KR20170003565A - Battery pack, battery system, and discharging method - Google Patents

Abstract

Thereby appropriately discharging the internal current of the battery pack and improving the maintainability. The battery system includes a lithium ion battery 16, a main circuit connected in series with the lithium ion battery 16 and serving as a power supply path, and a main circuit connected in parallel with the lithium ion battery 16, A second protection circuit 62 for consuming electric power and a switching means for switching the lithium ion battery 16 and the main circuit and for connecting the lithium ion battery 16 and the second protection circuit 62 And a second IC 18 connected to the main circuit and the second protection circuit of each battery pack 200 and controlling input and output from the respective battery packs 200, 2 IC 18 notifies an abnormality of the battery pack when an output current or voltage is detected from any one protection circuit of the battery pack 200. [

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery pack, a battery system,

The present invention relates to a battery system including a battery pack and a plurality of battery packs. More particularly, the present invention relates to a battery pack, a battery system, and a discharging method capable of adequately discharging surplus current from the inside of the battery pack. This application claims priority based on Japanese Patent Application No. 2014-099714, filed May 13, 2014, which is incorporated herein by reference in its entirety.

Most of the secondary batteries that can be charged and used repeatedly are processed into battery packs and provided to the user. Particularly, in a lithium ion secondary battery having a high weight energy density, in order to secure the safety of users and electronic equipment, several protection circuits such as overcharge protection and over discharge protection are generally incorporated in the battery pack, It has a function to block the output of the pack.

This type of protection device has an effect of performing on / off (ON / OFF) of output by using a FET (Field Effect Transistor) switch incorporated in the battery pack to perform overcharge protection or over discharge protection operation of the battery pack . However, when the FET switch is short-circuited for some reason, an instantaneous large current flows due to a lightning surge or the like, or an output voltage abnormally decreases due to the life of the battery cell, or an excessive abnormal voltage is output , Battery packs or electronic devices must be protected from accidents such as ignition. Therefore, in order to safely shut off the output of the battery cell even in such an assumed abnormal state, a protection element including a fuse element having a function of cutting off the current path by an external signal is used.

As a protective element of a protection circuit suitable for such a lithium ion secondary battery, as described in Patent Document 1, a usable conductor is connected between a first electrode on a current path, a conductor layer connected to a heating element, and a second electrode, And the usable conductor on the current path is fused by the self-heating by the overcurrent or by the heating element provided inside the protective element. In such a protection device, the current path is blocked by collecting the soluble conductor in the molten liquid on the conductor layer connected to the heating element.

In the LED lighting apparatus, a short-circuit element is connected in parallel to each of the series-connected LED (Light Emitting Diode) elements, and a short-circuit element is short-circuited at a predetermined voltage in the event of an LED failure, (Patent Document 2). In the short-circuit element described in Patent Document 2, a plurality of elements constituted by placing an insulating barrier layer having a predetermined film thickness between the metals are connected in series.

Japanese Patent Application Laid-Open No. 2005-206220 Japanese Patent Application Laid-Open No. 2007-012381

In recent years, electric vehicles (EVs) and hybrid electric vehicles (HEVs) using batteries and motors are rapidly spreading. Lithium ion secondary batteries have been used as energy sources for HEVs and EVs because of their energy density and output characteristics. In automotive applications, high voltage and large current are required. As a result, a dedicated cell capable of withstanding a high voltage and a large current has been developed. However, due to a problem of manufacturing cost, in many cases, a plurality of battery cells are connected in series and in parallel to secure a required voltage current by using a general-purpose cell .

Further, a module in which a plurality of battery cells are connected in series is used as a battery pack, a plurality of battery packs are arranged in parallel to form a battery system, and components can be exchanged in units of battery packs, thereby improving the maintenance property.

However, in the above-described battery system, since the battery packs are arranged in parallel when one battery pack fails, the output current is lowered although there is no drop in the output voltage. Even if the failure of the battery can be detected due to the decrease in the output current, it is impossible to determine which battery pack has failed, which is a factor that hinders the improvement in the maintenance property.

The present invention solves the above-described problems and provides a battery pack, a battery system and a discharging method for securing the safety of a battery system by notifying an abnormality of the battery pack using a protection circuit of the battery pack and improving the maintenance property The purpose is to provide.

In order to solve the above problems, a battery pack according to the present invention is a battery pack comprising: a secondary battery; a main circuit connected in series with the secondary battery and serving as a charging / discharging path of the secondary battery; Switching means for disconnecting the secondary battery and the main circuit under predetermined conditions and for connecting the secondary battery and the protection circuit; and switching means for switching the output current for the protection circuit from an error signal And an error signal output means for outputting the error signal to the outside.

A battery system according to the present invention is a battery system comprising: a main circuit connected in series with a secondary battery and serving as a power supply path; a protection circuit connected in parallel with the secondary battery and consuming internal power under predetermined conditions; A plurality of battery packs having switching means for interrupting the secondary battery and the main circuit and for connecting the secondary battery and the protection circuit, and a plurality of battery cells connected to the main circuit and the protection circuit of each battery pack, And control means for judging an error of the battery pack when detecting a current output from any one of the protection circuits of the battery packs.

A discharging method according to the present invention is a discharging method of a battery pack, comprising: a main circuit which is connected in series with a secondary battery and which serves as a power supply path, and a secondary battery which are connected in parallel with the secondary battery, A secondary battery is connected to the protection circuit that consumes power, internal discharge is performed by the protection circuit, and at least a part of the output current to the protection circuit is output to the outside of the battery pack as an error signal.

According to the present invention, when an abnormality of the battery pack is detected, the protection circuit is switched to the protection circuit, and the current flowing in the protection circuit of the battery pack can be output as an error signal. By this error signal, And it is easy to specify the battery pack which outputs the error signal, and the maintenance of the battery pack can be improved.

1 is a block diagram illustrating a battery system.
2 is a block diagram illustrating a configuration of a battery pack.
3 is a block diagram illustrating the configuration of a battery pack.
4 is a circuit diagram illustrating the operation of the switching element.
5 is a circuit diagram illustrating the operation of the battery pack.
6 is a circuit diagram illustrating the operation of the battery pack.
7 is a circuit diagram illustrating the operation of the battery pack.

Hereinafter, a battery pack, a battery system and a discharging method to which the present invention is applied will be described in detail with reference to the drawings. It is needless to say that the present invention is not limited to the following embodiments, but can be modified in various ways within the scope not departing from the gist of the present invention. Also, the drawings are schematic, and the ratios of the dimensions and the like may be different from those of the real world. The specific dimensions and the like should be judged based on the following description. Needless to say, the drawings also include portions having different dimensional relationships or ratios with each other.

[Battery system]

Hereinafter, a battery system in which a plurality of modules of a lithium ion battery used in an EV or the like are arranged in parallel will be described as an example.

1, the battery system 100 includes a plurality of battery packs 200 and a control unit 300 connected to these battery packs 200 for controlling charge and discharge of each battery pack 200 And a notification unit 400 for indicating and notifying the battery pack 200 that outputs an error signal to be described later.

Each of the battery packs 200 is a module in which the lithium ion battery and the protection circuit are modularized. The battery pack 200 is configured to output an error signal to the control unit 300 in the event of a battery failure, have.

The control unit 300 is constituted by an IC circuit or the like and controls the charging of each battery pack 200 and the power supply from each battery pack 200 so that the electric current Is performed. The control unit 300 detects an abnormality in the battery pack 200 that has issued an error signal based on an error signal from the battery pack 200 to be described later and controls the battery pack 200 200).

The notifying unit 400 is connected to the control unit 300 and includes light emitting means and acoustic means and notifies the abnormality of the battery pack 200 by light emission or sound. The specific configuration of the notifying unit 400 is substantially the same as that of the notifying means provided in the battery pack 200 described later, and thus the description thereof will be omitted.

[Battery pack]

2, the battery pack 200 includes a negative terminal 11 and a positive terminal 12 which are input / output terminals, a first FET (Field Effect Transistor) 13 and a second FET 14, A first IC (Integrated Circuit) 15 for controlling the first FET 13 and the second FET 14, a lithium ion battery 16, a switching element 17 for switching between the main circuit and the protection circuit, A second IC 18 for controlling the switching element 17, an external output terminal 19, an LED (Light Emitting Diode) 20 and a heat generating resistor 21.

The negative terminal 11 and the positive terminal 12 are connected to the control unit 300 of the battery system 100 and form a main circuit (first circuit) for charging and discharging the lithium ion battery 16. [ The negative terminal 11 and the positive terminal 12 are an interface connected to the control unit 300 and a connector or the like together with the external output terminal 19.

The first FET 13 and the second FET 14 are transistor elements arranged in series with the lithium ion battery 16 on the main circuit. The first IC 15 is connected to the first FET 13 and the second FET 14 and the first FET 13 and the second FET 14 and the first IC 15, Circuit.

The first protection circuit is connected to an overheat detection sensor or the like (not shown) of the first IC 15 and judges whether or not the internal temperature of the battery pack 200 is equal to or higher than a predetermined value. The first FET 13 or the second FET 14 is driven to block the main circuit in order to protect the lithium ion battery 16. [

In addition, the first protection circuit is connected to a current monitor or the like (not shown) of the first IC 15 and judges whether or not the current value of the main circuit is equal to or larger than a predetermined value. In order to protect the lithium ion battery 16, the first FET 13 or the second FET 14 is driven to block the main circuit.

The lithium ion battery 16 is configured to have a desired voltage value by serially arranging a plurality of cells in a multistage manner. Here, since the lithium ion battery 16 has a higher energy density and higher electromotive force than a lead-acid battery or a nickel-metal hydride battery, it is suitable for use in an EV or the like.

The switching element 17 is arranged in series with the lithium ion battery 16 on the main circuit and the second IC 18 is connected to the switching element 17. [ Here, the switching element 17 constitutes switching means for switching between the main circuit and the second protection circuit.

Here, the second protection circuit is disposed in parallel with the lithium ion battery 16, and one end is connected to the switching element 17 and the other end is connected between the second FET 14 and the lithium ion battery 16 It is the bypass route. An external output terminal 19, an LED (Light Emitting Diode) 20 and a heat generating resistor 21 are arranged in series in the second protection circuit. The arrangement order is not particularly limited, but the external output terminal 19 is arranged in the immediate vicinity of the switching element 17.

The external output terminal 19 is a terminal connected to the outside of the battery pack 200 and outputs at least a part of the current output on the second protection circuit to the outside as an error signal. Specifically, the external output terminal 19 is connected to the control unit 300 of the battery system 100, and functions as one of the notification means for notifying the battery system 100 of an error of the battery pack 200.

The LED 20 is provided in an unshown external portion of the battery pack 200 and functions as a light emitting means that emits light when a current flows through the second protection circuit. Specifically, the LED 20 functions as a notification means for notifying an abnormality of the battery pack 200 to the outside. Further, various lamps can be used as the light emitting means, but LEDs which operate at low power and are inexpensive compared with other light emitting means are particularly preferable.

The LED 20 also functions as a part of the discharging means in the second protection circuit. That is, since the power consumption by the light emission is performed, the internal current of the battery pack 200 can be consumed, and the surplus power in the battery pack 200 can be consumed to protect the lithium ion battery 16. [

The heat generating resistor 21 functions as a part of a discharging means which consumes a current flowing in the second protection circuit by heat generation. The heat generating resistor 21 can consume the internal current of the battery pack 200 and consume excess power in the battery pack 200 to protect the lithium ion battery 16. [

Although the external output terminal 19, the LED 20 and the heat generating resistor 21 are arranged in series on the second protection circuit in parallel with the lithium ion battery 16, Or may be arranged in parallel on the second protection circuit. In addition, a notification function for notifying an error of the battery pack 200 and a disposition change in a range capable of maintaining a discharging function consuming surplus electric power in the battery pack 200 Needless to say.

Next, switching of the circuit by the second IC 18 will be described. The battery pack 200 is connected to the overheat detection sensor 22 and the impact sensor 23 as shown in FIG. The second IC 18 is connected to the overheat detecting sensor 22 and the impact sensor 23, respectively.

As the overheat detecting sensor 22, for example, a PTC (Positive Temperature Coefficient) thermistor may be used. The overheat detecting sensor 22 is preferably installed in each battery pack 200 in order to detect overheating in the battery pack 200. The overheat detecting sensor 22 may be disposed outside the battery pack 200, .

The impact sensor 23 can use, for example, an acceleration sensor or the like. When the acceleration sensor is used, it is possible to detect that the EV has an impact such as a collision when the acceleration of the battery pack 200 becomes equal to or larger than a predetermined value. The impact sensor 23 may be embedded in the battery pack 200 to detect a shock in the battery pack 200. The impact sensor 23 may be disposed outside the battery pack 200, have.

Alternatively, the control unit 300 may be incorporated in a part of the entire EV, or may be obtained as a CAN (Controller Area Network) signal from a central control unit such as an ECU (Engine Control Unit) The control unit 300 outputs the acceleration information obtained as the CAN signal to each battery pack 200, thereby reducing the number of sensors as the whole EV.

The second IC 18 determines whether or not the internal temperature of the battery pack 200 is equal to or higher than a predetermined value by the overheat detecting sensor 22. When the internal temperature of the battery pack 200 is determined to be higher than the predetermined value, 16, the main circuit is cut off and the switching element 17 is controlled to switch to the second protection circuit.

The second IC 18 determines that a predetermined impact has been applied to the battery pack 200 by the impact sensor 23. For example, when it is determined that the acceleration is equal to or larger than the predetermined value, In order to protect the lithium ion battery 16 in the generated state, the main circuit is shut off and the switching element 17 is controlled to switch to the second protection circuit.

In the above description, the second IC 18 is connected to the heat detection sensor 22 and the impact sensor 23 to obtain information from these sensors. However, the second IC 18 may be connected to other sensors or the like to protect the battery pack 200 You can also enter the information you need. At least one sensor information is input to the second IC 18. Also, the second IC 18 does not hinder the configuration for timely controlling the switching element 17 by the timer logic.

Further, although the first IC 15 and the second IC 18 are described as separate components, they may be constituted by one IC. In the case of a single IC, the number of components can be reduced. On the other hand, when the respective ICs are provided separately, the first protection circuit and the second protection circuit can be operated independently, and the protection function can be provided with redundancy, resulting in a safer battery pack.

[Switching element]

The switching element 17 will be described in detail. As shown in Figs. 2 and 4, the switching element 17 is a four-terminal element composed of a first terminal a, a second terminal b, a third terminal c, and a fourth terminal d. The switching element 17 has a heat generating resistor 31, a usable conductor 32, and a switch 33, which are plane-mounted on an insulating substrate (not shown).

The switching element 17 has a first terminal a connected to the positive terminal of the lithium ion battery 16, a second terminal b connected to the positive terminal 12 of the battery pack 200, Is connected to the IC 18, and the fourth terminal d is connected to the protection circuit.

One end of the heating resistor 31, one end of the usable conductor 32 and one end of the switch 33 are connected to the first terminal a of the switching element 17, And the other end of the usable conductor 32 is connected. The other end of the switch 33 is connected to the fourth terminal d of the switching element 17, and the other end of the heating resistor 31 is connected to the third terminal c.

[Switch element circuit]

The switching element 17 has a circuit configuration as shown in Figs. 4A and 4B. That is, the first terminal a and the second terminal b of the switching element 17 are normally connected, that is, the first terminal a and the third terminal d are insulated when normal.

The switching element 17 constitutes the switch 33 which is short-circuited by the molten conductor when the usable conductor 32 is melted by the heat of the heat generating resistor 31 (Fig. 4 (B)). The first terminal a and the fourth terminal d constitute both terminals of the switch 33. The usable conductor 32 is connected to the second electrode b.

The switching element 17 is built in the battery pack 200 so that the first terminal a and the fourth terminal d on both sides of the switch 33 are connected to the main circuit of the battery pack 200 And a bypass current path (second protection circuit) for bypassing the battery pack 200 by shorting the switch 20 when an abnormality occurs in the battery pack 200 is formed.

Specifically, when an abnormality occurs in the lithium ion battery 16 or other electronic parts connected in parallel, power is supplied from the third terminal c side of the heat generating resistor 31 to the heat generating resistor 31 ) Is energized to generate heat. When the soluble conductor 32 is melted by this heat, the molten conductor is agglomerated on the switch 33 as shown in Fig. 4 (B). As a result, the first electrode a and the fourth electrode d are short-circuited. That is, the switching element 17 is short-circuited between both terminals of the switch 33 (Fig. 4 (B)).

Further, in the energization to the heat generating resistor 31, since the main circuit is cut off by the fuse of the usable conductor 32, and the current flows to the second protection circuit, it is detected that the supply of the current from the third terminal c is stopped . Also, this control can be controlled by the second IC 18.

The current output to the second protection circuit by the switching element 17 is output to the outside of the battery pack 200 as an error signal to be described later and used as a trigger to notify the abnormality of the battery pack 200. [

Further, the switching element 17 is not limited to the above-described structure, and may be configured to selectively switch between the main circuit and the second protection circuit as appropriate. For example, a method using two FETs described in the first protection circuit may be employed.

[Circuit configuration of battery pack]

Next, the circuit configuration of the battery pack 200 incorporating the switching element 17 will be described. 5, the circuit configuration of the battery pack 200 in which the lithium ion battery 16 is incorporated includes a lithium ion battery 16 and the operation of the first FET 13 and the second FET 14 A short circuit element 17, a current control element 41 and a second IC 18 for controlling the operation of the shorting element 17, and an LED 20 on the protection circuit. The negative terminal 12, the ground terminal 51, the control terminals 52 and 53, and the external terminal 19 of the battery pack 200 via the positive terminal 11, the negative terminal 12, the ground terminal 51, And is connected to the control unit 300.

The battery pack 200 includes a first protection circuit 61 for controlling the charging and discharging of the lithium ion battery 16 and a second protection circuit 61 for detecting the voltage of the lithium ion battery 16, A detection circuit for outputting an abnormal signal to the current control element 41 for controlling the operation and a second protection circuit 62 connected to the lithium ion battery 16 by the switching element 17. [

The first protection circuit 61 includes a first FET 13 and a second FET 14 connected in series to the current path from the control unit 300 to the lithium ion battery 16, And a first IC (15) for controlling the operation of the second FET (14).

In the battery pack 200, the switching element 17 is connected in series with the lithium ion battery 16, and the second terminal b of the switching element 17 is connected to the charge / discharge path of the lithium ion battery 16 , And the first terminal a is connected to the positive electrode of the lithium ion battery 16, thereby forming a main circuit. In the battery pack 200, the heat generating resistor 31 of the switching element 17 is connected to the current control element 41 via the third terminal c.

The first protection circuit 61 is connected to the lithium ion battery 16 via the second IC 18 so that the voltage value of each battery cell is detected to detect the voltage of the lithium ion battery 16, The first IC 15 outputs an abnormal signal to the first FET 13 and the second FET 14 when the overcurrent or overdischarge voltage is reached. Also, the first IC 15 may have a circuit configuration for directly detecting the voltage value of the lithium ion battery 16.

The current control element 41 is, for example, a FET. When the voltage value of the lithium ion battery 16 exceeds a predetermined overdischarge or overcharge state by the detection signal output from the second IC 18 The switch element operates so that a current flows in the heat generating resistor 31. [ The current control element 41 operates the switching element 17 so that the available conductor 32 is blown by flowing a current through the heat generating resistor 31 and the switch 33 is turned on so that the lithium ion battery 16) and the main circuit and connects the second protection circuit.

The current control device 41 controls the charge and discharge current path of the lithium ion battery 16 under the control of the second IC 18 regardless of the switch operation of the first FET 13 and the second FET 14 The switch 33 of the switching element 17 is short-circuited and the main circuit is bypassed to control the second protection circuit 62 to be formed.

Since the switch 33 of the switching element 17 is not short-circuited as shown in Fig. 5 at the normal time in such a battery pack 200, the current flows through the usable conductor 32 to the lithium ion battery 16 .

An abnormal signal is outputted from the second IC 18 to the current control element 41 and the third terminal c of the switching element 17 is connected to the ground. As a result, as shown in Fig. 6, current flows through the heat generating resistor 31 of the switching element 17, and the heat generating resistor 31 generates heat.

As shown in Fig. 7, the switching element 17 blocks the first terminal a and the second terminal b by heating and melting the usable conductor 32 by the heat generating resistor 31. As shown in Fig. As a result, as shown in Fig. 7, the lithium ion battery 16 having an abnormal battery cell can be cut off from the charge / discharge current path as a main circuit. After the fusible conductor 32 is fused, the current control element 41 is caused to operate by the control of the second IC 18, so that the power supply to the heat generating resistor 31 is stopped by preventing the current from flowing.

Subsequently, the switch 33 of the switching element 17 is connected to the battery pack 200, and the current of the lithium ion battery 16 flows to the second protection circuit 62. Thus, by turning on the LED 20 of the second protection circuit 62, it is possible to notify the abnormality of the battery pack 200, and the internal resistance of the heat generating resistor 21 can be discharged.

Here, the battery pack 200 is connected to the second protection circuit 62 with the external terminal 19, and at least a part of the current flowing through the second protection circuit 62 is supplied as an error signal to the control unit 300 . The control unit 300 controls to stop the charging of the battery pack 200 that receives the error signal and notifies the abnormality of the battery pack 200 by the notifying unit 400. [

Further, the control unit 300 may monitor the error signal as a current value or as a voltage value. That is, the current value of the current outputted from the external terminal 19 may be monitored, or the voltage value between the negative terminal 11 and the external terminal 19 may be monitored. The control unit 300 determines that an error signal is received when the monitored current value or voltage value is equal to or greater than a predetermined value. It is preferable that the predetermined value is appropriately set to a value excluding noise and the like.

The battery system 100 including a plurality of such battery packs 200 stops charging and discharging the battery packs 200 even when an error occurs in one battery pack 200, 200). ≪ / RTI >

As described above, in the battery system 100 according to the embodiment of the present invention, when the battery pack 200 satisfies a predetermined condition, it can emit an internal current and issue an error signal to the outside, Therefore, the abnormality of each battery pack 200 can be individually detected, and the maintenance performance such as replacement of the battery pack 200 can be improved.

In the battery system 100 according to the embodiment of the present invention, the failed battery pack 200 can be visually recognized by the LED 20, and an error signal is also output from the individual battery pack 200 It becomes easy to identify the fault location. As a result, a remarkable effect can be obtained in a device in which a plurality of battery packs 200, such as EVs, are mounted and the replacement of the battery packs 200 is required.

11: Negative terminal
12: Plus terminal
13: first FET
14: second FET
15: 1st IC
16: Lithium-ion battery
17: Switching element
18: Second IC
19: External terminal
20: LED
21: Heating resistor
22: Overheat detection sensor
23: Shock sensor
31: heating resistor
32: available conductor
33: Switch
41: current control element
51: Ground terminal
52: Control terminal
53: Control terminal
61: first protection circuit
62: Second protection circuit
100: Battery system
200: Battery pack
300: Control unit
400: Notification section

Claims (23)

A secondary battery,
A main circuit connected in series with the secondary battery and serving as a charging / discharging path of the secondary battery,
A protection circuit connected in parallel with the secondary battery and consuming electric power of the secondary battery under a predetermined condition,
Switching means for disconnecting the secondary battery and the main circuit and connecting the secondary battery and the protection circuit under the predetermined condition,
And an error signal output means for externally outputting an output current to the protection circuit as an error signal. The semiconductor device according to claim 1, further comprising an external terminal on the protection circuit,
And outputs a current or voltage on the protection circuit as an error signal to the outside via the external terminal. The light emitting device according to claim 1 or 2, further comprising light emitting means on the protection circuit,
And an error notification is performed by the light emission of the light emitting means. 3. The apparatus according to claim 1 or 2, further comprising acoustic means on the protection circuit,
And an error notification is performed by an acoustic output by the acoustic means. 4. The apparatus according to claim 3, further comprising acoustic means on the protection circuit,
And an error notification is performed by an acoustic output by the acoustic means. The apparatus according to claim 1 or 2, further comprising an overheat detecting sensor for detecting a temperature rise,
Wherein the switching means interrupts the secondary battery and the main circuit based on detection information of the overheat detection sensor and connects the secondary battery and the protection circuit. The apparatus according to claim 3, further comprising an overheat detecting sensor for detecting a temperature rise,
Wherein the switching means interrupts the secondary battery and the main circuit based on detection information of the overheat detection sensor and connects the secondary battery and the protection circuit. The apparatus according to claim 4, further comprising an overheat detection sensor for detecting a temperature rise,
Wherein the switching means interrupts the secondary battery and the main circuit based on detection information of the overheat detection sensor and connects the secondary battery and the protection circuit. The apparatus according to claim 5, further comprising an overheat detecting sensor for detecting a temperature rise,
Wherein the switching means interrupts the secondary battery and the main circuit based on detection information of the overheat detection sensor and connects the secondary battery and the protection circuit. 3. The apparatus according to claim 1 or 2, further comprising an impact sensor for detecting an impact,
Wherein the switching means interrupts the secondary battery and the main circuit based on detection information of the impact sensor and connects the secondary battery and the protection circuit. 4. The apparatus according to claim 3, further comprising an impact sensor for detecting an impact,
Wherein the switching means interrupts the secondary battery and the main circuit based on detection information of the impact sensor and connects the secondary battery and the protection circuit. 5. The apparatus according to claim 4, further comprising an impact sensor for detecting an impact,
Wherein the switching means interrupts the secondary battery and the main circuit based on detection information of the impact sensor and connects the secondary battery and the protection circuit. The apparatus according to claim 5, further comprising an impact sensor for detecting an impact,
Wherein the switching means interrupts the secondary battery and the main circuit based on detection information of the impact sensor and connects the secondary battery and the protection circuit. 7. The apparatus according to claim 6, further comprising an impact sensor for detecting an impact,
Wherein the switching means interrupts the secondary battery and the main circuit based on detection information of the impact sensor and connects the secondary battery and the protection circuit. 8. The apparatus according to claim 7, further comprising an impact sensor for detecting an impact,
Wherein the switching means interrupts the secondary battery and the main circuit based on detection information of the impact sensor and connects the secondary battery and the protection circuit. The apparatus according to claim 8, further comprising an impact sensor for detecting an impact,
Wherein the switching means interrupts the secondary battery and the main circuit based on detection information of the impact sensor and connects the secondary battery and the protection circuit. 10. The apparatus according to claim 9, further comprising an impact sensor for detecting an impact,
Wherein the switching means interrupts the secondary battery and the main circuit based on detection information of the impact sensor and connects the secondary battery and the protection circuit. A secondary battery,
A main circuit connected in series with the secondary battery and serving as a power supply path,
A protection circuit connected in parallel with the secondary battery and consuming internal power under predetermined conditions,
A plurality of battery packs having a switching means for disconnecting the secondary battery and the main circuit and for connecting the secondary battery and the protection circuit,
And control means connected to the main circuit and the protection circuit of each of the battery packs and controlling input and output from the battery packs,
Wherein the control unit determines an error of the battery pack when detecting a current or voltage output from any one of the protection circuits of the battery pack. 19. The battery system according to claim 18, wherein the control means stops power supply to the battery pack determined to be an error. 20. The display device according to claim 18 or 19, further comprising a light emitting means,
And an error notification is performed by the light emission of the light emitting means. 20. The apparatus according to claim 18 or 19, further comprising acoustic means,
And an error notification is performed by an acoustic output by the acoustic means. 21. The apparatus of claim 20, further comprising acoustic means,
And an error notification is performed by an acoustic output by the acoustic means. A method of discharging a battery pack
A main circuit connected in series with the secondary battery and serving as a power supply path,
A protection circuit connected in parallel to the secondary battery and consuming internal power under predetermined conditions,
Wherein the internal circuit is configured to perform internal discharge by the protection circuit and to output at least a part of the output current to the protection circuit as an error signal to the outside of the battery pack.

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