Patent Publication Number: US-2023163372-A1

Title: Fast-charging battery pack

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. Pat. Application No. 16/425,570, filed on May 29, 2019, which claims the benefit of U.S. Provisional Pat. Application No. 62/678,050, filed on May 30, 2018, the entire content of each of which is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to battery packs for electrical devices, such as power tools, and, more particularly, to such battery packs capable of fast charging. 
     BACKGROUND OF THE INVENTION 
     Cordless electrical devices (e.g., electrical devices, such as power tools, outdoors tools, other motorized devices, non-motorized devices, etc.) have a limited run-time compared to comparable corded electrical devices. The run-time of cordless electrical devices generally depends on the capacity (ampere-hours (Ah)) of the associated battery pack. The capacity of a battery pack depends on the capacity of the individual battery cells and the number and configuration of those cells. For example, a “5S1P” battery pack includes one string of five series-connected battery cells. With battery cells having a capacity of about 1.3 Ah, the capacity of the 5S1P battery pack is about 1.3 Ah. The capacity of a “5S2P” battery pack (having two parallel-connected strings of five series-connected battery cells) is about 2.6 Ah. The capacity of a “5S3P” battery pack (having three parallel-connected strings of five series-connected battery cells) is about 3.9 Ah. The capacity of the 1P, 2P, and 3P packs will vary based on the capacity of the individual battery cells. 
     The charging time of a battery pack generally depends on the amount of current provided by the charger (and accepted by the battery pack), the capacity of the battery cells, and the overall capacity of the battery pack. For example, a battery pack including battery cells having a capacity of 1.3 Ah being charged by a charger providing a charging current of 3 Amps (A) takes about 35-40 minutes to reach full charge. The higher the capacity of the battery cells, the longer the charging time to fully charge the battery pack. With the same 3 A charging current, the 3.9 Ah battery pack takes about 75-80 minutes to reach full charge. 
     While it may be desirable to increase the charging current to decrease the time to charge battery packs with higher capacity cells (e.g., provide a charging current of between about 6 A and about 18 A for battery packs with cells having a capacity of between about 3 Ah and about 4 Ah), components of the battery pack (e.g., the printed circuit board (PCB), a fuse, a field effect transistor (FET)) may not be capable of handling increased current (e.g., more than about 6 A) without adverse effects, such as excessive heating, wear, irreversible damage, etc. Accordingly, there may be a need for battery packs having charging circuitry and components able to handle charging current in the range of more than about 6 A to about 18 A or even higher. 
     SUMMARY OF THE INVENTION 
     One embodiment provides a battery pack including a housing, a plurality of battery cells supported by the housing, and a terminal block. The terminal block is configured to be coupled to a power tool to provide operating power from the plurality of battery cells to the power tool. The terminal block has a positive power terminal, a charging terminal, and a ground terminal. The battery pack also includes a charging circuit provided between the charging terminal and the plurality of battery cells. The charging circuit is configured to receive and transfer charging current above 12 Amperes to the plurality of battery cells during charging. The charging circuit includes a charging switch and a fuse coupled between the charging terminal and the charging switch. 
     In some constructions, the charging switch may include a N-Channel FET. The fuse may have at least about a 8 A rating; in some constructions, the fuse may have about a 20 A rating. The battery pack may include an electronic controller, the controller being configured to control the FET to selectively connect the charging terminal to the battery cells. 
     Another embodiment provides a battery pack charging system including a charger configured to provide a charging current between about 6 Amperes and about 20 Amperes and a battery pack detachably connectable to the charger and configured to be charged by the charger. The battery pack includes a plurality of battery cells and a terminal block. The terminal block is configured to be coupled to a power tool to provide operating power from the plurality of battery cells to the power tool. The terminal block has a positive power terminal, a charging terminal, and a ground terminal. The battery pack also includes a charging circuit provided between the charging terminal and the plurality of battery cells. The charging circuit is configured to receive and transfer charging current above 12 Amperes to the plurality of battery cells during charging. The charging circuit includes a charging switch and a fuse coupled between the charging terminal and the charging switch. 
     Other independent aspects of the invention may become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1 A- 1 E  are perspective views of battery packs for electrical devices, such as power tools, outdoors tools, other motorized devices, non-motorized devices, etc. 
         FIG.  2    is a block diagram of a battery pack connected to a fast-charging battery charger. 
         FIG.  3    is a block diagram of a charging circuit of the battery pack. 
         FIG.  4    is a schematic illustration of the charging circuit of  FIG.  3    on a circuit board of the battery pack. 
         FIG.  5    is a flowchart illustrating a method of enabling fast charging of the battery pack. 
         FIG.  6    is a flowchart illustrating a method of disabling fast charging of the battery pack. 
         FIG.  7    is a block diagram of a charging circuit of the battery pack. 
         FIG.  8    is a block diagram of a charging circuit of the battery pack. 
         FIG.  9    is a schematic illustrating the charging circuit of  FIG.  7    on a circuit board of the battery pack. 
     
    
    
     DETAILED DESCRIPTION 
     Before any independent embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other independent embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
     Use of “including” and “comprising” and variations thereof as used herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Use of “consisting of” and variations thereof as used herein is meant to encompass only the items listed thereafter and equivalents thereof. 
     Relative terminology, such as, for example, “about”, “approximately”, “substantially”, etc., used in connection with a quantity or condition would be understood by those of ordinary skill to be inclusive of the stated value and has the meaning dictated by the context (for example, the term includes at least the degree of error associated with the measurement of, tolerances (e.g., manufacturing, assembly, use) associated with the particular value, etc.). Such terminology should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4”. 
     The relative terminology may refer to plus or minus a percentage (e.g., 1%, 5%, 10% or more) of an indicated value. For example, with a 10% range, “about 20 Volts” may indicate a range of 18 Volts (V) to 22 V, and “about 1%” may mean from 0.9-1.1. Other meanings of relative terms may be apparent from the context, such as rounding off, so, for example “about 20 V” may also mean from 19.5 V to 20.4 V. 
     Also, the functionality described herein as being performed by one component may be performed by multiple components in a distributed manner. Likewise, functionality performed by multiple components may be consolidated and performed by a single component. Similarly, a component described as performing particular functionality may also perform additional functionality not described herein. For example, a device or structure that is “configured” in a certain way is configured in at least that way but may also be configured in ways that are not listed. 
     Furthermore, some embodiments described herein may include one or more electronic processors configured to perform the described functionality by executing instructions stored in non-transitory, computer-readable medium. Similarly, embodiments described herein may be implemented as non-transitory, computer-readable medium storing instructions executable by one or more electronic processors to perform the described functionality. As used in the present application, “non-transitory computer-readable medium” comprises all computer-readable media but does not consist of a transitory, propagating signal. Accordingly, non-transitory computer-readable medium may include, for example, a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a ROM (Read Only Memory), a RAM (Random Access Memory), register memory, a processor cache, or any combination thereof. 
     Many of the modules and logical structures described are capable of being implemented in software executed by a microprocessor or a similar device or of being implemented in hardware using a variety of components including, for example, application specific integrated circuits (“ASICs”). Terms like “controller” and “module” may include or refer to both hardware and/or software. Capitalized terms conform to common practices and help correlate the description with the coding examples, equations, and/or drawings. However, no specific meaning is implied or should be inferred simply due to the use of capitalization. Thus, the claims should not be limited to the specific examples or terminology or to any specific hardware or software implementation or combination of software or hardware. 
       FIGS.  1 A- 1 E  illustrate several embodiments of a battery pack  10  operable to power cordless electrical devices (e.g., electrical devices, such as power tools, outdoors tools, other motorized devices, non-motorized devices, etc.).  FIG.  1 A  illustrates a battery pack  10 A having a “5S3P” configuration (three parallel-connected strings of five series-connected battery cells),  FIG.  1 B  illustrates a battery pack  10 B having a “5S2P” configuration (two parallel-connected strings of five series-connected battery cells), and  FIG.  1 C  illustrates a battery pack  10 C having a “5S1P” configuration (one string of five series-connected battery cells). Similar battery packs are described and illustrated in U.S. Provisional Pat. Application Nos. 62/536,807, filed Jul. 25, 2017, and 62/570,828, filed Oct. 11, 2017, entitled “HIGH POWER BATTERY-POWERED SYSTEM,” and U.S. Pat. Application No. 16/045,513, filed on Jul. 25, 2018, the entire contents of all of which are hereby incorporated by reference. 
       FIG.  1 D  illustrates a battery pack  10 D having a “20S1P” configuration (one string of twenty series-connected cells), and  FIG.  1 E  illustrates a battery pack  10 E having a “20S2P” (two parallel-connected strings of twenty series-connected cells). Similar battery packs are described and illustrated in U.S. Provisional Pat. Application No. 62/527,735, filed Jun. 30, 2017, entitled “HIGH POWER BATTERY-POWERED SYSTEM,” and U.S. Pat. Application No. 16/025,491, filed on Jul. 2, 2018, the entire contents of both of which are hereby incorporated by reference. 
     The battery pack  10  includes battery cells  14  having a nominal voltage (e.g., between about 3 volts (V) and about 5 V) and a nominal capacity (e.g., between about 3 Amp-hours (Ah) and about 5 Ah or more (e.g., up to about 9 Ah)). The battery cells may be any rechargeable battery cell chemistry type, such as, for example, lithium (Li), lithium-ion (Li-ion), other lithium-based chemistry, nickel-cadmium (NiCd), nickel-metal hydride (NiMH), etc. 
     The battery pack  10  includes a number and arrangement of battery cells  14  to provide a desired output (e.g., nominal voltage, capacity, etc.) In  FIGS.  1 A- 1 C , the battery packs  10 A- 10 C have a nominal voltage of between about 16 V and about 21 V, and the capacity of the battery pack  10 A is about three times the capacity of the battery pack  10 C (e.g., about 9 Ah compared to about 3 Ah). In  FIGS.  1 D- 1 E , the battery packs  10 D- 10 E have a nominal voltage of between about 72 V and about 84 V, and the capacity of the battery pack  10 E is about two times the capacity of the battery pack  10 D (e.g., about 6 Ah compared to about 3 Ah). 
       FIG.  2    is a block diagram illustrating the battery pack  10  coupled to a charger  18 . The battery pack  10  includes the battery cells  14 , a battery controller  22 , an analog front end (AFE)  26 , a charging field effect transistor (FET)  30 , a positive battery terminal  34 , a positive charging terminal  38 , and a ground terminal  42 . 
     The positive battery terminal  34  and the ground terminal  42  are coupled to corresponding power terminals of a powered electrical device to provide operating power to the electrical device. The positive charging terminal  38  and the ground terminal  42  are coupled to corresponding charging terminals of the charger  18  to receive a charging current from the charger  18 . The charging FET  30  is coupled between the positive charging terminal  38  and the battery cells  14  to selectively provide the charging current to the battery cells  14 . 
     The charging FET  30  is controlled to open or close by the battery controller  22 . When the charging FET  30  is open, the battery cells  14  are disconnected from the charger  18  and, therefore, do not receive the charging current. When the charging FET  30  is closed, the battery cells  14  are connected to the charger  18  and, therefore, receive the charging current. The AFE  26  individually monitors and balances the battery cells  14  and provides operating power to the battery controller  22 . 
       FIG.  3    illustrates one example embodiment of a charging circuit  50  implemented in the battery pack  10 . The illustrated charging circuit  50  includes the charging FET  30 , a gate driver  54 , and a fuse  58 . In the illustrated example, the charging FET  30  includes a 40 V N-Channel power MOSFET, for example, a 40 V N-Channel power NexFET™ MOSFET CSD18511Q5A manufactured by Texas Instruments. The N-Channel FET may have a lower drain-source on resistance R DS(on)  and less current loss per unit area compared to a P-Channel FET. Compared to other charging circuits in which a charging FET and a fuse may limit the charging current to about 6 A, in the illustrated construction, the FET  30  and the fuse  58  may allow higher charging currents more than about 6 A to about 18 A or even higher (e.g., up to about 20 A). 
     The drain D of the charging FET  30  is coupled to the charging terminal  38  through the fuse  58 . The source S of the charging FET  30  is coupled to the battery cells  14  and, in particular, to the most positive terminal of the one or more strings of battery cell  14 . The source S of the charging FET  30  is also coupled to a source input of the gate driver  54 . The gate G of the charging FET  30  is coupled to a gate output of the gate driver  54 . As described above, the charging FET  30  selectively couples the charger  18  to the battery cells  14 . 
     The gate driver  54  is used to drive the charging FET  30 . In one example, the gate driver  54  is an ultra-small low-side MOSFET driver MC5060 manufactured by Micrel. As described above, a source input of the gate driver  54  is coupled to the source S of the charging FET  30 , and the gate output of the gate driver  54  is coupled to the gate G of the charging FET  30 . The gate driver  54  receives operating power from the battery cells  14  at a positive power supply input V+. The gate driver  54  receives a control input CHG EN from the battery controller  22 . The battery controller  22  provides control signals to open or close the charging FET  30  to the gate driver  54  through the control input CHG EN. In response to the control signals received from the battery controller  22 , the gate driver  54  opens or closes the charging FET  30  to selectively connect the charger  18  to the battery cells  14 . 
     A first switch  62  is coupled between the battery cells  14  and the power supply input V+. The drain of the first switch  62  is coupled to the battery cells  14 , and the source of the first switch  62  is coupled to the power supply input V+. The gate of the first switch  62  is controlled by a second switch  66 , and the gate of the second switch  66  is controlled by the battery controller  22  using a control signal CHG FET. The battery controller  22  sets the control signal CHG FET to a logical high to close the second switch  66  and sets the control signal CHG FET to a logical low to open the second switch  66 . The first switch  62  is closed when the second switch  66  is closed, and the first switch  62  is opened when the second switch  66  is opened. 
     A capacitor  70  (for example, a timer circuit) is coupled between the positive power input V+ and ground. When the first switch  62  is enabled, the capacitor  70  is first charged before the gate driver  54  is controlled to open the charging FET  30 . The capacitance value of the capacitor  70  may be selected to control the amount of time for the capacitor  70  to reach full charge (i.e., a time constant). 
     The charger  18  is configured to provide a charging current between about 6 A and about 20 A to charge the battery pack  10 . The charger  18  may provide a charging current corresponding to the configuration of the battery pack  10 . In one embodiment, the charger  18  provides a charging current of about 6 A to charge the 5S1P battery pack  10 C (or the 20S1P battery pack  10 D), provides a charging current of about 12 A to charge the 5S2P battery pack  10 B (or the 20S2P battery pack  10 E), and provides a charging current of about 18 A to charge the 5S3P battery pack  10 A. 
     In some embodiments, the charger  18  may limit the maximum charging current to about 13.5 A regardless of the configuration of the battery pack  10 . Accordingly, the charger  18  provides a maximum charging current of about 13.5 A to the 5S3P battery pack  10 A. The charging FET  30  and the fuse  58  are selected to allow fast charging of the battery pack  10  at high currents as described above. The illustrated charging FET  30  may be configured to handle a voltage of 40 V and a maximum current of approximately 20 A or more. The illustrated fuse  58  is, for example, an 8 A fuse rated to allow a maximum current of 13.5 A. In other embodiments, the fuse  58  may be rated (e.g., a 20 A fuse) to handle higher maximum currents, for example, up to 18 A or 20 A. 
       FIG.  4    illustrates placement of components of the illustrated charging circuit  50  on a printed circuit board  74  of the battery pack  10 . The charging FET  30 , the fuse  58 , and the capacitor  70  are placed immediately behind the terminal block  32  (including the positive battery terminal  34 , the charging terminal  38 , and the ground terminal  42 ). 
       FIG.  5    is a flowchart of an example method  78  for enabling fast charging of the battery pack  10 . The battery controller  22  enables charging of the battery cells  14  in response to detecting a connection to the charger  18 . The illustrated method  78  includes controlling, using the battery controller  22 , the first switch  62 , coupled between the battery cells  14  and the power supply input V+ of the gate driver  54 , to close (at block  82 ). The battery controller  22  opens the first switch  62  by setting the control signal CHG FET to high. As described above, the control signal CHG FET closes the second switch  66  which, in turn, closes the first switch  62 . When the first switch  62  is closed, the power supply input V+ of the gate driver  54  is coupled to the battery cells  14 , thereby providing operating power supply to the gate driver  54 . 
     The method  78  includes setting, using the battery controller  22 , a first delay timer corresponding to a time to full charge of the capacitor  70  coupled between the power supply input V+ and ground (at block  86 ). The battery controller  22  waits for the capacitor  70  to reach full charge by setting a timer corresponding to the amount of time the capacitor  70  takes to reach full charge. 
     The method  78  further includes controlling, using the battery controller  22 , the charging FET  30  to close when the first delay timer expires (at block  90 ). The battery controller  22  waits for the capacitor  70  to reach full charge before providing an enable signal to the control input CHG EN. The gate driver  54  controls the charging FET  30  to close to charge the battery cells  14  in response to the gate driver  54  receiving the enable signal over the control input CHG EN. 
       FIG.  6    is a flowchart of an example method  94  for disable fast charging of the battery pack  10 . The battery controller  22  disables charging of the battery cells  14  in response to, for example, detecting that the battery pack  10  is fully charged, disabled due to a fault condition, etc. or in response to detecting that the charger  18  is disconnected from the battery pack  10 . 
     The illustrated method  94  includes controlling, using the battery controller  22 , the charging FET  30  to open (at block  98 ). The battery controller  22  provides a disable signal to the control input CHG EN. When the gate driver  54  receives the disable signal over the control input CHG EN, the gate driver  54  control the charging FET  30  to open to disable charging of the battery cells  14 . 
     The method  94  includes setting, using the battery controller  22 , a second delay timer to ensure that the charging FET  30  is completely switched OFF (at block  102 ). The method  94  further includes controlling, using the battery controller  22 , the first switch  62 , coupled between the battery cells  14  and the power supply input V+ of the gate driver  54 , to open when the second delay timer expires (at block  106 ). The battery controller  22  waits for the charging FET  30  to be completely switched OFF before disabling the gate driver  54 . When the second delay timer expires, the battery controller  22  opens the second switch  66  to open the first switch  62 . The battery controller  22  thereby disables the power supply to the gate driver  54 . 
       FIG.  7    illustrates one example embodiment of a charging circuit  110  implemented in the battery pack  10 . The illustrated charging circuit  110  is similar to the charging circuit  50 , except that the gate driver  54  is on the high-side of the charging FET  30  rather than the low-side of the charging FET  30  such that the gate driver  54  receives operating power from the charging terminal  38 . In the example illustrated, the charging FET includes a 200 V  36 A N-Channel MOSFET BSC320N20NS3 manufactured by Infineon Technologies. The gate driver  54  is a surge protector LTC4380CMS manufactured by Linear Technologies. 
       FIG.  8    illustrates one example embodiment of a charging circuit  114  implemented in the battery pack  10 . The illustrated charging circuit  114  includes a first charging FET  118 , a second charging FET  122 , and a fuse  58 . In the illustrated example, the first charging FET  118  and the second charging FET  122  include  40 V P-Channel power MOSFET, for example, a  40 V P-Channel MOSFETs SiS443DN manufactured by Vishay® Siliconix. 
     The drain D of each charging FET  118 ,  122  is coupled to the charging terminal  38  through the fuse  58 . The source S of each charging FET  118 ,  122  is coupled to the battery cells  14  and, in particular, to the most positive terminal of the one or more strings of battery cell  14 . The gate G of each charging switch  118 ,  122  is coupled to a switch  126 . The battery controller  22  controls the switch  126  to open and close the charging FETs  118 ,  122 . For example, the battery controller  22  opens the switch  126  to open the charging FETs  118 ,  122  and closes the switch  126  to close the charging FETs  118 ,  122 . 
       FIG.  9    illustrates placement of components of the illustrated charging circuit  114  on the printed circuit board  74  of the battery pack  10 . The charging FETs  118 ,  122  and the fuse  58  are placed immediately behind the terminal block  32  (including the positive battery terminal  34 , the charging terminal  38 , and the ground terminal  42 ). 
     In other constructions (not shown), the charging circuit  50 ,  110 ,  114  may not include a fuse, such as the fuse  58 . In such constructions, the voltage may be measured across the FET (e.g., the FET  30  or the FET(s)  118  or  122 ), and the current through the FET may be determined (e.g., by the controller 22) based on a known internal resistance. If the calculated current is above a threshold, the FET can open. 
     Thus, the invention may provide, among other things, fast-charging battery packs. 
     Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described. 
     One or more independent features and/or independent advantages of the invention may be set forth in the claims.