JP2008245400A - Battery pack - Google Patents

Abstract

To improve the safety of a battery pack.
Fuses 24 and 25 and FETs 12 and 13 are interposed in series in a charging / discharging path 11 to an assembled battery 14, and a normal overcharge, overvoltage, overcurrent, overtemperature, and the like are first determined as abnormal by a control IC 18. The protection operation is performed such that the FETs 12 and 13 can be restored by turning off the FETs 12 and 13. When the protection operation expires, the double protection IC 23 turns on the FET 27 and energizes the heating resistor 26. In the battery pack 1 in which the unrecoverable protection operation is performed by blowing the fuses 24, 25, a diode 51 is provided in parallel with the fuses 24, 25 so as to be forward when discharging. Even if blown, the load device 2 can consume power, and the stored charge of the assembled battery 14 is released. Therefore, safety can be remarkably improved especially when the operation becomes impossible due to the protection operation against overcharge.
[Selection] Figure 1

Description

  The present invention relates to a safety measure for a battery pack, and in particular, protective means are interposed in series in a charging / discharging path to a secondary battery, and when a serious abnormality occurs, the protective means is shut off so that the protective operation cannot be restored. It is related with what is implemented suitably for the battery pack in which is performed.

Typical conventional techniques for performing the above-described protection operation are proposed in Patent Document 1 and Patent Document 2. According to the prior art, the PTC element and the thermal fuse are interposed in series in the charging / discharging path to the secondary battery, and the PTC element can first recover by limiting the current against a temperature rise due to a short circuit or the like. If the current cannot be limited even after that, the thermal fuse is blown and the protective operation is performed so that it cannot be restored. In Patent Document 2, the thermal fuse is blown by a heating resistor provided in parallel with the PTC element.
JP 2003-51304 A JP 2003-7285 A

  However, in the above-described conventional technology, even after the recovery cannot be performed by the double protection operation, the charge accumulated in the secondary battery is left as it is, particularly after overcharging, which is not preferable for safety. .

  An object of the present invention is to provide a battery pack capable of improving safety.

  The battery pack of the present invention includes a secondary battery, a protection unit that realizes a protection operation that disables subsequent use by blocking a charge / discharge path to the secondary battery, and a protection operation of the protection unit And discharge means for releasing the charge of the secondary battery.

  According to the above configuration, the protective means such as a fuse is interposed in series in the charge / discharge path to the secondary battery, and the protective means is shut off for safety against abnormalities such as overcharge. In the battery pack that performs the unrecoverable protection operation that cannot be used thereafter, the discharge means is provided, and when the protection means is operated, the discharge means is connected to the secondary battery. To release the charge. The protection means such as the fuse may be one that autonomously shuts off due to overtemperature or the like, or other means such that the control means heats the heating resistor according to the detection result to the abnormality detection means, It may be blocked by means.

  Therefore, the safety can be remarkably improved particularly when the secondary battery becomes unusable due to an overcharge protection operation in which a charge close to full charge is accumulated.

  Further, the battery pack of the present invention is interposed in series in the charging / discharging path to the secondary battery, and among the control element for controlling charging / discharging, the terminal voltage, the charging / discharging current and the temperature of the secondary battery, A detection unit that detects at least one and a detection result of the detection unit are compared with a predetermined first threshold value, and when it is determined to be abnormal, a protection operation is performed so that the control element can be restored by shutting off the control element. The control means and the detection result of the detection means are compared with a predetermined second threshold value that is higher than the first threshold value. And a second control means for performing the protective operation.

  According to the above configuration, normal overcharge, overvoltage, overcurrent, overtemperature, etc. are recovered by first judging the abnormality by the first control means and shutting off the control element that controls charge / discharge. When the protection operation is performed, and the protection operation expires, the second control unit performs an abnormality determination with a larger threshold value, and the protection operation that cannot be restored is performed by blocking the protection unit.

  Therefore, while ensuring the safety, the double protection operation does not suddenly disable the use, so the convenience can be improved.

  Furthermore, in the battery pack of the present invention, the protection means is a fuse interposed in a charging / discharging path to the secondary battery, and the discharging means is connected in parallel with the fuse and forwards during discharging. The diode is a bias.

  According to the above configuration, when the fuse is blown (broken) by the protection operation, the diode can be discharged but not discharged by the diode provided in parallel with the fuse.

  Therefore, the secondary battery can be discharged due to power consumption in the load device.

  In the battery pack of the present invention, the protection means includes, in the fuse, a heating resistor that can blow the fuse, and a switch connected in series with the heating resistor between the terminals of the secondary battery. In addition, when the second control means determines that there is an abnormality, the second control means conducts the switch and requests a predetermined amount of power from the load device.

  According to the above configuration, the second control means for detecting the abnormality and performing the protection operation when discharging the charge of the secondary battery due to the power consumption in the load device as described above is a protection that blows the fuse. Along with the operation, the load device is requested to have an appropriate power consumption capable of releasing the accumulated charge of the secondary battery in a predetermined period to the extent that the battery pack is not overheated by communication.

  Therefore, the secondary battery can be discharged due to power consumption in the load device as described above while maintaining an appropriate state.

  Furthermore, in the battery pack of the present invention, the protection means includes a fuse interposed in a charge / discharge path to the secondary battery, a heat generating resistor capable of blowing the fuse, and a terminal of the secondary battery. A switch that is connected in series with the heating resistor and is turned on by the second control means when it is determined to be abnormal, and the discharge means is connected between the terminals of the secondary battery. And a short-circuit resistance that allows a weak short-circuit current to pass therethrough.

  According to the above configuration, when it is determined that there is an abnormality from the detection result of the detection means, the second control means conducts the switch and energizes the heat generating resistor, thereby causing the fuse to blow and in series with the switch. Due to the short-circuit resistance provided, the terminals of the secondary battery are gently (soft) short-circuited, and a weak short-circuit current that does not overheat flows.

  Therefore, the secondary battery can be discharged due to power consumption at the short-circuit resistor.

  The battery pack of the present invention is characterized in that the fuse, the heating resistor, and the short-circuit resistor are packaged integrally.

  According to the above configuration, the structure of the fuse and the heat generation resistor (the amount of heat generated by the heat generation resistor required for the fuse to melt, such as the positional relationship and contact state) is made constant, and stable operation is achieved, and the short circuit resistance In other words, the number of terminals that are exposed to the outside becomes 3 terminals by sharing the terminals, and the assembly of the battery pack can be simplified.

  Furthermore, in the battery pack of the present invention, the discharging means is composed of a load resistance connected to the second control means, and the control output from the second control means to the protection means is also applied to the load resistance. It is characterized by giving.

  According to the above configuration, in relation to the second control means, a load resistance to which a control output to the protection means is commonly provided is provided as the discharge means, and abnormality is determined by the second control means, When the double protection operation is performed, the load resistance is also energized, so that the stored charge of the secondary battery is discharged by the power consumption.

  Therefore, the stored charge of the secondary battery can be discharged.

  Further, in the battery pack of the present invention, the discharging means includes the first control means, and the second control means shuts off the protection means and keeps the first control means operating. And

  According to the above configuration, when the first control unit performs the recoverable protection operation, the first control unit pauses a certain amount of operation until the abnormal state is resolved. When an abnormality is determined by the control means, the above-described double protection operation is performed, and the first control means is continuously operated, so that the stored charge of the secondary battery is discharged with the power consumption.

  Therefore, the power stored in the secondary battery can be discharged little by little without separately providing special discharge means.

  In the battery pack of the present invention, as described above, a protective means such as a fuse is interposed in series in the charging / discharging path to the secondary battery, and the protection is provided for safety against abnormalities such as overcharge. In a battery pack that performs an irreversible protection operation that makes subsequent use impossible by shutting off the means, a discharge means is provided, and when the protection means operates (is), the discharge is performed in conjunction with the discharge means. Means releases the charge of the secondary battery.

  Therefore, the safety can be remarkably improved particularly when the secondary battery becomes unusable due to an overcharge protection operation in which a charge close to full charge is accumulated.

[Embodiment 1]
FIG. 1 is a block diagram showing an electrical configuration of the electronic device system according to the first embodiment of the present invention. This electronic device system includes a load device 2 that incorporates a battery pack 1 and a charger 3 that supplies power to the load device 2 and charges the battery pack 1. The battery pack 1 may be provided separately from the load device 2. The battery pack 1, the load device 2, and the charger 3 are provided with DC high-side terminals T11, T21, and T31 that perform power supply, terminals T12, T22, and T32 for communication signals, and a GND terminal T13 for power supply and communication signals. They are connected to each other by T23 and T33.

  In the battery pack 1, fuses 24 and 25 are interposed in the charge / discharge path 11 that is a DC high-side power line extending from the terminal T <b> 11, and the overcharge protection and the overdischarge protection are mutually connected. FETs 12 and 13 having different conductivity types are interposed between the charge / discharge paths 11 and the high-side terminals of the assembled battery 14. The low-side terminal of the assembled battery 14 is connected to the GND terminal T13 via a charging / discharging path 15 that is a DC low-side power line. In the charging / discharging path 15, charging current and discharging current are set to voltage values. A current detection resistor 16 for conversion is interposed.

  The assembled battery 14 is formed by appropriately connecting one or a plurality of secondary battery cells in series and parallel. The temperature of the assembled battery 14 is detected by a temperature sensor 17 and input to an analog / digital converter 19 in a control IC 18 serving as first control means.

  The terminal voltage of each cell is selectively taken out by an ASIC (Application Specific Integrated Circuit) 29 and input to the analog / digital converter 19 in the control IC 18 as will be described later. The selection of the cell is performed by the control unit 21 in the control IC 18 via the communication unit 20. Furthermore, the current value detected by the current detection resistor 16 is also taken out by the ASIC 29 and input to the analog / digital converter 19 in the control IC 18.

  The control unit 21 includes a microcomputer and its peripheral circuits, and the voltage of a charging current that requests an output from the charger 3 in response to each input value via the analog / digital converter 19. The value and the current value are calculated and transmitted from the communication unit 22 to the charger 3 via the terminals T12 and T32; T13 and T33. The control unit 21 calculates the remaining amount of the assembled battery 14 from each input value via the analog / digital converter 19 and transmits it to the load device 2 via the terminals T12, T22; T13, T23. Furthermore, the control unit 21 detects an abnormality outside the battery pack 1 such as a short circuit between the terminals T11 and T13 or an abnormal current from the charger 3 from each input value via the analog / digital converter 19. Then, when an abnormal temperature rise of the assembled battery 14 is detected by the temperature sensor 17, a protective operation such as blocking the FETs 12 and 13 is performed.

  On the other hand, the terminal voltage of each cell of the assembled battery 14 is also taken into the double protection IC 23 which is the second control means, and the detection result is set to be equal to or higher than the abnormality determination threshold in the control unit 21. When the threshold value of the double protection IC 23 is exceeded, the FET 27 is turned on. The FET 27 is provided with respect to the fuses 24, 25 interposed in series in the charge / discharge path 11, and the connection point of the fuses 24, 25 is grounded via the heating resistor 26 and the FET 27. Therefore, when the double protection IC 23 turns on the FET 27, the fuses 24 and 25 are blown by the heat generated by the heating resistor 26. As a result, in the case of a serious abnormality that cannot cope with overcharge due to an abnormality of the control IC 18, the fuses 24 and 25 are blown, thereby realizing a double protection operation.

  For example, the charging end voltage targeted by the control unit 21 is 4.2 V per cell, and the threshold voltage of overvoltage during normal charging / discharging when the FETs 12 and 13 are turned off is 4.3 V per cell. The threshold voltage at which the heavy protection IC 23 blows the fuses 24 and 25 is 4.4 V per cell, for example. Therefore, the battery pack 1 can be recovered when it is overcharged during normal use, and the battery pack 1 cannot be reused when overvoltage occurs during an abnormality, thereby improving safety. In this way, the double protection operation prevents the sudden use of the device, and the convenience can be improved while ensuring safety.

  On the other hand, in the charger 3, the request is received by the communication unit 32 of the control IC 30, and the charging control unit 31 controls the charging current supply circuit 33 to supply the charging current with the voltage value and the current value. . The charging current supply circuit 33 is composed of an AC-DC converter, a DC-DC converter, etc., and converts an input voltage into a voltage value and a current value instructed by the charging control unit 31, and the terminals T31, T11; T33, It supplies to the charging / discharging paths 11 and 15 via T13. In the load device 2, the control unit 36 of the control IC 35 controls the load circuit 37, and the remaining amount or the like is received by the communication unit 38 to appropriately calculate the operable time.

  FIG. 2 is a block diagram for explaining the configuration in the battery pack 1 in more detail. In the example of FIG. 2, the assembled battery 14 includes four cells E1 to E4. A terminal T4 is connected to the charge / discharge path 11 on the high side from the terminal T11, and the low side from the terminal T13. The GND terminal T0 is connected to the charging / discharging path 15 of FIG. The four cells E1 to E4 are connected in series between the terminals T0 to T4, and each of the cells E1 to E4 may be composed of a plurality of cells connected in parallel to each other. And the connection point of each cell E1-E4 is connected to terminal T1-T3 used as an intermediate | middle tap.

  On the other hand, as shown in FIG. 3, connection lines L0 to L4 are connected to the terminals T0 to T4. In the ASIC 29 and the double protection IC 23, the terminals T1 to T4 except for the GND terminal T0. The voltages Vin1 to Vin4 are taken in from the terminals T30 to T34; T40 to T44 via the input resistors R11 to R14 and the input resistors R21 to R24, respectively, so as not to affect the mutual voltage detection. And between each terminal T30-T34; T40-T44, the capacitor | condenser C11-C14; C21-C24 for noise removal may be provided as needed. These capacitors C11 to C14; C21 to C24 may be provided not between the terminals T30 to T34; T40 to T44 but between the terminals T31 to T34; T41 to T44 and GND.

  The temperature sensor 17 is composed of a thermistor and the like. One end of the temperature sensor 17 is biased with a predetermined voltage V0 and the other end is ON / OFF driven by a control IC 18 from a switch 28 through the current detection resistor 16 to charge / discharge the low side. The voltage at the connection point with the switch 28 connected to the path 15 is taken into the analog / digital converter 19 of the control IC 18.

  FIG. 3 is a block diagram showing a configuration example of the ASIC 29. The terminals T30 to T34 are selectively connected via the input switching unit 41 to the analog / digital converter 19 of the control IC 18 for performing voltage measurement. The input switching unit 41 includes switches S0L; S1L, S1H; S2L, S2H; S3L, S3H; S4H; STL, STH.

  The switches S0L; S1L, S1H; S2L, S2H; S3L, S3H; S4H have one end connected to the terminals T30 to T34 and the other end connected to the high side input end 19H or the low side of the analog / digital converter 19. Connected to the input terminal 19L. One end of each of the switches STL and STH is connected to each terminal of the current detection resistor 16, and the other end is connected to a high side input terminal 19H and a low side input terminal 19L of the analog / digital converter 19, respectively. The switches S0L; S1L, S1H; S2L, S2H; S3L, S3H; S4H; STL, STH are selectively driven ON / OFF by the cell selector 42.

  Therefore, for example, by turning on the switches STL and STH and turning off the switches S0L; S1L, S1H; S2L, S2H; S3L, S3H; S4H, the analog / digital converter 19 Therefore, the charge / discharge current of each of the cells E1 to E4 can be detected. Further, for example, by turning on the switches S0L and S4H and turning off the switches S1L and S1H; S2L and S2H; S3L and S3H; S5L and S5H, the analog / digital converter 19 is charged or applied to the entire assembled battery 14 or The discharge voltage can be detected.

  The switching signals of the switches S0L; S1L, S1H; S2L, S2H; S3L, S3H; S4H; STL, STH are generated by the switching control unit 211 in the control unit 21 on the control IC 18 side, and are transmitted from the communication unit 20 to the ASIC 29 side. Is provided to the cell selection unit 42 via the communication unit 43. Then, from the detection result obtained by the analog / digital converter 19, the charge / discharge control unit 210 in the control unit 21 requests the charger 3 for the charging voltage and current as described above. The remaining amount calculation is performed, and the abnormality detection unit 212 detects an abnormality and performs a protection operation.

  The double protection IC 23 compares the voltages Vin1 to Vin4 between the input terminals T40 to T44 with the reference voltages Vref21 to Vref24 from the reference voltage sources B1 to B4 in the comparators A1 to A4, respectively. When the threshold voltage is, for example, 4.4 V or higher, a high level is output and the FET 27 is turned on. In contrast, overcharge determination threshold voltages Vref11 to Vref14 in the abnormality detection unit 212 of the control IC 18 are, for example, 4.3V.

  In the electronic device system configured as described above, it should be noted that, in the present embodiment, in the battery pack 1, when the double protection IC 23 performs a non-recoverable protection operation that makes subsequent use impossible, In conjunction with this, a diode 51 for discharging the charge of the assembled battery 14 is provided. The diode 51 as the discharge means is connected in parallel with the fuses 24 and 25 as the protection means in the high-side discharge path 11 and is provided with a forward bias at the time of discharge. Therefore, when the double protection IC 23 turns on the FET 27 and heats the heating resistor 26 to blow the fuses 24 and 25, charging is impossible but discharging is possible. The battery 14 can be discharged.

  With this configuration, safety can be significantly improved particularly when the battery pack 14 becomes unusable due to an overcharge protection operation in which a charge close to full charge is accumulated. Preferably, as shown by a broken line in FIG. 1, the protection operation by the double protection IC 23 is input to the charge / discharge control unit 210 in the control unit 21, and when the double protection operation is performed, the charge / discharge control unit 210 is configured to output a signal requesting predetermined power consumption to the control unit 36 of the load device 2 via the communication units 22 and 38. As a result, the load circuit 37 consumes an appropriate amount of power that can release the stored charge of the assembled battery 14 during a predetermined period, while preventing the battery pack 1 from overheating (suppressing heat generation of the diode 51). In this way, it is possible to release the charge of the assembled battery 14 due to power consumption in the load device 2 while maintaining an appropriate state.

  The fuses 24 and 25 are not blown by the control of the double protection IC 23, but are spontaneously blown by heat generated by an excessive current flowing through the resistance component of the fuses 24 and 25. However, the accuracy of the fusing voltage can be increased by controlling the double protection IC 23. The double protection IC 23 may also perform overcharge determination with a digital value after analog / digital conversion of the voltages Vin1 to Vin4 as in the control IC18. Instead of the diode 51, a switching element having a control terminal such as an FET that is turned on together with the FET 27 by the double protection IC 23 may be used.

[Embodiment 2]
FIG. 4 is a block diagram showing an electrical configuration of an electronic device system according to the second embodiment of the present invention. This electronic device system is similar to the electronic device system shown in FIGS. 1 to 3 described above, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. It should be noted that in the present embodiment, in the battery pack 1a, a short-circuit resistor 52 connected in series with the FET 27 is used as the discharging means. The short-circuit resistance 52 is controlled and set to a resistance value capable of passing a weak short-circuit current that does not overheat the battery pack 1a.

  With this configuration, when the double protection IC 23 performs the protection operation by turning on the FET 27, first, due to the resistance value, a predetermined current flows through the heating resistor 26 and the fuses 24 and 25 are blown. As a result, a current flows through the short-circuit resistor 52, and the terminals T0 to T4 of the assembled battery 14 are gently (soft) short-circuited, and a weak short-circuit current that does not overheat flows. Even with this configuration, the charge of the assembled battery 14 can be released.

  Also, it should be noted that in the present embodiment, the fuses 24 and 25, the heating resistor 26, and the short-circuit resistor 52 are integrally packaged as a fuse module 53. Therefore, the structure of the fuses 24, 25 and the heating resistor 26, that is, the positional relationship and the contact state, etc., can realize a stable operation by keeping the heat generation amount of the heating resistor 26 required for the fuses 24, 25 to blow. In addition, since the terminals including the short-circuit resistor 52 are exposed to the outside by sharing the terminals, three terminals are provided, and the assembly of the battery pack 1a can be simplified.

[Embodiment 3]
FIG. 5 is a block diagram showing an electrical configuration of a battery pack 1b according to the third embodiment of the present invention. The battery pack 1b is similar to the above-described battery packs 1 and 1a, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. Further, the load device 2 and the charger 3 are configured in the same manner as in FIG. 1 and FIG. It should be noted that in the present embodiment, the load resistor 54 as the discharging means is provided in the double protection IC 23b. Specifically, when the load resistor 54 is provided between the output terminals of the comparators A1 to A4 and the input terminal T40 of the GND, and at least one of the comparators A1 to A4 determines that overcharge occurs. The comparators A1 to A4 output a high level to turn on the FET 27 and energize the load resistor 54. Even with this configuration, the charge of the assembled battery 14 can be released.

[Embodiment 4]
FIG. 6 is a block diagram showing an electrical configuration of an electronic device system according to the fourth embodiment of the present invention. This electronic device system is similar to the electronic device system shown in FIGS. 1 to 3 described above, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. It should be noted that in this embodiment, the output from the double protection IC 23 to the FET 27 is also input to the control unit 21c of the control IC 18c. When the protective operation is performed, a certain amount of operation is suspended until the abnormal state is resolved. On the other hand, when the double protective IC 23 performs the double protective operation to turn on the FET 27, the control unit 21c The charge / discharge control unit 210 consumes the power of the assembled battery 14 by repeatedly calculating the remaining amount or operating the analog / digital converter 19 at a high speed. Even with this configuration, the charge of the assembled battery 14 can be released.

  Here, in Japanese Patent No. 3865723, a temperature fuse and a discharge circuit are provided outside the battery, and the charge circuit is reset after the discharge circuit is operated by a manual remote operation, so that the charge / discharge path reset time is changed. It can be shortened. However, this prior art relates to a large-sized battery for business use having no versatility, and in the case of the versatile battery packs 1, 1a, 1b, 1c as in the present invention, it is possible to attach or detach or use the equipment 2 The thermal fuse and discharge circuit cannot be provided outside, and when the thermal fuse is blown to be unusable, it is necessary to automatically discharge in conjunction with it. .

  In the battery pack in which the non-recoverable protection operation is performed by the double protection IC against an abnormality such as overcharge, the subsequent operation is disabled. Therefore, the stored charge of the secondary battery can be automatically discharged to improve the safety, so that the battery pack of the secondary battery can be implemented.

It is a block diagram which shows the electric constitution of the electronic device system which concerns on the 1st Embodiment of this invention. It is a block diagram explaining the structure in a battery pack in more detail. It is a block diagram which shows the example of 1 structure of ASIC which performs cell voltage detection, and the structure of the part concerning it in control IC. It is a block diagram which shows the electric constitution of the electronic device system which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the electrical constitution of the battery pack which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows the electric constitution of the electronic device system which concerns on the 4th Embodiment of this invention.

Explanation of symbols

1, 1a, 1b, 1c Battery pack 2 Load device 3 Charger 11, 15 Charge release path 12, 13, 27 FET
14 Battery assembly 16 Current detection resistor 17 Temperature sensor 18, 18c, 30, 35 Control IC
19 Analog / digital converter 20, 22, 32, 38, 43 Communication unit 21, 21c Control unit 210 Charge / discharge control unit 211 Switching control unit 212 Abnormality detection unit 23, 23b Double protection IC
24, 25 Fuse 26 Heating resistor 27 Switch 29 ASIC
31 Charging control unit 33 Charging current supply circuit 41 Input switching unit 42 Cell selection unit 51 Diode 52 Short circuit resistor 53 Fuse module 54 Load resistors C11 to C14; C21 to C24 Input capacitances E1 to E4 Cells L0 to L4 Connection lines R11 to R14; S21L, S1H; S2L, S2H; S3L, S3H; S4H switch STL, STH switch T0-T4 terminals T11, T21, T31; T12, T22, T32; T13, T23, T33 terminals T30-T34 ; T40 to T44 terminals

Claims (8)

A secondary battery,
By blocking the charging / discharging path to the secondary battery, a protection means for realizing a protective operation that makes subsequent use impossible,
A battery pack comprising discharge means for discharging the charge of the secondary battery in conjunction with a protection operation of the protection means. A control element that is interposed in series in a path of charge and discharge to the secondary battery and controls charge and discharge;
Detection means for detecting at least one of the terminal voltage, charge / discharge current and temperature of the secondary battery;
A first control unit that compares the detection result of the detection unit with a first threshold value that is determined in advance, and performs a protective operation so that the control element can be restored by shutting off the control element when it is determined to be abnormal;
The detection result of the detection means is compared with a predetermined second threshold value that is higher than the first threshold value, and if it is determined to be abnormal, the protection means is shut off to perform a protection operation that disables the subsequent use. The battery pack according to claim 1, further comprising second control means. The protection means is a fuse interposed in a charge / discharge path to the secondary battery,
3. The battery pack according to claim 2, wherein the discharging means is a diode connected in parallel with the fuse and having a forward bias at the time of discharging. The protective means is the fuse,
A heating resistor capable of blowing the fuse;
A switch connected in series with the heating resistor between the terminals of the secondary battery,
4. The battery pack according to claim 3, wherein, when the second control unit determines that an abnormality has occurred, the switch is turned on and a predetermined power consumption is requested from the load device. The protective means is
A fuse interposed in a charge / discharge path to the secondary battery;
A heating resistor capable of blowing the fuse;
A switch connected in series with the heating resistor between the terminals of the secondary battery, and configured to be turned on by the second control means when determined to be abnormal,
3. The battery pack according to claim 2, wherein the discharging means is a short-circuit resistor that is connected in series with the switch between terminals of the secondary battery and allows a weak short-circuit current to pass therethrough.   6. The battery pack according to claim 5, wherein the fuse, the heating resistor, and the short-circuit resistor are packaged integrally. The discharging means comprises a load resistance connected to the second control means,
The battery pack according to claim 2, wherein a control output from the second control means to the protection means is also applied to the load resistance. The discharging means comprises the first control means,
3. The battery pack according to claim 2, wherein the second control means shuts off the protection means and keeps the first control means in operation.

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