Battery pack

Abstract

The present invention provides a battery pack that can be appropriately protected. The battery pack includes: a control unit having a counter value. The control unit is configured to: when the battery pack discharges, perform a discharge-time calculation process for calculating an addition value, a discharge-time update process for updating the counter value to a value obtained by adding the addition value to the counter value, and a prohibition process for prohibiting discharge from the battery pack when the counter value reaches a predetermined protection counter threshold.

Description

Technical Field

[0001] The present invention relates to a battery pack. Background Art

[0002] The calorific value estimation device described in Patent Document 1 can periodically acquire the detected value of the charge and discharge current flowing in the battery, and calculate the addition and subtraction calculated value based on the acquired detected value. Further, the above device adds and subtracts the calculated addition and subtraction calculated value to and from the overcurrent counter value corresponding to the calorific value of the battery to update the overcurrent counter value, and prohibits discharging when the overcurrent counter value reaches a threshold value or more, thereby protecting the battery.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent No. 5524694 Summary of the Invention

[0006] The battery pack accumulates damage due to repeated use. Therefore, even if the battery pack with a relatively large accumulated damage and the battery pack with a relatively small accumulated damage are protected in the same manner, it may not be possible to perform appropriate protection.

[0007] One aspect of the present invention provides a battery pack that can be appropriately protected.

[0008] The battery pack according to one aspect of the present invention includes: a control unit having a counter value. The control unit is configured to: during discharging of the battery pack, execute a discharging calculation process for calculating an addition value, a discharging update process for updating the counter value to a value obtained by adding the addition value to the counter value, and a prohibition process for prohibiting discharging from the battery pack when the counter value reaches a specified protection counter threshold value.

[0009] With the above battery pack, the addition value is calculated based on the usage history of the battery pack, and the calculated addition value is added to the counter value to update the counter value. Further, when the counter value reaches the protection counter threshold value, discharging from the battery pack is prohibited. Therefore, according to the usage history of the battery pack, the arrival time when the counter value reaches the protection counter threshold value changes, and thus, according to the usage history of the battery pack, the battery pack can be appropriately protected.

[0010] In addition, the control unit may be configured to: in the discharging calculation process, the more the usage history, the larger the addition value is calculated.

[0011] The more usage history there is, the larger the addition value is calculated. Therefore, the greater the cumulative damage to the battery pack, the earlier the counter value reaches the protection counter threshold to prohibit discharging from the battery pack. Accordingly, the battery pack can be appropriately protected according to the usage history of the battery pack.

[0012] The addition value can also be a value of 0 or more when the discharge current value is equal to or greater than a specified value, and a value of less than 0 when the discharge current is less than the specified value.

[0013] When the discharge current value is equal to or greater than the specified value, the greater the cumulative damage to the battery pack, the more rapidly the counter value increases. When the discharge current value is less than the specified value, the greater the cumulative damage to the battery pack, the more slowly the counter value decreases. Accordingly, the battery pack can be appropriately protected according to the usage history of the battery pack.

[0014] In addition, the usage history can include: the number of operations of the battery pack for which the counter value has exceeded the overload counter threshold. The overload counter threshold can be set to a value smaller than the protection counter threshold.

[0015] When the battery pack operates and the counter value exceeds the overload counter threshold, even if discharging is not prohibited, the battery pack will still have cumulative damage. Accordingly, by using the number of operations of the battery pack for which the counter value has exceeded the overload counter threshold as the usage history, it is possible to achieve protection of the battery pack corresponding to the damage accumulated in the battery pack.

[0016] The usage history can include: the number of operations of the battery for which the temperature of the battery pack has exceeded a specified protection temperature threshold.

[0017] When the battery pack operates and the temperature of the battery pack exceeds the protection temperature threshold, even if discharging is not prohibited, the battery pack will still have cumulative damage. Accordingly, by using the number of operations of the battery pack for which the temperature of the battery pack has exceeded the protection temperature threshold as the usage history, it is possible to achieve protection of the battery pack corresponding to the damage accumulated in the battery pack.

[0018] In addition, the control unit can be configured to: when the battery pack is charging, perform a charging-time calculation process for calculating a subtraction value, which is a value less than 0, according to the usage history of the battery pack, and a charging-time update process for updating the counter value to a value obtained by adding the subtraction value to the counter value.

[0019] When the battery pack is charging, a subtraction value is calculated, and the counter value is updated to a value obtained by adding the subtraction value to the counter value. Even during charging, by updating the counter value, the counter value can be replaced with a value that appropriately represents the state of the battery pack.

[0020] In addition, the control unit can be configured such that during the charging calculation process, the more usage history is used, the larger the subtraction value is calculated.

[0021] Even during charging, the greater the cumulative damage to the battery pack, the more slowly the counter value decreases. Accordingly, appropriate protection of the battery pack can be achieved based on the usage history of the battery pack.

[0022] In addition, the control unit can be configured such that during charging of the battery pack, when the load state of the battery pack during the period from the previous charge to the current charge satisfies a specified condition, a history process for increasing the usage history is executed.

[0023] When the load state of the battery pack satisfies the specified condition, during the next charge, the usage history is increased. Accordingly, compared to the case where the usage history is increased during discharge, the process becomes easier, thereby reducing the processing load.

[0024] In addition, the control unit can be configured such that during discharge of the battery pack, a protection threshold setting process for setting a protection counter threshold based on the usage history is executed.

[0025] The protection counter threshold is set based on the usage history. Accordingly, since the time to reach the protection counter threshold of the counter value changes according to the usage history of the battery pack, appropriate protection of the battery pack can be achieved based on the usage history of the battery pack.

[0026] In addition, the control unit can be configured such that in the protection threshold setting process, the more usage history is used, the smaller the protection counter threshold is set.

[0027] The more usage history is used, the smaller the protection counter threshold is set. Therefore, the greater the cumulative damage to the battery pack, the earlier the counter value reaches the protection counter threshold to prohibit discharging from the battery pack. Accordingly, appropriate protection of the battery pack can be achieved based on the usage history of the battery pack.

[0028] In addition, the control unit can be configured such that during discharge of the battery pack, an overload threshold setting process for setting an overload counter threshold based on the usage history is executed.

[0029] The overload counter threshold is set based on the usage history. Accordingly, since the time to reach the overload counter threshold of the counter value changes according to the usage history of the battery, the increase speed of the usage history of the battery pack can be changed based on the usage history of the battery pack.

[0030] In addition, the control unit can be configured such that in the overload threshold setting process, the more usage history is used, the smaller the overload counter threshold is set.

[0031] The more usage history there is, the smaller the overload counter threshold is set. Therefore, the greater the cumulative damage to the battery pack, the earlier the counter value will reach the overload counter threshold. Accordingly, the more usage history the battery pack has, the higher the increase rate of the usage history can be improved. Furthermore, the battery pack can be protected earlier.

[0032] The battery pack according to another aspect of the present invention includes a control unit. The control unit is configured to perform a threshold setting process of setting a parameter threshold according to the usage history of the battery pack, and a prohibition process of prohibiting discharging from the battery pack when the operation parameter of the battery pack reaches the parameter threshold set in the threshold setting process.

[0033] With the above battery pack, a parameter threshold is set according to the usage history of the battery pack, and when the operation parameter of the battery pack reaches the set parameter threshold, discharging from the battery pack is prohibited. Therefore, according to the usage history of the battery pack, the time to reach the parameter threshold of the operation parameter changes, so the battery pack can be appropriately protected according to the usage history of the battery pack.

[0034] In addition, the operation parameter may include the temperature of the battery pack. The parameter threshold may include a protection temperature threshold. The control unit may be configured to set the protection temperature threshold to be smaller when the usage history is more in the threshold setting process. In the prohibition process, discharging is prohibited when the temperature of the battery pack reaches the protection temperature threshold.

[0035] The more usage history there is, the smaller the protection temperature threshold is set. When the temperature of the battery pack reaches the protection temperature threshold, discharging from the battery pack is prohibited. Therefore, the greater the cumulative damage to the battery pack, the earlier the temperature of the battery pack will reach the protection temperature threshold to prohibit discharging from the battery pack. Accordingly, the battery pack can be appropriately protected according to the usage history of the battery pack.

[0036] In addition, the control unit may also have a counter value. The operation parameter may also include the counter value. The parameter threshold may also include a protection counter threshold. The control unit may be configured to perform a discharge-time calculation process of calculating an addition value and a discharge-time update process of updating the counter value to a value obtained by adding the addition value to the counter value when discharging the battery pack. Furthermore, the control unit may be configured to set the protection counter threshold to be smaller when the usage history is more in the threshold setting process, and in the prohibition process, discharging is prohibited when the counter value reaches the protection counter threshold.

[0037] The more usage history there is, the smaller the protection counter threshold is set. When the counter value reaches the protection counter threshold, discharging from the battery pack is prohibited. Therefore, the greater the cumulative damage to the battery pack, the earlier the counter value will reach the protection counter threshold to prohibit discharging from the battery pack. Accordingly, the battery pack can be appropriately protected according to the usage history of the battery pack.

[0038] In addition, the control unit may be configured to: when the battery pack is charging, execute a charging-time calculation process for calculating a value less than 0, that is, a subtraction value, and a charging-time update process for updating the counter value to a value obtained by adding the subtraction value to the counter value.

[0039] Even during charging, by updating the counter value, the counter value can be replaced with a value that appropriately represents the state of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a view showing the appearance of the battery pack according to the first embodiment.

[0041] Figure 2 It is a view showing the circuit configuration of the battery pack and the power tool according to the first embodiment.

[0042] Figure 3 It is a view showing the circuit configuration of the battery pack and the charger according to the first embodiment.

[0043] Figure 4A It is a part of the flowchart showing the overcurrent-based discharge prohibition determination process according to the first embodiment.

[0044] Figure 4B It is the remaining part of the flowchart showing the overcurrent-based discharge prohibition determination process according to the first embodiment.

[0045] Figure 5 It is a flowchart showing the temperature-based discharge prohibition determination process according to the first embodiment.

[0046] Figure 6 It is a view showing three types of mappings between the addition value and the discharge current according to the first embodiment.

[0047] Figure 7 It is shown using Figure 6 A view showing the relationship between the discharge current and the time to reach over-discharge determination and discharge stop in the case of using the three types of mappings shown.

[0048] Figure 8A It is a part of the flowchart showing the overcurrent-based discharge prohibition determination process according to the second embodiment.

[0049] Figure 8B It represents the remaining part of the flowchart of the overcurrent-based discharge prohibition determination process according to the second embodiment.

[0050] Description of Reference Numerals

[0051] 10... Power tool; 40... Battery pack; 42... Connector portion; 44... Power terminal portion; 44... Second power terminal portion; 44... First power terminal portion; 44A... Positive terminal; 44B... Negative terminal; 46... Connection terminal portion; 46A, 46B, 46C... Signal terminals; 50... Battery; 60... Battery control circuit; 62... Current measurement circuit; 64... Voltage measurement circuit; 66... Temperature measurement circuit; 68... Switch operation detection circuit; 70... MCU; 70a... CPU; 70b... Memory; 72... Charger detection circuit; 80... Charger; M1... Motor. Detailed Embodiment

[0052] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0053] (First Embodiment)

[0054] <1 - 1. Configuration>

[0055] <1 - 1 - 1. Configuration of Battery Pack>

[0056] First, with reference to Figure 1 , the configuration of the battery pack 40 according to this embodiment will be described. When the battery pack 40 is assembled to the power tool 10 described later, it supplies power to the power tool 10. In addition, when the battery pack 40 is assembled to the charger 80 described later, it receives power from the charger 80.

[0057] The battery pack 40 includes: a connector portion 42 for electrical and mechanical connection to the power tool 10 or the charger 80. The connector portion 42 includes: two power terminal portions 44 and a connection terminal portion 46.

[0058] Among the two power terminal portions 44, the first power terminal portion 44 includes: a groove extending in the longitudinal direction of the battery pack 40 and having an open end, and a positive terminal 44A provided in the groove. Among the two power terminal portions 44, the second power terminal portion 44 includes: a groove identical to the first power terminal portion 44, and a negative terminal 44B provided in the groove. The connection terminal portion 46 includes three signal terminals 46A, 46B, 46C.

[0059] By sliding the battery pack 40 in the first direction, the plate-shaped terminals of the power tool 10 or the charger 80 can be inserted into the two power terminal portions 44, whereby the battery pack 40 is electrically and mechanically connected to the power tool 10 or the charger 80. Further, by sliding the battery pack 40 in the second direction opposite to the first direction, the electrical and mechanical connection between the battery pack 40 and the power tool 10 or the charger 80 can be released.

[0060] <1-1-2. Circuit configuration of battery pack and power tool>

[0061] Next, with reference to Figure 2 , the circuit configuration of the battery pack 40 and the power tool 10 will be described. Examples of the power tool 10 include an impact driver, a hammer drill, a grinder, etc. Further, in the present embodiment, although the power tool 10 is described as the connection device that receives power from the battery pack 40, the connection device that receives power may also be a power-operated machine other than the power tool 10. For example, it may be a gardening tool such as a lawn mower, a hedge trimmer, a blower, etc.

[0062] The battery pack 40 includes: a battery 50, a battery control circuit 60, a positive terminal 44A, a negative terminal 44B, and three signal terminals 46A, 46B, 46C.

[0063] The battery 50 includes a plurality of battery cells connected in series. The battery 50 is, for example, a lithium-ion secondary battery or the like. The positive electrode of the battery 50 is connected to the positive terminal 44A via the positive-side power line L2A. The negative electrode of the battery 50 is connected to the negative terminal 44B via the negative-side power line L2B.

[0064] The battery control circuit 60 includes: a current measurement circuit 62, a voltage measurement circuit 64, a temperature measurement circuit 66, a switch operation detection circuit 68, a charger detection circuit 72, a main control unit (hereinafter referred to as MCU) 70, and a transistor Q4.

[0065] The current measurement circuit 62 detects the current flowing in the positive-side power line L2A or the negative-side power line L2B, and outputs a current detection signal corresponding to the detected current to the MCU 70.

[0066] The voltage measurement circuit 64 sequentially measures the voltages of the respective battery cells included in the battery 50, and outputs a voltage detection signal corresponding to the measured voltage to the MCU 70.

[0067] The temperature measurement circuit 66 includes a thermistor disposed around the storage battery 50. The temperature of the storage battery is measured by the thermistor, and a temperature detection signal corresponding to the measured temperature is output to the MCU 70.

[0068] The transistor Q4 includes an N-channel MOSFET. The source terminal of the transistor Q4 is connected to the ground terminal, and the gate terminal of the transistor Q4 is connected to the MCU 70. The drain terminal of the transistor Q4 is connected to the switch operation detection circuit 68 and the signal terminal 46A. Normally, a high-level signal is output from the MCU 70 to the transistor Q4, and the transistor Q4 becomes conductive. Moreover, when a discharge inhibition signal, which is a low-level signal, is output from the MCU 70 to the transistor Q4, the transistor Q4 becomes non-conductive.

[0069] The switch operation detection circuit 68 includes the transistor Q3 and the resistors R6, R7, and R8, and is used to detect that the start switch of the power tool 10 is switched to the ON state.

[0070] The transistor Q3 includes an NPN bipolar transistor. The base terminal of the transistor Q3 is connected to the first end of the resistor R6 and the first end of the resistor R7. The second end of the resistor R6 is connected to the drain terminal of the transistor Q4. The connection point of the resistor R6 and the transistor Q4 is connected to the signal terminal 46A.

[0071] The second end of the resistor R7 and the emitter terminal of the transistor Q3 are connected to the ground terminal in the battery pack 40.

[0072] The first end of the resistor R8 is connected to a power supply of the voltage Vdd (for example, DC 5V), and the second end of the resistor R8 is connected to the collector terminal of the transistor Q3. The connection point of the resistor 8 and the transistor Q3 is connected to the MCU 70.

[0073] In addition, the ground terminal of the battery pack 40 is connected to the negative-side power supply line L2B. Thus, when the battery pack 40 is assembled on the power tool 10, the ground terminals of the battery pack 40 and the power tool 10 are at the same potential, and the above-mentioned ground terminals are also at the same potential as the negative electrode of the storage battery 50.

[0074] When a high-level signal is input from the charger 80 to the signal terminal 46C, the charger detection circuit 72 inputs a detection signal indicating that the charger 80 is connected to the MCU 70. The charger detection circuit 72 is configured in the same way as the switch operation detection circuit 68.

[0075] The MCU 70 includes a CPU 70a and a memory 70b. The memory 70b includes a non-volatile memory and a volatile memory. The CPU 70a executes various processes according to various programs stored in the memory 70b.

[0076] When the battery pack 40 is not connected to the power tool 10 and the charger 80, the MCU 70 goes to sleep to suppress power consumption. The MCU 70 outputs a discharge inhibition signal in the sleep state. When the MCU 70 detects that it is connected to the power tool 10 or the charger 80, it wakes up. When the MUC 70 wakes up, it determines whether the battery pack 40 is in a dischargeable state. Moreover, as long as the battery pack 40 is in a dischargeable state, the MCU 70 stops outputting the discharge inhibition signal, and as long as the battery pack 40 is in a non-dischargeable state, the MCU 70 outputs the discharge inhibition signal.

[0077] Next, the power tool 10 includes: a motor M1, a drive switch SW1, a control power supply circuit 36, an input / output circuit 38, a transistor Q1, a work machine positive terminal 32A, a work machine negative terminal 32B, and a work machine signal terminal 34A.

[0078] The work machine positive terminal 32A is connected to the positive terminal 44A, and the work machine negative terminal 32B is connected to the negative terminal 44B. In addition, the work machine signal terminal 34A is connected to the signal terminal 46A.

[0079] The drive switch SW1 is provided on the positive power supply line L1A connected to the work machine positive terminal 32A. When the start switch of the power tool 10 is pulled (i.e., turned on), the drive switch SW1 turns on, and when the start switch is released (i.e., turned off), the drive switch SW1 turns off.

[0080] The transistor Q1 includes an N-channel MOSFET. The transistor Q1 is provided on the negative power supply line L1B connected to the work machine negative terminal 32B. The source terminal of the transistor Q1 is connected to the work machine negative terminal 32B, the drain terminal of the transistor Q1 is connected to the negative electrode of the motor M1. In addition, the gate terminal of the transistor Q1 is connected to the input / output circuit 38.

[0081] The motor M1 is a brushed DC motor. The positive electrode of the motor M1 is connected to the work machine positive terminal 32A via the positive power supply line L1A and the drive switch SW1. The negative electrode of the motor M1 is connected to the work machine negative terminal 32B via the negative power supply line L1B and the transistor Q1.

[0082] In addition, between the positive electrode and the negative electrode of the motor M1, a diode D1 is connected in such a way that the direction from the negative electrode to the positive electrode is the positive direction. The diode D1 is a so-called flywheel diode.

[0083] The control power supply circuit 36 includes a Zener diode ZD1, a capacitor C1, and a resistor R1, and generates a power supply voltage for driving the internal circuit of the power tool 10. The cathode of the Zener diode ZD1 is connected to the positive power supply line L1A via the resistor R1, and the anode of the Zener diode ZD1 is connected to the ground terminal of the power tool 10.

[0084] The capacitor C1 is an electrolytic capacitor. The positive electrode of the capacitor C1 is connected to the positive power supply line L1A via the resistor R1 together with the cathode of the Zener diode ZD1, and the negative electrode of the capacitor C1 is connected to the ground terminal of the power tool 10.

[0085] The input / output circuit 38 includes a transistor Q2 and resistors R2, R3, R4, and R5. The transistor Q2 includes an NPN bipolar transistor. The first terminal of the resistor R2 is connected to the power supply of the voltage Vcc, and the second terminal of the resistor R2 is connected to the first terminal of the resistor R3. The connection point of the resistor R2 and the resistor R3 is connected to the work machine signal terminal 34A.

[0086] The second terminal of the resistor R3 is connected to the first terminal of the resistor R4. The connection point of the resistor R3 and the resistor R4 is connected to the base terminal of the transistor Q2. The second terminal of the resistor R4 and the emitter terminal of the transistor Q2 are connected to the ground terminal.

[0087] The first terminal of the resistor R5 is connected to the power supply of the voltage Vcc, and the second terminal of the resistor R5 is connected to the collector terminal of the transistor Q2. The connection point of the resistor R5 and the transistor Q2 is connected to the gate terminal of the transistor Q1.

[0088] When the battery pack 40 is assembled to the power tool 10 and the start switch is pulled, the drive switch SW1 is switched to the ON state. Accordingly, the positive power supply line L1A is connected to the positive power supply line L2A of the battery pack 40 via the work machine positive terminal 32A.

[0089] Accordingly, in the control power supply circuit 36, the battery voltage is applied to the cathode of the Zener diode ZD1 from the positive power supply line L1A via the resistor R1, and is stepped down to a specified DC voltage (for example, 5V) by the Zener diode ZD1. Moreover, the capacitor C1 is charged by the stepped-down DC voltage, and the voltage between the two terminals of the capacitor C1 is supplied as the power supply voltage Vcc for driving the internal circuit of the power tool 10 to various internal circuits.

[0090] In addition, when the drive switch SW1 is switched to the ON state, the transistor Q4 becomes the cut-off state. As a result, a high-level signal corresponding to the power supply voltage Vcc in the battery pack 40 is input to the signal terminal 46A from the work machine signal terminal 34A. Accordingly, the transistor Q3 is switched from the cut-off state to the conduction state, and the signal input from the switch operation detection circuit 68 to the MCU 70 changes from the high level to the low level. The MCU 70 detects the connection of the power tool 10 based on the change of the input signal from the switch operation detection circuit 68 and wakes up from the sleep state.

[0091] In addition, when the MCU 70 stops outputting the discharge inhibition signal and the transistor Q4 is switched to the conduction state, the work machine signal terminal 34A is connected to the ground terminal, and the transistor Q2 is switched to the cut-off state. As a result, the power supply voltage Vcc is applied to the gate terminal of the transistor Q1, and the transistor Q1 is switched to the conduction state. On the other hand, when the MCU 70 outputs the discharge inhibition signal and the transistor Q4 is switched to the cut-off state, current flows through the base terminal of the transistor Q2, and the transistor Q2 is switched to the conduction state. As a result, since the gate terminal of the transistor Q1 is connected to the ground terminal, the transistor Q1 is switched to the cut-off state.

[0092] Therefore, when the start switch is pulled and the drive switch SW1 is in the ON state, and the MCU 70 stops outputting the discharge inhibition signal and the transistor Q1 is in the conduction state, the motor M1 is driven by receiving power supply from the battery pack 40.

[0093] <1-1-3. Circuit Configuration of Battery Pack and Charger>

[0094] Next, with reference to Figure 3 , the circuit configuration of the battery pack 40 and the charger 80 will be described. The charger 80 includes: a rectifier circuit 92, a charging switch power supply circuit 94, a control switch power supply circuit 98, an MCU 96, a charger positive terminal 84A, a charger negative terminal 84B, and charger signal terminals 86C and 86B.

[0095] The charger positive terminal 84A is connected to the positive terminal 44A, and the charger negative terminal 84B is connected to the negative terminal 44B. In addition, the charger signal terminal 86B is connected to the signal terminal 46B, and the charger signal terminal 86C is connected to the signal terminal 46C.

[0096] The rectifier circuit 92 rectifies the AC voltage supplied from an AC power source such as a commercial power source. The output rectified by the rectifier circuit 92 is output to the charging switch power supply circuit 94 and the control switch power supply circuit 98.

[0097] The charging switch power supply circuit 94 is a switch circuit that charges the battery 50 based on the output from the rectifier circuit 92 and is driven and controlled by the MCU 96.

[0098] Similar to the MCU 70 in the battery pack 40, the MCU 96 has a CPU and a memory, and is connected to the charger signal terminal 86B. The MCU 96 obtains the battery state from the MCU 70 of the battery pack 40 via the charger signal terminal 86B. Further, the MCU 96 drives and controls the charging switching power supply circuit 94 based on the obtained battery state.

[0099] The control switching power supply circuit 98 generates a power supply voltage Vee (e.g., DC 5V) for driving the internal circuits such as the MCU 96.

[0100] The ground terminal of the charger 80 is connected to the negative electrode of the battery 50 via the charger negative terminal 84B and the negative terminal 44B. Further, the charging voltage generated by the charging switching power supply circuit 94 is applied to the positive electrode of the battery 50 via the charger positive terminal 84A and the positive terminal 44A.

[0101] In addition, the power supply voltage Vee generated by the control switching power supply circuit 98 is applied to the charger signal terminal 86C.

[0102] Thus, when the battery pack 40 is assembled to the charger 80 and the power supply voltage Vee is generated by the control switching power supply circuit 98, a high-level signal corresponding to the power supply voltage Vee is input to the charger detection circuit 72 via the signal terminal 46C. Accordingly, the signal level of the detection signal input from the charger detection circuit 72 to the MCU 70 changes from high level to low level. The MCU 70 detects the connection of the charger 80 based on the switching of the input signal from the charger detection circuit 72 and wakes up from the sleep state.

[0103] <1-2. Process>

[0104] <1-2-1. Overcurrent-based Discharge Prohibition Determination Process>

[0105] Next, with reference to Figure 4A and Figure 4B the flowchart, the overcurrent-based discharge prohibition determination process executed by the MCU 70 of the battery pack 40 will be described. The MCU 70 starts executing the discharge prohibition determination process when the power tool 10 or the charger 80 is connected to the battery pack 40 and wakes up. The MCU 70 has a value of the history counter OLD_C and a value of the overcurrent counter.

[0106] First, in S10, it is determined whether the device connected to the battery pack 40 is the power tool 10 or the charger 80. If it is determined in S10 that the connected device is the power tool 10, the process proceeds to S20.

[0107] In S20, read: the detection signal of the discharge current detected by the current measurement circuit 62.

[0108] Next, in S30, determine whether the value of the history counter OLD_C is less than or equal to the set value Y1. The value of the history counter OLD_C represents the usage history of the battery pack 40. The value of the history counter OLD_C is incremented when the discharge state of the battery pack 40 satisfies a specified condition. Specifically, the value of the history counter OLD_C is incremented when the battery pack 40 operates in an overload state. The larger the value of the history counter OLD_C, the greater the cumulative damage to the battery pack 40. The initial value of the history counter OLD_C is 0.

[0109] In S30, when it is determined that the value of the history counter OLD_C is less than the set value Y1, the process proceeds to S40.

[0110] In S40, calculate an addition value based on the usage history of the battery pack 40. Specifically, use the isopleth diagram (counter map) of mode A to calculate the addition value. The addition value is a value to be added to the overcurrent counter value. The overcurrent counter value represents the load state of the battery pack 40 and is used for determining whether the battery pack 40 can be discharged and also for determining whether to increment the value of the history counter OLD_C. The initial value of the overcurrent counter is 0.

[0111] Figure 6 This is an example of an isopleth diagram. The isopleth diagram of mode A is a mapping used when the cumulative damage to the battery pack 40 is the smallest among three levels. The MCU 70 uses the isopleth diagram of mode A to calculate an addition value greater than or equal to 0 when the discharge current value is greater than or equal to a specified value, and calculates an addition value less than 0 when the discharge current value is less than the specified value. The larger the discharge current value, the larger the addition value.

[0112] On the other hand, in S30, when it is determined that the value of the history counter OLD_C is greater than the set value Y1, the process proceeds to S50.

[0113] In S50, determine whether the value of the history counter OLD_C is greater than the set value Y1 and less than the set value Y2. The set value Y2 is a value larger than the set value Y1. In S50, when it is determined that the value of the history counter OLD_C is greater than the set value Y1 and less than the set value Y2, the process proceeds to S60.

[0114] In S60, an isogram of pattern B is used to calculate the addition value. The isogram of pattern B is a mapping when the accumulated damage of the battery pack 40 is at the medium level among the three levels. When using counting pattern B, the addition value is calculated to be larger than when using counting pattern A.

[0115] On the other hand, in S50, when it is determined that the value of the history counter OLD_C is greater than the set value Y2, the process proceeds to S70.

[0116] In S70, an isogram of pattern C is used to calculate the addition value. The isogram of pattern C is a mapping when the accumulated damage of the battery pack 40 is the largest among the three levels. When using counting pattern C, the addition value is calculated to be larger than when using counting pattern B. That is, the larger the value of the history counter OLD_C, the larger the MCU70 calculates the addition value.

[0117] Next, in S80, the overcurrent counter value is updated. Specifically, the overcurrent counter value is updated to the following value, that is: the value obtained by adding the addition value calculated in any one of S40, S60, and S70 to the current overcurrent counter value.

[0118] Next, in S90, it is determined whether the overcurrent counter value is equal to or greater than the overload counter threshold X1. The overload counter threshold X1 is a preset value and is a threshold for determining whether the load state of the battery pack 40 is overloaded. Although the overloaded state does not need to prohibit the discharge of the battery pack 40, it is a load state in which the battery pack 40 accumulates damage.

[0119] In S90, when it is determined that the overcurrent counter value is equal to or greater than the overload counter threshold X1, the process proceeds to S100. When it is determined that the overcurrent counter value is less than the overload counter threshold X1, the process proceeds to S120.

[0120] In S100, it is determined whether the overload determination flag has become OFF. In S100, when it is determined that the overload determination flag has become OFF, the process proceeds to S110. When it is determined that the overload determination flag has become ON, the process proceeds to S120. The initial state of the overload determination flag is OFF.

[0121] In S110, the overload determination flag changes from OFF to ON.

[0122] In S120, it is determined whether the overcurrent counter value is equal to or greater than the protection counter threshold X2. The protection counter threshold X2 is a threshold for determining whether the battery pack 40 is in an overdischarged state. The overload counter threshold X1 is a value less than the protection counter threshold X2.

[0123] In S120, when it is determined that the overcurrent counter value is equal to or greater than the protection counter threshold X2, the process proceeds to S130. When it is determined that the overcurrent counter value is less than the protection counter threshold X2, the process proceeds to S140.

[0124] In S130, a discharge prohibition signal is output.

[0125] Next, in S140, it is determined whether to output a discharge prohibition signal. In S140, when it is determined not to output a discharge prohibition signal, the process proceeds to S180. On the other hand, in S140, when it is determined to output a discharge prohibition signal, the process proceeds to S150.

[0126] In S150, it is determined whether the battery temperature measured by the temperature measurement circuit 66 is equal to or lower than the temperature threshold. In S150, when it is determined that the battery temperature is greater than the temperature threshold, the process proceeds to S180. On the other hand, in S150, when it is determined that the battery temperature is equal to or lower than the temperature threshold, the process proceeds to S160.

[0127] In S160, it is determined whether the overcurrent counter value is 0. In S160, when it is determined that the overcurrent counter value is greater than 0, the process proceeds to S180. On the other hand, in S160, when it is determined that the overcurrent counter value is 0, the process proceeds to S170.

[0128] In S170, the output of the discharge prohibition signal is stopped. That is, since the battery temperature is low enough and the overcurrent counter value is decreasing, it is determined that the battery pack 40 has recovered from the overdischarged state, and the output of the discharge prohibition signal is stopped.

[0129] Next, in S180, it is determined whether the power tool 10 is connected. In S180, when it is determined that the power tool 10 is connected, the process returns to S20. On the other hand, in S180, when it is determined that the power tool 10 is not connected, that is, when it is determined that the battery pack 40 has been detached from the power tool 10, the overcurrent counter value, the value of the history counter OLD_C, and the setting of the overload determination flag are stored in the memory 70b, and this process is terminated.

[0130] In addition, in S10, when it is determined that the connected device is the charger 80, the process proceeds to S190.

[0131] In S190, it is determined whether the overload determination flag is ON. In S190, if it is determined that the overload flag is ON, the process proceeds to S200. If it is determined that the overload determination flag is OFF, the process proceeds to S220.

[0132] In S200, the value of the history counter OLD_C is incremented by "1". That is, when the battery pack 40 is overloaded during the period from the previous charge to the current charge, the value of the history counter OLD_C is updated during the current charge. Accordingly, the value of the history counter OLD_C becomes a value corresponding to the number of operations when the battery pack 40 is overloaded. In this way, the value of the history counter OLD_C is updated during charging instead of discharging, making the discharge prohibition determination process easier.

[0133] Next, in S210, the overload determination flag changes from ON to OFF.

[0134] Next, in S220 - S270, the same processing as in S30 - S80 is executed. However, in S230, S250, and S260, instead of adding values, a subtraction value less than 0 is calculated. For example, in S230, S250, and S260, in the isopleth diagrams of modes A, B, and C, when the discharge current value is 0, a subtraction value less than 0 is calculated as the subtraction value. Here too, the larger the value of the history counter OLD_C, the larger the subtraction value calculated by the MCU70, that is, the smaller the absolute value of the subtraction value.

[0135] Next, in S280, it is determined whether charging has started. In S280, if it is determined that charging has not started, the process returns to S220. If it is determined that charging has started, the process proceeds to S290.

[0136] In S290, the output of the discharge prohibition signal is stopped.

[0137] In S300 - S350, the same processing as in S220 - S270 is executed. Next, in S360, it is determined whether charging has ended. In S360, if it is determined that charging has not ended, the process returns to S300. On the other hand, in S360, if it is determined that charging has ended, the overcurrent counter value, the value of the history counter OLD_C, and the setting of the overload determination flag are stored in the memory 70b, and this process is terminated.

[0138] Figure 7The arrival times indicated are as described below, that is, they are: in the overcurrent-based discharge inhibition determination process according to the first embodiment, when the isopleth diagrams of modes A, B, and C are used, the arrival time until overload determination and the arrival time until discharge stop. As Figure 7 shown, at the same discharge current value, when using the isopleth diagram of mode B, compared with the case of using the isopleth diagram of mode A, the arrival time until over-discharge determination and the arrival time until discharge stop are shorter. In addition, at the same discharge current value, when using the isopleth diagram of mode C, compared with the case of using the isopleth diagram of mode B, the arrival time until over-discharge determination and the arrival time until discharge stop become even shorter. That is, the greater the accumulated damage of the battery pack 40, the earlier the overload determination is performed, the easier it is for the value of the history counter OLD_C to increase, and the battery pack 40 can be protected earlier.

[0139] <1-2-2. Discharge inhibition determination process based on temperature>

[0140] Next, with reference to Figure 5 the flowchart, the discharge inhibition determination process based on the battery temperature executed by the MCU 70 of the battery pack 40 will be described. When the MCU 70 detects that the power tool 10 is connected to the battery pack 40, this process is executed in parallel with the Figure 4A and Figure 4B shown flowcharts.

[0141] First, in S400, the battery temperature measured by the temperature measurement circuit 66 is read.

[0142] Next, in S410, it is determined whether the value of the history counter OLD_C is equal to or less than the set value Y1. When it is determined in S410 that the value of the history counter OLD_C is equal to or less than the set value Y1, the process proceeds to S420.

[0143] In S420, the first set value Z1a of mode A is set as the first protection temperature threshold Z1, and the second set value Z2a of mode A is set as the second protection temperature threshold Z2. The first protection temperature threshold Z1 is a threshold for determining whether the battery pack 40 is in an overload state that can cause damage to the battery 50. The second protection temperature threshold Z2 is a threshold for determining whether the battery pack 40 is in a temperature state where it can be used.

[0144] On the other hand, when it is determined that the value of the history counter OLD_C is greater than the set value Y1, the process proceeds to S430.

[0145] In S430, it is determined whether the value of the history counter OLD_C is greater than the set value Y1 and less than the set value Y2. When it is determined in S430 that the value of the history counter OLD_C is greater than the set value Y1 and less than the set value Y2, the process proceeds to S440.

[0146] In S440, the first set value Z1b of mode B is set as the first protection temperature threshold Z1, and the second set value Z2b of mode B is set as the second protection temperature threshold Z2. The first set value Z1a > the first set value Z1b, and the second set value Z2a > the second set value Z2b.

[0147] On the other hand, when it is determined in S430 that the value of the history counter OLD_C is greater than the set value Y2, the process proceeds to S450.

[0148] In S450, the first set value Z1c of mode C is set as the first protection temperature threshold Z1, and the second set value Z2c of mode C is set as the second protection temperature threshold Z2. The first set value Z1b > the first set value Z1c, and the second set value Z2b > the second set value Z2c.

[0149] Next, in S460, it is determined whether the battery temperature is equal to or higher than the first protection temperature threshold Z1. When it is determined in S460 that the battery temperature is equal to or higher than the first protection temperature threshold Z1, the process proceeds to S470. When it is determined that the battery temperature is less than the first protection temperature threshold Z1, the process proceeds to S480.

[0150] In S470 and S480, the same processing as in S100 and S110 is executed.

[0151] Next, in S490, it is determined whether the battery temperature is equal to or higher than the second protection temperature threshold Z2. When it is determined in S490 that the battery temperature is equal to or higher than the second protection temperature threshold Z2, the process proceeds to S500. When it is determined that the battery temperature is less than the second protection temperature threshold Z2, the process proceeds to S510.

[0152] Next, in S500 to S550, the same processing as in S130 to S180 is executed.

[0153] By executing the discharge prohibition process based on the battery temperature according to the first embodiment, the larger the value of the history counter OLD_C, that is, the greater the accumulated damage of the battery pack 40, the earlier the battery temperature will reach the first protection temperature threshold Z1, and the value of the history counter OLD_C is likely to increase. In addition, the larger the value of the history counter OLD_C, the earlier the battery temperature will reach the second protection temperature threshold Z2, and the battery pack 40 can be protected earlier.

[0154] <1 - 3. Effects>

[0155] According to the first embodiment described above, the following effects can be obtained.

[0156] (1) According to the value of the history counter OLD_C, calculate the addition value, and add the calculated addition value to the overcurrent counter value to update the overcurrent counter value. Moreover, when the overcurrent counter value reaches the protection counter threshold X2, discharging from the battery pack 40 is prohibited. Therefore, according to the usage history of the battery pack 40, the time when the overcurrent counter value reaches the protection counter threshold X2 changes. Therefore, according to the usage history of the battery pack 40, the battery pack 40 can be appropriately protected.

[0157] (2) The larger the value of the history counter OLD_C, the larger the calculated addition value. Therefore, the greater the accumulated damage of the battery pack 40, the earlier the overcurrent counter value will reach the protection counter threshold X2. Based on this, according to the usage history of the battery pack 40, the battery pack 40 can be appropriately protected.

[0158] (3) When the discharge current value is equal to or greater than the specified value, calculate an addition value of 0 or more. When the discharge current value is less than the specified value, calculate an addition value of less than 0. Based on this, when the discharge current value is equal to or greater than the specified value, the greater the accumulated damage of the battery pack, the more rapidly the counter value will increase. When the discharge current value is less than the specified value, the greater the accumulated damage of the battery pack 40, the more slowly the overcurrent counter value will decrease. Based on this, according to the usage history of the battery pack 40, the battery pack 40 can be appropriately protected.

[0159] (4) Use the number of operations of the battery pack 40 whose overcurrent counter value exceeds the overload counter threshold X1 as the usage history. Thus, it is possible to achieve protection of the battery pack 40 corresponding to the damage accumulated in the battery pack 40.

[0160] (5) Use the number of operations of the battery pack 40 whose battery temperature exceeds the first protection temperature threshold Z1 as the usage history. Thus, it is possible to achieve protection of the battery pack 40 corresponding to the damage accumulated in the battery pack 40.

[0161] (6) When the battery pack 40 is charging, calculate a subtraction value less than 0, and update the overcurrent counter value to the value obtained by adding the subtraction value to the overcurrent counter value. Even during charging, by updating the overcurrent counter value, the overcurrent counter value can be replaced with a value that appropriately represents the state of the battery pack 40.

[0162] (7) Even when charging, the greater the cumulative damage of the battery pack 40, the more slowly the overcurrent counter value decreases. Accordingly, based on the usage history of the battery pack 40, the battery pack 40 can be appropriately protected.

[0163] (8) When the battery pack 40 is discharging and the overload determination flag is set to ON, the value of the history counter OLD_C is incremented during the next charging. Accordingly, compared to the case where the value of the history counter OLD_C is incremented during discharging, the discharge prohibition determination process becomes easier, thereby reducing the processing load.

[0164] (9) The larger the value of the history counter OLD_C, the smaller the first protection temperature threshold Z1 is set, and the earlier the battery temperature reaches the first protection temperature threshold Z1. Therefore, it is easy to increase the value of the history counter OLD_C. In addition, the larger the value of the history counter OLD_C, the smaller the second protection temperature threshold Z2 is set, and the earlier the battery temperature reaches the second protection temperature threshold Z2. Therefore, the battery pack 40 can be protected earlier. Accordingly, based on the usage history of the battery pack, the battery pack can be appropriately protected.

[0165] (Second Embodiment)

[0166] <2-1. Differences from the First Embodiment>

[0167] The basic configuration of the second embodiment is the same as that of the first embodiment. Therefore, the description of the common configuration is omitted, and only the differences will be mainly described. In addition, the same reference numerals as those in the first embodiment denote the same components, and reference may be made to the previous description.

[0168] In the above first embodiment, in the discharge prohibition determination process based on overcurrent, different equal-line graphs are used according to the value of the history counter OLD_C, and the larger the value of the history counter OLD_C, the larger the addition value is calculated. In contrast, in the second embodiment, regardless of the value of the history counter OLD_C, the same equal-line graph is used, and it is different from the first embodiment in that the overload counter threshold X1 and the protection counter threshold X2 are changed according to the value of the history counter OLD_C.

[0169] <2-2. Processing>

[0170] <2-2-1. Discharge Determination Process Based on Overcurrent>

[0171] Next, referring to Figure 8A and Figure 8BFlowchart showing the overcurrent-based discharge inhibition determination process executed by the MCU 70 of the battery pack 40. When the MCU 70 wakes up by connecting the power tool 10 or the charger 80 to the battery pack 40, it starts executing the discharge inhibition determination process. The MCU 70 has the value of the history counter OLD_C and the overcurrent counter value. In addition, when the MCU 70 detects that the power tool 10 is connected to the battery pack 40, it executes in parallel with this process Figure 5 the flowchart shown.

[0172] First, in S600 and S610, the same processing as in S10 and S20 is executed.

[0173] Next, in S620, an addition value is calculated using an isometric line diagram. For example, using Figure 6 the isometric line diagram of Mode B shown, an addition value is calculated. In this embodiment, regardless of the magnitude of the value of the history counter OLD_C, the same isometric line diagram is used.

[0174] Next, in S630, the same processing as in S80 is executed.

[0175] Next, in S640, it is determined whether the value of the history counter OLD_C is below the set value Y1. If it is determined in S640 that the value of the history counter OLD_C is below the set value Y1, the process proceeds to S650.

[0176] In S650, the first set value X1a of Mode A is set as the overload counter threshold X1, and the second set value X2a of Mode A is set as the protection counter threshold X2. On the other hand, if it is determined that the value of the history counter OLD_C is greater than the set value Y1, the process proceeds to S660.

[0177] In S660, it is determined whether the value of the history counter OLD_C is greater than the set value Y1 and less than the set value Y2. If it is determined in S660 that the value of the history counter OLD_C is greater than the set value Y1 and less than the set value Y2, the process proceeds to S670.

[0178] In S670, the first set value X1b of Mode B is set as the overload counter threshold X1, and the second set value X2b of Mode B is set as the protection counter threshold X2. The first set value X1a > the first set value X1b, and the second set value X2a > the second set value X2b.

[0179] On the other hand, if it is determined in S660 that the value of the history counter OLD_C is greater than the set value Y2, the process proceeds to S680.

[0180] In S680, set the first setting value X1c of mode C to the overload counter threshold X1, and set the second setting value X2c of mode C to the protection counter threshold X2. The first setting value X1b > the first setting value X1c, and the second setting value X2b > the second setting value X2c.

[0181] Next, in S690 - S780, perform the same processing as in S90 - S180.

[0182] On the other hand, in S600, if it is determined that the connected device is the charger 80, proceed to the processing in S790.

[0183] In S790 - S810, perform the same processing as in S190 - S210.

[0184] Next, in S820, calculate the subtraction value. For example, in the isopleth diagram of mode B, calculate the addition value less than 0 when the discharge current value is 0 as the subtraction value. Here too, regardless of the magnitude of the value of the history counter OLD_C, the same isopleth diagram is used. Additionally, a pre-set subtraction value can also be used.

[0185] Next, in S830 - S850, perform the same processing as in S270 - S290.

[0186] Next, in S860, calculate the subtraction value in the same way as in S820.

[0187] Next, in S870 and S880, perform the same processing as in S350 and S360.

[0188] Execute the overcurrent-based discharge prohibition process according to the second embodiment. The larger the value of the history counter OLD_C, that is, the greater the accumulated damage of the battery pack 40, the earlier the overcurrent counter value will reach the overload counter threshold X1, and the value of the history counter OLD_C is likely to increase. Additionally, the larger the value of the history counter OLD_C, the earlier the overcurrent counter value will reach the protection counter threshold X2, and the battery pack 40 can be protected earlier.

[0189] <2 - 3. Effects>

[0190] According to the second embodiment described above, in addition to the effects (4) - (6), (8), (9) of the first embodiment, the following effects can also be obtained.

[0191] (10) The larger the value of the history counter OLD_C, the smaller the protection counter threshold X2 is set. Therefore, the greater the accumulated damage to the battery pack 40, the earlier the overcurrent counter value will reach the protection counter threshold X2 to prohibit the discharge of the battery pack 40. Accordingly, the battery pack 40 can be appropriately protected according to the usage history of the battery pack 40.

[0192] (11) The larger the value of the history counter OLD_C, the smaller the overload counter threshold X1 is set. Therefore, the greater the accumulated damage to the battery pack 40, the earlier the overcurrent counter value will reach the overload counter threshold X1. Accordingly, the larger the value of the history counter OLD_C, the easier it is for the value of the history counter OLD_C to increase, and the battery pack 40 can be protected earlier.

[0193] (Other embodiments)

[0194] As described above, although the embodiments of the present invention have been described, the present invention is not limited to the above embodiments and can be implemented with various modifications.

[0195] (a) In the second embodiment, although the Figure 4A and Figure 4B flowcharts related to the first embodiment are replaced and the Figure 8A and Figure 8B flowcharts are executed, the two flowcharts can also be executed in parallel. That is, the following can be executed in parallel: Figure 4A and Figure 4B the flowcharts shown, Figure 5 the flowchart shown, and Figure 8A and Figure 8B the flowcharts shown. In addition, only the Figure 4A and Figure 4B the flowcharts shown, Figure 5 the flowchart shown, Figure 8A and Figure 8B one of the three flowcharts shown can be executed. In the case of parallel execution, the addition calculation of the history counter OLD_C can be performed by making the following two determination flags common, or the determination flags can be set in different history counters by making them different respectively. That is, the above two determination flags are: a determination flag set to ON when the overcurrent counter exceeds the overload protection counter threshold, and a determination flag set to ON when the battery temperature exceeds the first protection temperature threshold.

[0196] (b) According to the above-described embodiment, when the overload determination flag is set to ON, although the value of the history counter OLD_C is increased during charging, the present invention is not limited thereto. That is, the value of the history counter OLD_C may also be increased during discharging. In this case, each time the overcurrent counter value reaches the overload counter threshold X1, the value of the history counter OLD_C may be increased by "1" during charging. Alternatively, when the number of times the overcurrent counter value reaches the overload counter threshold X1 is a specified number, the value of the history counter OLD_C may be increased by "1" during charging.

[0197] (c) As the usage history, it is also possible to use: the number of times the battery pack 40 operates in a low-temperature environment where the temperature of the surrounding environment is relatively low compared to the reasonable operating range, and the number of times the battery pack 40 operates in a high-temperature environment where the temperature of the surrounding environment is relatively high compared to the reasonable operating range. The reasonable operating range is preset according to the type of the battery pack 40. In addition, as the usage history, it is also possible to use: the number of times the discharge of the battery pack 40 is prohibited. That is, as the usage history, it is also possible to use: the number of times the overcurrent counter value reaches the protection counter threshold X2, and the number of times the battery temperature reaches the second protection temperature threshold Z2.

[0198] (d) According to the above-described embodiment, although the subtraction value is calculated and the overcurrent counter value is updated during charging of the battery pack 40, the overcurrent counter value may not be updated during charging.

[0199] (e) In addition, multiple functions of one component in the above-described embodiment may be implemented by multiple components, or one function of one component may be implemented by multiple components. In addition, multiple functions of multiple components may be implemented by one component, or one function implemented by multiple components may be implemented by one component. In addition, a part of the configuration of the above-described embodiment may be omitted. In addition, at least a part of the configuration of the above-described embodiment may be added to the configuration of other above-described embodiments, or at least a part of the configuration of the above-described embodiment may be replaced with the configuration of other above-described embodiments.

Claims

1. A battery pack, the battery pack comprising: a control unit having a counter value, characterized in that the control unit is configured to: during discharge of the battery pack, perform a discharge-time calculation process for calculating an addition value based on the usage history of the battery pack, a discharge-time update process for updating the counter value to a value obtained by adding the addition value to the counter value, and a prohibition process for prohibiting discharge from the battery pack when the counter value reaches a specified protection counter threshold; the usage history of the battery pack is represented by the value of a history counter, and the value of the history counter is incremented when the counter value exceeds an overload counter threshold and / or the temperature of the battery pack exceeds a specified protection temperature threshold.

2. The battery pack according to claim 1, characterized in that the control unit is configured to: in the discharge-time calculation process, the more the usage history, the larger the addition value is calculated.

3. The battery pack according to claim 1 or 2, characterized in that the addition value is a value of 0 or more when the discharge current value is equal to or greater than a specified value, and a value of 0 or less when the discharge current is less than the specified value.

4. The battery pack according to claim 1 or 2, characterized in that the overload counter threshold is set to a value smaller than the protection counter threshold.

5. The battery pack according to claim 1 or 2, characterized in that the control unit is configured to: during charging of the battery pack, perform a charge-time calculation process for calculating a subtraction value, which is a value less than 0, based on the usage history, and a charge-time update process for updating the counter value to a value obtained by adding the subtraction value to the counter value.

6. The battery pack according to claim 5, characterized in that the control unit is configured to: in the charge-time calculation process, the more the usage history, the larger the subtraction value is calculated.

7. The battery pack according to claim 1 or 2, characterized in that the control unit is configured to: during charging of the battery pack, when the load state of the battery pack during the period from the previous charge to the current charge satisfies a specified condition, perform a history process for incrementing the usage history.

8. The battery pack according to claim 1 or 2, characterized in that the control unit is configured to: during discharge of the battery pack, perform a protection threshold setting process for setting the protection counter threshold based on the usage history.

9. The battery pack according to claim 8, characterized in that the control unit is configured to: in the protection threshold setting process, the more the usage history, the smaller the protection counter threshold is set.

10. The battery pack according to claim 4, characterized in that the control unit is configured to: during discharge of the battery pack, perform an overload threshold setting process for setting the overload counter threshold based on the usage history.

11. The battery pack according to claim 10, characterized in that The control unit is configured such that in the overload threshold setting process, the more the usage history, the smaller the overload counter threshold is set.

12. A battery pack, characterized in that the battery pack includes a control unit, the control unit is configured to perform a threshold setting process for setting a parameter threshold according to the usage history of the battery pack, and a prohibition process for prohibiting discharging from the battery pack when the operation parameter of the battery pack reaches the parameter threshold set in the threshold setting process, the control unit has a counter value, the operation parameter includes the counter value, the parameter threshold includes a protection counter threshold, the usage history of the battery pack is represented by the value of a history counter, and the value of the history counter is incremented when the counter value exceeds an overload counter threshold, the control unit is configured to perform a discharge-time calculation process for calculating an addition value and a discharge-time update process for updating the counter value to a value obtained by adding the addition value to the counter value when the battery pack discharges, the control unit is configured such that in the threshold setting process, the more the usage history, the smaller the protection counter threshold is set, and in the prohibition process, discharging is prohibited when the counter value reaches the protection counter threshold.

13. The battery pack according to claim 12, characterized in that the value of the history counter is also incremented when the temperature of the battery pack exceeds a specified protection temperature threshold, the operation parameter includes the temperature of the battery pack, the parameter threshold includes the protection temperature threshold, the control unit is configured such that in the threshold setting process, the more the usage history, the smaller the protection temperature threshold is set, and in the prohibition process, discharging is prohibited when the temperature of the battery pack reaches the protection temperature threshold.

14. The battery pack according to claim 12, characterized in that the control unit is configured to perform a charge-time calculation process for calculating a subtraction value that is less than 0 and a charge-time update process for updating the counter value to a value obtained by adding the subtraction value to the counter value when the battery pack is charged.

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