Reverse connection prevention device

Abstract

In the protection device for an electronic device, a first switch has an input terminal to which a positive or negative wiring is connected, a first output terminal connected to a first node, and a second output terminal connected to a second node, and a second switch has an input terminal to which a positive or negative wiring is connected, a first output terminal connected to a third node, and a second output terminal connected to a fourth node. In the first relay, the relay switch is connected between the first node and a positive input terminal of the electronic device, and an input terminal of the first driver is connected to the first node. In the second relay, the relay switch is connected between the negative input terminal of the electronic device and the third node, and the second driver has an input terminal connected to an output terminal of the first driver and an output terminal connected to the third node.

Description

[Technical field]

[0001] Cross-reference to related applications This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0143322 dated October 26, 2021, and all contents disclosed in the documents of the Korean Patent Application are incorporated herein by reference.

[0002] The present invention relates to a protection device for preventing reverse connection. [Background technology]

[0003] Energy storage systems (ESS), which store electricity and then provide the stored electricity, are used in various fields. For example, energy storage systems can be used to store excess electricity produced at power plants and provide electricity when there is a temporary power shortage. In addition, energy storage systems can be made compact and used in buildings, factories, homes, etc. as a power outage countermeasure or to reduce peak power. Energy storage systems can also be used to store electricity produced using renewable energy and use the stored electricity when it is needed.

[0004] The energy storage system uses a rechargeable battery, which can be used as an energy source for various external devices such as electronic devices and vehicles in addition to the energy storage system.

[0005] Electronic devices such as battery management systems are used together with batteries to protect and manage the batteries. Direct current (DC) voltage is supplied to operate the electronic devices. To this end, a power supply that supplies DC voltage is generally connected to a power supply input terminal of the electronic device. However, when connecting a power supply to a power supply input terminal of the electronic device, a reverse connection may occur in which the positive terminal of the power supply is connected to the negative terminal of the power supply input terminal. In this case, a reverse voltage may be applied to the electronic device, causing the electronic device to malfunction. Summary of the Invention [Problem to be solved by the invention]

[0006] An embodiment may provide a protection device that can prevent reverse connection of a DC power source. [Means for solving the problem]

[0007] According to an embodiment, a protection device for an electronic device that receives power from a DC power source having a positive wiring and a negative wiring can be provided. The protection device can include a first switch, a second switch, a first relay, and a second relay. The first switch can have an input terminal to which the positive wiring or the negative wiring is connected, a first output terminal connected to a first node, and a second output terminal connected to a second node. The second switch can have an input terminal to which the positive wiring or the negative wiring is connected, a first output terminal connected to a third node, and a second output terminal connected to a fourth node. The first relay can include a first relay switch and a first driver. The first relay switch can have a first terminal connected to the first node and a second terminal connected to a positive input terminal of the electronic device. The first driver can drive the first relay switch and have an input terminal connected to the first node. The second relay can include a second relay switch and a second driver. The second relay switch may have a first terminal coupled to a negative input terminal of the electronic device and a second terminal coupled to the third node. The second driver may drive the second relay switch and have an input terminal coupled to an output terminal of the first driver and an output terminal coupled to the third node.

[0008] In an embodiment, the protection device may further include a diode that blocks a current flowing from the third node through the second driver and the first driver to the first node.

[0009] In an embodiment, the protection device may further include a display element coupled between the first node and the third node, and configured to perform a display operation when a current flows from the third node to the first node.

[0010] In one embodiment, the display element may include a light emitting diode that lights up when a current flows from the third node to the first node.

[0011] In an embodiment, the protection device may further include a display element coupled between the second node and the fourth node, and configured to perform a display operation when a current flows from the fourth node to the second node.

[0012] In one embodiment, the display element may include a light emitting diode that lights up when a current flows from the fourth node to the second node.

[0013] In one embodiment, the electronic device may include electronic device for managing a battery.

[0014] According to another embodiment, a protection device for an electronic device that receives power from a DC power source having a positive wiring and a negative wiring can be provided. The protection device can include a first switch, a second switch, a first relay, a second relay, and a display element. The first switch can have an input terminal to which the positive wiring or the negative wiring is connected, a first output terminal connected to a first node, and a second output terminal connected to a second node. The second switch can have an input terminal to which the positive wiring or the negative wiring is connected, a first output terminal connected to a third node, and a second output terminal connected to a fourth node. The first relay can be connected between the first node and a positive input terminal of the electronic device, and the second relay can be connected between the third node and a negative input terminal of the electronic device. The display element is connected between the second node and the fourth node, and can perform a display operation when the first switch is switched to the second output terminal, the second switch is switched to the second output terminal, the negative wiring is connected to the input terminal of the first switch, and the positive wiring is connected to the input terminal of the second switch.

[0015] In one embodiment, the display element may include a light emitting diode that lights up when a current flows from the fourth node to the second node.

[0016] In one embodiment, when the first switch is switched to the first output terminal and the second switch is switched to the first output terminal, the positive pole wire is connected to the input terminal of the first switch and the negative pole wire is connected to the input terminal of the second switch, and the first relay and the second relay are turned on.

[0017] In one embodiment, when the first switch is switched to the first output terminal and the second switch is switched to the first output terminal, the negative pole wire is connected to the input terminal of the first switch and the positive pole wire is connected to the input terminal of the second switch, the first relay and the second relay are turned off.

[0018] In one embodiment, the electronic device may include an electronic device for managing a battery.

[0019] According to another embodiment, a protection device for an electronic device that receives power from a DC power source having a positive wiring and a negative wiring can be provided. The protection device can include a first switch, a second switch, a first relay, a second relay, and a display element. The first switch can have an input terminal to which the positive wiring or the negative wiring is connected, a first output terminal connected to a first node, and a second output terminal connected to a second node. The second switch can have an input terminal to which the positive wiring or the negative wiring is connected, a first output terminal connected to a third node, and a second output terminal connected to a fourth node. The first relay can be connected between the first node and a positive input terminal of the electronic device, and the second relay can be connected between the third node and a negative input terminal of the electronic device. The display element is connected between the first node and the third node, and when the first switch is switched to the first output terminal and the second switch is switched to the first output terminal, the negative wiring is connected to the input terminal of the first switch and the positive wiring is connected to the input terminal of the second switch, a display operation can be performed.

[0020] In one embodiment, the display element may include a light emitting diode that lights up when a current flows from the third node to the first node.

[0021] In one embodiment, when the first switch is switched to the first output terminal and the second switch is switched to the first output terminal, the positive pole wire is connected to the input terminal of the first switch and the negative pole wire is connected to the input terminal of the second switch, and the first relay and the second relay are turned on.

[0022] In one embodiment, when the first switch is switched to the first output terminal and the second switch is switched to the first output terminal, the negative pole wire is connected to the input terminal of the first switch and the positive pole wire is connected to the input terminal of the second switch, the first relay and the second relay are turned off.

[0023] In one embodiment, the first switch is switched to the second output terminal, and the second switch is switched to the second output terminal, and the first relay and the second relay are turned off.

[0024] In one embodiment, the electronic device may include an electronic device for managing a battery. Effect of the Invention

[0025] According to an embodiment, reverse connection between an electronic device used for battery management and a DC power source can be prevented. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 illustrates an example of a battery device according to one embodiment. [Diagram 2] FIG. 2 illustrates an example of a protection device according to one embodiment. [Diagram 3] FIG. 13 is a diagram showing an example of operation of a protection device according to one embodiment in a positive connection state. [Figure 4] FIG. 13 is a diagram showing an example of operation of a protection device in a reverse connection state according to one embodiment. [Diagram 5] FIG. 13 is a diagram showing an example of operation of a protection device according to one embodiment in a positive connection state. [Figure 6] FIG. 13 is a diagram showing an example of operation of a protection device in a reverse connection state according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, the present invention may be realized in various different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts that are not necessary for the explanation are omitted, and similar parts are designated by similar reference numerals throughout the specification.

[0028] When a component is said to be "connected" to another component, it should be understood that the component may be directly connected to the other component, but there may also be other components in between. Conversely, when a component is said to be "directly connected" to another component, it should be understood that there are no other components in between.

[0029] In the following description, expressions described as "a" or "the single" can be interpreted as singular or plural, unless expressly stated otherwise, such as "one" or "single".

[0030] In the flow charts described with reference to the figures, the order of operations may be changed, various operations may be combined or certain operations may be separated, and certain operations may not be performed.

[0031] FIG. 1 is a diagram illustrating an example of a battery device according to an embodiment.

[0032] Referring to FIG. 1, a battery device 100 includes a battery 110, a battery management system 120, and a protection device .

[0033] Battery 110 is a rechargeable secondary battery. Battery 110 may be, for example, a lithium battery, such as a lithium ion battery or a lithium ion polymer battery, or a nickel battery, such as a nickel-cadmium (NiCd) battery or a nickel metal hydride (NiMH) battery. In one embodiment, battery 110 may be a single battery cell, an assembly of multiple battery cells, a battery module in which multiple assemblies are connected in series or parallel, a battery pack (or battery rack) in which multiple battery modules are connected in series or parallel, or a device in which multiple battery packs (or battery racks) are connected in series or parallel.

[0034] The battery management system 120 is an electronic device that manages the battery 110, protects the battery 110, and monitors information and status of the battery 110. The battery management system (BMS) 120 is also called a battery protection unit (BPU). The battery management system 120 operates by receiving a direct current (DC) voltage from a direct current (DC) power source 10.

[0035] The DC power source 10 has a positive terminal and a negative terminal, the positive terminal is connected to a positive wiring 11, and the negative terminal is connected to a negative wiring 12. The DC power source 10 can supply power through the positive wiring 11 and the negative wiring 12.

[0036] In one embodiment, the battery system 100 may be an energy management system, in which case the DC power source 10 may include a power converter, such as a switching mode power supply (SMPS), that converts power from an external alternating current (AC) power source into direct current.

[0037] The protection device 130 is connected between the DC power source 10 and a power input terminal of the battery management system 120. The protection device 130 performs a protection function such that the positive wiring 11 of the DC power source 10 is connected to the positive input terminal of the battery management system 120 and the negative wiring 12 of the DC power source 10 is connected to the negative input terminal of the battery management system 120. In one embodiment, the protection device 130 may cut off the connection between the DC power source 10 and the power input terminal of the battery management system 120 when the positive wiring 11 of the DC power source 10 is connected to the negative input terminal of the battery management system 120. In one embodiment, the protection device 130 may transmit power of the DC power source 10 to the battery management system 120 when the positive wiring 11 of the DC power source 10 is connected to the positive input terminal of the battery management system 120 and the negative wiring 12 of the DC power source 10 is connected to the negative input terminal of the battery management system 120.

[0038] FIG. 2 is a diagram illustrating an example of a protection device according to an embodiment.

[0039] Referring to FIG. 2, the protection device includes switches S1, S2, S3, and S4.

[0040] The switch S1 has an input terminal P1 and first and second output terminals T11 and T12, and the switch S2 has an input terminal P2 and first and second output terminals T21 and T22. The input terminals P1 and P2 of the switches S1 and S2 correspond to the input terminals of the protection device. In one embodiment, the switches S1 and S2 may each be a single pole double throw (SPDT) switch. In one embodiment, the two switches S1 and S2 may be formed as one double pole double throw (DPDT) switch. In one embodiment, the switch S1 may connect the input terminal P1 to the first output terminal T11 when turned on, and connect the input terminal P1 to the second output terminal T12 when turned off. In addition, the switch S2 may connect the input terminal P2 to the first output terminal T21 when turned on, and connect the input terminal P2 to the second output terminal T22 when turned off. The second output terminal T12 of the switch S1 is connected to one node (e.g., the "second node") N2, and the second output terminal T22 of the switch S2 is connected to another node (e.g., the "fourth node") N4. That is, the second output terminal T12 of the switch S1 and the second output terminal T22 of the switch S2 are connected to each other.

[0041] The switch S3 has an input terminal (or "first terminal") P3 and an output terminal T3 (or "second terminal"), and the switch S4 has an input terminal (or "first terminal") P4 and an output terminal (or "second terminal") T4. In one embodiment, the switches S3 and S4 may each be a relay. Hereinafter, the switches S3 and S4 will be described as a relay. The relay S3 includes a relay switch S3a and a relay driver S3b, and when a current flows through the relay driver S3b, the relay switch S3a is turned on. The relay S4 includes a relay switch S4a and a relay driver S4b, and when a current flows through the relay driver S4b, the relay switch S4a is turned on. In one embodiment, the relay drivers S3b and S4b may be light emitting diodes (LEDs), and the relay switches S3a and S4a may be metal oxide semiconductor field-effect transistors (MOSFETs). In one embodiment, the relays S3 and S4 may be, for example, photoMOS relays.

[0042] An input terminal P1 of the switch S1 and an input terminal P2 of the switch S2 are connected to a positive wiring 21 and a negative wiring 22 of the DC power source 20. A first output terminal T11 of the switch S1 is connected to one node (or “first node”) N1, and an input terminal (or “first terminal”) P3 of the relay switch S3a is connected to the node N1. A first output terminal T21 of the switch S2 is connected to another node (or “third node”) N3, and an output terminal (or “second terminal”) of the relay switch S4a is connected to the node N3. Thus, the first output terminal T11 of the switch S1 is connected to the input terminal P3 of the relay switch S3a, and the first output terminal T21 of the switch S2 is connected to the output terminal T4 of the relay switch S4a. The output terminal (or “second terminal”) T3 of the relay switch S3a and the input terminal (or “first terminal”) P4 of the relay switch S4a are connected to a product 23 that receives power from the DC power source 20. In one embodiment, the product 23 may include an electronic device such as a battery management system (e.g., 120 in FIG. 1). In this case, the output terminal T3 of the relay switch S3a is connected to the positive input terminal (IN(+)) of the product 23, and the input terminal P4 of the relay switch S4a is connected to the negative input terminal (IN(-)) of the product 23. Thus, when the positive wiring 21 of the DC power source 20 is connected to the input terminal P1 of the switch S1 and the negative wiring 22 of the DC power source 20 is connected to the input terminal P2 of the switch S2, the DC power source 20 can be connected to the protection device in the positive direction.

[0043] An input terminal (or "first terminal") of relay driver S3b is connected to node N1, an output terminal (or "second terminal") of relay driver S3b is connected to an input terminal (or "first terminal") of relay driver S4b, and an output terminal (or "second terminal") of relay driver S4b is connected to node N3. Thus, an input terminal of relay driver S3b is connected to a first output terminal T11 of switch S1, and an output terminal of relay driver S4b is connected to a first output terminal T21 of switch S2.

[0044] In one embodiment, a diode D1 for preventing a current in the opposite direction may be formed in a path formed between nodes N1 and N3 through relay drivers S3b and S4b. The diode D1 allows a current to flow from node N1 to node N3 through relay drivers S3b and S4b, and prevents a current from flowing from node N3 to node N1 through relay drivers S3b and S4b. For example, the anode of the diode D1 may be connected to an output terminal of the relay driver S3b, and the cathode of the diode D1 may be connected to an input terminal of the relay driver S4b. In one embodiment, resistors R2 and R3 may be formed in a path formed between nodes N1 and N3 through relay drivers S3b and S4b.

[0045] In one embodiment, a display element LD1 may be connected between the nodes N1 and N3. In one embodiment, a resistor R1 may be further connected between the nodes N1 and N3. For example, the resistor R1 and the display element LD1 may be connected in series between the nodes N1 and N3. The display element LD1 may perform a display operation when a current flows from the node N3 to the node N1. In one embodiment, the display element LD1 may be a light emitting diode that performs a display operation by lighting up when a current flows. For example, a cathode of the light emitting diode LD1 may be connected to the node N1, and an anode of the light emitting diode LD1 may be connected to the node N3.

[0046] In one embodiment, a display element LD2 may be connected between nodes N2 and N4. In one embodiment, a resistor R4 may be further connected between nodes N2 and N4. For example, the resistor R4 and the display element LD2 may be connected in series between nodes N2 and N4. The display element LD2 may perform a display operation when a current flows from node N4 to node N2. In one embodiment, the display element LD2 may be a light emitting diode that performs a display operation by lighting up when a current flows. For example, a cathode of the light emitting diode LD2 may be connected to node N2, and an anode of the light emitting diode LD2 may be connected to node N4.

[0047] Next, the protective operation of the protective device shown in FIG. 2 will be described with reference to FIGS.

[0048] 3 and 5 are diagrams showing an example of the operation of a protection device according to an embodiment in a forward connection state, and FIGS. 4 and 6 are diagrams showing an example of the operation of a protection device according to an embodiment in a reverse connection state.

[0049] 3 and 4, when the switches S1 and S2 are turned off, the DC power source 20 can be connected to the input terminals of the protection device, i.e., the input terminals P1 and P2 of the switches S1 and S2. That is, when the switch S1 is switched to the second output terminal T12 (or node N2) and the switch S2 is switched to the second output terminal T22 (or node N4), the DC power source 20 can be connected to the input terminals P1 and P2 of the switches S1 and S2. When the switches S1 and S2 are turned off, no current is supplied to the relay drivers S3b and S4b, so the relays S3 and S4 are in the turned-off state.

[0050] 3, when the DC power supply 20 is connected in the positive direction, the positive wiring 21 of the DC power supply 20 is connected to the input terminal P1 of the switch S1, and the negative wiring 22 of the DC power supply 20 is connected to the input terminal P2 of the switch S2. In this case, no current flows through the display element LD2, so that the display element LD2 does not perform a display operation. For example, the light emitting diode LD2 does not light up.

[0051] 4, when the DC power supply 20 is connected in the reverse direction, the negative wiring 22 of the DC power supply 20 is connected to the input terminal P1 of the switch S1, and the positive wiring 21 of the DC power supply 20 is connected to the input terminal P2 of the switch S2. In this case, the current I1 flows from node N4 to node N2 through the display element LD2 due to the DC power supply 20 connected in the reverse direction. Since the current I1 flows to the display element LD2, the display element LD2 performs a display operation. For example, the current I1 flows to the light emitting diode LD2, and the light emitting diode LD2 lights up.

[0052] In this way, it is possible to distinguish whether the DC power source 20 is connected to the protection device in the forward direction or in the reverse direction depending on whether the display element LD2 displays anything. When the display element LD displays a reverse connection, the user can connect the protection device in the forward direction by connecting the wires 21 and 22 to the protection device in the opposite direction.

[0053] 5 and 6, when the switches S1 and S2 are turned on, the DC power supply 20 can be connected to the input terminals of the protection device, i.e., the input terminals P1 and P2 of the switches S1 and S2. That is, when the switch S1 is switched to the first output terminal (or node N1) and the switch S2 is switched to the second output terminal (or node N3), the DC power supply 20 can be connected to the input terminals P1 and P2 of the switches S1 and S2.

[0054] 5, when the DC power source 20 is connected in the positive direction, the positive wiring 21 of the DC power source 20 is connected to the input terminal P1 of the switch S1, and the negative wiring 22 of the DC power source 20 is connected to the input terminal P2 of the switch S2. Then, a current I2 flows from the node N1 to the node N3 through the resistor R2, the relay driver S3b, the diode D1, the relay driver S4b, and the resistor R3. The current I2 drives the relay drivers S3b and S4b, and the relay switches S3a and S4a, i.e., the relays S3 and S4, are turned on. Therefore, the power I3 can be normally supplied from the DC power source 20 to the product 23 through the switch S1, the relay S3, the relay S4, and the switch S2.

[0055] 6, when the DC power source 20 is connected in the reverse direction, the negative wiring 22 of the DC power source 20 is connected to the input terminal P1 of the switch S1, and the positive wiring 21 of the DC power source 20 is connected to the input terminal P2 of the switch S2. In this case, the current path from the node N1 to the node N3 through the relay drivers S3b and S4b is blocked by the diode D1. Since no current is supplied to the relay drivers S3b and S4b, the relay drivers S3b and S4b are not driven, and the relay switches S3a and S4a, i.e., the relays S3 and S4, are maintained in the turned-off state. Therefore, the protection device can block the reverse voltage of the DC power source 20 from being supplied to the product 23.

[0056] Meanwhile, a current I4 flows from node N3 to node N1 through display element LD1 due to the DC power supply 20 connected in the reverse direction. Since a current I3 flows through the display element LD1, the display element LD1 performs a display operation. For example, the current I3 flows through the light emitting diode LD1, and the light emitting diode LD1 lights up.

[0057] In this way, it is possible to distinguish whether the DC power source 20 is connected to the protection device in the forward direction or in the reverse direction depending on whether the display element LD1 displays anything. When the display element LD1 displays a reverse connection, the user can connect the protection device in the forward direction by connecting the wires 21 and 22 to the protection device in the opposite direction. Also, when the DC power source 20 is connected to the protection device in the reverse direction, the power supply from the DC power source 20 to the product 23 can be cut off.

[0058] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention. [Explanation of symbols]

[0059] 10 Direct current (DC) power supply 11 Positive Wiring 12 Negative Wiring 20 DC power supply 21 Positive wiring 22 Negative Wiring 23 Products 100 Battery Equipment 110 Battery 120 Battery Management System (BMS) 130 Protective devices

Claims

1. A protection device for an electronic device that receives power from a DC power source having positive and negative wiring, a first switch having an input terminal to which the positive wiring or the negative wiring is connected, a first output terminal connected to a first node, and a second output terminal connected to a second node; a second switch having an input terminal to which the positive wiring or the negative wiring is connected, a first output terminal connected to a third node, and a second output terminal connected to a fourth node; a first relay including a first relay switch having a first terminal connected to the first node and a second terminal connected to a positive input terminal of the electronic device, and a first driver for driving the first relay switch and having an input terminal connected to the first node; a second relay including a second relay switch having a first terminal connected to the negative input terminal of the electronic device and a second terminal connected to the third node; and a second driver for driving the second relay switch, the second driver having an input terminal connected to the output terminal of the first driver and an output terminal connected to the third node; Protective devices including:

2. 2. The protection device of claim 1, further comprising a diode that blocks current flow from the third node through the second driver and the first driver to the first node.

3. The protection device of claim 1 , further comprising a display element coupled between the first node and the third node, the display element performing a display operation when a current flows from the third node to the first node.

4. 4. The protection device of claim 3, wherein the indicator element comprises a light emitting diode that lights up when a current flows from the third node to the first node.

5. The protection device of claim 1 , further comprising a display element coupled between the second node and the fourth node, the display element performing a display operation when a current flows from the fourth node to the second node.

6. The protection device of claim 5 , wherein the indicator element comprises a light emitting diode that lights up when a current flows from the fourth node to the second node.

7. The protection device of claim 1 , wherein the electronic device comprises an electronic device for managing a battery.

8. A protection device for an electronic device that receives power from a DC power source having positive and negative wiring, a first switch having an input terminal to which the positive wiring or the negative wiring is connected, a first output terminal connected to a first node, and a second output terminal connected to a second node; a second switch having an input terminal to which the positive wiring or the negative wiring is connected, a first output terminal connected to a third node, and a second output terminal connected to a fourth node; a first relay coupled between the first node and a positive input terminal of the electronic device; a second relay connected between the third node and a negative input terminal of the electronic device; a display element that is connected between the second node and the fourth node, and performs a display operation when the negative wiring is connected to the input terminal of the first switch and the positive wiring is connected to the input terminal of the second switch in a state in which the first switch is switched to the second output terminal and the second switch is switched to the second output terminal; Protective devices including:

9. 9. The protection device of claim 8, wherein the indicator element comprises a light emitting diode that lights up when a current flows from the fourth node to the second node.

10. 9. The protection device of claim 8, wherein when the first switch is switched to the first output terminal and the second switch is switched to the first output terminal, the positive pole wiring is connected to the input terminal of the first switch and the negative pole wiring is connected to the input terminal of the second switch, and the first relay and the second relay are turned on.

11. 9. The protection device of claim 8, wherein when the first switch is switched to the first output terminal and the second switch is switched to the first output terminal, the negative pole wiring is connected to the input terminal of the first switch and the positive pole wiring is connected to the input terminal of the second switch, the first relay and the second relay are turned off.

12. The protection device of claim 8 , wherein the electronic device includes an electronic device for managing a battery.

13. A protection device for an electronic device that receives power from a DC power source having positive and negative wiring, a first switch having an input terminal to which the positive wiring or the negative wiring is connected, a first output terminal connected to a first node, and a second output terminal connected to a second node; a second switch having an input terminal to which the positive wiring or the negative wiring is connected, a first output terminal connected to a third node, and a second output terminal connected to a fourth node; a first relay coupled between the first node and a positive input terminal of the electronic device; a second relay connected between the third node and a negative input terminal of the electronic device; a display element connected between the first node and the third node, performing a display operation when the negative wiring is connected to an input terminal of the first switch and the positive wiring is connected to an input terminal of the second switch in a state in which the first switch is switched to the first output terminal and the second switch is switched to the first output terminal; Protective devices including:

14. 14. The protection device of claim 13, wherein the indicator element comprises a light emitting diode that illuminates when a current flows from the third node to the first node.

15. 14. The protection device of claim 13, wherein when the first switch is switched to the first output terminal and the second switch is switched to the first output terminal, the positive pole wiring is connected to the input terminal of the first switch and the negative pole wiring is connected to the input terminal of the second switch, and the first relay and the second relay are turned on.

16. 14. The protection device of claim 13, wherein when the first switch is switched to the first output terminal and the second switch is switched to the first output terminal, the negative pole wiring is connected to the input terminal of the first switch and the positive pole wiring is connected to the input terminal of the second switch, the first relay and the second relay are turned off.

17. 14. The protection device of claim 13, wherein the first relay and the second relay are turned off with the first switch switched to the second output terminal and the second switch switched to the second output terminal.

18. The protection device of claim 13 , wherein the electronic device includes an electronic device for managing a battery.

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