Monitoring system and method for a battery pack

Abstract

The present disclosure is directed to a monitoring system and method for monitoring a battery pack. The battery pack includes a fuse circuit and a protection circuit. The protection circuit includes (A) an overvoltage protection circuit, (B) a temperature sensing / monitoring circuit, (C) a first terminal OV coupled internally to the overvoltage protection circuit and externally to the control module and to a most positive terminal of the plurality of battery cells through a resistor and (D) a second terminal Z coupled internally to the overvoltage protection circuit and to the temperature sensing / monitoring circuit and externally to the fuse circuit.

Description

Title: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142Monitoring System and Method for a Battery PackRELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Serial No. 63 / 697,248, filed September, 20, 2024, titled "Monitoring System and Method for a Battery Pack," which is incorporated by reference in its entirety.BACKGROUND

[0002] Generally, monitoring and controlling the current and temperature of a Li-Ion battery pack during charging and discharging is critical to its safety.SUMMARY

[0003] An aspect of the present invention includes a battery pack including a system for monitoring the temperature and current of a battery pack. An example embodiment of the battery pack comprises a housing, a plurality of battery cells connected in series, a plurality of battery pack terminals, a control module, the control module coupled to the plurality of battery cells to monitor the voltage of one or more of the plurality of battery cells, a fuse circuit, and a protection circuit, the protection circuit including (A) an overvoltage protection circuit, (B) a temperature sensing / monitoring circuit, (C) a first terminal OV coupled internally to the overvoltage protection circuit and externally to the control module and to a most positive terminal of the plurality of battery cells through a resistor and (D) a second terminal Z coupled internally to the overvoltage protection circuit and to the temperature sensing / monitoring circuit and externally to the fuse circuit.

[0004] In some aspects, the embodiments described herein relate to a battery pack, wherein the overvoltage protection circuit includes a first terminal OV1 and a second terminal Zl.

[0005] In some aspects, the embodiments described herein relate to a battery pack, wherein the first terminal OV1 of the overvoltage protection circuit is connected to the first terminal OV of the protection circuit and the second terminal Zl of the overvoltage protection circuit is connected to the second terminal Z of the protection circuit.Title: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142

[0006] In some aspects, the embodiments described herein relate to a battery pack, wherein the overvoltage protection circuit includes a control circuit and a switch.

[0007] In some aspects, the embodiments described herein relate to a battery pack, wherein the control circuit includes a first terminal OV2 connected to the first terminal OV1 of the overvoltage protection circuit and a second terminal Cl connected to the switch.

[0008] In some aspects, the embodiments described herein relate to a battery pack, wherein the control circuit includes a timer, the timer including an RC circuit, a switch and a capacitor bank.

[0009] In some aspects, the embodiments described herein relate to a battery pack, wherein the RC circuit includes a first terminal and a second terminal, the first terminal of the RC circuit connected to the first terminal OV1 of the overvoltage protection circuit and the second terminal of the RC circuit connected to a node N1 and the node N1 connected to the second, control terminal Cl of the control circuit.

[0010] In some aspects, the embodiments described herein relate to a battery pack, wherein the switch includes a first (control) terminal Gl, a second terminal SI, and a third terminal DI, the control terminal Gl of the switch connected to the control terminal Cl of the control circuit, the second terminal SI of the first switch connected to a first voltage source VI and the third terminal DI of the first switch connected to the output terminal Z1 of the overvoltage protection circuit.

[0011] In some aspects, the embodiments described herein relate to a battery pack, wherein the fuse circuit includes a 3-terminal fuse.

[0012] In some aspects, the embodiments described herein relate to a battery pack, wherein the fuse circuit includes a fuse switch and a 3-terminal fuse, the fuse switch of the fuse circuit including a first terminal connected to an input terminal Z of the fuse circuit, a second terminal connected to the 3-terminal fuse, and a third terminal connected to a ground.

[0013] In some aspects, the embodiments described herein relate to a battery pack, wherein the 3-terminal fuse includes a first terminal 1 connected to the B+ terminal of the plurality ofTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142 battery cells, a second terminal 2 connected to the BT2 / batt+ terminal of the battery pack and a third terminal 3 connected to the second terminal of the fuse switch of the fuse circuit, the 3- terminal fuse including a resistive heating element.

[0014] In some aspects, the embodiments described herein relate to a battery pack, wherein the fuse switch of the fuse circuit includes two MOSFET switches Q3 and Q4 and the fuse of the fuse circuit includes two 3-terminal fuses, each 3-terminal fuse including two fuse elements, the fuse elements of each 3-terminal fuse connected in series in a charging path between the B+ terminal and the BT2 / batt+ terminal.

[0015] In some aspects, the embodiments described herein relate to a battery pack, wherein the resistive heating element of each 3-terminal fuse includes a first terminal connected to a node at the connection of the first fuse element and the second fuse element and a second terminal connected to the third terminal of the fuse.

[0016] In some aspects, the embodiments described herein relate to a battery pack, wherein each of the switches Q3, Q4 includes a gate terminal connected to the input terminal Z of the fuse circuit, a drain terminal connected to the third terminal of the 3-terminal fuse, and a source terminal connected to a ground and each of the 3-terminal fuses includes a first terminal 1 connected to the B+ terminal of the plurality of battery cells, a second terminal 2 connected to the BT2 / batt + terminal of the battery pack, and a third terminal 3 connected to the drain terminal of one of the switches Q3, Q4 of the fuse switch.

[0017] In some aspects, the embodiments described herein relate to a battery pack, wherein the first 3-terminal fuse and the second 3-terminal fuse are connected in parallel between the BT2 / batt+ battery pack terminal and B+ cell stack terminal.

[0018] These and other advantages and features will be apparent from the description and the drawings.TECHNICAL FIELD

[0019] This application relates to a battery pack and a method for monitoring a battery pack. In one implementation, the battery pack includes a protection circuit and a fuse.Title: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1A is a schematic block diagram of an example battery pack and an example charger of an example power tool system.

[0021] FIG. IB is a schematic block diagram of an example battery pack and an example power tool of an example power tool system.

[0022] FIG. 2 is a schematic block diagram of an example protection circuit of the battery pack of FIGs. lA and IB.

[0023] FIG. 3 is a schematic block diagram of another example protection circuit of the battery pack of FIGs. 1A and IB.

[0024] FIG. 4 is an example graph of the operation of the protection circuit of FIGs. 2 and 3.

[0025] FIG. 5 is a schematic block diagram of an example temperature sensing / monitoring circuit of the battery pack of FIGs. 1A and IB.

[0026] FIG. 6 is a schematic block diagram of another example temperature sensing / monitoring circuit of the battery pack of FIGs. 1A and IB.

[0027] FIG. 7 is a schematic block diagram of an example fuse circuit of the battery pack ofFIGs. lA and IB.

[0028] FIG. 8 is a schematic block diagram of another example fuse circuit of the battery pack of FIGs. lA and IB.DETAILED DESCRIPTION

[0029] A cordless power tool system 10 may include a battery pack 12, a battery pack charger 14 and a power tool 60.

[0030] Referring to FIG. 1A, the pack charger 14 may include a battery charger control module 16. The control module 16 may be or be referred to as a charger processing circuit 16 and may include, among other components, a microcontroller, a microprocessor or another type ofTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142 integrated circuit. The charger processing circuit 16 may also simply be or simply be referred to as a charger microprocessor or charger controller or simply a controller. The charger processing circuit 16 may also be or be referred to as a charger management system (CMS). The charger 14 may also include a set (plurality) of charger terminals CT1, CT2, CT3, CT4. The set of charger terminals may include a subset of power terminals CT1 (charger -) and CT2 (charger +). The set of charger terminals may also include a subset of signal terminals CT3 (ID) and CT4 (TH). The charger 14 may also include a power supply 18 for converting AC power to DC power and providing DC power to the battery pack 12. The charger 14 may also include a plug 17 and cordset 19 for electrically connecting the charger 14 to a source of alternating current (AC) power. The charger 14 may also include a charge control switch 20. The charge control switch 20 may be electrically connected in series between the charger + terminal CT2 and the power supply 18. The charge control switch 20 may be electrically connected to and controlled by the CMS 16. If the charge control switch 20 is open than the power supply 18 / charger 14 may not provide charging power (current) to the battery pack 12. If the charge control switch 20 is closed than the power supply 18 / charger 14 may provide charging power (current) to the battery pack 12.

[0031] Referring to FIG. IB, the power tool 60 may include a power tool control module 62. The control module 62 may be or be referred to as a power tool processing circuit 62 and may include, among other components, a microcontroller, a microprocessor or another type of integrated circuit. The power tool processing circuit 62 may also simply be or simply be referred to as a power tool microprocessor or power tool controller or simply a controller. The power tool processing circuit 62 may also be or be referred to as a power tool management system (PMS). The power tool 60 may also include a set (plurality) of power tool terminals TT1, TT2, TT3, TT4. The set of power tool terminals may include a subset of power terminals TT1 (tool -) and TT2 (tool +). The set of power tool terminals may also include a subset of signal terminals TT3 (ID) and TT4 (TH). The power tool 60 may also include a motor 64 for providing an output force / power to a power tool accessory / load (not shown). The power tool 60 may also include a discharge control switch 66. The discharge control switch 66 may be electricallyTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142 connected in series between the tool + terminal TT2 and the motor 64. The discharge control switch 66 maybe electrically connected to and controlled by the PMS 62. If the discharge control switch 66 is open than the battery pack 12 may not provide output power (current) to the motor 64 / the power tool 60. If the discharge control switch 66 is closed than the battery pack 12 may provide output power (current) to the motor 64 / the power tool 60.

[0032] Referring to FIG. 1A or IB, the battery pack 12 may also include a battery pack control module 22. The battery pack control module 22 may be or be referred to as a battery pack processing circuit 22 and may include, among other components, a microcontroller, a microprocessor or another type of integrated circuit. The battery pack processing circuit 22 may also simply be or simple be referred to as a pack microprocessor or pack controller or simply a controller. The battery pack processing circuit 22 may also be or be referred to as a battery pack management system (BMS). The battery pack 12 may also include a plurality of battery cells 24 (sometimes referred to as a cell stack). The plurality of battery cells 24 may include a set of five battery cells Bl - B5. The plurality of battery cells 24 may be electrically connected to each other in series.

[0033] The BMS 22 may monitor the voltage of one or more of the plurality of battery cells 24. The BMS 22 may receive voltages from the positive node of each of the plurality of battery cells, i.e., VB1, VB2, VB3, VB4, VB5 and ground. The BMS 22 may determine the voltage of each of the plurality of battery cells or a set of the plurality of battery cells 24.

[0034] The battery pack 12 may include an identification circuit (ID) 26. The battery pack 12 may include a first temperature sensing / monitoring circuit (TH) 28.

[0035] The battery pack 12 may include a fuse circuit 30. The fuse circuit 30 may include a 3- terminal fuse. The battery pack 12 may include a protection circuit 32. The protection circuit 32 may include a first terminal OV coupled to an overvoltage protection terminal OVP of the BMS 22 and a second terminal Z coupled to the fuse circuit 30. The first terminal of the protection circuit 32 may also be coupled to a most positive (B+) terminal of the cell stack 24 through a resistor Rl. The protection circuit 32 may include an overvoltage protection circuit 34 and a second temperature sensing / monitoring circuit 36.Title: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142

[0036] The battery pack 12 may also include a set (plurality) of battery pack terminals BT1, BT2, BT3, BT4. The set of battery pack terminals may include a subset of power terminals BT1 (batt - ) and BT2 (batt +). The set of battery pack terminals may also include a subset of signal terminals BT3 (ID) and BT4 (TH).

[0037] Referring to FIG. 2, the overvoltage protection circuit 34 may have a first terminal OV1 and a second terminal Zl. The first terminal OV1 of the overvoltage protection circuit 34 is connected to the first terminal OV of the protection circuit 32 and the second terminal Zl of the overvoltage protection circuit 34 is connected to the second terminal Z of the protection circuit 32. The overvoltage protection circuit 34 may include a control circuit 40 and a switch 42 (sometimes referred to as a first switch or an overvoltage protection circuit switch).

[0038] The control circuit 40 may have a first terminal OV2 and a second terminal Cl. The first terminal OV2 of the control circuit 40 may be connected to the first terminal OV1 of the overvoltage protection circuit 34. The second terminal Cl of the control circuit 40 may be connected to the first switch 42.

[0039] The first switch 42 may have a first (control) terminal Gl, a second (input) terminal SI, and a third (output) terminal DI. The control terminal Gl of the first switch 42 may be connected to the second terminal Cl of the control circuit 40. The input terminal SI of the first switch 42 may be connected to a first voltage source VI. The output terminal DI of the first switch 42 may be connected to the second (output) terminal Zl of the overvoltage protection circuit 34.

[0040] The control circuit 40 may include a timer. The timer may include an RC circuit 44, a switch 46 (sometimes referred to as a second switch or a control circuit switch) and a capacitor bank 48.

[0041] The RC circuit 44 may have a first terminal and a second terminal. The first terminal of the RC circuit 44 may be connected to the first terminal OV1 of the overvoltage protection circuit 34 (which is coupled to the overvoltage protection terminal OVP of the BMS 22). TheTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142 second terminal of the RC circuit 44 may be connected to a node N1 and the node N1 may be connected to the second (control) terminal Cl of the control circuit 40.

[0042] The control circuit switch 46 may include a first terminal D2 connected to the node Nl, a second terminal S2 connected to the capacitor bank 48, and a third (control) terminal G2 connected to a second voltage source V2 that provides a control signa l / voltage V2 to the control circuit switch 46. The second voltage source V2 may be a voltage regulator connected to the plurality of battery cells 24.

[0043] The capacitor bank 48 may include a first terminal connected to the second terminal S2 of the control circuit switch 46. The capacitor bank 48 may include at least one capacitor.

[0044] The voltage V2 supplied to the control terminal G2 of the control circuit switch 46 is always present on the control terminal G2 of the control circuit switch 46. If all of the plurality of battery cells 24 are under the overvoltage threshold ("normal" circumstance / condition) the first terminal OV1 of the overvoltage protection circuit 34 will not be connected to a ground and will be connected to the highest voltage (B+) of the cell stack 24. This will charge the capacitor bank 48 through the RC circuit 44 and the control circuit switch 46. The capacitor bank 48 will charge to approximately the highest voltage (B+) of the cell stack 24. When the capacitor bank 48 is charged to the approximate cell stack voltage, (a) the relationship between the voltage at the first terminal of the capacitor bank and the voltage V2 will be such that the control circuit switch 46 will remain in a closed / on state and (b) the relationship between the voltage at the first terminal D2 / node Nl / the control terminal G1 of the first switch 42 and the control voltage CV1 will be such that the first switch 42 will remain in an open / off state.

[0045] Referring to FIG. 3, there is illustrated an example embodiment of the overvoltage protection circuit 34.

[0046] The first switch 42 of the overvoltage protection circuit 34 may be a MOSFET QI having a gate terminal (connected to the first / control terminal of the first switch 42) G1 connected to the Cl terminal of the control circuit 40, a source terminal (connected to the second / input terminal of the first switch 42) SI connected to a voltage source, e.g., 5V (the voltage sourceTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142VI) and a drain terminal (connected to the third / output terminal of the first switch 42) DI connected to the output terminal Zl.

[0047] The RC circuit 44 may include a second resistor R2 and a third resistor R3 connected in series between the first terminal OV2 of the control circuit 40 / the first terminal OV1 of the overvoltage protection circuit 34 and the node Nl. The second resistor R2 may be rated at approximately 2MQ and the third resistor R3 may be rated at approximately 2 MQ. The RC circuit 44 may also include a capacitor C8 having a first terminal connected to a node G2 at the connection of the second resistor R2 and the third resistor R3 and a second terminal connected to a ground. The capacitor C8 may be a ceramic capacitor and may be rated at approximately IpF, 50V. The RC circuit 44 may also include a diode DI connected in parallel with the first resistor R2 and the third resistor R3. The diode DI may have a first (anode) terminal connected to the first terminal of the RC circuit 44 / the first terminal OV2 of the control circuit 40 / the first terminal OV1 of the overvoltage protection circuit 34 and a second (cathode) terminal connected to the node Nl.

[0048] The control circuit switch 46 may be a MOSFET Q2 having a gate terminal (connected to the first / control terminal of the control circuit switch 46) G2 connected to a voltage source, e.g., 5V (the control voltage source V2), a source terminal (connected to the second terminal of the control circuit switch 46) S2 connected to the capacitor bank 48 and a drain terminal (connected to the third terminal of the control circuit switch 46) D2 connected to the node Nl.

[0049] The capacitor bank 48 may include three capacitors C2, C4, C6 connected in parallel. The parallel connected capacitors C2, C4, C6 may have a terminal connected to the source terminal S2 of the control circuit switch 46 and a terminal connected to a ground. The capacitors C2, C4, C6 may each be a ceramic capacitor and rated at 2.2pF, 50V.

[0050] The 5V signal supplied to the gate terminal G2 of the control circuit switch Q2 is always present on the gate terminal G2 of the control circuit switch Q2. If all of the plurality of battery cells 24 are under the overvoltage threshold ("normal" circumstance / condition) the first terminal OV1 of the overvoltage protection circuit 34 will not be connected to a ground and will be connected to the highest voltage (B+) of the cell stack 24. This will charge the capacitors C2,Title: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142C4, C6 through the diode DI of the RC circuit 44 and the control circuit switch Q2 of the first switch 42. The capacitors C2, C4, C6 will charge to approximately the highest voltage (B+) of the cell stack 24. When the capacitors C2, C4, C6 are charged to the approximate cell stack voltage, the voltage at the source terminal S2 of the control circuit switch Q2 (the voltage at the positive terminals of the capacitors C2, C4, C6) is greater than the turn on threshold voltage of the control circuit switch Q2 and the control circuit switch Q2 will remain in a closed / on state and the voltage at the second terminal Cl / the node Nl / the gate terminal G1 of the switch QI will remain higher than the turn off threshold voltage of the switch QI and the switch QI will remain in the off / open state.

[0051] During charging, the charger 14 will provide a charging current to the battery pack 12 / the plurality of battery cells 24 (B1-B5) through the subset of charger terminals CT1 and CT2. The battery pack 12 / the plurality of battery cells 24 may receive the charging current through pack terminals BT1 and BT2 (coupled to charger terminals CT1 and CT2, respectively). The BMS 22 may provide / send / transmit a voltage monitoring signal - a voltage - (OV) to the protection circuit 32 / the overvoltage protection circuit 34 / the control circuit 40. The BMS 22 may also provide / send / transmits the voltage monitoring signal OV to the charger 14 through the ID circuit 26.

[0052] Under a first instance ("normal" circumstance / condition, i.e., the BMS determines that the voltage of all of the plurality of battery cells 24 is below a cell overvoltage cutoff threshold, e.g., 4.275 V / cell), the voltage monitoring signal OV that the BMS 22 may provide / send / transmit to the protection circuit 32 / the overvoltage protection circuit 34 / the control circuit 40 may indicate that the voltage of all of the plurality of battery cells 24 is below the cell overvoltage cutoff threshold. In this first instance, the voltage monitoring signal OV may be referred to as an operate or OK signal. For example, the OK signal may be an open circuit signal or a HIGH signal (e.g., the OV pin / terminal of the BMS 22 may present an open circuit such that the OV pin of the protection circuit 32 / the overvoltage protection circuit 34 / the control circuit 40 is "connected to" or "pulled up to" the highest voltage (B+) of the cellTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142 stack 24, e.g., 20V, through the resistor Rl). The BMS 22 may also provide / send / transmits the OK signal to the charger 14 through the ID circuit 26.

[0053] The control circuit 40 receives the OK signal from the BMS 22 and provides / presents / sends / transmits a control signal to the node Nl / the terminal Cl / the control terminal G1 of the first switch 42. In the first instance, the control signal to the control terminal G1 of the overvoltage protection circuit switch 42 may be an OFF signal and the first switch 42 may remain or be placed in an open / off state. In this instance, the output signal on the output terminal Z1 of the overvoltage protection circuit 34 is an OFF signal.

[0054] Under a second instance ("overvoltage" circumstance / condition, i.e., the BMS 22 determines that the voltage of any of the plurality of battery cells 24 or a set of the plurality of battery cells 24 exceeds the cell overvoltage cutoff threshold), the voltage monitoring signal OV that the BMS 22 may provide / send / transmit to the protection circuit 32 / the overvoltage protection circuit 34 / the control circuit 40 may indicate that the voltage of any of the plurality of battery cells 24 or a set of the plurality of battery cells 24 exceeds the cell overvoltage cutoff threshold. In this second instance, the voltage monitoring signal OV may be referred to as a shutdown or SD signal. For example, the SD signal may be a ground or a LOW signal (e.g., the BMS 22 may internally connect the OV pin / terminal of the BMS 22 to a relatively low voltage, e.g., ground or 0V). The BMS 22 may also provide / send / transmits the SD signal to the charger 14 through the ID circuit 26.

[0055] The control circuit 40 may receive the SD signal from the BMS 22 and provides / presents / sends / transmits a control signal to the node Nl / the terminal Cl / the control terminal G1 of the first switch 42.

[0056] When the SD signal is provided to the overvoltage protection circuit 34 / the control circuit 40, the control circuit 40 is activated. If the control circuit 40 is activated, then the timer may be activated (started). If the timer reaches its end, then the control circuit 40 may provide the ON signal to the control terminal of the first switch 42.Title: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142

[0057] The timer may include the RC circuit 44, the second switch 46 and the capacitor bank 48. The control signal for the first switch 42 may be the voltage at the second node Nl / the terminal Cl. In other words, the RC circuit 44 may be electrically connected between the first terminal OV1 of the overvoltage protection circuit 34 and the control terminal G1 of the first switch 42.

[0058] The timer may have two steps or stages. A first step / stage of the timer will begin when the first terminal OV1 of the overvoltage protection circuit 34 is coupled to ground. The capacitors of the capacitor bank 48 - having been charged to a voltage greater than the ON voltage of the control circuit switch 46 and therefore the control circuit switch 46 being in a closed / on state - will discharge through the control circuit switch 46 and the first terminal OV1 of the overvoltage protection circuit 34 to the ground of the BMS 22. When all of the capacitors of the capacitor bank 48 have discharged to a voltage less than the ON threshold voltage of the control circuit switch 46, the control circuit switch 46 will open (transition to an off / open state). This will conclude the first step / stage 1 of the timer, as illustrated in FIG. 4.

[0059] A second step / stage of the timer will begin when the control circuit switch 46 is open. The capacitor of the RC circuit 44 will begin to discharge. Once the RC circuit 44 has discharged such that the voltage at the node Nl / the second (control) terminal Cl is less than the OFF threshold voltage of the first switch 42, the first switch 42 will close (transition to an on / closed state) and the first switch 42 will present an ON signal on the Z1 terminal to the Z node. This will conclude the second step / stage 2 of the timer, as illustrated in FIG. 4.

[0060] Referring to FIG. 3, in the second instance, if the battery pack goes into an overvoltage condition / state / circumstance, (i.e., the BMS 22 determines that the voltage of one or more of the plurality of battery cells 24 has exceeded the overvoltage threshold and the BMS 22 connects the overvoltage protection terminal OVP of the BMS 22 to a ground) the capacitors C2, C4, C6 will discharge through the control circuit switch Q2 and the first terminal OV1 of the overvoltage protection circuit 34 to the ground in the BMS 22 and a voltage at node N1 will decrease accordingly - the first step / stage 1 of the timer, see FIG. 4. Once the voltage at the source terminal S2 of the control circuit switch Q2 (the voltage at the positive terminals of theTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142 capacitors C2, C4, C6) is less than the ON threshold voltage of the control circuit switch Q2, the control circuit switch Q2 will open (transition to an off / open state). Once the control circuit switch Q2 is in an open state, the capacitor C8 of the RC circuit 44 will discharge through the first terminal OV1 of the overvoltage protection circuit 34 to the ground in the BMS 22 and a voltage at node N1 will decrease accordingly - the second step / stage 2 of the timer, see FIG. 4. Once the voltage at gate of the first switch QI is less than the OFF threshold of first switch QI, the first switch QI will close (transition to an on / closed state) and will present the ON, e.g., 5V, signal to the Z node and Z1 terminal.

[0061] As illustrated in FIG. 4, as there are multiple capacitors C2, C4, C6 in parallel in the capacitor bank 48, each with a relatively high capacitance (e.g., 2pF) and the multiple capacitors C2, C4, C6 of the capacitor bank 48 will discharge through both the resistors R2 and R3 in the RC circuit 44, together with a relatively high resistance (e.g., 4MQ), the slope of the voltage at the node N1 is relatively flat (i.e., the discharge rate of the capacitors of the capacitor bank is relatively slow, approximately 30 seconds) during the timer stage 1 and as there is only a single capacitor in the RC circuit 44 with a relatively low capacitance (e.g., lpF) and the single capacitor C8 in the RC circuit 44 will discharge through only the second resistor R2 in RC circuit 44 with a relatively low resistance (e.g., 2MQ), the slope of the volage at the node N1 is very steep (i.e., the discharge rate of the capacitor of the RC circuit is very fast, approximately 0.5 seconds) during the timer stage 2.

[0062] During a charging process, the battery pack 12 / the plurality of battery cells 24 (B1-B5) may receive a charging current through the subset of battery pack terminals BT1 and BT2 from the charger 14. The charger 14 may provide the charging current to the battery pack 12 through the subset of charger terminals CT1 and CT2 (coupled to the battery pack terminals BTl and BT2, respectively).

[0063] During a discharging process, the battery pack 12 may provide a discharging current from the plurality of battery cells 24 (B1-B5) through the subset of battery pack terminals BT1 and BT2 to the power tool 60. The power tool 60 may receive the dischargingTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142 current from the battery pack 12 through subset of power tool terminals TT1 and TT2 (coupled to battery pack terminals BT1 and BT2, respectively).

[0064] During the charging process and / or during the discharging process the first temperature sensing / monitoring circuit 28 may provide / send / transmit a first temperature monitoring signal (VTH1) representative of the temperature of the battery pack and / or one or more specific cells of the plurality of battery cells 24 - a voltage signal associated with a first thermistor TH1 of the first temperature sensing / monitoring circuit 28 - to the charger 14 or the power tool 60, as the case may be. The BT4 terminal may be connected to the first thermistor TH1 in the first temperature sensing / monitoring circuit 28. The first temperature monitoring signal VTH1 may be provided / sent / transmitted by the battery pack 12 on the BT4 terminal and received by the charger 14 on the CT4 terminal or the power tool 60 on the TT4 terminal. The first temperature monitoring signal VTH1 may be provided to the charger controller 16 during the charging process and to the power tool controller 62 during the discharging process.

[0065] Under a first instance during the charging process and / or during the discharging process ("normal" circumstance / condition, i.e., the battery pack and / or all of the plurality of battery cells 24 having a temperature below a first temperature cutoff threshold, e.g., 75°C), the first temperature monitoring signal VTH1 that the first temperature sensing / monitoring circuit 28 may provide / send / transmit to the charger 14 during charging and to the power tool 60 discharging may indicate that the temperature of all of the plurality of battery cells 24 and / or the battery pack 12 is below the first temperature cutoff threshold. In this first instance, the first temperature monitoring signal VTH1 may be referred to as an operate or OK signal. If the temperature monitoring signal is the OK signal, i.e., the voltage of the first temperature monitoring signal VTH1 is less than a voltage associated with the first temperature cutoff threshold, that is stored in the charger controller 16 and the power tool controller 62, the charger 14 or the power tool 60 may continue to operate.

[0066] However, under a second instance during the charging process and / or during the discharging process, ("overtemperature" circumstance / condition, i.e., the battery pack and / or all of the plurality of battery cells 24 having a temperature that exceeds / is greater than the firstTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142 temperature cutoff threshold), the first temperature monitoring signal VTH1 that the first temperature sensing / monitoring circuit 28 may provide / send / transmit may indicate that the temperature of all of the plurality of battery cells 24 and / or the battery pack 12 exceeds / is greater than the first temperature cutoff threshold. In this second instance, the first temperature monitoring signal VTH1 may be referred to as a shutdown or SD signal. If the temperature monitoring signal is the SD signal, i.e ., the voltage of the first temperature monitoring signal VTH1 exceeds / is greater than a voltage associated with the first temperature cutoff threshold, that is stored in the charger controller 16 and the power tool controller 62, the charger 14 may cease to operate, e.g., the charger controller 16 may open the charge control switch 20 or the power tool 60 may cease to operate, e.g., the power tool controller 62 may open the discharge control switch 66

[0067] If the charger 14 does not stop the charging current from reaching the battery pack 12, e.g., the charger controller 16 opening the charge control switch 20 or if the power tool 60 does not stop the discharge current from reaching the motor 64, e.g., the power tool controller 62 opening the discharge control switch 66, the temperature of the battery pack 12 and / or the plurality of battery cells 24 may continue to rise.

[0068] Referring to FIGs. 5 and 6, the second temperature sensing / monitoring circuit 36 may provide a secondary temperature monitoring function if charger does not shutdown the charging current or the power tool does not shutdown the discharging current in response to first temperature monitoring signal VTH1 from the first temperature sensing / monitoring circuit 28 being the SD signal. The second temperature sensing / monitoring circuit 36 may include a thermistor circuit 50. The thermistor circuit 50 of the second temperature sensing / monitoring circuit 36 may include a second thermistor TH2. The second thermistor TH2 of the thermistor circuit 50 of the second temperature sensing / monitoring circuit 36 may output / provide a second temperature monitoring signal VTH2 representative of the temperature of the battery pack and / or one or more specific cells of the plurality of battery cells 24 - a voltage signal associated with the second thermistor TH2 of the second temperature sensing / monitoring circuit 36. The second temperature sensing / monitoring circuit 36 may include a comparatorTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142 circuit 52. The second temperature monitoring signal VTH2 may be provided from the thermistor circuit 50 to the comparator circuit 52. The comparator circuit 52 may compare a voltage of the second temperature monitoring signal VTH2 to a voltage representative of a second temperature cutoff threshold. The second temperature cutoff threshold used by the comparator circuit 52 may be greater than the first temperature cutoff threshold used by the power tool 60, e.g., the first temperature cutoff threshold used by the power tool 60 may be 75°C and the second temperature cutoff threshold used by the comparator circuit 52 may be 100°C. If the comparator circuit 52 determines that the temperature of the battery pack 12 and / or one or more specific cells of the plurality of plurality of battery cells 24 is greater than the second temperature cutoff threshold used by the comparator circuit 52 than the comparator circuit 52 may output an ON signal at the Z terminal / Z node of the second temperature sensing / monitoring circuit 36 indicating a second level overtemperature circumstance / event. It is understood by one of ordinary skill in the art that the second temperature sensing / monitoring circuit 36, and in particular the comparator circuit 52, may include a hysteresis function which may affect the output of the comparator circuit 52.

[0069] Referring to FIG. 7, the fuse circuit 30 may include an input terminal Z and a first charging path terminal B+ connected a positive terminal of the plurality of battery cells 24 and a second charging path terminal batt+ connected to the BT2 / batt+ battery pack terminal. The input terminal Z of the fuse circuit 30 is coupled to the output terminal Z of the overvoltage protection circuit 34 and the output terminal Z of the second temperature sensing / monitoring circuit 36. The output signal from the output terminal Z1 of the overvoltage protection circuit 34 and the output signal from the output terminal Z2 of the temperature sensing circuit 36 are input / connected / transmitted to the input terminal Z of the fuse circuit 30.

[0070] As illustrated, the fuse circuit 30 may include a fuse switch 54 and a 3-terminal fuse 56. The fuse switch 54 of the fuse circuit 30 may have a first terminal connected to the input terminal Z of the fuse circuit 30, a second terminal connected to the 3-terminal fuse 56, and a third terminal connected to a ground. The 3-terminal fuse 56 may have a first terminal 1 connected to the B+ terminal of the plurality of battery cells 24, a second terminal 2 connectedTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142 to the BT2 / batt+ terminal of the battery pack 12 and a third terminal 3 connected to the second terminal of the fuse switch 54 of the fuse circuit 30. The 3-terminal fuse may include a resistive heating element.

[0071] If the battery pack 12 is connected to the charger 14 and the charger 14 is providing a charging current IC to the plurality of battery cells 24 / the battery pack 12 and the charging current IC exceeds the IT curve specification of the fuse 56, then fuse 56 between the first terminal 1 and the second terminal 2 will open. If the battery pack 12 is connected to the power tool 60 and the battery pack is providing a discharging current ID to the motor 64 / the power tool 60 and the discharging current ID exceeds the IT curve specification of the fuse 56, then fuse 56 between the first terminal 1 and the second terminal 2 will open.

[0072] If the battery pack 12 is connected to the charger 14 and the charger 14 is providing a charging current IC to the plurality of battery cells 24 / the battery pack 12 or if the battery pack 12 is connected to the power tool 60 and the power tool is receiving a discharge current ID from the plurality of battery cells 24 / the battery pack 12 and if (a) the overvoltage protection circuit 34 is activated by the SD signal from the BMS 22 in response to one or more of the plurality of battery cells 24 exceeding the overvoltage threshold and the overvoltage protection circuit 34 presents an ON signal to the fuse circuit 30 or (b) the temperature monitoring circuit 36 determines that the battery pack 12 or one or more of the plurality of battery cells 24 has exceeded the temperature threshold and the temperature monitoring circuit 36 presents an ON signal to the fuse circuit 30, then the switch 54 of the fuse circuit 30 will transition to a closed / on stated and connect the 3-terminal fuse 56 to a ground. When the 3-terminal fuse switch 54 is connected to ground a shutdown current ISD will flow from the B+ terminal and the batt+ terminal through the 3-terminal fuse 56 and the fuse switch 54 to ground. Due to the rating of the 3-terminal fuse 56, the shutdown current ISD will cause the 3-terminal fuse to open. If the 3-terminal fuse 56 opens, then the charging / discharging path between the battery pack terminal BT2 / batt+ and the B+ terminal of the plurality of battery cells 24 will be opened / interrupted. If the charging / discharging path between the battery pack terminal 1Title: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142BT2 / batt+ and the B+ terminal of the plurality of battery cells 24 is opened / interrupted, then the charging / discharging of the plurality of battery cells 24 will stop.

[0073] Referring to FIG. 8, there is illustrated an example embodiment of the fuse circuit 30. The fuse switch 54 of the fuse circuit 30 may include two MOSFET switches Q3 and Q4. The fuse 56 of the fuse circuit 30 may include two 3-terminal fuses 56a and 56b. Each 3-terminal fuse 56a, 56b may include two fuse elements 58. The fuse elements 58 of each 3-terminal fuse 56a, 56b are connected in series in the charging path between the B+ terminal and the BT2 / batt+ terminal. Each 3-terminal fuse 56a, 56b may include a resistive heating element R14. The resistive heating element R14 may be a resistor R14. The resistive heating element R14 of each 3-terminal fuse 56a, 56b may have a first terminal connected to a node at the connection of the first fuse element 58 and the second fuse element 58 and a second terminal connected to the third terminal of the fuse 56. In this illustrated embodiment, the example fuse 56 includes two 3-terminal fuses 56a, 56b for sizing purposes related to the current flowing through the charging / discharging path during charging or discharging of the battery pack and costs related to the fuses. In alternate example embodiments, the fuse 56 may include a single 3-terminal fuse having a higher rating (rated for a higher current and / or voltage) or three or more 3-terminal fuses having a lower rating. The fuse switch 54 includes two switches Q3 and Q4 because there are two 3-terminal fuses 56a, 56b. If the fuse circuit 30 included a single 3- terminal fuse 56 then the fuse switch 54 would include a single switch Q3.

[0074] As illustrated, each of the switches Q3, Q4 may have a gate terminal connected to the input terminal Z of the fuse circuit 30, a drain terminal connected to the third terminal of the 3- terminal fuse 56, and a source terminal connected to a ground. Each of the 3-terminal fuses 56a, 56b may have a first terminal 1 connected to the B+ terminal of the plurality of battery cells 24, a second terminal 2 connected to the BT2 / batt+ terminal of the battery pack 12, and a third terminal 3 connected to the drain terminal of one of the switches Q3, Q4 of the fuse switch 54.Title: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142

[0075] As illustrated in FIG. 8, the first 3-terminal fuse 56a and the second 3-terminal fuse 56b are connected in parallel between the BT2 / batt+ battery pack terminal and B+ cell stack terminal.

[0076] If the battery pack 12 is connected to the charger 14 and the charger 14 is providing a charging current IC to the plurality of battery cells 24 / the battery pack 12 or if the battery pack 12 is connected to the power tool 60 and the power tool is receiving a discharge current ID from the plurality of battery cells 24 / the battery pack 12 and the charging current or the discharging current exceeds the IT curve specification of the fuse elements 58, then fuse elements 58 between the first terminal 1 and the second terminal 2 will open.

[0077] If the battery pack 12 is connected to the charger 14 and the charger 14 is providing a charging current IC to the plurality of battery cells 24 / the battery pack 12 or if the battery pack 12 is connected to the power tool 60 and the power tool is receiving a discharge current ID from the plurality of battery cells 24 / the battery pack 12, then (a) if the overvoltage protection circuit 34 is activated by the SD signal from the BMS 22 in response to one or more of the plurality of battery cells 24 exceeding the overvoltage threshold, then the overvoltage protection circuit 34 will transmits / provides / presents an ON signal on the output terminal Z of the overvoltage protection circuit 34 and (b) if the temperature monitoring circuit 36 determines that the battery pack 12 or one or more of the plurality of battery cells 24 has exceeded the temperature cutoff threshold then the temperature monitoring circuit 36 will transmits / provides / presents an ON signal on the output terminal Z of the temperature monitoring circuit 36.

[0078] If the input terminal Z of the fuse circuit 30 / the input terminal Z of the fuse switch 54 / the gate terminal of the switches Q3, Q4 receives a HIGH (ON) signal, e.g., 5V from either the output terminal Z of the overvoltage protection circuit 34 or the output terminal Z of the temperature sensing circuit 36 - as described in detail above, then both the switches Q3, Q4 will transition to a closed / on state. When the switches Q3 and Q4 transition to a closed / on state the third terminal 3 of each 3-terminal fuse 56a, 56b will be connected to a ground. When the third terminal 3 of each 3-terminal fuse 56a, 56b is connected to ground a shutdownTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142 current ISD will flow from the B+ terminal and the batt+ terminal through the fuse elements 58 and the resistors R14 of the 3-terminal fuses 56a, 56b and the fuse switches Q3, Q4 to ground. Due to the rating of the 3-terminal fuses 56a, 56b, the shutdown current ISD will cause the fuse elements 58 of the 3-terminal fuses 56a, 56b to open. In other words, if during an overvoltage event / circumstance or an overtemperature event / circumstance the shutdown current ISD exceeds the fuse rating, then the fuse elements 58 will open. In an example embodiment, when the heating elements R14 are connected to ground and the shutdown current ISD passes through the heating elements R14, the temperature of the heating elements R14 will increase. As the heating elements R14 are located in close proximity to the fuse elements 58, the thermal heat produced by the heating elements R14 will exceed the temperature rating of the fuse elements R14 and cause the fuse elements R14 to open. If the fuse elements 58 of the 3- terminal fuses 56a, 56b open, then the charging / discharging path between the battery pack terminal BT2 / batt + and the B+ terminal of the plurality of battery cells 24 will be opened / interrupted. If the charging / discharging path between the battery pack terminal BT2 / batt + and the B+ terminal of the plurality of battery cells 24 is opened / interrupted, then the charging / discharging of the plurality of battery cells 24 will stop.

[0079] In a first circumstance (charging), the charger 14 may receive an SD signal from the battery pack 12 through the BT3 / CT3 terminals that indicates an overvoltage circumstance / event or a temperature monitoring signal VTH1 from the battery pack 12 through the BT4 / CT4 terminals that indicates an overtemperature circumstance / event. If the charger 14 (a) receives the SD signal from the battery pack 12 through the BT3 / CT3 terminals or (b) receives the temperature monitoring signal VTH1 from the battery pack 12 through the BT4 / CT4 terminals indicating an overtemperature circumstance / event, then the charger 14 should stop charging the battery pack 12.

[0080] If the charger 14 does stop charging the battery pack 12 upon receipt of the SD signal before the timer of the overvoltage protection circuit 34 expires, then the voltage of the plurality of battery cells 24 that caused the BMS 22 to generate the SD signal will fall below the overvoltage threshold and the BMS 22 will terminate the SD signal to the protection circuitTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-014232 / the overvoltage protection circuit 34. And, if the charger 14 does stop charging the battery pack 12 upon receipt of the temperature monitoring signal VTH1 indicating an overtemperature circumstance / event before the second thermistor TH2 of the second temperature sensing / monitoring circuit 32 exceeds the second temperature cutoff threshold, then the temperature of the plurality of battery cells 24 and / or the battery pack 12 that caused the first temperature sensing / monitoring circuit 28 to generate the temperature monitoring signal VTH1 indicating an overtemperature circumstance / event will fall below the first temperature cutoff threshold and the first temperature sensing / monitoring circuit 28 will terminate the temperature monitoring signal VTH1 indicating an overtemperature circumstance / event to the charger 14.

[0081] If, however, the charger 14 does not stop charging the battery pack 12 in response to the SD signal provided to the charger 14 through the ID circuit 26 or the overtemperature monitoring signal VTH1 indicating an overtemperature circumstance / event provided to the charger 14 through the first temperature sensing / monitoring circuit 28, then the battery pack 12 will stop the charging of the battery pack, as described above.

[0082] In a second circumstance (discharging), the power tool 60 may receive a SD signal from the battery pack 12 through the BT3 / TT3 terminals that indicates an overvoltage circumstance / event or a temperature monitoring signal VTH1 from the battery pack 12 through the BT4 / CT4 terminals that indicates an overtemperature circumstance / event. If the power tool 60 (a) receives the SD signal from the battery pack 12 through the BT3 / TT3 terminals indicating an overvoltage circumstance / event or (b) receives the temperature monitoring signal VTH1 from the battery pack 12 through the BT4 / CT4 terminals indicating an overtemperature circumstance / event, then the power tool 60 should stop discharging the battery pack 12.

[0083] If the power tool 60 does stop discharging the battery pack 12 upon receipt of the SD signal before the timer of the overvoltage protection circuit 34 expires, then the voltage of the plurality of battery cells 24 that caused the BMS 22 to generate the SD signal will fall below the overvoltage threshold and the BMS 22 will terminate the SD signal to the protection circuit 32 / the overvoltage protection circuit 34. And, if the power tool 60 does stop discharging theTitle: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142 battery pack 12 upon receipt of the temperature monitoring signal VTH1 indicating an overtemperature circumstance / event before the second thermistor TH2 of the second temperature sensing / monitoring circuit 32 exceeds the second temperature cutoff threshold, then the temperature of the plurality of battery cells 24 and / or the battery pack 12 that caused the first temperature sensing / monitoring circuit 28 to generate the temperature monitoring signal VTH1 indicating an overtemperature circumstance / event will fall below the first temperature cutoff threshold and the first temperature sensing / monitoring circuit 28 will terminate the temperature monitoring signal VTH1 indicating an overtemperature circumstance / event to the power tool60.

[0084] If, however, the power tool 60 does not stop discharging the battery pack 12 in response to the SD signal provided to the power tool 60 through the ID circuit 26 or the overtemperature monitoring signal VTH1 indicating an overtemperature circumstance / event provided to the power tool 60 through the first temperature sensing / monitoring circuit 28, then the battery pack 12 will stop the discharging of the battery pack 12, as described above.

[0085] Numerous modifications may be made to the exemplary implementations described above. These and other implementations are within the scope of this application.

Claims

1. Title: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-0142Claims1. A battery pack, comprising: a housing; a plurality of battery cells connected in series; a plurality of battery pack terminals; a control module, the control module coupled to the plurality of battery cells to monitor the voltage of one or more of the plurality of battery cells: a fuse circuit; and a protection circuit, the protection circuit including (A) an overvoltage protection circuit, (B) a temperature sensing / monitoring circuit, (C) a first terminal OV coupled internally to the overvoltage protection circuit and externally to the control module and to a most positive terminal of the plurality of battery cells through a resistor and (D) a second terminal Z coupled internally to the overvoltage protection circuit and to the temperature sensing / monitoring circuit and externally to the fuse circuit.

2. The battery pack as recited in claim 1, wherein the overvoltage protection circuit includes a first terminal OV1 and a second terminal Zl.

3. The battery pack as recited in claim 2, wherein the first terminal OV1 of the overvoltage protection circuit is connected to the first terminal OV of the protection circuit and the second terminal Zl of the overvoltage protection circuit is connected to the second terminal Z of the protection circuit.

4. The battery pack as recited in claim 3, wherein the overvoltage protection circuit includes a control circuit and a switch.

5. The battery pack as recited in claim 4, wherein the control circuit includes a first terminal OV2 connected to the first terminal OV1 of the overvoltage protection circuit and a second terminal Cl connected to the switch.Title: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-01426. The battery pack as recited in claim 5, wherein the control circuit includes a timer, the timer including an RC circuit, a switch and a capacitor bank.

7. The battery pack as recited in claim 6, wherein the RC circuit includes a first terminal and a second terminal, the first terminal of the RC circuit connected to the first terminal OV1 of the overvoltage protection circuit and the second terminal of the RC circuit connected to a node N1 and the node N1 connected to the second, control terminal Cl of the control circuit.

8. The battery pack as recited in claim 5, wherein the switch includes a first (control) terminal Gl, a second terminal SI, and a third terminal DI, the control terminal G1 of the switch connected to the control terminal Cl of the control circuit, the second terminal SI of the first switch connected to a first voltage source VI and the third terminal DI of the first switch connected to the output terminal Z1 of the overvoltage protection circuit.

9. The battery pack as recited in claim 1, wherein the fuse circuit includes a 3-terminal fuse.

10. The battery pack as recited in claim 1, wherein the fuse circuit includes a fuse switch and a 3-terminal fuse, the fuse switch of the fuse circuit including a first terminal connected to an input terminal Z of the fuse circuit, a second terminal connected to the 3-terminal fuse, and a third terminal connected to a ground.

11. The battery pack as recited in claim 10, wherein the 3-terminal fuse may have a first terminal connected to the B+ terminal of the plurality of battery cells, a second terminal connected to the BT2 / batt+ terminal of the battery pack and a third terminal connected to the second terminal of the fuse switch of the fuse circuit, the 3-terminal fuse including a resistive heating element.

12. The battery pack as recited in claim 10, wherein the fuse switch of the fuse circuit includes two MOSFET switches Q3 and Q4 and the fuse of the fuse circuit includes two 3- terminal fuses, each 3-terminal fuse including two fuse elements, the fuse elements of each 3- terminal fuse connected in series in a charging path between the B+ terminal and the BT2 / batt+ terminal.Title: MONITORING SYSTEM AND METHOD FOR A BATTERY PACK Applicant: Black & Decker Inc.Docket No. P-WO-TN-2023-014213. The battery pack as recited in claim 12, wherein the resistive heating element of each 3- terminal fuse includes a first terminal connected to a node at the connection of the first fuse element and the second fuse element and a second terminal connected to the third terminal of the fuse.

14. The battery pack as recited in claim 13, wherein each of the switches Q3, Q4 includes a gate terminal connected to the input terminal Z of the fuse circuit, a drain terminal connected to the third terminal of the 3-terminal fuse, and a source terminal connected to a ground and each of the 3-terminal fuses includes a first terminal connected to the B+ terminal of the plurality of battery cells, a second terminal connected to the BT2 / batt+ terminal of the battery pack, and a third terminal connected to the drain terminal of one of the switches Q3, Q4 of the fuse switch.

15. The battery pack as recited in claim 14, wherein the first 3-terminal fuse and the second 3-terminal fuse are connected in parallel between the BT2 / batt+ battery pack terminal and B+ cell stack terminal.

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