starter motor 110, so a measured speed of the starter motor 110 can be used as well as the proposed RPM speed of the internal combustion engine 120.

The temperature measuring means is configured to measure at least one temperature related to the machine in which the starter motor 110 is included. The at least one temperature may, for example, refer to an ambient temperature, an oil temperature in the engine, a cooling water temperature, an engine block temperature, a starter engine temperature and / or a battery temperature. It is advantageous to register more than one temperature, as this enables an assessment of whether a cold start takes place (all temperatures are essentially the same), a warm start (the oil temperature in the engine and a cooling water temperature significantly exceeds the ambient temperature), or if the engine is started in a semi-hot state (the cooling water temperature significantly exceeds the ambient temperature, but the oil temperature in the engine is relatively low; alternatively the oil temperature is relatively high, but the water temperature is relatively low).

The processor 160 is configured to, based on the supply voltage U and the RPM speed, determine a status indicator S, which indicates a quality measure of the performance of the starter 110. The status indicator S is stored in the storage means 170. Advantageously, a respective value of the status indicator S is stored at each activation of the electric starter 110, so that the storage means 170 after a time contains a data series M of status indicators S. The processor 160 is further configured to analyze the data series M and on that basis assess whether the function of the electric starter 110 is acceptable. If the function is not judged to be acceptable, the processor 160 is configured to generate an error code E. 10 15 20 25 30 35 536 552 Since the start conditions can vary highly considerably, it is advantageous to register two or more data series M in parallel, where the status indicators S within a certain data series M has been generated under similar conditions, such as ambient temperature T, battery voltage U, type of start (cold, semi-hot or hot). This is advantageous as one can thus decide whether a given start went worse (or better) than a previous start under corresponding circumstances. Thus, the decision on the generation of a possible error code E can also be made on adequate grounds, so that the reliability of the error code becomes relatively high E.

For example, therefore, the processor 160 may be configured to consider at least one parameter which describes the conditions under which the status indicator S has been generated. If the status indicator S is judged to have been generated under a first type of conditions, then the processor 160 is further configured to control storage of the status indicator S in a first data series in the storage means 170. If instead the status indicator S is judged to have been generated under a second type of conditions , the processor 160 is configured to control the storage of the status indicator S in a second data series in the storage means 170, and so on. The processor 160 then analyzes the respective data series individually, and on that basis assesses whether the function of the electric starter 110 is acceptable. In the event that the function is not judged to be acceptable, the processor 160 generates an error code E.

According to embodiments of the invention, the system also comprises means for in turn processing the error code E. For example, the error code E can form the basis for generating an acoustic and / or visual signal suitable for being perceived by an operator. Alternatively, or as a complement, the error code E can be stored in a memory unit for reading at a later workshop visit. Furthermore, the system may comprise means for generating a signal arranged to be transmitted to a monitoring equipment connected to the system (for example in a workshop) and / or means for generating a wireless signal arranged to be transmitted via at least one communication network to a monitoring network. ningsnod. This offers an opportunity for convenient remote monitoring of the function of the electric starter 110.

Figure 2a shows a first graph of an example of how the status indicator S can change over time, where the horizontal axis indicates a number n of activations of the starter motor 110 and the vertical axis represents values of the status indicator S in a data series M. Figure 2b shows a second graph with the same values for the status indicator S, but where the horizontal axis instead shows chronological time t. The horizontal axis thus not only indicates an order, but also reflects a mutual time distance between the values in the data series M.

According to one embodiment of the invention, the actuations of the electric starter 110 which the data series M comprise are consecutive; that is, there are no gaps in the data series M, and the values therein are processed in the same order as they are stored.

According to one embodiment of the invention, the processor 160 is configured to analyze the data series M by examining a rate Rn or Rt at which the status indicator S changes over time.

If an absolute amount of the rate Rn or Rt exceeds a first predetermined limit value, the processor 160 is configured to generate the error code E.

In Figures 2a and 2b, the rates Rn and Rt, respectively, are represented by the slope of the graph. The processor 160 may advantageously be configured to examine the slope between two consecutive activations n of the starter motor 110, such as Rn_3; n_2 between n-3 and n-2, or Rnm fl between n and n + 1. As can be seen, the rate Rn and Rt (or the slope of the graph) between two consecutive activations can vary depending on whether the graph alone represents an order (as in Figure 2a), or whether the graph also shows a mutual time interval between the values in the data series. M (as in Figure 2b). For example, the slope of the graph Rt_3; t_2 between a measuring time t_3 and a measuring time t_2 corresponding to the activations n-3 and n-2, respectively, is relatively flat, while the slope of the graph Rn_3; n_2 between n-3 and n-2 is relatively steep. On the other hand, the slope of the graph Space 10 15 20 25 30 536 552 between a measuring time to and a measuring time t1 corresponding to the activations n and n + 1, respectively, is relatively steep while the slope of the graph Rnzn fi between n and n + 1 is relatively flat. The first predetermined limit value at which the processor 160 is configured to generate the error code E thus depends on whether the data series M represents, in addition to a sequence, also includes information on a mutual time interval between the values. Although a sudden positive development of the status indicator S may indicate an anomaly in the operation of the starter 110, a negative development is typically more problematic. According to an embodiment of the invention, therefore, the processor 160 reacts only to a negative development of the values of the status indicator S.

Specifically, this means that the processor 160 is configured to analyze the data series M by examining a rate Rn and Rt, respectively, at which the status indicator S changes over time. The processor 160 is configured to generate the error code E if the status indicator S drops at a rate Rn or Rt which is faster than a second predetermined limit value. For the same reasons as above, the second predetermined limit value also depends on whether the data series M only represents one sequence or whether mutual time intervals between the values in the data series M are also included.

According to an embodiment of the invention, the processor 160 is configured to analyze the data series M by calculating an average value SM of the status indicator S over a subset of the values in the data series M, such as within a scrolling measurement window representing a certain number n of measured values or a certain time t. If the average value SM is less than a third predetermined limit value, the processor 160 is configured to generate the error code E.

According to a preferred embodiment of the invention, the processor 160 is configured to determine the status indicator S on a further basis of one or more of the above-mentioned temperatures. For increased reliability / robustness, the measuring means 130 and 140 are suitably configured to measure the technical quantities during a measuring interval, say 1 second during which measuring interval, for example 10 10 15 20 25 30 536 552 10 individual measurements are registered.

Alternatively, the measurement range may be adaptively coupled to one or more compression cycles of the internal combustion engine 120, so that the measurement range represents an integer number of compression cycles.

A typical compression cycle is about 15 ms long. As an alternative to a pure averaging RPM, the processor 160 in such a case may be configured to record a minimum speed during a compression cycle. Starting performance has been shown to depend on the speed when it is at its lowest.

Furthermore, the processor 160 may be configured to average between a respective lowest measured supply voltage U to the starter motor 110 in each of a number of compression cycles.

The processor 160 may thus be configured to average the measured quantities U and RPM over the measuring range and determine the status indicator S on the basis of an average value of the supply voltage Uavg to the starter motor 110 during the measuring range and an average value of the RPMaVg speed of the internal combustion engine 120 below the combustion engine 120. .

Correspondingly, any temperature measuring means are suitably configured to measure at least one temperature during a measuring interval. If so, of course, the processor 160 is configured to average the at least one measured temperature over the measurement range, and utilize at least one of the at least one averaged temperature in determining the status indicator S.

It may further be advantageous to adapt the diagnostic method performed by the processor 160 depending on seasonal changes. For example, a temperature adjustment can be made in two steps (summer / winter), in several steps (such as below -25 ° C, between -25 ° C and -20 ° C, between -20 ° C and -10 ° C , between -10 ° C and 10 ° C, between 10 ° C and 10 ° C, and above 10 ° C), or continuously on the basis of a defined ratio, for example: RPMeXp = U> <P1 / (T + P2), where RPMeXp indicates the expected speed, U indicates the measured supply voltage to the starter motor 110, T indicates a measured temperature and P1 and P2 are adaptation parameters.

It is advantageous to calculate the status indicator S continuously by comparing a measured RPM with an expected speed and applying at least one threshold level (for example a first level representing an acceptable starter motor function OK and a second level corresponding to an unacceptable starter motor function NOT) for example according to the ratio below: _ RPM + N1 (T) u / Nzn) S = 8O where RPM indicates a measured speed at a starting test, T indicates a measured or calculated temperature (such as a characteristic motor temperature), U indicates a measured supply voltage at the starting test, N1 (T) indicates a speed offset at temperature T, and N2 (T) indicates a speed parameter at temperature T.

In the above condition, the status indicator becomes S = 80 if the starter motor function is good. S 2 70 can thus correspond to an acceptable starter motor function. If, on the other hand, S <70, the starter motor function is considered unacceptable. Therefore, if the trend of the status indicator S does not reverse, or at least stabilizes, a replacement of the starter motor is normally recommended in this case.

If the measured supply voltage U is below a voltage threshold, it is impossible to determine the function of the starter motor.

According to an embodiment of the invention, therefore, in such a case, the processor 160 is configured to assign the status indicator S a certain value representing that the function of the starter motor cannot be determined.

The processor 160 is suitably controlled to implement the above mode of operation by means of a computer program stored in a memory unit 180 which is either included in the processor 160 or is communicatively connected thereto. In order to summarize, the general method according to the invention will now be described with reference to the flow chart in Figure 3.

In a first step 310 it is examined whether the starter motor has been activated.

If not, the procedure Ioopar returns and stops in step 310. Otherwise, a step 320 follows, which records a measured speed of the internal combustion engine. As described above, the speed is suitably recorded during a measurement interval, which may be synchronized with one or more compression cycles. A step 330, parallel to step 320, registers a supply voltage to the starter motor.

Based on the measured quantities: speed and supply voltage, a step 340 then determines a status indicator for the starter motor. The status indicator indicates a quality measure of the current performance of the starter motor. A step 350 thereon stores a value for the status indicator in a storage means, after which a step 360 examines whether there are thus at least two status indicators stored in the storage means in the form of a data series. If so, a step 370 follows. Otherwise, the procedure returns to step 310.

In step 370, the data series is analyzed and an overall function of the starter motor is estimated. Then, in a step 380, it is assessed whether the function is acceptable or not. If the function is judged to be acceptable, the procedure returns to step 310. Otherwise, a step 390 follows in which an error code is generated. Then Ioopar the procedure back to step 310.

The method steps described with reference to Figure 3 can be controlled by means of a programmed computer apparatus. In addition, although the embodiments of the invention described above with reference to the figures include a computer and processes performed in a computer, the invention extends to computer programs, especially computer programs on or in a carrier adapted to practically implement the invention. The program may be in the form of source code, object code, a code which is an intermediate between source and object code, such as in partially compiled form, or in any other form suitable for use in implementing the project. the process according to the invention. The carrier can be any entity or device which is capable of carrying the program. For example, the carrier may comprise a storage medium such as a flash memory, a Read Only Memory (ROM), for example a CD (Compact Disc) or a semiconductor ROM, EPROM (Electrically Programmable ROM), EEPROM (Erasable EPROM ), or a magnetic recording medium, such as a floppy disk or hard disk. In addition, the carrier may be a transmitting carrier such as an electrical or optical signal, which may be conducted through an electrical or optical cable or via radio or otherwise. When the program is formed by a signal which can be conducted directly by a cable or other device or means, the carrier can be constituted by such a cable, device or means. Alternatively, the carrier may be an integrated circuit in which the program is embedded, where the integrated circuit is adapted to perform, or to be used in performing, the actual processes.

The invention is not limited to the embodiments described with reference to the figures but can be varied freely within the scope of the appended claims. 14

Claims (22)

10 15 20 25 30 536 552 Patent claims A system for diagnosing an electric starter motor (110) adapted to start an internal combustion engine (120), the system comprising: measuring means (130, 140) configured to measure a supply voltage (U) to the electric starter motor and an internal combustion engine (RPM), and a processor (160) configured to determine, based on the measured supply voltage (U) and the measured speed (RPM), a Status Indicator (S) for the starter motor (110), which status indicator (S) indicates a quality measure of the performance of the starter motor (110), characterized in that the status indicator (S) is determined according to the ratio: _RPM + N «T) s = so u / Naf) where RPM indicates a measured speed in a start test, T indicates a measured or calculated temperature, U indicates a measured supply voltage at the start test, N1 (T) indicates a speed offset at temperature T, and N2 (T) indicates a speed parameter at temperature T, the system comprises a storage means (170) configured to store a respective value of the status indicator (S) at a number of activations of the electric starter motor (110) in a data series (M), and the processor (160) is configured to analyze the data series (M), judging on this basis whether the electric starter motor (110) ) function is acceptable, and if the function is not judged to be acceptable, generate an error code (E). The system of claim 1, wherein said number of actuations of the electric starter motor (110) which the data series (M) comprises is consecutive. The system of any of claims 1 or 2, wherein the processor 15 10 15 20 25 30 536 552 (160) is configured to analyze the data series (M) by examining a rate (Rn; Rt) at which the status indicator (S) changes over time, and generates the error code (E) if an absolute amount of the rate (Rn; Rt) exceeds a first predetermined limit value. The system of any of claims 1 or 2, wherein the processor (160) is configured to analyze the data series (M) by examining a rate (Rn; Rt) at which the status indicator (S) changes over time, and generating the error code (E) if the status indicator (S) decreases at a rate (Rn; Rt) which is faster than a second predetermined limit value. The system according to any of the preceding claims, wherein the processor (160) is configured to analyze the data series (M) by calculating an average value (SM) of the status indicator (S) over a subset of the values in the data series (M), and generating the error code (E) if the mean value (SM) is less than a third predetermined limit value. The system of any preceding claim, wherein the processor (160) is configured to: consider at least one parameter describing the conditions under which the status indicator (S) has been generated, control storage of the status indicator (S) to a first data series on the status indicator (S) has been generated under a first type of conditions, control storage of the status indicator (S) to at least a second data series if the status indicator (S) has been generated under at least a second type of conditions, analyze said respective first and at least one second data series individually, and on that basis assess whether the function of the electric starter motor (110) is acceptable. The system according to any one of the preceding claims, comprising means for generating, on the basis of the error code (E), at least one of: an acoustic signal suitable for being perceived by an operator, a visual signal adapted to be perceived by an operator, store an error code in a memory unit, a signal set up to be transmitted to a monitoring equipment connected to the system and a wireless signal arranged to be transmitted via at least one communication network to a monitoring node. The system of any preceding claim, wherein: the system comprises temperature measuring means (150) configured to measure at least one temperature related to the electric starter motor (110), and the processor (160) is configured to determine the status indicator (S) on further basis of the at least one measured temperature. The system according to any of the preceding claims, wherein the measuring means (130, 140) are configured to measure the supply voltage (U) and the speed (RPM) during a measuring interval, and the processor (160) is configured to: average the supply voltage (U) and the speed (RPM) over the measuring range and determine the status indicator (S) on the basis of an average value of the supply voltage (Uavg) to the starter motor (110) during the measuring range and an average value of the speed (RPMaVg) of the internal combustion engine during the measuring range. The system of claim 8, wherein if the measured supply voltage (Uavg) is below a voltage threshold, the processor is configured to assign the status indicator (S) a special value representing that the function of the starter motor cannot be determined. A method of diagnosing an electric starter motor (110) adapted to start an internal combustion engine (120), the method comprising: measuring a supply voltage (U) to the starter motor and a speed (RPM) of the internal combustion engine, and 536 552 determining a status indicator (S) for the starter motor (110) based on the measured supply voltage (U) and the measured speed (RPM), where the status indicator (S) indicates a quality measure of the performance of the starter motor (110) , characterized by determining the status indicator (S) according to the ratio _ RPM + N1 (T) S = 80 U / N2 (T) where RPM indicates a measured speed at a start test, T indicates a measured or calculated temperature, U indicates a measured supply voltage at the start test, N1 (T) indicates a speed offset at temperature T, and N2 (T) indicates a speed parameter at temperature T; storing in a storage means (170) a respective value of the status indicator (S) at a number of activations of the electric starter motor (110), said values constituting a data series (M); analysis of the data series (M); judging whether the operation of the electric starter motor (110) is acceptable on the basis of said analysis; and if the function is not judged to be acceptable generation of an error code (E). The method of claim 11, wherein said number of actuations of the electric starter motor (110) comprising the data series (M) are consecutive. The method of any of claims 11 or 12, wherein the analysis of the data series (M) comprises examining a rate (Rn; Rt) at which the status indicator (S) changes over time, and the error code (E) is generated about an absolute amount of the rate ( Rn; Rt) exceeds a first predetermined limit value. The method of any of claims 11 or 12, wherein the analysis of the data series (M) comprises examining a rate (Rn; Rt) at which the status indicator (S) changes over time, and the error code (E) 18 10 15 20 25 30 536 552 is generated if the status indicator (S) decreases at a rate (Rn; Rt) which is faster than a second predetermined limit value. The method according to any one of claims 11 to 14, wherein the analysis of the data series (M) comprises calculating an average value (SM) of the status indicator (S) over a subset of the values in the data series (M), and the error code (E) is generated if the average value (SM) is less than a third predetermined limit value. The method according to any one of claims 11 to 15, comprising: observing at least one parameter describing the conditions under which the status indicator (S) has been generated, storing the status indicator (S) in a first data series if the status indicator (S) has been generated under a first type of conditions, storing the status indicator (S) in at least a second data series if the status indicator (S) has been generated under at least a second type of conditions, individual analysis of said respective first and at least a second data series, and on the basis of which an assessment is made as to whether the function of the electric starter motor (110) is acceptable. The method according to any one of claims 11 to 16, comprising, on the basis of the error code (E), generating at least one of: an acoustic signal suitable to be perceived by an operator, a visual signal suitable to be perceived by an operator , storing an error code in a memory unit, a signal arranged to be transmitted to a monitoring equipment connected to the system and a wireless signal arranged to be transmitted via at least one communication network to a monitoring node. The method of any of claims 11 to 17, comprising measuring at least one temperature related to the electric starter motor (110), and determining the status indicator (S) on a further basis of the at least one measured temperature. 19 10 15 536 552 The method according to any one of claims 11 to 18, comprising: measuring the supply voltage (U) and the speed (RPM) during a measuring interval, averaging the supply voltage (U) and the speed (RPM) during a measuring interval over the measuring interval, and utilizing the averaged supply voltage (Uavg) and the speed (RPMaVg) when determining the status indicator (S). The method of claim 19, comprising, if the measured supply voltage (Uavg) is below a voltage threshold, assigning the status indicator (S) a special value representing that the function of the starter motor cannot be determined. A computer program directly downloadable to the internal memory (180) of a computer, comprising software for controlling the steps of any of claims 11 to 20 when said program is run on the computer. A computer readable medium (180) having a program stored thereon, the program being adapted to cause a computer to control the steps of any of claims 11 to 20.