Series-parallel converter and battery pack

Abstract

This utility model relates to the field of lithium-ion batteries and discloses a series-parallel converter battery pack and a battery pack. The series-parallel converter includes a housing; a plurality of balanced charging output ports and a plurality of discharge line input ports are respectively provided on one end face of the housing; a discharge line output port and a balanced charging input port are provided on the other end face of the housing; a series-parallel circuit module is provided inside the housing, including a controller and a series-parallel circuit; a switching circuit is provided in the series-parallel circuit; the control terminal of each switching circuit is electrically connected to the controller; the electrical terminals of each balanced charging output port are respectively electrically connected to the electrical terminals of the balanced charging input ports through the series-parallel circuit, one-to-one, to charge each battery cell in each battery pack electrically connected to each balanced charging output port; each discharge line input port is electrically connected to the discharge output port through the series-parallel circuit; the discharge line input ports are connected in series, parallel, or a combination of series and parallel connections; the discharge line output port serves as a discharge output port. This converter is applied to battery pack combinations, improving the application flexibility of the battery pack.

Description

Technical Field

[0001] This utility model relates to the field of batteries, and in particular to a series-parallel converter and a battery pack. Background Technology

[0002] With the increasing application of batteries, especially lithium-ion batteries, more and more devices are using lithium-ion batteries.

[0003] During the research of this invention, the inventors discovered that the interchangeability and versatility of lithium-ion batteries need improvement, and users' demand for freely combinable battery packs to adapt to different devices and usage environments is constantly increasing. Currently, most battery packs are manufactured using a PVC insulating sleeve fixing process, which lacks interoperability in the battery pack structure, preventing series and parallel connections between battery packs. Once assembled, the voltage, capacity, and other performance parameters of the battery pack are unique and unchangeable, thus limiting the application of lithium-ion batteries in different devices and to meet different needs. Summary of the Invention

[0004] One of the objectives of this utility model embodiment is to provide a series-parallel converter and a battery pack, which are applied to the combination of battery packs to improve the application flexibility of the battery pack.

[0005] This utility model provides a series-parallel converter, comprising:

[0006] The housing has a plurality of balanced charging output ports and a plurality of discharge line input ports on one end face.

[0007] A discharge line output interface and a balanced charging input interface are provided on the other end face of the housing.

[0008] The housing contains a series-parallel circuit module, including a controller and the series-parallel circuits. The series-parallel circuits include switching circuits, and the control terminals of each switching circuit are electrically connected to the controller.

[0009] Each of the electrical nodes of the balanced charging output interface is electrically connected to the electrical node of the balanced charging input interface through the series-parallel circuit, so as to charge each battery cell in each battery pack electrically connected to each balanced charging output interface.

[0010] Each of the discharge line input interfaces is electrically connected to the discharge output interface through the series-parallel circuit. Each of the discharge line input interfaces is electrically connected in series, in parallel, or in a combination of series and parallel. The discharge line output interface serves as the discharge output interface.

[0011] Optionally, a plurality of the balanced charging output interfaces and a plurality of the discharge line input interfaces are disposed on the first end face of the housing;

[0012] The discharge line output interface and the balanced charging input interface are located on the second end face of the housing, which is opposite to the first end face.

[0013] Optionally, an electronic display screen is also provided on the surface of the housing, which is electrically connected to the controller.

[0014] Optionally, a plurality of buttons are provided on the surface of the housing, and each button is electrically connected to the controller.

[0015] Optionally, a rechargeable battery is also provided inside the housing, which is electrically connected to the series-parallel circuit module to provide operating current.

[0016] Optionally, a charging interface is also provided on the side of the housing, which is electrically connected to the rechargeable battery.

[0017] Secondly, an embodiment of the present invention provides a battery pack comprising:

[0018] A plurality of battery cells are connected in series, in parallel, or a combination of both. Each battery cell has a discharge output connector and a balance charging input connector extending from its top.

[0019] The series-parallel converter according to claims 1 to 4, wherein the discharge output connector of each battery cell is electrically connected to the discharge line input interface of the series-parallel converter, and the balance charging input connector of each battery cell is electrically connected to the balance charging output interface of the series-parallel converter.

[0020] The discharge line output interface of the series-parallel converter serves as the discharge output interface of a battery pack formed by combining a plurality of battery cells.

[0021] The balanced charging input interface of the series-parallel converter serves as the charging input interface for charging each individual battery cell within each battery pack.

[0022] Optionally, each of the battery cells has a snap-fit ​​hole on its side wall.

[0023] The battery pack also includes,

[0024] The connecting buckle has two opposite ends, each with a snap-fit ​​portion. Each snap-fit ​​portion mates with a snap-fit ​​hole on the housing, allowing for engagement with the snap-fit ​​hole.

[0025] When one of the latching portions of the connecting buckle is engaged with one of the latching holes of the housing, the other latching portion of the connecting buckle is located outside the side wall of the housing.

[0026] As can be seen from the above, using the series-parallel converter of this embodiment, users can further electrically connect two or more battery cells (in series, parallel, or a combination of series and parallel) to form a new battery pack, which then powers the external system. This allows users to further electrically connect the battery pack according to different devices and usage environments to meet their needs. This solution improves the application flexibility of battery packs and meets the increasingly diverse market demands.

[0027] Furthermore, when charging individual cells within each battery pack, there is no need to configure a charging power supply for each individual cell. Instead, by using the series-parallel converter of this embodiment, the charging power supply can be connected to the balanced charging input interface of the series-parallel converter through a balanced charging adapter cable. This allows for balanced charging of each individual cell within each battery pack electrically connected to the series-parallel converter, greatly reducing the need for charging connection wiring in the battery pack. Attached Figure Description

[0028] The accompanying drawings, which are provided to further illustrate the present invention and form part of this application, do not constitute an undue limitation of the present invention.

[0029] Figure 1 , 2 Figures 3 and 4 are three-dimensional structural diagrams of the series-parallel converter provided in Embodiment 1 of this utility model;

[0030] Figure 4 These are schematic diagrams of the discharge wire adapter provided in Embodiment 1 of this utility model;

[0031] Figure 5 These are schematic diagrams of the balanced charging adapter cable provided in Embodiment 1 of this utility model;

[0032] Figure 6 These are schematic diagrams showing the connection structure between the series-parallel converter provided in Embodiment 1 of this utility model and a single battery cell during use.

[0033] Figure 7 This is a schematic diagram of the battery pack structure provided in Embodiment 2 of this utility model;

[0034] Figure 8 This is an exploded view of the battery pack provided in Embodiment 2 of this utility model;

[0035] Figure 9 This is an exploded structural diagram of a battery pack assembly consisting of two battery packs, provided in Embodiment 2 of this utility model.

[0036] Figure 10 This is a schematic diagram of the assembly structure of a battery pack assembly consisting of two battery packs, provided in Embodiment 2 of this utility model.

[0037] Figure 11 This is an exploded structural diagram of a battery pack assembly consisting of three battery packs, provided in Embodiment 2 of this utility model.

[0038] Figure 12 This is a schematic diagram of the assembly structure of a battery pack assembly consisting of 3 battery packs, provided in Embodiment 2 of this utility model.

[0039] Figure 13 This is an exploded structural diagram of a battery pack assembly consisting of four battery packs, provided in Embodiment 2 of this utility model.

[0040] Figure 14 This is a schematic diagram of the assembly structure of a battery pack assembly consisting of four battery packs, provided in Embodiment 2 of this utility model.

[0041] Figure 15 for Figure 14 A side view of the battery pack assembly shown.

[0042] Figure 16 for Figure 15 A schematic diagram of the AA cross-sectional structure of the battery pack assembly shown.

[0043] Figure 17 for Figure 16 A schematic diagram of the BB cross-sectional structure of the battery pack assembly shown.

[0044] Figure 18 This is a three-dimensional structural diagram of the connecting buckle provided in Embodiment 2 of this utility model;

[0045] Figure 19 This is a side view of the connecting buckle provided in Embodiment 2 of this utility model.

[0046] 91: Housing; 92: Balanced charging output interface; 93: Discharge wire input interface;

[0047] 94: Discharge output interface; 95: Balance charging input interface; 96: Electronic display; 97: Buttons; 98: Charging interface; 99: Individual battery cells

[0048] 2: Discharge output section; 21: Power connector;

[0049] 3: Voltage acquisition unit; 31: Wiring terminal;

[0050] 4: Insulating tube; 41: Clip hole; 42: Clip concealed hole;

[0051] 5: Connecting buckle; 51: First buckle part; 52: Second buckle part; 53: Connecting post;

[0052] 54: Notch; 56: Chamfered bevel; 57: Through hole;

[0053] 6: Bottom cover; 7: Top cover; 71: Cable outlet; 8: Line sheath. Detailed Implementation

[0054] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention. Example

[0055] See Figures 1-6 As shown.

[0056] This embodiment provides a series-parallel converter, which mainly includes a housing 91, wherein the housing 91 may be, but is not limited to, a plastic shell.

[0057] A series-parallel circuit module is provided inside the housing 91. This series-parallel circuit module may be, but is not limited to, a PCBA module. A series-parallel circuit formed by aluminum foil traces is provided on the series-parallel circuit module. An electronic switch is provided in the series-parallel circuit. The control terminal of each electronic switch is electrically connected to the controller. The controller controls the conduction and cutoff of each electronic switch to control the series-parallel circuit to be a series circuit, a parallel circuit, or a combination of series and parallel circuits.

[0058] A plurality of balanced charging output interfaces 92 and a plurality of discharge line input interfaces 93 are provided at one end of the housing 91.

[0059] Referring to the diagram, four balanced charging output interfaces 92 and four discharge line input interfaces 93 are provided at the rear end of the housing 91. The interfaces at this end are electrically connected to the individual battery cells 99 that need to be electrically connected into a large battery pack through this series-parallel converter.

[0060] At the other end of the housing 91, there is a discharge line output interface 94 and a balance charging input interface 95. The discharge line output interface 94 is a two-pin interface, serving as the positive and negative terminals of the overall battery pack. The balance charging input interface 95 is used to connect to an external charging power source to charge the individual battery cells 99 connected to this series-parallel converter. The end of the housing 91 serves as the end face for electrical connection to external electrical equipment or charging power sources.

[0061] The number of electrical connection pins of each balanced charging output interface 92 is determined according to the number of battery cells in the battery pack 99 it is connected to. For example, when the battery pack 99 consists of four battery cells, the balanced charging output interface 92 has five pins, one of which is the common negative terminal, and the other four correspond to the positive terminals of the four battery cells respectively.

[0062] Each discharge line input interface 93 includes two electrical connection pins, one of which is positive and the other is negative, corresponding to the positive and negative terminals of each battery cell 99, respectively.

[0063] Each discharge line input interface 93 is electrically connected to the discharge output interface through a series-parallel circuit. Each discharge line input interface 93 is electrically connected in series, parallel, or a combination of series and parallel to electrically connect the individual battery cells 99 connected to each discharge line input interface 93 into an integrated battery pack. The discharge line output interface 94 serves as the discharge output interface of the individual battery pack.

[0064] Each electrical node of the balance charging output interface 92 is electrically connected to the electrical node of the balance charging input interface 95 through a series-parallel circuit, so as to input the charging current connected to the balance charging input interface 95 to each battery cell in each battery pack electrically connected to each balance charging output interface 92, and charge each battery cell.

[0065] As can be seen from the above, using the series-parallel converter of this embodiment, users can further electrically connect two or more battery pack cells 99 (in series, parallel, or a combination of series and parallel) to form a new battery pack, which then provides power to the outside world. This allows users to further electrically connect the battery pack according to different devices and usage environments to meet their needs. This solution improves the application flexibility of the battery pack and meets the increasingly diverse market demands.

[0066] Furthermore, when charging the individual cells within each battery pack 99, there is no need to configure a charging power supply for each battery pack 99. Instead, by using the series-parallel converter of this embodiment, the charging power supply can be connected to the balanced charging input interface 95 of the series-parallel converter through a balanced charging adapter cable. This allows for balanced charging of each individual cell within each battery pack 99 electrically connected to the series-parallel converter, greatly reducing the need for charging connection wiring for the battery pack.

[0067] As an illustration of this embodiment, an electronic display screen is further provided on the shell surface of the housing 91. The electronic screen 96 is electrically connected to the controller inside the housing 91 and displays the parameter information of the current battery pack, such as the number of series and parallel batteries and the output voltage of the battery pack.

[0068] As an illustration of this embodiment, a plurality of buttons 97 are also provided on the surface of the housing 91, and each button 97 is electrically connected to the controller. For example, one button can be set as a series button and another as a parallel button.

[0069] When the corresponding button is triggered, the controller controls the electronic switches in the series-parallel circuit according to the trigger signal, adjusting the series-parallel circuit to be connected in series or parallel. For example, but not limited to, there are buttons to represent the number of battery pack cells 99. If the maximum number of battery pack cells supported by this series-parallel converter is 4, there is a set of buttons for the number of battery pack cells including three buttons. When the button corresponding to 2 battery pack cells 99 is triggered, the controller controls the electronic switches of the two circuits in the series-parallel circuit to be turned on, and the other electronic switches are in the off state. The two battery pack cells 99 form a battery pack. Similarly, when the button corresponding to 3 battery pack cells 99 is triggered, the controller controls the electronic switches of the three circuits in the series-parallel circuit to be turned on, and the other electronic switches are in the off state. The three battery pack cells 99 form a battery pack.

[0070] As an illustration of this embodiment, a rechargeable battery is also provided inside the housing 91. The rechargeable battery is electrically connected to the series-parallel circuit module, providing operating current to the module. This allows the user to easily adjust the series-parallel connection status and the number of connections by pressing buttons before electrically connecting the individual battery cells 99. This further enhances the intelligence of the series-parallel converter and makes it more convenient for users.

[0071] As an illustration of this embodiment, a charging interface 98 is also provided on one side of the housing 91, such as, but not limited to, Type-A, Type-B, Type-C, Mini USB, Micro USB, etc., to connect to an external charging power source to charge the rechargeable battery and improve the portability of the series-parallel converter.

[0072] As an illustration of this embodiment, the series-parallel converter of this embodiment can be applied to the series or parallel connection of battery pack cells 99, and can also be applied to the series or parallel connection, or a combination of series and parallel connection, of three or four sets of battery pack cells 99. The above is only for illustration; it can also be applied to the electrical connection of more sets of battery pack cells 99. During connection, the discharge output connector of each battery pack cell 99 is electrically connected to the discharge line input interface 93 on the series-parallel converter, and the balance charging input connector of each battery pack cell 99 is electrically connected to the balance charging output interface 92 on the series-parallel converter. The series-parallel converter electrically connects the battery pack cells 99 together to form a battery pack assembly. The discharge line output interface 94 serves as the discharge output interface of the assembled battery pack, and a discharge line adapter cable is connected to its side for external power supply. The balance charging input interface 95 of the series-parallel converter forms the external charging interface 98 of the assembled battery pack assembly, which is connected to an external charger via a balance charging adapter cable to charge the individual battery cells within each battery pack cell 99. Example

[0073] See Figures 7-19 As shown.

[0074] As an illustration of this embodiment, this embodiment also provides a battery pack unit 99 that is easy to combine with each other, which includes a battery pack body, a housing, and a matching connectable and detachable connector 5.

[0075] The housing in this embodiment is a rigid housing, and the battery pack body is encapsulated inside the housing. The side wall of the housing has a snap-fit ​​hole 41 that matches the snap-fit ​​portion on the matching connecting buckle 5. As an illustration of this embodiment, taking a rectangular battery pack body as an example, snap-fit ​​holes 41 are provided on the four side walls of the rectangular housing. The number of snap-fit ​​holes 41 on each side wall can be one or more.

[0076] The middle part of the connecting buckle 5 is the connecting post 53. The outer diameter of the connecting post 53 is smaller than the diameter of the buckle hole 41 on the housing. The two opposite ends of the connecting post 53 are respectively provided with a first buckle part 51 and a second buckle part 52. In the natural state, the outer diameter of the first buckle part 51 and the second buckle part 52 at both ends is larger than the outer diameter of the middle connecting post 53, and slightly larger than the diameter of the buckle hole 41 on the housing.

[0077] The connecting buckle 5 in this embodiment is made of a material with good elasticity, and can be made by injection molding, but is not limited to that.

[0078] The battery cells in the pack can be, but are not limited to, lithium-ion batteries.

[0079] Among them, the battery pack cell 99 is composed of at least two battery cells connected in series or in parallel or a combination of series and parallel. The overall tab of the battery pack cell 99 is used as the electrode of the battery pack cell 99, and the overall electrode is used as the current output terminal to output current to the outside. The specific series and parallel connection scheme between battery cells can be, but is not limited to, the prior art.

[0080] Each battery cell is arranged together, and each tab is located at one end of the battery cell 99. The end where the tab is located is called the top end, the end opposite the top end is called the bottom end, and the surfaces between the top end and the bottom end are called the side ends.

[0081] A discharge output section 2 and a voltage acquisition section 3 are provided on the top of the battery cell 99. The discharge output section 2 may be, but is not limited to, a discharge line, and the voltage acquisition section 3 may be, but is not limited to, a voltage acquisition line.

[0082] Each discharge output unit 2 is electrically connected to the overall positive "+" and negative "-" electrodes of the battery pack cell 99, outputting current externally. Each voltage acquisition unit 3 is electrically connected to the "+" and "-" electrodes of each battery cell that makes up the battery pack cell 99, realizing voltage sampling of each battery cell. This allows for charging of each battery cell based on its voltage, ensuring voltage and charge balance among the cells and maintaining a balanced charge distribution within the battery pack. Further balanced charging technology can be found in existing technologies.

[0083] The electrical connection between the discharge output unit 2, the voltage acquisition unit 3 and each electrode can be, but is not limited to, existing technologies such as laser welding, soldering, and ultrasonic welding.

[0084] As an illustration of this embodiment, individual battery cells can be bundled together using strapping, but is not limited to this method.

[0085] As an illustration of this embodiment, the discharge output section 2 of this embodiment is a discharge line, and a power connector 21 is connected to the end of the discharge line to connect with another power connector 21 of an external electric device.

[0086] Similarly, the voltage acquisition unit 3 is a voltage acquisition line, and a terminal 31 is connected to the end of each voltage acquisition line as a balanced charging connector, which is connected to the charger.

[0087] In this embodiment, the battery cell 99 can be used as a power source independently. The snap-fit ​​hole 41 serves as a heat dissipation hole, improving the heat dissipation effect of the battery cell 99 and preventing heat accumulation inside the casing from causing danger.

[0088] In this embodiment, the multiple battery cells 99 can be flexibly combined into a battery pack assembly, which can then be used as a power source to provide current. Specifically, a connector 5 is snapped into the snap-fit ​​hole 41 on the side wall of each battery cell 99's housing, and each connector 5 laterally combines two adjacent battery cells 99 together. Figures 3-11 As shown, any number of battery packs can be assembled in any direction to form a battery pack combination according to user application needs. The discharge output sections of each battery pack can be connected in series or parallel through a series-parallel circuit structure, so that the battery pack combination outputs current as a whole. Alternatively, each battery pack can be used as a power source to supply power to the outside world separately. The specific application depends on the user's needs.

[0089] As an illustration of this embodiment, the housing includes an insulating tube 4, a bottom cover 6, and a top cover 7. The insulating tube 4 can be, but is not limited to, an insulating square tube. Both ends of the insulating tube 4 are open openings. During assembly, the insulating tube 4 is inserted from the top of the battery pack body, and the battery pack body is placed inside the insulating tube 4. The bottom cover 6 is installed at the bottom opening of the insulating tube 4, allowing the battery pack body to rest on the bottom cover 6. The top cover 7 is fixed at the top opening of the insulating tube 4. A discharge output section 2 and a voltage acquisition section 3 are installed on the top cover 7 of the insulating tube 4. Both the insulating tube 4 and the top cover 7 have outlet holes 71 for protruding from or extending from the top cover 7. As an illustration of this embodiment, a wire sheath 8 is also provided inside the outlet hole 71. The housing structure of this embodiment facilitates the assembly and disassembly of the battery pack cells 99, saving time and effort.

[0090] As an illustration of this embodiment, a matching recessed snap hole 41 and a protruding third snap part are provided between the inner wall of the insulating tube 4 and the outer wall of the top cover 7. The insulating tube 4 and the top cover 7 are connected by snaps, which further facilitates the disassembly and installation of the top cover 7 of the battery pack unit 99, and makes it convenient for users to maintain and repair the battery pack unit 99.

[0091] As an illustration of this embodiment, a snap-fit ​​concealed hole is also provided on the inner wall of the side wall of the housing. Each snap-fit ​​concealed hole corresponds one-to-one with each snap-fit ​​hole 41, and they are directly connected to each other, even if the wall thickness of the part where the snap-fit ​​concealed hole is located is thinner than the wall thickness of other parts. In this way, when the first snap-fit ​​part 51 (or the second snap-fit ​​part 52) ​​of the connecting buckle 5 is snapped into the snap-fit ​​hole 41, the connecting buckle 5 extending into the housing is located in the snap-fit ​​concealed hole, and does not protrude from the inner wall of the side wall of the housing. This does not occupy the space inside the housing used for assembling the battery pack body, which is beneficial to increasing the capacity of the battery pack cell 99.

[0092] Each connecting buckle 5 is provided with a through hole 57 that passes through the first buckle part 51, the second buckle part 52 and the connecting post 53. This design is beneficial to saving materials. On the other hand, when buckling is required, the first buckle part 51 (or the second buckle part 52) ​​deforms elastically under the pressure of the buckle hole 41. The first buckle part 51 (or the second buckle part 52) ​​deforms radially, making it easier to elastically compress and deform. This makes the buckling assembly between the connecting buckle 5 and the battery pack unit 99 easier, saving time and effort.

[0093] As an illustration of this embodiment, taking the first latching part 51 of the connecting buckle 5 as an example, the structure of the second latching part 52 is the same as that of the first latching part 51. The first latching part 51 is also provided with a plurality of notches 54, each notch 54 dividing the first latching part 51 into a plurality of latching fixing parts that are distributed around the through hole 57 and protrude from the outer periphery of the connecting post 53. The notches 54 are spaced between adjacent circumferentially arranged latching fixing parts. When the latching part is latched into the latching hole 41, the notches 54 between the latching fixing parts narrow, and each latching fixing part converges and compresses towards the center, making it easier for the latching part to enter the latching hole 41 and confine it within the latching concealment hole through the latching hole 41. This further facilitates the latching assembly between the connecting buckle 5 and the battery pack unit 99, saving time and effort.

[0094] As an illustration of this embodiment, the latching fixing parts of each latching part are evenly distributed around the through hole 57, and may be, but not limited to, symmetrical with respect to the axis of the through hole 57.

[0095] As an illustration of this embodiment, a chamfered bevel 56 is provided on the outer end face of each buckle part facing away from the connecting post 53, that is, on the outer edge of the outward-facing end face of each buckle fixing part of the buckle part. This makes the distance from each point on each chamfered bevel 56 to the axis of the through hole 57 gradually decrease along the direction away from the connecting post 53. This makes it easier for the buckle part to enter the buckle hole 41 when the buckle part is buckled into the buckle hole 41. The front end of the chamfered bevel 56 of each buckle fixing part that is closest to the axis enters the buckle hole 41 first, and the buckle part is pushed along the bevel. This makes it easier for the buckle part to enter the buckle hole 41, and makes the buckle assembly between the connecting buckle 5 and the battery pack unit 99 easier to operate, saving time and effort.

[0096] The embodiments described above do not constitute a limitation on the scope of protection of this technical solution. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the above embodiments should be included within the scope of protection of this technical solution.

Claims

1. A series-parallel converter, characterized in that, include, The housing has a plurality of balanced charging output ports and a plurality of discharge line input ports on one end face. A discharge line output interface and a balanced charging input interface are provided on the other end face of the housing. The housing contains a series-parallel circuit module, including a controller and the series-parallel circuits. The series-parallel circuits include switching circuits, and the control terminals of each switching circuit are electrically connected to the controller. Each of the electrical nodes of the balanced charging output interface is electrically connected to the electrical node of the balanced charging input interface through the series-parallel circuit, so as to charge each battery cell in each battery pack electrically connected to each balanced charging output interface. Each of the discharge line input interfaces is electrically connected to the discharge output interface through the series-parallel circuit. Each of the discharge line input interfaces is electrically connected in series, in parallel, or in a combination of series and parallel. The discharge line output interface serves as the discharge output interface.

2. The series-parallel converter according to claim 1, characterized in that, A plurality of the balanced charging output interfaces and a plurality of the discharge line input interfaces are disposed on the first end face of the housing; The discharge line output interface and the balanced charging input interface are located on the second end face of the housing, which is opposite to the first end face.

3. The series-parallel converter according to claim 1, characterized in that, An electronic display screen is also provided on the surface of the housing, which is electrically connected to the controller.

4. The series-parallel converter according to claim 1, characterized in that, A plurality of buttons are also provided on the surface of the housing, and each button is electrically connected to the controller.

5. The series-parallel converter according to claim 1, characterized in that, A rechargeable battery is also provided inside the housing, which is electrically connected to the series-parallel circuit module to provide operating current.

6. The series-parallel converter according to claim 5, characterized in that, A charging interface is also provided on the side of the housing, which is electrically connected to the rechargeable battery.

7. A battery pack, characterized in that, include: A plurality of battery cells, which are composed of a plurality of battery cells connected in series, parallel, or a combination of both, are provided with a discharge output connector and a balance charging input connector at the top of each battery cell. The series-parallel converter according to claims 1 to 4, wherein the discharge output connector of each battery cell is electrically connected to the discharge line input interface of the series-parallel converter, and the balance charging input connector of each battery cell is electrically connected to the balance charging output interface of the series-parallel converter. The discharge line output interface of the series-parallel converter serves as the discharge output interface of a battery pack formed by combining a plurality of the battery cells. The balanced charging input interface of the series-parallel converter serves as the charging input interface for charging each individual battery cell within each battery pack.

8. A battery pack according to claim 7, characterized in that, Each of the battery cells has a snap-fit ​​hole on the side wall of its casing. The battery pack also includes, The connecting buckle has two opposite ends, each with a snap-fit ​​portion. Each snap-fit ​​portion mates with a snap-fit ​​hole on the housing, allowing for engagement with the snap-fit ​​hole. When one of the latching parts of the connecting buckle is latched with one of the latching holes of the housing, the other latching part of the connecting buckle is located outside the side wall of the housing.

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