Charging device, battery pack charging method and charging system

Abstract

This application discloses a charging device, a charging method for a battery pack, and a charging system, including: a power input port for connecting to an external power source; a power output port for connecting to the battery pack to charge it; and a charging control unit disposed between the power input port and the power output port, for at least controlling the electrical energy output from the power output port. The charging control unit is configured to periodically output pulsed electrical energy to charge the battery pack; wherein the frequency of the pulsed electrical energy is greater than or equal to 1 Hz. Compared to constant current charging, this method can reduce battery pack polarization, decrease battery pack impedance and reduce loss of active materials, thereby delaying battery pack aging, extending battery pack lifespan, and improving long-term discharge performance. By setting the frequency of the pulsed electrical energy to be greater than or equal to 1 Hz, the polarization of the battery pack can be further reduced through a larger pulse frequency, further extending the battery pack lifespan.

Description

Technical Field

[0001] This application relates to the field of battery pack charging technology in power tools, specifically to a charging device, a battery pack charging method, and a charging system. Background Technology

[0002] Power tools on the market that use brushless motors are usually powered by battery packs, which makes the power tools not limited by power supply and location, and enables flexible application of power tools.

[0003] Currently, fast charging is commonly used to charge battery packs. During fast charging, the charger continuously outputs the same current to charge the battery pack, which gradually exacerbates the polarization of the battery pack and accelerates the degradation of cell life.

[0004] This section provides background information related to this application, which is not necessarily prior art. Summary of the Invention

[0005] One objective of this application is to solve or at least mitigate some or all of the aforementioned problems. Therefore, one objective of this application is to provide a charging device, a battery pack charging method, and a charging system that can extend the battery pack's lifespan and improve its long-term discharge performance.

[0006] To achieve the above objectives, this application adopts the following technical solution: a charging device, including a power input port for connecting to an external power source; a power output port for connecting to a battery pack for charging the battery pack; a charging control unit disposed between the power input port and the power output port, for at least controlling the electrical energy output by the power output port; the charging control unit is configured to periodically output pulse electrical energy to charge the battery pack; the frequency of the pulse electrical energy is greater than or equal to 1 Hz.

[0007] In some embodiments, electrical energy includes a current source, and pulsed electrical energy includes a pulsed current.

[0008] In some embodiments, the effective output current range of the pulse current is 5C to 15C.

[0009] In some embodiments, the frequency of the pulsed electrical energy is greater than or equal to 2 Hz.

[0010] In some embodiments, the frequency of the pulse current is a fixed value or a variable value.

[0011] In some embodiments, the charging control unit is also configured to charge the battery pack in a constant current and constant voltage manner.

[0012] In some embodiments, the charging device also includes user controls; The charging control unit is configured to control the output of the power output port based on user-controlled control commands.

[0013] A charging system, characterized in that it comprises: a battery pack including rechargeable cell components; a charger for outputting a current source to provide charging current to the cell components; a power management unit connected at least to the cell components to control the charging and discharging of the cell components; the power management unit is configured to selectively charge the battery pack using a first charging mode or a second charging mode; wherein, in the first charging mode, the battery pack is configured to be charged using a periodic pulse current; and in the second charging mode, the battery pack is configured to be charged using a constant current and constant voltage method.

[0014] In some embodiments, the frequency of the pulse current is greater than or equal to 1 Hz.

[0015] In some embodiments, the charging system further includes a user control for selecting a first charging mode and a second charging mode.

[0016] In some embodiments, user controls are located on the charger or battery pack.

[0017] In some embodiments, the power management unit is configured to control the current source output by the charger based on control commands provided by the user control.

[0018] In some embodiments, the effective discharge rate of the pulse current ranges from 5C to 15C.

[0019] In some embodiments, the rated current range of the current source is 1A to 20A.

[0020] In some embodiments, in a first charging mode, the maximum current output to the battery pack is the maximum allowable charging current of the charger; in a second charging mode, the maximum current output to the battery pack is the maximum allowable charging current of the charger.

[0021] In some embodiments, the battery pack is configured to power a power tool; the power tool includes at least one of a handheld tool, a benchtop tool, a manned work vehicle, or an electric fan.

[0022] A method for charging a battery pack, the battery pack being configured to power at least a power tool, the battery pack comprising: a charging terminal for receiving electrical energy; a rechargeable cell assembly; the method for charging the battery pack comprising: periodically supplying pulsed electrical energy to the cell assembly; the frequency of the pulsed electrical energy being greater than or equal to 1 Hz.

[0023] The advantages of this application are: during the charging process of the battery pack, periodically outputting pulsed electrical energy to charge the battery pack, compared with the constant current charging method, can reduce the polarization of the battery pack, thereby reducing the thickening of the SEI (Sediment Interlayer). This reduces the impedance of the battery pack and the loss of active materials, thus delaying the aging phenomenon caused by impedance and active material loss, which is beneficial to extending the service life of the battery pack and improving its long-term discharge performance. By setting the frequency of the pulsed electrical energy to be greater than or equal to 1Hz, the polarization of the battery pack can be further reduced through a larger pulse frequency, thereby further extending the service life of the battery pack. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a charging device provided in this application; Figure 2 This is a comparative test diagram of constant current charging and pulse charging provided in this application; Figure 3 This is another comparative test diagram of constant current charging and pulse charging provided in this application; Figure 4 This is a waveform diagram of a pulse current provided in this application; Figure 5 This is a schematic diagram of another charging device provided in this application; Figure 6 This is a schematic diagram of the structure of a charging system provided in this application; Figure 7 This is an exploded view of the structure of a battery pack provided in this application; Figure 8 This is an exploded view of another battery pack structure provided in an embodiment of the present invention; Figure 9 This is a schematic diagram of the structure of a charging system provided in this application; Figure 10 This is a diagram of a type of power tool provided in this application. Detailed Implementation

[0025] Before explaining any implementation of this application in detail, it should be understood that this application is not limited to its application to the structural details and component arrangements set forth in the following description or shown in the above drawings.

[0026] In this application, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0027] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this application generally indicates that the preceding and following related objects have an "and / or" relationship.

[0028] In this application, the terms "connection," "combination," "coupling," and "installation" can refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, a direct connection refers to two parts or components being connected together without the need for an intermediary, while an indirect connection refers to two parts or components each being connected to at least one intermediary, with the connection achieved through the intermediary. Furthermore, "connection" and "coupling" are not limited to physical or mechanical connections or couplings, but can also include electrical connections or couplings.

[0029] In this application, those skilled in the art will understand that relative terms (e.g., “about,” “approximately,” “basically,” etc.) used in conjunction with quantities or conditions are inclusive of values ​​and have the meaning indicated by the context. For example, such relative terms include at least the degree of error associated with the measurement of a particular value, tolerances associated with the particular value due to manufacturing, assembly, use, etc. Such terms should also be considered as disclosing a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​not using relative terms should also be disclosed as specific values ​​with tolerances. Furthermore, “basically” when expressing relative angular relationships (e.g., substantially parallel, substantially perpendicular) may refer to a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) added to or subtracted from the indicated angle.

[0030] In this application, those skilled in the art will understand that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0031] In this application, the directional terms "upper," "lower," "left," "right," "front," and "rear" are used to describe the orientation and positional relationships shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when an element is mentioned as being connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected through an intermediate element. It should also be understood that directional terms such as upper side, lower side, left side, right side, front side, and rear side not only represent positive orientation but can also be understood as lateral orientation. For example, "below" can include directly below, lower left, lower right, lower front, and lower rear.

[0032] In this application, the terms "controller," "processor," "central processing unit," "CPU," and "MCU" are used interchangeably. When using the unit "controller," "processor," "central processing unit," "CPU," or "MCU" to perform a specific function, unless otherwise stated, these functions may be performed by a single or multiple of the aforementioned units.

[0033] In this application, the terms "device," "module," or "unit" are used to describe devices that can be implemented in hardware or software to perform a specific function.

[0034] In this application, the terms “calculation,” “judgment,” “control,” “determine,” “identify,” etc., refer to the operation and process of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0035] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0036] Figure 1 This is a schematic diagram of the structure of a charging device provided in this application, such as... Figure 1 As shown, the charging device 10 includes a power input port 11, a power output port 12, and a charging control unit 13. The power input port 11 is used to connect to an external power source. The power output port 12 is used to connect to a battery pack for charging the battery pack. The charging control unit 13 is disposed between the power input port 11 and the power output port 12, and is used at least to control the electrical energy output from the power output port 12. The charging control unit 13 is configured to periodically output pulsed electrical energy to charge the battery pack.

[0037] Specifically, the external power source can be either DC power or AC mains power; this application does not impose any specific limitations on this. The power input port 11 is electrically connected to the external power source, allowing the power signal provided by the external power source to be transmitted to the charging control unit 13 through the power input port 11. The power output port 12 is electrically connected to the battery pack, and the charging control unit 13 can process the power signal to generate pulsed electrical energy, which is then output to the battery pack through the power output port 12 to charge the battery pack.

[0038] The active material used in secondary battery packs is stabilized by a solid electrolyte membrane called SEI (Solid Electrolyte Interface) formed on its surface. Battery pack polarization can easily lead to SEI thickening, thereby increasing the battery pack's impedance and the loss of active material. In this embodiment, the charging control unit 13 is configured to periodically output pulsed electrical energy to charge the battery pack. Compared to constant current charging, pulsed charging allows ions additional diffusion time, compensating for imbalances in electron and ion transport, thus reducing battery pack polarization and SEI thickening. This reduces battery pack impedance and active material loss, delaying aging caused by impedance and active material loss, extending battery pack lifespan, and improving long-term discharge performance.

[0039] Figure 2 This is a comparative test graph of constant current charging and pulse charging provided in this application. The horizontal axis represents the number of charge-discharge cycles (unit: times), and the vertical axis represents the state of charge (SOC) of the battery pack after charging (unit: %). The first curve L1 in the graph shows the relationship between the number of charge-discharge cycles and the battery SOC when using a pulseless constant current charging method, and the second curve L2 shows the relationship between the number of charge-discharge cycles and the battery SOC when using a 1Hz pulse energy charging method. Figure 2 As shown, when the battery pack has undergone 300 charge-discharge cycles, the battery capacity SOC of the second relationship curve L2 is about 70%, while the battery capacity SOC of the first relationship curve L1 is about 50%. The battery capacity SOC of the battery pack using pulse energy charging is significantly higher than that of the battery pack using constant current charging. That is, compared with constant current charging, pulse charging can effectively improve the long-term discharge performance of the battery pack.

[0040] Figure 3This is another comparative test chart of constant current charging and pulse charging provided in this application. The horizontal axis of the chart represents the battery pack capacity SOC (unit: %), and the vertical axis represents the battery pack impedance DCR (unit: mΩ). Two battery packs with identical specifications, usage time, and usage methods can be compared and tested. Let's assume the two battery packs are designated as the first and second battery packs, respectively. In the chart, the third curve L3 shows the relationship between battery capacity SOC and impedance DCR before constant current charging of the first battery pack; the fourth curve L4 shows the relationship between battery capacity SOC and impedance DCR before pulse charging of the second battery pack; the fifth curve L5 shows the relationship between battery capacity SOC and impedance DCR after constant current charging of the first battery pack; and the sixth curve L6 shows the relationship between battery capacity SOC and impedance DCR after pulse charging of the second battery pack. The frequency of the pulse energy is 1Hz. Figure 3 As shown, comparing the third relationship curve L3 and the fourth relationship curve L4, the impedance DCR of the first and second battery packs is almost the same when the battery capacity SOC is the same before testing. Comparing the fifth relationship curve L5 and the sixth relationship curve L6, after 300 charge-discharge cycles, when the battery capacity SOC is the same, the impedance DCR of the first battery pack is significantly greater than that of the second battery pack. Therefore, compared with constant current charging, pulse charging can effectively reduce the impedance DCR of the battery pack, thereby extending the battery pack's lifespan.

[0041] The charging control unit 13 can generate pulsed electrical energy at a higher frequency, for example, the frequency of the pulsed electrical energy can be greater than or equal to 1Hz. This allows the use of higher frequency pulsed electrical energy to charge the battery pack, which can further reduce the polarization of the battery pack and thus further extend the service life of the battery pack.

[0042] The charging device provided in this application periodically outputs pulsed electrical energy to charge the battery pack during the charging process. Compared with constant current charging, this reduces battery pack polarization, thereby reducing SEI thickening. This lowers battery pack impedance and reduces the loss of active materials, thus delaying aging caused by impedance and active material loss, extending battery pack lifespan, and improving long-term discharge performance. By setting the pulsed electrical energy frequency to be greater than or equal to 1Hz, the polarization of the battery pack can be further reduced through a larger pulse frequency, thereby further extending the battery pack lifespan.

[0043] In one embodiment, the pulsed electrical energy may include a pulsed current. Figure 4This is a waveform diagram of a pulsed current provided in this application. The horizontal axis represents time t (unit: ms), the left vertical axis represents voltage U (unit: V), and the right vertical axis represents current I (unit: A). The first waveform curve L01 is the voltage pulse waveform curve, and the second waveform curve L02 is the current pulse waveform curve. Figure 4 As shown, the charging device 10 can periodically output a 5A pulse current to charge the battery pack.

[0044] In one embodiment, the effective discharge rate of the pulse current ranges from 5C to 15C. For example, the effective discharge rate of the pulse current can be 5C, 6C, 7C, 8C, 9C, 10C, 11C, 12C, 13C, 14C, or 15C.

[0045] In one embodiment, the frequency of the pulsed electrical energy is F, where 0.1Hz ≤ F ≤ 1000Hz. The frequency of the pulsed electrical energy can be greater than or equal to 2Hz. For example, the frequency of the pulsed electrical energy can be 2Hz, 5Hz, 10Hz, 100Hz, 200Hz, 300Hz, 400Hz, 500Hz, 600Hz, 700Hz, 800Hz, 900Hz, or 1000Hz.

[0046] In one embodiment, the frequency of the pulse current is a fixed value or a variable value. Specifically, during the charging process, the frequency of the pulse current can remain constant at a fixed frequency, or the frequency of the pulse current can vary. For example, the frequency of the pulse current can be automatically adjusted according to the state of the battery pack during charging, or the frequency of the pulse current can be adjusted according to user instructions. This application does not specifically limit this.

[0047] In one embodiment, the charging control unit 13 is further configured to charge the battery pack using a constant current and constant voltage method. Specifically, when the battery pack needs to be charged quickly, constant current and constant voltage electrical energy can be output to the battery pack so that the battery pack can be charged quickly.

[0048] Figure 5 This is a schematic diagram of another charging device provided in this application, such as... Figure 5 As shown, in one embodiment, the charging device 10 further includes a user control 14, and the charging control unit 13 is configured to control the output of the power output port 12 based on the control commands of the user control 14.

[0049] Specifically, the charging control unit 13 is electrically and / or communicatively connected to the user control 14. The user control 14 can receive control commands from the user, process the commands, and send them to the charging control unit 13. The charging control unit 13 can then control the electrical energy output from the power output port 12 according to the control commands. For example, the control commands may include charging mode selection commands and frequency adjustment commands, allowing the charging control unit 13 to select either pulse charging or constant current / constant voltage charging modes according to the charging mode selection command. And in pulse charging mode, the charging control unit 13 can adjust the frequency of the output pulse electrical energy according to the frequency adjustment command.

[0050] In one embodiment, the charging control unit 13 can wirelessly communicate with an external terminal, such as via Bluetooth or Wi-Fi. The external terminal can be a mobile phone, PC, tablet, or similar device. This allows the user to directly send control commands to the charging control unit 13 via the external terminal, causing the charging control unit 13 to perform corresponding operations.

[0051] In this application, the charging device 10 can be a charger. In the above embodiments, the charging control unit 13 can be disposed in the charging device 10. In other embodiments of this application, the charging control unit 13 can also be disposed in the battery pack, and this application does not specifically limit this.

[0052] Based on the same inventive concept, this application also provides a charging system. Figure 6 This is a schematic diagram of the structure of a charging system provided in this application. Figure 7 This is an exploded structural view of a battery pack provided in this application. (Refer to reference...) Figure 6 and Figure 7 The charging system 100 includes a battery pack 20, a charger 30, and a power management unit 40. The battery pack 20 includes rechargeable cell assemblies 21. The charger 30 is used to output a current source to provide charging current to the cell assemblies 21. The power management unit 40 is connected at least to the cell assemblies 21 to control the charging and discharging of the cell assemblies 21.

[0053] The battery pack 20 includes a housing 22 and a cell assembly 21, wherein the housing 22 is used to form a receiving space, and the cell assembly 21 is located in the receiving space formed by the housing 22. Figure 8 This is an exploded view of another battery pack structure provided in an embodiment of the present invention. Figure 8 and Figure 7 The difference lies in the different cell assembly 21 of the battery pack 20.

[0054] Specifically, the power management unit 40 is at least connected to the battery cell assembly 21. When the battery pack 20 is connected to the charger 30, the power management unit 40 controls the charger 30 to provide charging current to the battery cell assembly 21 to charge the battery cell assembly 21. When the battery pack 20 is connected to a load, the power management unit 40 can control the battery cell assembly 21 to discharge to the load to provide power to the load.

[0055] The power management unit 40 is configured to selectively charge the battery pack 20 using either a first charging mode or a second charging mode. In the first charging mode, the battery pack 20 is configured to be charged using periodic pulse current. In the second charging mode, the battery pack 20 is configured to be charged using a constant current and constant voltage method.

[0056] Specifically, when charging the battery cell assembly 21, the power management unit 40 can choose to control the charger 30 to charge the battery pack 20 using a first charging mode, or choose to control the charger 30 to charge the battery pack 20 using a second charging mode. The first and second charging modes can be selected according to the user's control commands.

[0057] The first charging mode can be a pulse charging mode. When the power management unit 40 selects the first charging mode to charge the battery pack 20, the power management unit 40 can control the charger 30 to periodically output pulse current to the battery pack 20, so that the battery pack 20 completes charging through periodic pulse current. This can extend the service life of the battery pack 20 and improve its long-term discharge performance.

[0058] The second charging mode can be a constant current and constant voltage charging mode. When the power management unit 40 selects to use the second charging module to charge the battery pack 20, the power management unit 40 can control the charger 30 to output constant current and constant voltage electrical energy to the battery pack 20, so that the battery pack 20 can complete charging through constant current and constant voltage electrical energy. This enables the battery pack 20 to complete charging quickly and improves the charging efficiency of the battery pack 20.

[0059] The charging system provided in this application includes a power management unit configured to selectively charge the battery pack using either a first charging mode or a second charging mode, enabling flexible battery pack charging. When the first charging mode is selected, the battery pack is charged using periodic pulse current, which extends its lifespan and improves its long-term discharge performance. When the second charging mode is selected, the battery pack is charged using constant current and constant voltage power, allowing for rapid charging and improving charging efficiency.

[0060] In one embodiment, the frequency of the pulse current is greater than or equal to 1 Hz. For example, the frequency of the pulse current can be 1 Hz, 2 Hz, 5 Hz, 10 Hz, 100 Hz, 200 Hz, 300 Hz, 400 Hz, 500 Hz, 600 Hz, 700 Hz, 800 Hz, 900 Hz, or 1000 Hz.

[0061] Figure 9 This is a schematic diagram of a charging system provided in this application, such as... Figure 9 As shown, in one embodiment, the charging system 100 further includes a user control 50 for selecting a first charging mode and a second charging mode.

[0062] Specifically, the user control 50 can receive control commands from the user, and the power management unit 40 is electrically and / or communicatively connected to the user control 50. After receiving the control command, the user control 50 can process the control command and send it to the power management unit 40, so that the power management unit 40 can determine the charging mode according to the control command and select the charging mode corresponding to the control command to charge the battery pack 20.

[0063] In one embodiment, the user control 50 is disposed on the charger 30 or the battery pack 20. This application does not specifically limit this.

[0064] In one embodiment, the power management unit 40 is configured to control the current source output by the charger 30 based on control commands provided by a user control. This enables the power management unit 40 to process and transform the current source output by the charger 30, ensuring that the charging current output to the battery pack 20 conforms to the charging mode and charging state of the battery pack.

[0065] In one embodiment, the discharge rate of the pulse current ranges from 5C to 15C. For example, the discharge rate of the pulse current can be 5C, 6C, 7C, 8C, 9C, 10C, 11C, 12C, 13C, 14C, or 15C.

[0066] In one embodiment, the rated current range of the current source is 1A to 20A. For example, the rated current of the current source can be 3A, 5A, 10A, or 15A.

[0067] In one embodiment, in the first charging mode, the maximum current output to the battery pack 20 is the maximum allowable charging current of the charger 30; in the second charging mode, the maximum current output to the battery pack 20 is also the maximum allowable charging current of the charger 30. This is to prevent excessive current from damaging the electronic components of the charger 30 due to overcurrent.

[0068] Figure 10 This is a diagram of a type of power tool provided in this application, such as... Figure 10As shown, battery pack 20 is configured to power power tools; the power tools include at least one of a handheld tool 01, a benchtop tool 02, a manned work vehicle 03, or an electric fan 04. In another feasible embodiment, battery pack 20 can also charge a lighting device. The charger 30 can charge either battery pack 20a or battery pack 20b.

[0069] Based on the same inventive concept, this application also provides a method for charging a battery pack, wherein the battery pack is configured to power at least a power tool. (Reference) Figure 7 or Figure 8 The battery pack 20 includes a charging terminal 23 and a rechargeable cell assembly 21. The charging terminal 23 can be disposed on the housing 22 for receiving electrical energy. The cell assembly 21 is used to store electrical energy. The charging method of the battery pack includes periodically providing pulsed electrical energy to the cell assembly. The frequency of the pulsed electrical energy is greater than or equal to 1 Hz.

[0070] The battery pack charging method provided in this application periodically provides pulsed electrical energy to the cell components during the charging process. Compared with constant current charging, this reduces battery pack polarization, thereby reducing SEI thickening. This lowers battery pack impedance and reduces active material loss, thus delaying aging caused by impedance and active material loss, extending battery pack lifespan, and improving long-term discharge performance. By setting the pulsed electrical energy frequency to be greater than or equal to 1Hz, the battery pack polarization can be further reduced through a larger pulse frequency, thereby further extending battery pack lifespan.

[0071] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that the above embodiments do not limit this application in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of this application.

Claims

1. A charging device, comprising: Power input port, used to connect to an external power source; Power output port, used to connect the battery pack to charge the battery pack; A charging control unit is disposed between the power input port and the power output port, and is used at least to control the electrical energy output by the power output port; Its features are, The charging control unit is configured to periodically output pulsed electrical energy to charge the battery pack. The frequency of the pulsed electrical energy is greater than or equal to 1 Hz.

2. The charging device according to claim 1, characterized in that, The electrical energy includes a current source, and the pulsed electrical energy includes a pulsed current.

3. The charging device according to claim 2, characterized in that, The effective discharge rate of the pulse current ranges from 5C to 15C.

4. The charging device according to claim 1, characterized in that, The frequency of the pulsed electrical energy is greater than or equal to 2 Hz.

5. The charging device according to claim 2, characterized in that, The frequency of the pulse current is either a fixed value or a variable value.

6. The charging device according to claim 1, characterized in that, The charging control unit is also configured to charge the battery pack using a constant current and constant voltage method.

7. The charging device according to claim 1, characterized in that, It also includes a user control; the charging control unit is configured to control the output of the power output port based on the control commands of the user control.

8. A charging system, characterized in that, include: Battery pack, including rechargeable cell assemblies; A charger for outputting a current source to provide charging current to the battery cell assembly; A power management unit is connected at least to the battery cell assembly to control the charging and discharging of the battery cell assembly; Its features are, The power management unit is configured to selectively charge the battery pack using either a first charging mode or a second charging mode; wherein... In the first charging mode, the battery pack is configured to be charged using periodic pulse current; In the second charging mode, the battery pack is configured to be charged using a constant current and constant voltage method.

9. The charging system according to claim 8, characterized in that, It also includes user controls for selecting a first charging mode and a second charging mode.

10. A method for charging a battery pack, the battery pack being configured to power at least a power tool, characterized in that, The battery pack includes: Charging terminal, used to connect to electrical energy; Rechargeable battery cell assembly; The charging method for the battery pack includes: Periodically supply pulsed electrical energy to the battery cell assembly; wherein the frequency of the pulsed electrical energy is greater than or equal to 1 Hz.

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