Battery Packs and Automotive Systems

Abstract

The present invention relates to a battery pack and an automobile system. The battery pack of the present invention includes: a first resistor and a second resistor connected in series between a power source that supplies a predetermined voltage and a ground terminal; a case that surrounds the first resistor and the second resistor; a detection voltage measurement unit including a variable resistor that is connected in parallel between one end and the other end of the second resistor and located outside the case; and a coolant leakage diagnosis unit that diagnoses a coolant leak if a detection voltage at a junction between the first resistor and the second resistor falls within a reference range calculated based on the conductivity of the coolant.

Description

[Technical Field]

[0001] [Cross-reference to related applications] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0079238 dated June 20, 2023, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a battery pack and an automobile system capable of detecting coolant leaks. [Background technology]

[0003] Batteries are used in a variety of fields, and recent fields where batteries are widely used, such as electric vehicles and smart grid systems, often require large capacities. While increasing the capacity of a battery pack can be achieved by increasing the capacity of the secondary battery, i.e., the battery cell itself, this approach has drawbacks, such as a limited capacity increase, physical limitations on expanding the size of the secondary battery, and inconvenient management. Therefore, battery packs in which multiple battery modules are connected in series and parallel are commonly used.

[0004] Such battery packs often include a battery management system (BMS) that manages the battery modules. The BMS monitors the temperature, voltage, and current of the battery modules and controls the balancing, cooling, charging, or discharging operations of the battery pack based on the monitored battery module status.

[0005] The temperature of the battery module, i.e., the temperature of the secondary battery, is a factor that significantly affects the performance of the battery pack. Generally, a battery pack can operate efficiently when the temperature of the secondary battery is properly distributed. For example, if the temperature of the secondary battery is excessively high, the stability of the negative electrode crystal lattice of the secondary battery may be reduced, resulting in a decrease in the performance of the battery pack. Therefore, the temperature of the secondary battery needs to be appropriately controlled.

[0006] Generally, a battery pack may be configured such that a coolant is provided inside the battery pack and the coolant flows around the secondary battery to maintain an appropriate temperature of the secondary battery. However, if the coolant leaks, the amount of circulating coolant decreases, which can cause problems such as the temperature of the secondary battery not being maintained. Furthermore, the leaking coolant can cause problems such as an electrical accident that damages components inside the battery pack. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a battery pack and an automobile system that can detect coolant leakage with a simple configuration. [Means for solving the problem]

[0008] According to one aspect of the present invention, a battery pack includes a first resistor and a second resistor connected in series between a power source that supplies a predetermined voltage and a ground terminal, a case that surrounds the first resistor and the second resistor, a detection voltage measurement unit including a variable resistor that is connected in parallel between one end and the other end of the second resistor and located outside the case, and a coolant leakage diagnosis unit that diagnoses a coolant leak if a detection voltage at a junction between the first resistor and the second resistor falls within a reference range calculated based on the conductivity of the coolant.

[0009] The variable resistor includes a first detection node connected to one end and a second detection node connected to the other end at a predetermined distance from the first detection node, and the first detection node and the second detection node can be electrically connected by the cooling water.

[0010] The coolant leakage diagnosis unit may diagnose no leakage of the coolant if the magnitude of the detected voltage corresponds to a first reference value that is greater than a maximum value of the reference range by a predetermined voltage.

[0011] The coolant leakage diagnosis unit may further include a control unit that diagnoses whether or not the coolant is leaking based on the magnitude of the detected voltage, and an RC filter circuit that receives the detected voltage and transfers it to the control unit.

[0012] The battery pack may further include a plurality of the detection voltage measuring units, which may be installed at predetermined intervals from a bottom surface to a top surface of the battery pack.

[0013] The detection voltage measuring unit may further include a first capacitor connected between a junction between the power source and the first resistor and a ground terminal.

[0014] According to another aspect of the present invention, an automobile system includes an automobile control unit that sets a reference range that is used as a reference for determining whether a coolant leaks based on the conductivity of the coolant; and a battery pack that diagnoses whether a coolant leaks based on the reference range. The battery pack includes a first resistor and a second resistor connected in series between a power source that supplies a predetermined voltage and a ground terminal, a case that surrounds the first resistor and the second resistor, a detection voltage measurement unit that includes a variable resistor that is connected in parallel between one end and the other end of the second resistor and located outside the case, and a coolant leakage diagnosis unit that diagnoses whether a coolant leaks if a detection voltage at a junction of the first resistor and the second resistor falls within the reference range calculated based on the conductivity of the coolant.

[0015] The variable resistor includes a first detection node connected to one end and a second detection node connected to the other end at a predetermined distance from the first detection node, and the first detection node and the second detection node can be electrically connected by the cooling water.

[0016] The coolant leakage diagnosis unit may diagnose no leakage of the coolant if the magnitude of the detected voltage corresponds to a first reference value that is greater than a maximum value of the reference range by a predetermined voltage.

[0017] The coolant leakage diagnosis unit may further include a control unit that diagnoses whether or not the coolant is leaking based on the magnitude of the detected voltage, and an RC filter circuit that receives the detected voltage and transfers it to the control unit. [Effects of the Invention]

[0018] The embodiment of the present invention can effectively detect cooling water leakage with a simple configuration. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a block diagram illustrating an automotive system according to one embodiment. [Figure 2] FIG. 2 is a conceptual diagram illustrating the relationship between the components shown in FIG. [Figure 3] 2 is a circuit diagram for explaining in detail the configuration of a detection voltage measurement unit and a coolant leakage diagnosis unit in FIG. 1. FIG. [Figure 4] 1 is an exemplary diagram illustrating a situation in which cooling water leaks according to an embodiment; [Figure 5] FIG. 2 is a conceptual diagram for explaining a reference range and a first reference value according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, the embodiments disclosed herein will be described in detail with reference to the accompanying drawings. Identical or similar components will be designated by the same or similar reference numerals, and redundant descriptions thereof will be omitted. The suffixes "module" and / or "section" for components used in the following description are assigned or used interchangeably solely for the convenience of writing the specification, and do not have any distinct meanings or functions. Furthermore, when describing the embodiments disclosed herein, if it is determined that a detailed description of related known technology may obscure the gist of the embodiments disclosed herein, such a detailed description will be omitted. Furthermore, the accompanying drawings are merely intended to facilitate understanding of the embodiments disclosed herein, and the accompanying drawings should not be construed as limiting the technical ideas disclosed herein, and should be understood to include all modifications, equivalents, or alternatives within the spirit and technical scope of the present invention.

[0021] Terms including ordinal numbers such as "first," "second," etc. may be used to describe various components, but the components are not limited by the terms. The terms are used only to distinguish one component from another.

[0022] When a component is said to be "coupled" or "connected" to another component, it should be understood that it may be directly coupled or connected to the other component, but that there may be other components in between. Conversely, when a component is said to be "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0023] In this application, the terms "comprise" or "have" and the like are intended to specify the presence of any feature, number, step, operation, component, part, or combination thereof described in the specification, and should be understood not to preclude the presence or possible addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0024] FIG. 1 is a block diagram illustrating an automobile system according to an embodiment, and FIG. 2 is a conceptual diagram illustrating the relationship between the components shown in FIG.

[0025] Referring to FIG. 1, an automobile system 1 includes an automobile communication unit 11, an automobile control unit 13, and a battery pack 100.

[0026] The vehicle communication unit 11 can transmit various commands and receive various data by communicating with the battery pack 100. For example, the vehicle communication unit 11 can transmit a reference range and a first reference value set by the vehicle control unit 13 to the battery pack 100. As another example, the vehicle communication unit 11 can receive a message corresponding to a coolant leakage diagnosis.

[0027] The vehicle control unit 13 can set a reference range that serves as a criterion for determining whether a coolant leaks based on the conductivity of the coolant. The vehicle control unit 13 can also set a first reference value that serves as a criterion for determining whether a coolant non-leak event occurs based on the internal circuitry of the battery pack 100, etc.

[0028] The battery pack 100 includes a coolant storage device 10, a detection voltage measurement unit 20, and a coolant leakage diagnosis unit 30.

[0029] Although not shown in FIG. 1 , the battery pack 100 may further include a battery module (not shown). The battery module may include a plurality of battery cells (not shown). In one embodiment, the battery cells may be rechargeable batteries, and each battery cell may include a positive electrode, a negative electrode, and an electrolyte. In one embodiment, a predetermined number of battery cells may be connected in series or parallel to form a battery module.

[0030] The coolant storage device 10 may be a device that stores coolant that absorbs heat from the battery cells to prevent the battery cells from overheating. For example, the coolant storage device 10 may be disposed adjacent to the battery modules. As another example, if the battery pack 100 includes multiple battery modules, the coolant storage device 10 may be configured in the form of a plate located between the multiple battery modules. However, the coolant storage device 10 is not limited thereto, and may be formed in various shapes at various positions inside the battery pack 100.

[0031] The detection voltage measurement unit 20 is a device that detects coolant leaking from the coolant storage device 10. According to an embodiment, the detection voltage measurement unit 20 may be disposed adjacent to the inner bottom surface of the battery pack 100. For example, referring to FIG. 4, when the coolant leaking from the coolant storage device 10 fills the inner bottom surface of the battery pack 100 up to a predetermined height h, the detection voltage measurement unit 20 may be disposed in a position that allows it to come into contact with the leaked coolant.

[0032] Referring to FIG. 2, according to an embodiment, the battery pack 100 may include a plurality of detection voltage measurement units 20-1, 20-n. The plurality of detection voltage measurement units 20-1, 20-n may be installed at various positions inside the battery pack 100. For example, when the plurality of detection voltage measurement units 20-1, 20-n are installed at predetermined intervals from the bottom surface to the top surface inside the battery pack 100, the height of the leaked coolant can be inferred. Although FIG. 2 illustrates the plurality of detection voltage measurement units 20-1, 20-n being installed at substantially the same height, this is not limited thereto and the plurality of detection voltage measurement units 20-1, 20-n may be installed at different heights as described above. Furthermore, the plurality of detection voltage measurement units 20-1, 20-n may be installed at various positions inside the battery pack 100 where coolant detection is required.

[0033] The coolant leakage diagnosis unit 30 can detect whether or not there is a coolant leakage based on the electrical signal received from the detection voltage measurement unit 20. For example, the coolant leakage diagnosis unit 30 may be a Battery Management System (BMS). However, the coolant leakage diagnosis unit 30 is not limited thereto, and a separate control unit other than the BMS or the vehicle control unit 13 of the vehicle system 1 can perform the function of the coolant leakage diagnosis unit 30.

[0034] The configurations of the detected voltage measurement unit 20 and the coolant leakage diagnosis unit 30 will be described in detail below with reference to FIGS.

[0035] FIG. 3 is a circuit diagram for explaining in detail the configuration of the detection voltage measurement unit and the coolant leakage diagnosis unit of FIG. 1, FIG. 4 is an illustrative diagram for explaining a situation in which coolant has leaked according to one embodiment, and FIG. 5 is a conceptual diagram for explaining the reference range and the first reference value according to one embodiment.

[0036] 3 and 4, one detection voltage measurement unit 20 will be described, but the description can be equally applied to the plurality of detection voltage measurement units 20-1, 20-n in FIG 2. Hereinafter, when referring to a specific detection voltage measurement unit among the plurality of detection voltage measurement units 20-1, 20-n, the reference numeral "20-j" will be used, and the first resistor, first capacitor, voltage measurement node, second resistor, first detection node, second detection node, and variable resistor included in the detection voltage measurement unit 20-j will be referred to as "201-j, 204-j, Nd-j, 202-j, N1-j, N2-j, 203-j," respectively.

[0037] The detection voltage measuring unit 20-j includes a first resistor 201-j, a second resistor 202-j, a variable resistor 203-j, and a case CA that accommodates the first resistor 201-j and the second resistor 202-j. In one embodiment, the detection voltage measuring unit 20-j may further include a first capacitor 204-j.

[0038] In one embodiment, the power supply that supplies the predetermined voltage Vs may be generated from the voltage of a battery module (e.g., 110 in FIG. 1). To this end, the detection voltage measurement unit 20-j may further include a voltage regulator (not shown). The voltage Vs may be, for example, 5 V. In one embodiment, when the voltage Vs is set to 5 V, it is assumed that the first resistor 201-j, the second resistor 202-j, and the first capacitor 204-j have resistances of 100 kΩ, 510 kΩ, and 100 nF, respectively. However, this is not limited thereto, and various resistance values ​​may be set according to various designs.

[0039] The first capacitor 204-j can pass noise components of the power supply to ground, that is, the first capacitor 204-j can be installed in the detected voltage measuring unit 20-j for a noise removal filter or bypass function.

[0040] The case CA may be configured to house the first resistor 201-j and the second resistor 202-j inside, and the variable resistor 203-j located outside. In this way, when the coolant leaks, the first resistor 201-j and the second resistor 202-j do not come into contact with the coolant, and only the variable resistor 203-j may come into contact with the coolant. In Figures 2 to 4, the case CA is configured to be separated from the coolant leak diagnosis unit 30 by a predetermined distance, but is not limited to this and may be formed integrally with the case of the coolant leak diagnosis unit 30.

[0041] The first resistor 201-j is connected between a power supply that supplies a predetermined voltage Vs and the voltage measurement node Nd-j, and the second resistor 202-j is connected between the voltage measurement node Nd-j and ground. That is, the first resistor 201-j and the second resistor 202-j can be connected in series between the power supply and ground. Also, the variable resistor 203-j can be connected in parallel between one end and the other end of the second resistor 202-j.

[0042] The variable resistor 203-j does not form a current path when coolant does not leak from the coolant storage device 10, but when coolant leaks from the coolant storage device 10, it can form a current path due to the leaked coolant.

[0043] 3, the variable resistor 203-j may include two detection nodes N1 and N2 spaced apart from each other. The variable resistor 203-j may include a first detection node N1 connected to one end of the second resistor 202-j and a second detection node N2 spaced a predetermined distance from the first detection node N1 and connected to the other end of the second resistor 202-j. According to one embodiment, if the coolant in the coolant storage device 10 leaks, the first detection node N1 and the second detection node N2 may be electrically connected by the coolant.

[0044] 3, if there is no cooling water leakage, the magnitude of the resistance between the first detection node N1 and the second detection node N2 can be infinite (∞). That is, no current flows between the first detection node N1 and the second detection node N2. This has the effect of connecting the first resistor 201-j and the second resistor 202-j in series between the voltage Vs and ground. Then, the magnitude of the detected voltage at the voltage measurement node Nd-j, which is the junction of the first resistor 201-j and the second resistor 202-j, can be calculated using the following equation (1):

number

[0045] As shown in FIG. 4, the coolant Col may leak from the coolant storage device 10 for various reasons. When the coolant Col is located between the first detection node N1 and the second detection node N2, the first detection node N1 and the second detection node N2 may be electrically connected through the coolant Col. At this time, the resistance value of the variable resistor 203-j may be determined based on the components contained in the coolant Col. For example, when the coolant Col is located between the first detection node N1 and the second detection node N2, the resistance value of the variable resistor 203-j is assumed to be 250 kΩ. However, the present invention is not limited to this example, and the resistance value of the variable resistor 203-j may be determined based on the conductivity determined by various components contained in the coolant Col.

[0046] If the cooling water Col is located between the first detection node N1 and the second detection node N2, the variable resistor 203-j can be connected in parallel with the second resistor 202-j. The magnitude of the parallel resistance of the second resistor 202-j and the variable resistor 203-j can be calculated using the following equation (2).

number

[0047] Referring again to FIG. 4, the first resistor 201-j and the parallel resistor R_pall are connected in series between the power supply and the ground, and the magnitude of the detected voltage at the voltage measurement node Nd-j, which is the junction of the first resistor 201-j and the parallel resistor R_pall, can be calculated from the following equation (3).

number

[0048] 3, when the cooling water Col is not leaking, air exists between the first detection node N1 and the second detection node N2. Because the conductivity of air is nearly zero, the magnitude of the variable resistor 203-j can be regarded as infinity (∞). Referring again to FIG. 4, when the cooling water Col, which is conductive, leaks, the cooling water Col exists between the first detection node N1 and the second detection node N2, and the first detection node N1 and the second detection node N2 are electrically connected through the cooling water Col. That is, because a current flows between the first detection node N1 and the second detection node N2, the state changes from a state in which there is no current flowing to a state in which there is current flowing, and the magnitude of the variable resistor 203-j can be regarded as decreasing.

[0049] The cooling water Col may contain water (50% to 60%), organic compounds (ethylene glycol), preservatives, pH adjusters, and other metals (e.g., Si, Na, etc.) For example, if there are three types of cooling water Col widely sold on the market, it is assumed that the magnitudes of the variable resistors 203-j are 250 kΩ, 100 kΩ, 50 kΩ, etc. [Table 1] Table 1 above summarizes the magnitude of the detected voltage V'_Nd depending on the magnitude of the variable resistor 203-j. This is calculated based on the magnitude of the variable resistor 203-j calculated based on the components of the coolant Col actually used in the city. In other words, the magnitude of the variable resistor 203-j may differ depending on the type of coolant Col.

[0050] For example, if the magnitude of variable resistor 203-j is 250 kΩ, the magnitude of detected voltage V_Nd may be approximately 4.18 V if coolant Col is not leaking, and approximately 3.13 V if coolant Col is leaking. As another example, if the magnitude of variable resistor 203-j is 100 kΩ, the magnitude of detected voltage V_Nd may be approximately 4.18 V if coolant Col is not leaking, and approximately 2.28 V if coolant Col is leaking. As another example, if the magnitude of variable resistor 203-j is 50 kΩ, the magnitude of detected voltage V_Nd may be approximately 4.18 V if coolant Col is not leaking, and approximately 1.57 V if coolant Col is leaking. In other words, if coolant Col is not leaking, the magnitude of detected voltage V_Nd is constant at approximately 4.18 V, but if coolant Col is leaking, the magnitude of detected voltage V_Nd varies depending on the magnitude of variable resistor 203-j.

[0051] According to the embodiment, if the coolant Col does not leak, the magnitude of the detected voltage V_Nd is substantially equal to the first reference value Vth_1, and if the coolant Col leaks, the magnitude of the detected voltage V_Nd falls within the reference range ΔVth_2.

[0052] The reference range ΔVth_2 may be calculated as a voltage range reflecting various magnitudes of the variable resistor 203-j determined by various types of coolant Col. For example, referring to FIG. 5, assuming that the magnitudes of the first resistor 201-j, the second resistor 202-j, the voltage Vs, and the first capacitor 204-j are 100 kΩ, 510 kΩ, 5 V, and 100 nF, respectively, the first reference value Vth_1 may be 4.18 V, and the reference range ΔVth_2 may correspond to 1.57 V or more and 3.13 V or less. According to an embodiment, the lower limit of the reference range ΔVth_2 may be determined based on the minimum value of the magnitudes of the variable resistor 203-j calculated for each of the various coolants, and the upper limit of the reference range ΔVth_2 may be determined based on the maximum value of the magnitudes of the variable resistor 203-j. In this case, the first reference value Vth_1 and the reference range ΔVth_2 may be determined to reflect a predetermined error. The first reference value Vth_1 may be a predetermined voltage greater than the maximum value of the reference range ΔVth_2.

[0053] 3, the coolant leakage diagnosis unit 30 includes RC filter circuits 301-j and 302-j, a communication unit 31, a control unit 33, and a storage unit 32. According to one embodiment, the coolant leakage diagnosis unit 30 may be configured as a battery management system (BMS) of a battery pack.

[0054] The detection voltage V_Nd is transmitted to the RC filter circuits 301-j and 302-j. The detection voltage V_Nd passing through the RC filter circuits 301-j and 302-j is input to the control unit 33. According to an embodiment, the coolant leakage diagnosis unit 30 may further include an analog-to-digital converter (ADC) (not shown) for converting the detection voltage V_Nd of the detection voltage measurement unit 20-j into a digital signal that can be received by the control unit 33.

[0055] 3 and 4, the RC filter circuits 301-j and 302-j may be configured in a number (n) corresponding to each of the plurality of detection voltage measurement units 20-1 and 20-n. In FIG. 3, the RC filter circuits 301-j and 302-j are shown to be included in the coolant leakage diagnosis unit 30, but are not limited thereto and may be configured to be included in the detection voltage measurement unit 20-j.

[0056] The communication unit 31 can communicate with the automobile system 1 to receive various control signals and transmit information regarding the presence or absence of leakage of the coolant Col. For example, the communication unit 31 can receive information regarding the first reference value Vth_1 and the reference range ΔVth_2 from the automobile system 1.

[0057] The control unit 33 can diagnose leakage of the cooling water Col and the occurrence of a defect in the detected voltage measurement unit 20-j based on the detected voltage V_Nd transmitted from the detected voltage measurement unit 20-j.

[0058] 5, for example, if the detected voltage V_Nd falls within the reference range ΔVth_2, it is diagnosed that the coolant Col has leaked. As another example, if the detected voltage V_Nd is substantially equal to the first reference value Vth_1, the control unit 33 may diagnose that the coolant Col has not leaked and that the detected voltage measurement unit 20-j is in a normal state. As another example, if the detected voltage V_Nd falls within a first fault diagnosis range corresponding to 0 V or more and the lower limit of the reference range ΔVth_2 or less, the control unit 33 may diagnose that the power supply and the voltage measurement node Nd-j are shorted. As another example, if the detected voltage V_Nd falls within a second fault diagnosis range corresponding to 0 V or more and the upper limit of the reference range ΔVth_2 or less and the voltage Vs or less, the control unit 33 may diagnose that the power supply and the ground are shorted.

[0059] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to these, and various modifications and improvements made by those skilled in the art to which the present invention pertains also fall within the scope of the present invention.

Claims

1. a first resistor and a second resistor connected in series between a power supply supplying a predetermined voltage and a ground terminal; a case surrounding the first resistor and the second resistor; a detection voltage measuring unit including a variable resistor connected in parallel between one end and the other end of the second resistor and positioned outside the case; a coolant leakage diagnosis unit that diagnoses the coolant leakage when a detected voltage of the junction of the first resistor and the second resistor falls within a reference range calculated based on the conductivity of the coolant; A battery pack comprising:

2. The variable resistor is 2. The battery pack of claim 1, further comprising: a first detection node connected to the one end; and a second detection node connected to the other end at a predetermined distance from the first detection node, wherein the first detection node and the second detection node are electrically connected by the coolant.

3. The cooling water leakage diagnosis unit The battery pack of claim 1 , wherein the non-leakage of the coolant is diagnosed when the magnitude of the detected voltage corresponds to a first reference value that is greater than a maximum value of the reference range by a predetermined voltage.

4. The cooling water leakage diagnosis unit a control unit that diagnoses whether or not there is a leakage of the cooling water based on the magnitude of the detected voltage; The battery pack of claim 3 , further comprising: an RC filter circuit that receives the detected voltage and transmits it to the control unit.

5. The detection voltage measuring unit further includes a plurality of the detection voltage measuring units, The plurality of detected voltage measurement units include: The battery pack according to claim 4 , wherein the battery pack is installed with a predetermined distance between the bottom surface and the top surface of the battery pack.

6. The detected voltage measurement unit The battery pack of claim 1 , further comprising a first capacitor coupled between a junction between the power source and the first resistor and a ground terminal.

7. a vehicle control unit that sets a reference range that is a criterion for determining whether or not the cooling water is leaking based on the conductivity of the cooling water; a battery pack that diagnoses a cooling water leak based on the reference range, The battery pack a first resistor and a second resistor connected in series between a power supply supplying a predetermined voltage and a ground terminal; a case surrounding the first resistor and the second resistor; a detection voltage measuring unit including a variable resistor connected in parallel between one end and the other end of the second resistor and positioned outside the case; a coolant leakage diagnosis unit that diagnoses the coolant leakage when a detected voltage of the junction of the first resistor and the second resistor falls within a reference range calculated based on the conductivity of the coolant; , including, automotive systems.

8. The variable resistor is 8. The automotive system of claim 7, further comprising: a first detection node connected to the one end; and a second detection node connected to the other end at a predetermined distance from the first detection node, wherein the first detection node and the second detection node are electrically connected by the coolant.

9. The cooling water leakage diagnosis unit 8. The automobile system according to claim 7, wherein if the magnitude of the detected voltage corresponds to a first reference value that is a predetermined voltage greater than the maximum value of the reference range, the system diagnoses that there is no leakage of the coolant.

10. The cooling water leakage diagnosis unit a control unit that diagnoses whether or not there is a leakage of the cooling water based on the magnitude of the detected voltage; The automobile system according to claim 7 , further comprising: an RC filter circuit that receives the detected voltage and transmits it to the control unit.

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