JP5036341B2 - Pack battery - Google Patents

Description

  The present invention relates to a battery pack provided with a sub-protection circuit in addition to a main protection circuit, and more particularly to a battery pack that detects the deterioration of the battery and improves the safety of the deteriorated battery with the sub-protection circuit operating.

The battery pack is provided with a protection circuit to prevent the battery voltage from becoming abnormally high. This is because if the battery is charged to an abnormally high voltage, it causes a decrease in safety. The protection circuit for the battery pack includes a voltage detection circuit that detects the voltage of the battery, and a switching element that compares the detected battery voltage with the charge prohibition voltage and cuts off the battery current when the battery voltage becomes higher than the charge prohibition voltage. It has. When the battery pack including the protection circuit is charged and the battery voltage rises to the charge inhibition voltage, the switching element is turned off to cut off the charging current and prevent the battery voltage from rising. In this battery pack, as long as the protection circuit operates normally, the battery voltage does not exceed the charge inhibition voltage. However, if the protection circuit fails and does not operate normally, the battery charging current cannot be cut off and the battery voltage rises abnormally. In order to prevent this problem, a battery pack having a double protection circuit composed of a main protection circuit and a sub protection circuit has been developed. (See Patent Document 1)
JP 2001-37096 A

  Since the battery pack having the double protection circuit operates both the main protection circuit and the sub protection circuit, the sub protection circuit operates when the main protection circuit does not operate normally. For this reason, even if the main protection circuit fails, the sub protection circuit operates to limit the battery voltage rise. However, in this battery pack, the main protection circuit sets the second charge prohibition voltage at which the sub protection circuit operates higher than the first charge prohibition voltage at which the main protection circuit cuts off the battery current. When a failure occurs, the battery voltage rises higher. Even if the abnormal voltage rise of the battery can be prevented, this is less safe than the main protection circuit operating when the sub protection circuit is operating.

  Further, the battery deteriorates with time as it is used. Furthermore, the probability of failure of the protection circuit increases as it is used. If the battery is deteriorated in a state where the main protection circuit fails, the battery of Patent Document 1 is charged to a higher charge inhibition voltage and cannot be used safely.

  The present invention has been developed for the purpose of solving this drawback. An important object of the present invention is to provide a battery pack that can be used safely even if the battery deteriorates.

The battery pack of the present invention has the following configuration in order to achieve the aforementioned object.
The battery pack includes a main protection circuit 2, 32, 42 that detects the voltage of the battery 1 and cuts off the current of the battery 1 when the battery voltage rises to the first charge prohibition voltage, and the battery voltage is the second charge prohibition voltage. Sub protection circuits 3, 33, and 43 that cut off the current of the battery 1 when the voltage rises to the upper limit, and a control circuit that detects deterioration of the battery 1 and controls the main protection circuits 2, 32, and 42 and the sub protection circuits 3, 33, and 43 4 and the second charge inhibition voltage is set lower than the first charge inhibition voltage. Further, the control circuit 4 includes a deterioration degree detection unit 11 that detects deterioration of the battery 1, a memory 12 that stores a setting deterioration degree for switching the sub protection circuit 3 to the operating state, and detection detected by the deterioration degree detection unit 11. A switching unit 13 that switches the sub protection circuits 3, 33, and 43 to the operating state in comparison with the set deterioration level stored in the memory 12 is provided. In the battery pack, when the deterioration degree of the battery 1 does not exceed the set deterioration degree, the main protection circuits 2, 32, and 42 are in the operating state, and the voltage that cuts off the current of the battery 1 is the first charge. When the deterioration level of the battery 1 exceeds the set deterioration level, the switching unit 13 sets the sub protection circuits 3, 33, and 43 to the operating state, and the voltage for cutting off the current of the battery 1 is set as the first charging prohibition voltage. To the second charge prohibition voltage.

  In the battery pack of claim 2 of the present invention, in addition to the configuration of claim 1, the control circuit 4 includes the main protection circuits 2 and 32, the sub protection circuit 3, Both are set in an operating state.

  The battery pack according to claim 3 of the present invention has a voltage detection circuit 5 in which the main protection circuits 2, 32 and 42 and the sub protection circuits 3, 32 and 42 detect the voltage of the battery 1 in addition to the configuration of claim 2. And a switching element 6 that is switched from on to off in a state where the battery voltage detected by the voltage detection circuit 5 rises to the charge inhibition voltage.

  The battery pack of the present invention has a feature that it can be used safely even if the battery deteriorates. In the battery pack according to the present invention, when the deterioration level of the battery does not exceed the set deterioration level, the main protection circuit is set to the operating state, the voltage for cutting off the battery current is set as the first charge prohibition voltage, and the battery deterioration This is because when the degree exceeds the set deterioration degree, the sub protection circuit is set in the operating state, and the voltage for cutting off the battery current is lowered from the first charge inhibition voltage to the second charge inhibition voltage. The battery pack with this structure uses a sub-protection circuit that activates when the battery deteriorates, so the charge prohibition voltage that cuts off the battery current is lowered. it can.

  The battery pack according to claim 2 of the present invention operates both the main protection circuit and the sub protection circuit in a state where the battery is deteriorated from the set deterioration level. There is a feature that prevents voltage rise and can be used safely. Even if the battery voltage rises above the second charge prohibition voltage because the sub-protection circuit fails and does not operate normally, the main protection circuit in the operating state does not operate at the first charge prohibition voltage. This is because the battery voltage does not rise higher than the first charge prohibition voltage because the voltage rise is prevented. Therefore, this battery pack can realize higher safety.

  Embodiments of the present invention will be described below with reference to the drawings. However, the example shown below illustrates the battery pack for embodying the technical idea of the present invention, and the present invention does not specify the battery pack as follows.

  Further, in this specification, in order to facilitate understanding of the scope of claims, numbers corresponding to the members shown in the examples are indicated in the “claims” and “means for solving problems” sections. It is added to the members. However, the members shown in the claims are not limited to the members in the embodiments.

  The battery pack shown in FIG. 1 has a plurality of rechargeable batteries 1 connected in series, and detects the voltage of each battery 1 and cuts off the current of the battery 1 when the battery voltage rises to the first charge prohibition voltage. The main protection circuit 2, the sub protection circuit 3 that cuts off the current of the battery 1 when the battery voltage rises to the second charge inhibition voltage, the deterioration of the battery 1 is detected, and the main protection circuit 2 and the sub protection circuit 3 are And a control circuit 4 for controlling.

  The main protection circuit 2 and the sub protection circuit 3 are turned on from off in a state where the voltage detection circuits 5 and 5 for detecting the voltage of the battery 1 and the battery voltage detected by the voltage detection circuits 5 and 5 rise to the charge prohibition voltage. Switching elements 6 and 6 that can be switched to each other. The main protection circuit 2 and the sub protection circuit 3 switch the switching elements 6 and 6 from on to off when any battery voltage detected by the voltage detection circuits 5 and 5 exceeds the charge inhibition voltage. When the switching element 6 is switched off, the charging current of the battery 1 is cut off. Since the switching element 6 has the parasitic diode 7 in the direction in which the discharge current flows, the switching element 6 allows the battery 1 to discharge in the off state. The switching element 6 is in the on state when the battery voltage is lower than the charge inhibition voltage. In this state, the battery pack is in a state where the battery 1 can be charged.

  FIG. 2 shows the voltage detection circuit 5 of the main protection circuit 2 and the sub protection circuit 3. The voltage detection circuit 5 in this figure includes either a differential amplifier 8 that detects the voltage of each battery 1 and a comparator 9 that compares each battery voltage charged from the differential amplifier 8 with a charge inhibition voltage. When an off signal for switching off the switching element 6 is output from the comparator 9, the input circuit 10 inputs this signal to the input side of the FET that is the switching element 6.

  The differential amplifier 8 has positive and negative input terminals connected to the positive and negative electrodes of each battery 1. The differential amplifier 8 outputs a voltage proportional to each battery voltage. The differential amplifier may be a buffer amplifier with an amplification factor of 1. The differential amplifier of the buffer amplifier outputs a voltage equal to the battery voltage. Further, the differential amplifier, which is a buffer amplifier, connects the + side input terminal to the positive electrode of the battery and the − side input terminal to the negative electrode of the battery, and outputs the voltage of the battery as it is.

  The comparator 9 inputs the output of the differential amplifier 8 to the input terminal on the + side which is one input terminal, and inputs the charge prohibition voltage as a reference voltage to the input terminal on the − side which is the other input terminal. Yes. A battery voltage at which the protection circuit switches the switching element 6 from on to off is specified by a reference voltage input to one input terminal of the comparator 9. In the battery pack in which the battery 1 is a lithium ion secondary battery, the first charge prohibition voltage at which the main protection circuit 2 cuts off the current of the battery 1 is set to 4.35 V, for example. The voltage detection circuit 5 of the main protection circuit 2 inputs a reference voltage of 4.35 V as a charge prohibition voltage to one input terminal of the comparator 9. The voltage detection circuit 5 that sets the second charge prohibition voltage of the sub protection circuit 3 to 4.25 V inputs a reference voltage of 4.25 V as a charge prohibition voltage to one input terminal of the comparator 9. However, the first charge inhibition voltage at which the main protection circuit 2 cuts off the current of the battery 1 is not necessarily specified as 4.35V. The first charge prohibition voltage is set, for example, higher than 4.25V and lower than 4.4V. The second charge prohibition voltage is lower than the first charge prohibition voltage, for example, higher than 4.2V and lower than 4.25V.

  The voltage detection circuit 5 in FIG. 2 outputs “High” as an off signal for turning off the switching element 6 from the comparator 9 when any battery voltage becomes equal to or higher than the charge inhibition voltage. When a “High” signal is input as an OFF signal from any of the comparators 9, the input circuit 10 outputs an FET OFF signal to the base on the input side of the switching element 6. Further, when a “Low” signal that is not an off signal is input from all the comparators 9, the input circuit 10 inputs an on signal to the base of the switching element 6 in order to keep the switching element 6 on.

  The main protection circuit 2 and the sub protection circuit 3 are in an operating state when power is supplied from the battery 1. Although the main protection circuit 2 is always in an operating state (illustration of the power supply path from the battery 1 is omitted), the sub protection circuit 3 supplies power power and switches to the operating state after the battery 1 has deteriorated. The operation state of the sub protection circuit 3 is controlled by the control circuit 4.

When the deterioration level of the battery 1 does not exceed the set deterioration level, the control circuit 4 sets the main protection circuit 2 to the operating state and sets the voltage for cutting off the current of the battery 1 as the first charge prohibition voltage. When the battery 1 deteriorates to the set deterioration level, the control circuit 4 activates the sub protection circuit 3 to lower the voltage for cutting off the current of the battery 1 from the first charge inhibition voltage to the second charge inhibition voltage. The control circuit 4 that operates as described above is detected by the deterioration level detection unit 11 that detects the deterioration of the battery 1, the memory 12 that stores the set level of deterioration for switching the sub protection circuit 3 to the operating state, and the deterioration level detection unit 11. The detected deterioration degree is compared with the set deterioration degree stored in the memory 12, and when it is determined that the detection deterioration degree exceeds the set deterioration degree and the deterioration is progressing, it is determined that the battery has deteriorated. And a switching unit 13 for switching the sub protection circuit 3 to the operating state.
In this embodiment, the smaller the numerical value indicating the degree of deterioration, the more the deterioration is advanced (maximum capacity described later), and the higher the numerical value indicating the degree of deterioration is, the more advanced the deterioration is (described later). (Internal resistance value, number of cycles). Therefore, in this specification, when the detection deterioration degree exceeds the set deterioration degree, the deterioration is advanced and the battery is deteriorated.

The degradation level detection unit 11 can determine the degradation level by the following method, but the degradation level can also be determined by other methods. In this embodiment, as a method for determining the degree of deterioration,
(1) Method of detecting by internal resistance (2) Method of detecting from maximum chargeable capacity (3) At least one method of detecting by the number of charge / discharge cycles can be used.

In the method (1) of detecting the deterioration degree of the battery by the internal resistance, the deterioration degree of the battery 1 is determined by detecting the internal resistance of the battery 1. Since the battery has the property that the internal resistance increases when it deteriorates, the degree of deterioration can be detected from the internal resistance. However, since the capacity of the battery decreases as the battery deteriorates, the maximum capacity that can be charged can be detected to determine the degree of deterioration. The internal resistance (R) of the battery 1 can be calculated by the following equation by detecting the current and voltage flowing through the battery 1 in a state where current flows through the battery 1.
R = (Eocv−Eccv) / I
In this equation, Eocv is the no-load voltage of the battery, Eccv is the battery voltage in a state where the current I flows, and I is the current.
Here, Eocv and Eccv are detected by the voltage detection circuit 5 and input to the deterioration degree detection unit 11. In addition, the current I flowing through the battery 1 is detected by a current detection circuit 15 including a current detection resistor 16 connected in series with the battery 1 and input to the deterioration degree detection unit 11.
The deterioration degree detection unit 11 stores a function or table that specifies the deterioration degree from the internal resistance (R) of the battery calculated from the above formula, and determines the deterioration degree of the battery from the stored function or table. . Further, when the detected internal resistance exceeds the set resistance value when the detected internal resistance of the battery is used as the detected deterioration level and the set resistance value is used as the set deterioration level stored in the memory 12, It can also be determined that the battery has deteriorated.

  In the method (2) of detecting the battery deterioration level from the maximum chargeable capacity, the deterioration level detection unit for detecting the battery deterioration level from the maximum battery chargeable capacity (= substantial capacity or learning capacity) When used, the capacity from a fully discharged state to full charge is detected, and the degree of deterioration is detected from this capacity. The deterioration level detection unit also stores a function or table for detecting the deterioration level from the maximum capacity that can be charged, and converts the capacity into a deterioration level from the stored function or table. Furthermore, when such a detected maximum capacity is used as the above-mentioned detected deterioration level and the set maximum capacity is used as the set deterioration level stored in the memory 12, the detected maximum capacity is smaller than the set maximum capacity. It is determined that the battery has deteriorated.

  Further, in the method (3) of detecting the degree of deterioration of the battery by the number of charge / discharge cycles, the deterioration degree detection unit 11 fully satisfies a battery that is completely discharged, in other words, a battery having a remaining capacity of 0%. After charging, the completely discharged state is counted as one cycle, the number of cycles in which such cycles are accumulated is detected, and the degree of deterioration is detected from the number of cycles. This deterioration level detection unit also stores a function or table for detecting the deterioration level from the accumulated number of cycles, and converts the accumulated number of cycles from the stored function or table into a deterioration level. Furthermore, when such a cumulative number of cycles is used as the degree of detection deterioration and the number of set cycles is used as the degree of deterioration of setting stored in the memory 12, the detected number of accumulated cycles is greater than the number of set cycles. When it is determined that the battery has deteriorated. Furthermore, when the predetermined number of cycles stored exceeds the accumulated number of cycles, it is determined that the state has deteriorated.

  As for the cycle, one cycle of the charge / discharge cycle indicating repetition of charge / discharge, as described above, is not limited to the fully discharged state, but also the charge capacity or discharge. Capacitance can also be accumulated and counted. The method of counting from the charge capacity accumulates the integrated value of the charge capacity of the battery to be charged / discharged. Every time the cumulative amount of charge capacity reaches the actual capacity of the battery, one cycle is counted, and the cumulative number of cycles is increased based on the count. For example, when the actual capacity of the current battery is 1000 mAh, the charge amount reaches 500 mAh when the first charge is 500 mAh, the second charge is 200 mAh, and the third charge is 300 mAh. It is determined that the battery has been charged. During this time, the battery can be discharged or fully charged. These charges are repeated, and the number of cycles is increased each time the integrated amount reaches the actual capacity of the battery at that time.

  Further, instead of the charge capacity, one cycle can be counted from the accumulated amount of discharge capacity. This method accumulates the actual discharge capacity, counts as one cycle each time the accumulated amount reaches the actual capacity of the battery, and increments the deterioration counter based on the count. For example, when the actual capacity of the current battery is 1000 mAh, when the discharge of 500 mAh is performed for the first discharge, 200 mAh for the second discharge, and 300 mAh for the third discharge, the accumulated amount of discharge capacity reaches 1000 mAh. It is determined that the cycle has been discharged. During this time, the battery can be charged and discharged, or can be fully charged. These discharges are repeated, and the number of cycles is increased each time the integrated amount reaches the actual capacity of the battery at that time.

  Further, instead of the charge capacity or the discharge capacity, one cycle can be counted from the accumulated amount of the charge capacity and the discharge capacity. This method accumulates the actual charge capacity and discharge capacity, counts as one cycle each time the accumulated quantity reaches twice the actual capacity of the battery, and increments the deterioration counter based on the count. . For example, if the actual capacity of the current battery is 1000 mAh, the first charge is 800 mAh, the first discharge is followed by 500 mAh, the second discharge is 200 mAh, the second charge is 200 mAh, and then the third time. When the charging of 300 mAh is performed, the cumulative value of charging capacity reaches 1000 mAh and the cumulative amount of discharging capacity reaches 1000 mAh. Therefore, the cumulative value of charging and discharging becomes 2000 mAh, and it is determined that one cycle of charging is performed.

  The switching unit 13 of the control circuit 4 controls the power switch 14 that activates the sub protection circuit 3. The power switch 14 is connected between the positive side of the battery 1 and a power supply circuit (not shown) of the voltage detection circuit 5, and supplies power to the voltage detection circuit 5 in the on state so as to activate it. . When the power switch 14 is in the OFF state, the power supply power is not supplied to the voltage detection circuit 5 and the operation is not performed. When the degree of deterioration of the detected battery 1 exceeds the set degree of deterioration, the switching unit 13 turns on the power switch 14 to put the sub protection circuit 3 into an operating state.

  In the battery pack of FIG. 1, the control circuit 4 does not control the operating state of the main protection circuit 2. The main protection circuit 2 is always kept in an operating state. In this battery pack, when the battery 1 is deteriorated and the sub protection circuit 3 is in an operating state, the sub protection circuit 3 cuts off the current when the battery voltage rises. This is because the second charge inhibition voltage at which the sub protection circuit 3 cuts off the current is lower than the first charge inhibition voltage at which the main protection circuit 2 cuts off the current. In this state, when the sub protection circuit 3 fails and does not operate normally, the voltage of the battery 1 rises above the second charge inhibition voltage. Since the main protection circuit 2 is in an operating state in this state, the main protection circuit 2 prevents the voltage of the battery 1 from rising at the first charge prohibition voltage. Therefore, in the battery pack in which the main protection circuit 2 is always in an operating state, the battery voltage does not rise higher than the first charge inhibition voltage even if the sub protection circuit 3 fails.

  However, the battery pack of the present invention can switch the main protection circuit to the non-operation state when the sub protection circuit is in the operation state. To realize this, although not shown, the main protection circuit can be configured to supply power from the battery via the main power switch, and the main power switch can be switched on and off by the control circuit. In the state where the power switch of the sub protection circuit is turned on, the control circuit switches the main power switch off, stops the operation of the main protection circuit when the battery deteriorates, and sets the sub protection circuit to the operating state. can do.

The above battery pack prevents the battery voltage from rising abnormally in the following operation.
[Battery degradation level does not exceed the set degradation level (battery has not degraded to the set degradation level)]
In this state, only the main protection circuit 2 is in an operating state, and the sub protection circuit 3 is not in an operating state. Since the deterioration degree detection unit 11 of the control circuit 4 detects the deterioration degree of the battery 1 and the detected deterioration degree does not exceed the set deterioration degree, the switching unit 13 holds the power switch 14 of the sub protection circuit 3 off. Because it does. The battery 1 that has not deteriorated is used safely by charging up to the first charge inhibition voltage and with a large charge capacity.

[Battery degradation level exceeding the set degradation level (battery degraded to the set degradation level)]
When the degradation level of the battery 1 exceeds the set degradation level, this state is detected by the degradation level detection unit 11 of the control circuit 4. The deterioration degree detection unit 11 that has detected this state switches the power switch 14 of the sub protection circuit 3 from OFF to ON by the switching unit 13. When the power switch 14 is turned on, power is supplied to the sub protection circuit 3 via the power switch 14 and the sub protection circuit 3 enters an operating state. When the sub protection circuit 3 is in an operating state, the current of the battery 1 is cut off by the second charge inhibition voltage. Since the second charge prohibition voltage is set to a voltage lower than the first charge prohibition voltage, the deteriorated battery is limited to the second charge prohibition voltage with a voltage that rises the highest when charged. Therefore, the battery pack in which the battery has deteriorated can be used more safely by limiting the maximum voltage to a low level.

  In the battery pack of FIG. 1, the main protection circuit 2 and the sub protection circuit 3 include dedicated switching elements 6, and the respective switching elements 6 are connected in series. In this battery pack, any of the switching elements 6 can be turned off to cut off the charging current. However, in the battery pack of the present invention, as shown in FIG. 3, the main protection circuit 32 and the sub protection circuit 33 can control one switching element 6 to cut off the charging current of the battery 1. The switching element 6 of the battery pack is switched off by inputting an off signal from either the main protection circuit 32 or the sub protection circuit 33. FIG. 3 shows another embodiment. The same reference numerals are used for the same components as those in the embodiment shown in FIGS. 1 and 2, and the description thereof is omitted.

  Further, the battery pack of FIG. 1 has the main protection circuit 2 and the sub protection circuit 3 mounted as separate dedicated circuits. The battery pack of FIG. 4 implements the main protection circuit 42 and the sub protection circuit 43 with a single protection circuit as a protection circuit that can be switched between the first charge inhibition voltage and the second charge inhibition voltage. In this battery pack, the switching unit 13 of the control circuit 4 switches between the first charging inhibition voltage and the second charging inhibition voltage of the protection circuit. That is, when the deterioration level detection unit 11 detects that the battery 1 has deteriorated from the set deterioration level, the charge prohibition voltage at which the protection circuit switches the switching element 6 off is changed from the first charge prohibition voltage to the second charge prohibition. Switch to voltage and lower. For this reason, when the battery 1 deteriorates, the main protection circuit 42 is substantially deactivated and the sub protection circuit 43 is activated, and the voltage increase of the battery 1 is lower than the second charge prohibition voltage. Limited. FIG. 4 shows another embodiment, and the same components as those in the embodiment shown in FIGS. 1 and 2 are denoted by the same reference numerals and description thereof is omitted.

1 is a block diagram of a battery pack according to an embodiment of the present invention. It is a circuit diagram which shows an example of a voltage detection circuit. It is a block diagram of the pack battery concerning the other Example of this invention. It is a block diagram of the pack battery concerning the other Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery 2, 32, 42 ... Main protection circuit 3, 33, 43 ... Sub protection circuit 4 ... Control circuit 5 ... Voltage detection circuit 6 ... Switching element 7 ... Parasitic diode 8 ... Differential amplifier 9 ... Comparator 10 ... Input circuit DESCRIPTION OF SYMBOLS 11 ... Deterioration degree detection part 12 ... Memory 13 ... Switching part 14 ... Power switch 15 ... Current detection circuit 16 ... Current detection resistance

Claims (3)

When the voltage of the battery (1) is detected and the battery voltage rises to the first charge prohibition voltage, the main protection circuit (2), (32), (42) that cuts off the current of the battery (1) Sub-protection circuit (3), (33), (43) that cuts off the current of battery (1) when it rises to the second charge prohibition voltage, and main protection circuit (2) while detecting deterioration of battery (1) , (32), (42) circuit and a control circuit (4) for controlling the sub protection circuit (3), (33), (43),
The second charge prohibition voltage is set lower than the first charge prohibition voltage, and the control circuit (4) further includes a deterioration degree detection unit (11) for detecting deterioration of the battery (1), and a sub protection circuit. (3), (33), (43) memory to store the setting deterioration degree to switch to the operating state (12), and the detection deterioration degree detected by the deterioration degree detection unit (11) is stored in the memory (12) A switching unit (13) that switches the sub protection circuit (3), (33), (43) to the operating state compared to the set deterioration level is provided.
When the deterioration level of the battery (1) does not exceed the set deterioration level, the voltage that blocks the current of the battery (1) when the main protection circuit (2), (32), (42) is in the operating state. Is the first charge prohibition voltage, and when the deterioration level of the battery (1) exceeds the set deterioration level, the switching unit (13) sets the sub protection circuits (3), (33), (43) to the operating state, A battery pack configured to lower a voltage for interrupting a current of the battery (1) from a first charge prohibition voltage to a second charge prohibition voltage.   Request that the control circuit (4) puts both the main protection circuit (2) and (32) and the sub protection circuit (3) and (33) into the operating state when the battery (1) is deteriorated below the set deterioration level. Item 4. A battery pack according to item 1.   Main protection circuit (2), (32), (42) and sub protection circuit (3), (33), (43) are voltage detection circuit (5) that detects the voltage of battery (1), and voltage detection The battery pack according to claim 1, further comprising a switching element (6) that is switched from on to off in a state in which the battery voltage detected by the circuit (5) rises to a charge inhibition voltage.

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