Electric leakage detection device, battery system, and method for checking characteristic of battery pack

Abstract

To provide an electric leakage detection device capable of detecting electric leakage without using an AC signal.SOLUTION: An electric leakage device 11 includes a high potential line 21b and a low potential line 21c which are connected to each of a positive electrode 18b and a negative electrode 18c of a battery arrangement 16, a capacitor 23 which is connected to a node NDb and a node NDc, a signal generating circuit 25 for generating a signal indicating a potential difference between the node NDb and the node NDc, a circuit 27 which is connected between one of the high potential line 21b and the low potential line 21c, and the node NDb, a circuit 29 which is connected between the other of the high potential line 21b and the low potential line 21c and the node NDc, and a determination circuit which is connected to the signal generating circuit 25, and determines presence / absence of electric leakage in the battery arrangement 16 on the basis of the signal, wherein the circuit 27 includes a switch 26b and a capacitor 26c which are connected in series between a first end 27b and a second end 27c of the circuit, and a circuit 29 further includes a referential potential switch 28d which is connected between the node NDc and the reference potential line 21d.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a leakage detection device, a battery system, and a method for examining characteristics of a battery pack.

Background Art

[0002] Patent Document 1 discloses a leakage detection system. This leakage detection system can detect leakage from a battery pack, which is a series connection of battery cells, to a vehicle body. Specifically, the leakage detection system generates an alternating current (AC) signal in the form of a rectangular wave, applies the AC signal to the battery pack, and detects attenuation of the applied AC signal. Detection of leakage is performed based on the amount of attenuation of the applied AC signal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to detect leakage from the battery pack to the vehicle body, the above-described leakage detection system requires respective circuits for AC signal generation, application of the AC signal to the battery pack, and detection of the amount of attenuation of the applied AC signal. For example, use of an AC signal is complicated, and thus, what is required is leakage detection without using an AC signal.

[0005] An object of the present invention is to provide a leakage detection device, a battery system, and a method for examining characteristics of a battery pack that enable leakage detection without using an AC signal.

Means for Solving the Problems

[0006] The leakage detection device according to the first aspect of the present invention includes a high potential line and a low potential line configured to be connected to the positive electrode and the negative electrode, respectively, in an array of a plurality of secondary batteries connected in series, a capacitor having one end and the other end connected to a first node and a second node, respectively, a signal generation circuit connected to the first node and the second node and configured to generate one or more electrical signals associated with a first potential of the first node and a second potential of the second node, a first circuit connected between one of the high potential line and the low potential line and the first node, a second circuit connected between the other of the high potential line and the low potential line and the second node, and a determination circuit connected to the signal generation circuit and configured to determine the presence or absence of leakage in the array of the secondary batteries based on the electrical signals. The first circuit has a first end connected to the first node and a second end connected to one of the high potential line and the low potential line, and the first circuit includes at least a first switch and a first capacitor connected in series between the first end of the first circuit and the second end of the first circuit. The second circuit further includes a reference potential switch connected between the second node and a reference potential line.

[0007] The battery system according to the second aspect of the present invention includes the leakage detection device described in the first aspect and a battery device connected to the leakage detection device in the high potential line and the low potential line. The battery device includes the array of the secondary batteries.

[0008] A method for examining the characteristics of a battery pack according to the third aspect of the present invention includes connecting one end of a capacitor to a reference potential line 21d, connecting a first capacitor between one of the positive electrode and the negative electrode in a battery pack including an array of a plurality of secondary batteries connected in series and the other end of the capacitor to form a series connection of the first capacitor and the capacitor, generating a first potential difference signal indicating a potential difference between the one end and the other end of the capacitor, and determining the presence or absence of a leakage location in the array of the secondary batteries based on the first potential difference signal.

Advantages of the Invention

[0009] According to the above disclosure, it is possible to provide a leakage detection device that enables leakage detection without using an alternating current signal, a battery system, and a method for examining the characteristics of a battery pack.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Figure 5

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Figure 7

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Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0011] Hereinafter, each embodiment for carrying out the present invention will be described with reference to the drawings. The same parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0012] FIG. 1 is a drawing schematically showing a leakage detection device and a battery system according to the present embodiment. FIG. 2 is a drawing schematically showing the leakage detection device according to the present embodiment.

[0013] Referring to FIG. 1, the battery system 11 includes a leakage detection device 13 and a battery device 15. The battery device 15 includes an array of a plurality of secondary batteries 17 connected in series (hereinafter, referred to as "battery array 16"). The battery device 15 has a positive electrode 18b and a negative electrode 18c in the battery array 16. The battery device 15 can have a first external terminal 14b and a second external terminal 14c, and the first external terminal 14b and the second external terminal 14c can be connected to the positive electrode 18b and the negative electrode 18c in the battery array 16, respectively, or can be connected via a first isolation switch 22b and a second isolation switch 22c. The secondary battery 17 can include, for example, a lithium battery.

[0014] Referring to FIGS. 1 and 2, the leakage detection device 13 can include a high potential line 21b, a low potential line 21c, a capacitor 23, a signal generation circuit 25, a first circuit 27, and a second circuit 29.

[0015] The high potential line 21b and the low potential line 21c are configured to be connected to the positive electrode 18b and the negative electrode 18c in the battery array 16, respectively.

[0016] The capacitor 23 has one end 23b and the other end 23c, and the one end 23b and the other end 23c are connected to a first node NDb and a second node NDc, respectively. The capacitor 23 can be used as, for example, a flying capacitor.

[0017] The signal generation circuit 25 has a first input 25b, a second input 25c, and an output 25d. The first input 25b and the second input 25c are connected to a first node NDb and a second node NDc, respectively. The signal generation circuit 25 is configured to generate one or more electrical signals SV (analog signals or digital signals) associated with a first potential Vb of the first node NDb and a second potential Vc of the second node NDc.

[0018] The first circuit 27 is connected between the first node NDb and one of the high potential line 21b and the low potential line 21c, for example, the high potential line 21b. The second circuit 29 is connected between the second node NDc and the other of the high potential line 21b and the low potential line 21c, for example, the low potential line 21c.

[0019] The first circuit 27 can include at least one capacitor, for example, the first capacitor 26c. The first circuit 27 can function to selectively form a series connection of this capacitor and the capacitor 23 in the leakage detection device 13. One end of this series connection is connected to one of the positive electrode 18b and the negative electrode 18c in the battery array 16, for example, the positive electrode 18b. The formation of this selective connection can be provided by a switch in the first circuit 27. An exemplary first circuit 27 can include at least one switch, for example, the first switch 26b, and at least one capacitor, for example, the first capacitor 26c. The first switch 26b and the first capacitor 26c can be connected in series between one end 23b of the capacitor 23 and the positive electrode 18b.

[0020] Specifically, the first circuit 27 can have a first terminal 27b and a second terminal 27c. The first terminal 27b is connected to the first node NDb, and the second terminal 27c is connected to one of the high potential line 21b and the low potential line 21c, for example, the high potential line 21b. In the first circuit 27, an exemplary first switch 26b and an exemplary first capacitor 26c can be connected in series between the first terminal 27b and the second terminal 27c of the first circuit 27. The exemplary first circuit 27 can further include a first resistor 26e, and the first switch 26b, the first capacitor 26c, and the first resistor 26e can be connected in series. The first resistor 26e can gently change the voltage when connecting the first capacitor 26c to the battery device 15.

[0021] The second circuit 29 can include at least one switch.

[0022] The second circuit 29 can function to selectively connect the other end of the series connection of the selectively formed capacitor 23 and the first capacitor 26c to the reference potential line 21d, for example, the ground line, in the leakage detection device 13. The formation of this selective connection can be provided by the switch of the second circuit 29. The exemplary second circuit 29 can include at least one switch, for example, a reference potential switch 28d. The reference potential switch 28d is connected between the other end 23c of the capacitor 23 and the reference potential line 21d.

[0023] Specifically, the second circuit 29 can have a first terminal 29b and a second terminal 29c. The first terminal 29b is connected to the second node NDc, and the second terminal 29c is connected to the other of the high potential line 21b and the low potential line 21c, for example, the low potential line 21c.

[0024] The leakage detection device 13 can further include an initialization circuit 19. The initialization circuit 19 can be configured to initialize the charge of the first node NDb and the second node NDc, or the capacitor 23, prior to the measurement of leakage detection. Specifically, the initialization circuit 19 initializes the first node NDb and applies a desired potential, for example, a ground potential, to the potential of the first node NDb. Similarly, the initialization circuit 19 initializes the second node NDc and applies a desired potential, for example, a ground potential, to the potential of the second node NDc.

[0025] An exemplary initialization is to temporarily connect the first node NDb to the reference potential line 21d using a switch, and after the completion of the initialization, the first node NDb is disconnected from the reference potential line 21d. Similarly, the initialization circuit 19 initializes the second node NDc and applies a desired potential, for example, a ground potential, to the potential of the second node NDc. An exemplary initialization is to temporarily connect the second node NDc to the reference potential line 21d using a switch, and after the completion of the initialization, the second node NDc is disconnected from the reference potential line 21d.

[0026] The exemplary initialization circuit 19 can include a first initialization switch 19b connected between the first node NDb and the reference potential line 21d. In addition, the exemplary initialization circuit 19 can include a second initialization switch 19c connected between the second node NDc and the reference potential line 21d. Alternatively / Additionally, the exemplary initialization circuit 19 can include an equivalent switch 19d connected between the first node NDb and the second node NDc. By the conduction of the equivalent switch 19d, the first node NDb and the second node NDc can be initialized to the same potential, and specifically, can be connected to the reference potential line 21d via the reference potential switch 28d.

[0027] The leakage detection device 13 can further include a determination circuit 31 (determination device). The determination circuit 31 is connected to the signal generation circuit 25 and is configured to determine the presence or absence of leakage in the arrangement of the secondary battery 17 based on the electrical signal SV.

[0028] As shown in FIG. 1, the battery device 15 is connected to the leakage detection device 13 and is connected to the leakage detection device 13 at the high potential line 21b and the low potential line 21c. Specifically, the high potential line 21b and the low potential line 21c are respectively connected to the positive electrode 18b and the negative electrode 18c in the arrangement of the secondary battery 17.

[0029] The battery system 11 can be configured to be mounted on a moving body such as a vehicle, a ship, and an aircraft. The reference potential line 21d can be connected to an electrical conductor of a moving body, for example, a vehicle.

[0030] Next, a general description will be given of detecting the presence or absence of leakage in the battery device 15 using the leakage detection device 13.

[0031] The leakage in the battery device 15 is understood as follows. For example, a certain node (hereinafter referred to as "leakage node") of the secondary battery 17 in the battery array 16 of the battery device 15 is connected to the ground line via a conductive path (hereinafter referred to as "leakage path") that does not exist in design. The leakage path has an unknown resistance value (leakage resistance). When a closed conduction path is formed, the leakage path flows a current according to this resistance value and the potential of the output of the battery device 15. If there is a leakage path in the battery device 15, the battery device 15 is grounded at the leakage node via the leakage resistance.

[0032] First, during a period for sufficiently charging the battery array 16 of the battery device 15, the battery array 16 of the battery device 15 is placed in a charged state.

[0033] (Connection 1) After initializing the capacitor 23, a series connection of the capacitor 23 and the first capacitor 26c is formed using the first circuit 27, and the capacitor 23 is connected to the reference potential line 21d using the second circuit 29. The series-connected capacitor 23 and the first capacitor 26c are connected between one of the positive electrode 18b and the negative electrode 18c in the battery array 16, for example, between the positive electrode 18b and the reference potential line 21d.

[0034] After this connection is formed, information regarding the potential difference between the terminals of the capacitor 23 is obtained using the signal generation circuit 25.

[0035] When the battery device 15 does not include a leakage node, the electrical path to the reference potential line 21d within the battery array 16 is not formed. Therefore, the potential between the terminals of the capacitor 23 becomes the value at the time of initialization.

[0036] When the battery device 15 includes a leakage node, the series-connected capacitor 23 and the first capacitor 26c receive a voltage (applied voltage) corresponding to the number of secondary batteries 17 arranged between the leakage node and the positive electrode 18b and the charging voltage of each secondary battery 17 from the battery array 16 of the battery device 15. The value of this applied voltage is voltage-divided by the series-connected capacitor 23 and the first capacitor 26c, and the divided voltage value is applied to the capacitor 23. Therefore, the potential between the terminals of the capacitor 23 becomes a value different from the initialization value, specifically, the voltage value of the voltage division.

[0037] As a result, the determination circuit 31 can detect the presence or absence of a leakage node in the battery device 15, that is, the existence and non-existence of the leakage node.

[0038] Also, the voltage value of the voltage division depends on the number of secondary batteries 17 arranged between the leakage node and the positive electrode 18b. This makes it possible to specify the position of the leakage node in the battery device 15. The determination circuit 31 can be configured to specify the position of the leakage in the array of secondary batteries 17 based on the potential difference of the capacitor 23.

[0039] While referring to FIGS. 1 and 2, the leakage detection device 13 will be continuously described.

[0040] The second circuit 29 can further include at least one capacitor, for example, the second capacitor 28c. The second circuit 29 can function to selectively form a series connection of this capacitor and the capacitor 23 to the leakage detection device 13. One end of this series connection is connected to the other of the positive electrode 18b and the negative electrode 18c in the battery array 16, for example, the negative electrode 18c. The formation of this selective (exclusive with respect to the reference potential switch 28d) connection can be provided by the switch of the second circuit 29. An exemplary second circuit 29 can include at least one capacitor, for example, the second capacitor 28c, and at least one switch, for example, the second switch 28b. The second capacitor 28c and the second switch 28b can be connected in series between the other end 23c of the capacitor 23 and the negative electrode 18c.

[0041] As already described, the second circuit 29 can have a first end 29b and a second end 29c. The first end 29b is connected to the second node NDc, and the second end 29c is connected to the other of the high potential line 21b and the low potential line 21c, for example, the low potential line 21c.

[0042] Specifically, the second circuit 29 can include, for example, at least one second switch 28b and at least one second capacitor 28c. The exemplary second switch 28b and the exemplary second capacitor 28c can be connected in series between the first end 29b and the second end 29c of the second circuit 29.

[0043] The exemplary second circuit 29 can further include a second resistor 28e. The second switch 28b, the second capacitor 28c, and the second resistor 28e can be connected in series. The second resistor 28e can gently change the voltage when connecting the battery device 15 to the leakage detection device 13.

[0044] The first circuit 27 can include at least one additional switch. Specifically, the first circuit 27 can further include a first reference potential switch 28d connected between the first node NDb and the reference potential line 21d.

[0045] The first circuit 27 can function to selectively connect the other end of the series connection of the selectively formed capacitor 23 and the second capacitor 28c to the reference potential line 21d, for example, the ground line, in the leakage detection device 13. The formation of this selective (exclusive with respect to the switch 26b) connection can be provided by an additional switch of the first circuit 27. The exemplary first circuit 27 can include at least one switch, for example, the first reference potential switch 26d. The first reference potential switch 26d is connected between the other end of the capacitor 23 and the reference potential line 21d.

[0046] Note that the connection 1 enables the detection of leakage when there is leakage in the low potential line 21c and no leakage in the high potential line 21b.

[0047] Subsequently, a schematic description will be given of detecting the presence or absence of leakage in the battery device 15 using the leakage detection device 13.

[0048] First, during a period for sufficiently charging the battery array 16 of the battery device 15, the battery array 16 of the battery device 15 is placed in a charged state.

[0049] (Connection 2) After initializing the capacitor 23, the second circuit 29 is used to form a series connection of the capacitor 23 and the second capacitor 28c, and the first circuit 27 is used to connect the capacitor 23 to the reference potential line 21d. The series-connected capacitors 23 and 28c are connected between the other of the positive electrode 18b and the negative electrode 18c in the battery array 16, for example, between the negative electrode 18c and the reference potential line 21d.

[0050] After this connection is formed, the signal generation circuit 25 is used to obtain information regarding the potential difference between the terminals of the capacitor 23.

[0051] Also, in Connection 2, when the battery device 15 does not include a leakage node, the electrical path to the reference potential line 21d in the battery array 16 of the battery device 15 is not formed. Therefore, the potential between the terminals of the capacitor 23 becomes the initialized value.

[0052] When the battery device 15 includes a leakage node, the series-connected capacitor 23 and the second capacitor 28c receive a voltage (applied voltage) corresponding to the number of secondary batteries 17 arranged between the leakage node and the negative electrode 18c and the charging voltage of each secondary battery 17 from the battery array 16 of the battery device 15. The value of this applied voltage is voltage-divided by the series-connected capacitor 23 and the second capacitor 28c, and the divided voltage is applied to the capacitor 23. Therefore, the potential between the terminals of the capacitor 23 becomes a value different from the initialized value, specifically, the voltage value of the voltage division.

[0053] Thereby, the determination circuit 31 can detect the presence or absence of a leakage node, that is, the presence of a leakage node, in the battery device 15.

[0054] Also, the voltage value of the voltage division depends on the number of secondary batteries 17 arranged between the leakage node and the negative electrode 18c. This makes it possible to specify the position of the leakage node in the battery device 15.

[0055] In Connection 2, the battery array 16 of the battery device 15 has the opposite polarity to the battery array 16 of the previous Connection 1. Therefore, the signal generation circuit 25 is configured to be able to measure the potentials of both positive and negative polarities, and also generates an electrical signal SV representing the values of both polarities.

[0056] Note that Connection 2 enables detection of leakage when there is leakage in the high potential line 21b and no leakage in the low potential line 21c.

[0057] The leakage current detection device 13 will be further described. The leakage current detection device 13 can further include a first switch control circuit 33. The first switch control circuit 33 can be configured to control the conduction / non-conduction of the first switch 26b and the conduction / non-conduction of the reference potential switch 26d. The first switch control circuit 33 can be configured to control any one, any two, or all of the first initialization switch 19b, the second initialization switch 19c, and the equivalent switch 19d.

[0058] The leakage current detection device 13 can further include a second switch control circuit 35. The second switch control circuit 35 can be configured to control the conduction / non-conduction of the second switch 28b and the conduction / non-conduction of the reference potential switch 28d. The second switch control circuit 35 can be configured to control any one, any two, or all of the first initialization switch 19b, the second initialization switch 19c, and the equivalent switch 19d, if possible.

[0059] The leakage current detection device 13 can further include a third switch control circuit 37.

[0060] The third switch control circuit 37 can be configured to control a switch 38b connected between the first node NDb and the first input 25b of the signal generation circuit 25, and a switch 38c connected between the second node NDc and the second input 25c of the signal generation circuit 25. The switches 38b and 38c control the timing at which the signal generation circuit 25 and the determination circuit 31 acquire a signal related to the potential difference between the terminals of the capacitor 23. Also, after the divided voltage value has stabilized during voltage division by the capacitor, it enables the first node NDb and the second node NDc to be connected to the signal generation circuit 25. In addition, the third switch control circuit 37 can be configured to control the first initialization switch 19b and the second initialization switch 19c. Also, the third switch control circuit 37 can be configured to control the equivalent switch 19d. Further, the third switch control circuit 37 can be configured to control any one, any two, or all of the first initialization switch 19b, the second initialization switch 19c, and the equivalent switch 19d.

[0061] The leakage detection device 13 can further include a multiplexer circuit 39.

[0062] An exemplary multiplexer circuit 39 can include a first connection terminal 39b, a second connection terminal 39c, and a plurality of third connection terminals 39d. The first connection terminal 39b and the second connection terminal 39c are connected to the first node NDb and the second node NDc, respectively.

[0063] The multiplexer circuit 39 can include a multiplexer switch 39f and a resistor element 39g, and the multiplexer switch 39f is connected in series with the corresponding resistor element 39g. The multiplexer switch 39f and the resistor element 39g connected in series are connected to the corresponding third connection terminal 39d. The multiplexer switches 39f are all made non-conductive during the leakage inspection. Note that the multiplexer circuit 39 can include one or more additional circuit components, while those circuit components are not depicted in the drawings for simplicity.

[0064] The leakage detection device 13 can further include a fourth switch control circuit 34. The fourth switch control circuit 34 can individually control the conduction / non-conduction of the multiplex switch 39f.

[0065] The first switch control circuit 33, the second switch control circuit 35, the third switch control circuit 37, and the fourth switch control circuit 34 can constitute a switch control circuit and can be controlled by respective control signals from the determination circuit 31.

[0066] The battery device 15 can include a plurality of connection terminals 14d. The connection terminals 14d can be used to monitor the potentials and potential differences of the positive electrode 18b and the negative electrode 18c of the secondary battery 17. The connection terminals 14d can be connected to either the positive electrode and / or the negative electrode of the secondary battery 17 in the battery array 16. Specifically, the positive electrode of the secondary battery 17 on the low potential side of adjacent secondary batteries 17 is connected to the negative electrode of the secondary battery 17 on the high potential side at the node NDCM. The positive electrode 18b is connected to the positive electrode of the highest-potential-side secondary battery 17 in the battery array 16. The negative electrode 18c is connected to the negative electrode of the lowest-potential-side secondary battery 17 in the battery array 16.

[0067] Also, the node NDCM of the battery device 15 can be numbered, for example, in the direction from the positive electrode 18b (the first external terminal 14b) to the negative electrode 18c (the second external terminal 14c). These nodes NDCM can be connected to either the positive electrode and / or the negative electrode of the secondary battery 17.

[0068] The numbered nodes NDCM can be connected to each of the connection terminals 14d of the battery device 15, and the connection terminals 14d can also be numbered in the same way.

[0069] The leakage detection device 13 can include a connection terminal 13d connected to the connection terminal 14d of the battery device 15. The connection terminal 13d is numbered according to the connection terminal 14d of the battery device 15. The connection terminal 13d can also be connected to the third connection terminal 39d of the multiplexing circuit 39, and the third connection terminal 39d is also numbered according to the connection terminal 14d of the battery device 15. The multiplexing switch 39f can also be numbered similarly according to such numbering, and the series connection body of the multiplexing switch 39f and the resistance element 39g can also be numbered.

[0070] The even-numbered series connection bodies (39f, 39g) in the array of the series connection of the multiplexing switch 39f and the resistance element 39g are connected to the first connection terminal 39b, and the first connection terminal 39b is configured to be connected to the first node NDb. The odd-numbered series connection bodies (39f, 39g) in the array of the multiplexing switch 39f are connected to the second connection terminal 39c, and the second connection terminal 39c is configured to be connected to the second node NDc.

[0071] The high-potential line 21b is connected to the positive electrode 18b of the battery array 16 and the connection terminal 13d connected to the first external terminal 14b. The low-potential line 21c is connected to the negative electrode 18c of the battery array 16 and the connection terminal 13d connected to the second external terminal 14c.

[0072] The exemplary signal generation circuit 25 can include a potential measurement circuit 41 and an A / D conversion circuit 43. The potential measurement circuit 41 is configured to generate one or more analog signals SVA associated with the first potential Vb of the first node NDb and the second potential Vc of the second node NDc. The A / D conversion circuit 43 is connected to the output of the potential measurement circuit 41 and is configured to convert the analog signal SVA into a digital signal SVD.

[0073] FIG. 3 is a block diagram showing exemplary hardware resources of a microcomputer as a processing device of the leakage detection device and the battery system according to the present embodiment. The exemplary determination circuit 31 can include the microcomputer 20. However, the determination circuit 31 can be configured by a configuration of another circuit without using the microcomputer 20.

[0074] In the microcomputer 20, hardware resources are used to determine the presence or absence of leakage, identify the location of the leakage, and control the switches in the leakage detection device 13. The exemplary microcomputer 20 can include a processor (central processing unit: CPU) 141, a memory 142, an input / output port 143, and a network port 144, and can include an input device 145, a display 146, and a peripheral circuit 148 if necessary. The memory 142 is communicably coupled to the processor 141. The input / output port 143 is communicably coupled to the processor 141, receives data from an external sensor, and sends out the received data. The network port 144 is communicably coupled to the processor 141 and is connected to an (external) network. The input device 145 is communicably coupled to the processor 141. The display 146 is communicably coupled to the processor 141 and the memory 142. Information for identifying the leakage node is stored in the memory 142 or provided from a network via the network port 144. The processor 141, the memory 142, the input / output port 143, the network port 144, the input device 145, and the display 146 are connected via a system bus 147. The peripheral circuit 148 can include, for example, an A / D converter, and this A / D converter can convert the analog signal SVA into a digital signal SVD.

[0075] The microcomputer 20 can be an example of the processing device 45.

[0076] Referring to FIGS. 1 and 2, the processing device 45 can be placed within the determination circuit 31. The processing device 45 is configured to include one or more memories (142) configured to store one or more instructions, and one or more processors (141) coupled to the memory (142). In the processing device 45 including an A / D converter, the processing device 45 may perform the function of the A / D conversion circuit 43. In this processing device 45, an analog signal SVA is provided to the processing device 45, and this analog signal SVA is converted into a digital signal SVD by an A / D converter (e.g., equivalent to the A / D conversion circuit 43) built into the processing device 45.

[0077] FIG. 4 is a block diagram showing modules for a leakage detection device and a processing device of a battery system according to the present embodiment. The module 140c (see FIG. 3) can be stored in the memory (142) in the form of program code defining instructions.

[0078] Specifically, the memory (142) is configured to store one or more instructions. Also, the memory (142) can be configured to store information 140b (see FIG. 3) available for the operation of the determination circuit 31 in a form available for the operation of the determination circuit 31.

[0079] When executed, the instructions can be configured to cause the processor (141) to perform operations defined by the following module 140c.

[0080] Module MD1: Set the measurement mode for the leakage detection device 13. In the measurement mode, control the switch to separate the high potential line 21b and the low potential line 21c from other circuits. Specifically, the first separation switch 22b and the second separation switch 22c are made non-conductive. Also, the multiplex switch 39f of the multiplex circuit 39 is made non-conductive. Module MD2: Control the initialization circuit 19 to initialize the capacitor 23 in the leakage detection device 13. Module MD3: Controls the first circuit 27 and the second circuit 29 to form connection 1 and / or connection 2 to the leakage detection device 13. Module MD4: After forming either connection 1 or connection 2 in the leakage detection device 13, uses the signal generation circuit 25 to measure the potential and / or potential difference at the terminals of the capacitor 23. Module MD5: Determines the presence or absence of leakage in the array of the secondary battery 17 using the digital signal SVD and the information 140b.

[0081] Specifically, determining the presence or absence of a leakage location in module MD5 can include at least one of the following sub-modules. Module MD5-1: Identifies the presence or absence of leakage in the array of the secondary battery 17 using the digital signal SVD and the information 140b. Module MD5-2: Identifies the location of leakage in the array of the secondary battery 17 using the digital signal SVD and the information 140b.

[0082] Also, when executed, the instruction can be configured to cause the processor 141 to perform the operations defined by the following module 140c.

[0083] Module MD6: Releases the measurement mode of the leakage detection device 13. When the measurement mode is released, the high potential line 21b and the low potential line 21c can be connected to other circuits. For example, the non-conduction limit of the multiplex switch 39f of the multiplex circuit 39 is also released. Also, the non-conduction limits of the first isolation switch 22b and the second isolation switch 22c can be released.

[0084] To control the first circuit 27 and the second circuit 29 to form connection 1 to the leakage detection device 13, when executed, the instruction can be configured to cause the processor 141 to perform the operations defined by the following module 140c. Module MD7: Set the leakage detection device 13 to the first state that provides connection 1. The first circuit 27 and the second circuit 29 can be controlled to perform the following operations. Specifically, module MD7 makes the first switch 26b in the first circuit 27 conductive and the first reference potential switch 26d non-conductive, and makes the second switch 28b in the second circuit 29 non-conductive and the second reference potential switch 28d conductive.

[0085] To control the first circuit 27 and the second circuit 29 to form connection 2 to the leakage detection device 13, the instruction can be configured to cause the processor 141 to perform the operations defined by the following module 140c when executed. Module MD8: Set the leakage detection device 13 to the second state that provides connection 2. Specifically, the first circuit 27 and the second circuit 29 can be controlled to perform the following operations. Make the first switch 26b in the first circuit 27 non-conductive and the first reference potential switch 26d conductive, and make the second switch 28b in the second circuit 29 conductive and the second reference potential switch 28d non-conductive.

[0086] Also, the instruction can be configured to cause the processor 141 to perform the operations defined by the following module 140c when executed. Module MD9: After setting to the first state or the second state, receive the first signal or the second signal as an electrical signal SV including information related to the potentials of both terminals of the capacitor 23 by measurement using the signal generation circuit 25.

[0087] The electrical signal SV can include at least two signals representing the potentials of the first node NDb and the second node NDc respectively. Alternatively / Additionally, the electrical signal SV can include at least one signal representing the potential difference between the first potential of the first node NDb and the second potential of the second node NDc.

[0088] Furthermore, the leakage detection device 13 can include a module that causes the following operations to control the first circuit 27 and the second circuit 29 after forming connection 1 and / or connection 2 to the leakage detection device 13.

[0089] Module MD10: Identify the presence or absence of a leakage location in the battery array 16 based on at least one of the first signal and the second signal.

[0090] Identifying the presence or absence of a leakage location in module MD10 can include at least one of the following sub-modules. Module MD10-1: Identify the location of leakage in the battery array 16 based on the first signal. Module MD10-2: Identify the location of leakage in the battery array 16 based on the second signal. Module MD10-3: Identify the location of leakage in the battery array 16 based on the first signal and the second signal.

[0091] Also, identifying the presence or absence of a leakage location in module 10 can include at least one of the following sub-modules. Module MD10-4: Compare the value of the first signal with one or more reference values. Module MD10-5: Compare the value of the second signal with one or more reference values. Module MD10-6: Compare the values of each of the first signal and the second signal with one or more reference values.

[0092] The information in the memory (142) can include relationship information with data related to the number of series stages of the secondary battery 17 and the charging voltage value (e.g., the voltage value of substantially full charge) in each of the series stages, and / or reference values for comparison (e.g., the relationship between the occurrence of leakage at the shared node and the divided voltage assumed). This information can be obtained, for example, from experiments or calculations that measure the characteristics of the battery system 11. At least one of the above modules can be provided by program code that causes the processor 141 to execute that module.

[0093] FIG. 5 and FIG. 6 are flowcharts showing main operations in a method for examining characteristics of a battery pack according to this embodiment. This method can be provided by program code that causes a processor 141 to execute at least one of the following steps.

[0094] As shown in FIG. 5, this method 100 can include at least one of the following steps.

[0095] In step ST1, a leakage detection device 13 and a battery device 15 are prepared. Also, the leakage detection device 13 and the battery device 15 are connected to each other.

[0096] In step ST2, after preparing the leakage detection device 13 and the battery device 15, the power storage of the capacitor 23 is initialized. Prior to the initialization, the first capacitor 26c is disconnected from the electrodes and / or the capacitor 23 in the battery pack. Exemplary initialization can be provided by any one of turning on the switches (19b, 19c, see FIG. 1), turning on the switch (19d, see FIG. 1), and / or turning on the switch (19d) and the switch (28d). In the drawings referred to in the following description, the dashed line LK1 indicates a potential leakage location.

[0097] In step ST3, after canceling the initialization, a series connection of the capacitor 23 and the first capacitor 26c is formed, and the capacitor 23 is connected to the reference potential line 21d. Specifically, the first capacitor 26c is connected between one of the positive electrode 18b and the negative electrode 18c in a battery pack including an array of secondary batteries 17 connected in series and one end of the capacitor 23 to form a series connection of the first capacitor 26c and the capacitor 23. Forming the series connection is, for example, either connecting the capacitor 23 to the first capacitor 26c connected to the battery pack by a conductor or connecting the battery pack to the first capacitor 26c connected to the capacitor 23 by a conductor.

[0098] In step ST4, a first signal S1 indicating the respective potentials of one end and the other end of the capacitor 23 and / or the potential difference between one end and the other end of the capacitor 23 is generated as a potential difference signal. After the generation, the series connection of the capacitor 23 and the first capacitor 26c may be eliminated.

[0099] In step ST5, based on the first signal S1, it is determined whether there is a leakage location in the arrangement of the secondary battery 17.

[0100] As shown in FIG. 6, this method 100 can include at least one of the following steps.

[0101] In step ST6, the power storage of the capacitor 23 is initialized. Prior to the initialization, the second capacitor 28c (and, if possible, also the first capacitor 26c) is disconnected from the electrodes in the battery pack and / or the capacitor 23. The initialization can be performed by the exemplary initialization already described. In the drawings referred to in the following description, the dashed line LK2 indicates a potential leakage location.

[0102] In step ST7, after releasing the initialization, a series connection of the capacitor 23 and the capacitor 28c is formed, and the capacitor 23 is connected to the reference potential line 21d. Specifically, the second capacitor 28c is connected between the other of the positive electrode 18b and the negative electrode 18c in the battery pack including the arrangement of the plurality of secondary batteries 17 connected in series and the other end of the capacitor 23 to form a series connection of the second capacitor 28c and the capacitor 23. Forming the series connection is, for example, either connecting the capacitor 23 to the second capacitor 28c already connected to the battery pack by a conductor or connecting the battery pack to the second capacitor 28c already connected to the capacitor 23 by a conductor.

[0103] In step ST8, a second signal S2 indicating the respective potentials of one end and the other end of the capacitor 23 and / or the potential difference between one end and the other end of the capacitor 23 is generated as a potential difference signal.

[0104] In step ST9, based on the second signal S2, it is determined whether there is a leakage location in the arrangement of the secondary battery 17.

[0105] In step ST10, based on the first signal S1 and the second signal S2, it is determined whether there is a leakage location in the arrangement of the secondary battery 17. Each of the first signal S1 and the second signal S2 can indicate the respective potentials of one end and the other end of the capacitor 23 and / or the potential difference between one end and the other end of the capacitor 23. Also, determining whether there is a leakage location includes identifying the position of the leakage location in the battery array 16.

[0106] FIG. 7 is a flowchart showing the main operations in a method of manufacturing a battery system according to the present embodiment. In this method 200, it can include at least one of the following operations. This method can be provided by program code that causes the processor 141 to execute at least one of the following steps.

[0107] In step ST21, a battery device 15 including the battery array 16 and a leakage detection device 13 are prepared.

[0108] In step ST22, the battery device 15 and the leakage detection device 13 are assembled to manufacture the battery system 11.

[0109] In step ST23, the capacitor 23 is initialized and one terminal of the capacitor 23 of the leakage detection device 13 is connected to the reference potential line 21d.

[0110] In step ST24, the first capacitor 26c of the leakage detection device 13 is connected between one of the positive electrode 18b and the negative electrode 18c in the battery device 15 and the capacitor 23 to form a series connection of the first capacitor 26c and the capacitor 23.

[0111] In step ST25, using the signal generation circuit 25 of the leakage detection device 13, a first signal S1 indicating the respective potentials of one end and the other end of the capacitor 23 and / or the potential difference between one end and the other end of the capacitor 23 is generated.

[0112] In step ST26, the capacitor 23 is initialized and the other end of the capacitor 23 is connected to the reference potential line 21d.

[0113] In step ST27, the second capacitor 28c of the leakage detection device 13 is connected between the other one of the positive electrode 18b and the negative electrode 18c in the battery device 15 and the other terminal of the capacitor 23 to form a series connection of the second capacitor 28c and the capacitor 23.

[0114] In step ST28, using the signal generation circuit 25, a second signal S2 indicating the respective potentials of one end and the other end of the capacitor 23 and / or the potential difference between one end and the other end of the capacitor 23 is generated.

[0115] In step ST29, based on the first signal and the second signal, the presence or absence of a leakage location in the battery array 16 is determined.

[0116] In step ST30, when no leakage location is found, the battery system 11 is selected as a good product, and when no leakage location is found, the battery device 15 is selected as a defective product.

[0117] Figures 8 to 13 are drawings for explaining the presence or absence of a leakage location. In Figures 8 to 13, an exemplary battery device 15 includes four secondary batteries 17. The charging voltage of all the secondary batteries 17 is the value Vm. Figures 8 to 13 depict a part of the leakage detection device 13 and the battery device 15 shown in FIGS. 1 and 2, specifically, capacitors (23, 26c, 28c) and switches (26b, 26d, 28b, 28d). A resistor is connected to the node (NDCM). Each individual resistor represents the equivalent resistance between its respective node and the ground wire and is not an actual resistor element. The equivalent resistance of the reference symbol "RH" means a very large resistance, that is, insulation resistance. The equivalent resistance of the reference symbol "R0" means a very small resistance, that is, the presence of leakage. For example, leakage of a node may occur due to leakage of the node itself and a defect in the secondary battery 17 connected to that node. For the convenience of the following explanation, the capacitances of the capacitors (23, 26c, 28c) are represented by the reference symbols of capacitances (C23, C26c, C28c), respectively. It is convenient to set the capacitance (C26c) equal to the capacitance (C28c).

[0118] Referring to FIG. 8, a leakage detection device 13 setting connection 1 is shown. The voltage of the positive electrode 18b of the battery device 15 is approximately +4×Vm. The charging voltage VC23 of the capacitor 23 is expressed as follows. VC23 = +4×Vm×C23 / (C23 + C26c) This value indicates the presence of leakage at the node on the lowest potential side (NDCM, NDO2 in FIG. 1). The presence or absence of leakage and the identification of the leakage location are performed by the leakage detection device 13.

[0119] Referring to FIG. 9, a leakage detection device 13 setting connection 1 is shown. The voltage of the positive electrode 18b of the battery device 15 is approximately +3×Vm. The charging voltage VC23 of the capacitor 23 is expressed as follows. VC23 = +3×Vm×C23 / (C23 + C26c) This value indicates that there is a leakage current from the third node (NDCM) to the node on the highest potential side (NDCM, NDO1 in FIG. 1). The presence or absence of the leakage current and the location of the leakage are detected by the leakage detection device 13.

[0120] In connection 1, the secondary battery 17 is stacked in the forward direction between the node (NDCM) indicating the leakage current and the node on the highest potential side (NDCM, NDO1 in FIG. 1). The total voltage of the stacked secondary batteries 17 is applied to the capacitors (23, 26c) connected in series. The charging voltage of the capacitor (23) is given by the capacitance division of the capacitors (23, 26c). Note that the leakage current of this node can be detected in the same manner by connection 2, which will be described later.

[0121] Referring to FIG. 10, the leakage detection device 13 for setting connection 2 is shown. The voltage of the node on the lowest potential side (NDO2 in FIG. 1) of the battery device 15 is approximately -4×Vm. The charging voltage VC23 of the capacitor 23 is expressed as follows. VC23 = -4×Vm×C23 / (C23 + C26c) This value indicates that there is a leakage current at the node on the highest potential side (NDCM, NDO1 in FIG. 1). The presence or absence of the leakage current and the location of the leakage are detected by the leakage detection device 13.

[0122] Referring to FIG. 11, the leakage detection device 13 for setting connection 2 is shown. The voltage of the node on the lowest potential side (NDCM, NDO2 in FIG. 1) of the battery device 15 is approximately -3×Vm. The charging voltage VC23 of the capacitor 23 is expressed as follows. VC23 = -3×Vm×C23 / (C23 + C26c) This value indicates that there is a leakage current from the third node (NDCM) to the node on the lowest potential side (NDCM, NDO2 in FIG. 1). The presence or absence of the leakage current and the location of the leakage are detected by the leakage detection device 13. Note that the leakage current of this node can be detected in the same manner by connection 1, which has already been described.

[0123] In Connection 2, a secondary battery 17 is stacked in the reverse direction between a node (NDCM) indicating leakage current and the node on the lowest potential side (NDCM, NDO2 in FIG. 1). The total voltage of the stacked secondary batteries 17 is applied to the capacitors (23, 26c) connected in series. The charging voltage of the capacitor (23) is given by the capacitance division of the capacitors (23, 26c).

[0124] Referring to FIG. 12, a leakage current detection device 13 for setting Connection 2 is shown. The potential of the node on the lowest potential side (NDCM, NDO2 in FIG. 1) of the battery device 15 is indefinite. The charging voltage VC23 of the capacitor 23 holds the initialized value. VC23 = 0 (volts) This value indicates that there is no leakage current location in the battery device 15. The presence or absence of leakage current and the identification of the leakage location are performed by the leakage current detection device 13.

[0125] Referring to FIG. 13, a leakage current detection device 13 for setting Connection 1 is shown. The potential of the node on the highest potential side (NDCM, NDO1 in FIG. 1) of the battery device 15 is indefinite. The charging voltage VC23 of the capacitor 23 holds the initialized value. VC23 = 0 (volts) This value indicates that there is no leakage current location in the battery device 15. The presence or absence of leakage current and the identification of the leakage location are performed by the leakage current detection device 13.

[0126] According to the above description with reference to FIGS. 8 to 13, a battery system 11 and a leakage current detection device 13 that enable leakage current detection without using an AC signal, as well as a characteristic measurement method and a manufacturing method, can be provided. In an exemplary embodiment, a series connection of a plurality of capacitors including a flying capacitor is formed, and this series connection is connected between the positive electrode 18b or the negative electrode 18c of the battery array 16 and the reference potential line 21d. After this connection, an electrical signal SV related to the potential difference between the terminals of the flying capacitor is generated. The electrical signal SV provides information regarding the presence or absence of leakage current in the battery device 15 and the location of the leakage position.

[0127] According to the present embodiment, it is possible to provide a battery monitor device, a battery system, a method for examining characteristics of a battery pack, a method for manufacturing a battery system, and a program that enable leakage detection without using an alternating current signal.

[0128] As described above, the present embodiment can have various aspects shown below.

[0129] The leakage detection device according to the first aspect of the present embodiment includes a high potential line and a low potential line configured to be connected to a positive electrode and a negative electrode, respectively, in an array of a plurality of secondary batteries connected in series, a capacitor having one end and the other end connected to a first node and a second node, respectively, a signal generation circuit connected to the first node and the second node and configured to generate one or more electrical signals associated with a first potential of the first node and a second potential of the second node, a first circuit connected between one of the high potential line and the low potential line and the first node, a second circuit connected between the other of the high potential line and the low potential line and the second node, and a determination circuit connected to the signal generation circuit and configured to determine the presence or absence of leakage in the array of the secondary batteries based on the electrical signal. The first circuit has a first end connected to the first node and a second end connected to the one of the high potential line and the low potential line, and the first circuit includes at least a first switch and a first capacitor connected in series between the first end of the first circuit and the second end of the first circuit. The second circuit includes a reference potential switch connected between the second node and a reference potential line.

[0130] The leakage detection device according to the second aspect according to the first aspect of the present embodiment can further include a switch control circuit configured to control conduction / non - conduction of the first switch and conduction / non - conduction of the reference potential switch.

[0131] In the leakage detection device for the third side according to the first side or the second side of the present embodiment, the first circuit further includes a first reference potential switch connected between the first node and the reference potential line, and the second circuit has a first end connected to the second node and a second end connected to the other of the high potential line and the low potential line. The second circuit can include at least a second switch and a second capacitor connected in series between the first end and the second end of the second circuit.

[0132] The leakage detection device for the fourth side according to the third side of the present embodiment can further include a switch control circuit configured to control conduction / non-conduction of the second switch and conduction / non-conduction of the first reference potential switch.

[0133] In the leakage detection device for the fifth side according to any one of the first side to the fourth side of the present embodiment, the first circuit further includes a first resistor, and the first resistor, the first switch, and the first capacitor can be connected in series between the first end and the second end of the first circuit.

[0134] In the leakage detection device for the sixth side according to any one of the first side to the fourth side of the present embodiment, the determination circuit can be configured to identify the position of leakage in the battery array based on the electrical signal.

[0135] In the leakage detection device for the seventh side according to the fifth side or the sixth side of the present embodiment, the determination circuit includes an A / D conversion circuit connected to the output of the signal generation circuit to convert the electrical signal into a digital signal, a processing device including one or more memories configured to store one or more instructions, and one or more processors. The memory stores information available for the operation of the determination circuit in a form available for the operation. The instructions, when executed, can be configured to cause the processor to determine the presence or absence of a leakage location in the battery array using the digital signal and the information.

[0136] In the leakage detection device of the eighth aspect according to the seventh aspect of the present embodiment, determining the presence or absence of a leakage location may include identifying the leakage location in the arrangement of the secondary batteries using the digital signal and the information.

[0137] The battery system of the ninth aspect according to the present embodiment includes the leakage detection device described in any one of the first to eighth aspects, and a battery device connected to the leakage detection device in the high potential line and the low potential line, and the battery device may include the arrangement of the secondary batteries.

[0138] A method for examining the characteristics of a battery pack according to the tenth aspect of the present embodiment includes connecting one end of a capacitor to a reference potential line 21d, connecting a first capacitor between one of the positive electrode and the negative electrode in a battery pack including an arrangement of a plurality of serially connected secondary batteries and the other end of the capacitor to form a series connection of the first capacitor and the capacitor, generating a first potential difference signal indicating the potential difference between the one end and the other end of the capacitor, and determining the presence or absence of a leakage location in the arrangement of the secondary batteries based on the first potential difference signal.

[0139] The present invention is not limited to the above-described embodiments, and various modifications can be made and implemented without departing from the gist of the present invention. And all of them are included in the technical idea of the present invention.

Explanation of Reference Numerals

[0140] 11... Battery system, 13... Leakage detection device, 13d... Connection terminal, 14b, 14c... External terminals 14d... Connection terminal, 15... Battery device, 16... Battery arrangement, 17... Secondary battery, 18b... Positive electrode, 18c ··· Negative electrode, 19 ··· Initialization circuit, 19b, 19c ··· Initialization switches, 19d ··· Equivalent switch, 20 ··· Microcomputer, 21b ··· High potential line, 21c ··· Low potential line, 21d ··· Reference potential line, 22b, 22c ··· Isolation switches, 23 ··· Capacitor, 25 ··· Signal generation circuit, 26b ··· First switch, 26c ··· First capacitor, 26d ··· Reference potential switch, 26e ··· Resistor 27 ··· First circuit, 28b ··· Second switch, 28c ··· Second capacitor, 28d ··· Reference potential switch 28e ··· Resistor, 29 ··· Second circuit, 31 ··· Judgment circuit, 33, 34, 35, 37 ··· Switch control circuits, 38b, 38c ··· Switches, 39 ··· Multiplexer circuit, 39b, 39c, 39d ··· Connection terminals 39f ··· Multiplexer switch, 39g ··· Resistance element, 41 ··· Potential measurement circuit, 43 ··· A / D conversion circuit, 45 ··· Processing device

Claims

1. A high-potential line and a low-potential line configured to be connected to a positive electrode and a negative electrode, respectively, in an array of a plurality of secondary batteries connected in series; A capacitor having one end and the other end connected to a first node and a second node, respectively; A signal generation circuit connected to the first node and the second node and configured to generate one or more electrical signals associated with a first potential of the first node and a second potential of the second node; A first circuit connected between one of the high-potential line and the low-potential line and the first node; A second circuit connected between the other of the high-potential line and the low-potential line and the second node; A determination circuit connected to the signal generation circuit and configured to determine the presence or absence of leakage in the array of the secondary batteries based on the electrical signal; Comprising; The first circuit has a first end connected to the first node and a second end connected to one of the high-potential line and the low-potential line; The first circuit includes at least a first switch and a first capacitor connected in series between the first end of the first circuit and the second end of the first circuit; The second circuit includes a reference potential switch connected between the second node and a reference potential line; Leakage detection device.

2. Further comprising a switch control circuit configured to control conduction / non-conduction of the first switch and conduction / non-conduction of the reference potential switch; The leakage detection device according to Claim 1.

3. The first circuit further includes a first reference potential switch connected between the first node and the reference potential line; The second circuit has a first end connected to the second node and a second end connected to the other of the high-potential line and the low-potential line; The second circuit includes at least a second switch and a second capacitor connected in series between the first end of the second circuit and the second end of the second circuit; The leakage detection device according to Claim 1.

4. Further comprising a switch control circuit configured to control conduction / non-conduction of the second switch and conduction / non-conduction of the first reference potential switch; The leakage detection device according to Claim 3.

5. The first circuit further includes a first resistor, and the first resistor, the first switch, and the first capacitor are connected in series between the first end of the first circuit and the second end of the first circuit; The leakage detection device according to claim 1.

6. The determination circuit is configured to identify the position of leakage in the arrangement of the secondary batteries based on the electrical signal. The leakage detection device according to claim 1.

7. The determination circuit includes an A / D conversion circuit connected to the output of the signal generation circuit for converting the electrical signal into a digital signal, and a processing device including one or more memories configured to store one or more instructions and one or more processors. The determination circuit is provided with wherein the memory stores information available for the operation of the determination circuit in a form available for the operation, and the instructions are configured to cause the processor to perform the following operations when executed: determining the presence or absence of a leakage location in the arrangement of the secondary batteries using the digital signal and the information. The leakage detection device according to claim 5.

8. Determining the presence or absence of a leakage location includes identifying the leakage location in the arrangement of the secondary batteries using the digital signal and the information. The determination includes The leakage detection device according to claim 7.

9. The leakage detection device according to any one of claims 1 to 8, and a battery device connected to the leakage detection device on the high potential line and the low potential line. The battery device is provided with wherein the battery device includes the arrangement of the secondary batteries. A battery system.

10. A method for examining the characteristics of a battery pack, the method comprising: connecting one end of a capacitor to a reference potential line; connecting a first capacitor between one of the positive and negative electrodes in a battery pack including an arrangement of a plurality of serially connected secondary batteries and the other end of the capacitor to form a series connection of the first capacitor and the capacitor; generating a first potential difference signal indicating the potential difference between the one end and the other end of the capacitor; and determining the presence or absence of a leakage location in the arrangement of the secondary batteries based on the first potential difference signal. A method comprising the above steps.

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