Patent Publication Number: US-2023138183-A1

Title: Charging device and control method therefor

Description:
RELATED APPLICATION INFORMATION 
     This application claims the benefit under 35 U.S.C. § 119(a) of Chinese Patent Application No. CN 202111268864.8, filed on Oct. 29, 2021, which application is incorporated herein by reference in its entirety. 
     BACKGROUND 
     A user generally uses a charger to charge a battery pack. 
     In the related art, one charger is generally provided with only one charging interface and can charge only one battery pack, resulting in relatively low charging efficiency. 
     SUMMARY 
     The present application provides a charging device and a control method therefor, so as to improve charging efficiency. Technical solutions are described below. 
     In some examples, a charging device includes a first charging interface, a second charging interface, a first power output module, a second power output module, and a controller. The first charging interface is connected to a first battery pack. The second charging interface is connected to a second battery pack. The first power output module is connected to the first charging interface to charge the first battery pack. The second power output module is connected to the second charging interface to charge the second battery pack. The controller is connected to at least the first charging interface and the second charging interface and configured to, when the first battery pack is fully charged or not connected to the first charging interface, control the first power output module and the second power output module to be electrically connected to the second charging interface to charge the second battery pack. 
     In some examples, a charging device includes a first power output module, a second power output module, a first charging interface, a second charging interface, and a controller. A first switch is coupled between the first power output module and the first charging interface. A second switch is coupled between the first power output module and the second charging interface. A third switch is coupled between the second power output module and the first charging interface. A fourth switch is coupled between the second power output module and the second charging interface. The controller is used for controlling the first switch, the second switch, the third switch and the fourth switch to be turned on or off. 
     The technical solutions provided by examples of the present application have the beneficial effects described below. 
     Two charging interfaces are provided in the charging device so that two battery packs can be charged, thereby improving the charging efficiency. 
     In addition, the first switch is coupled between the first power output module and the first charging interface, the second switch is coupled between the first power output module and the second charging interface, the third switch is coupled between the second power output module and the first charging interface, the fourth switch is coupled between the second power output module and the second charging interface, and the switches are controlled by the controller so that the charging device can control the switches to be turned on or off according to an actual application situation, thereby improving the charging efficiency and achieving high flexibility. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       To illustrate technical solutions in examples of the present application more clearly, drawings used in the description of the examples are briefly described below. The drawings described below illustrate only part of the examples of the present application, and those of ordinary skill in the art may obtain other drawings based on the drawings described below on the premise that no creative work is done. 
         FIG.  1    is a schematic diagram of a charging device according to an example of the present application; 
         FIG.  2    is a schematic diagram of a charging device according to an example of the present application; 
         FIG.  3    is a schematic diagram of switches according to an example of the present application; 
         FIG.  4    is a schematic diagram of a state of switches according to the example of  FIG.  1   ; 
         FIG.  5    is a schematic diagram of a state of switches according to the example of  FIG.  3   ; 
         FIG.  6    is a schematic diagram of a state of switches according to the example of  FIG.  3   ; 
         FIG.  7    is a schematic diagram of a state of switches according to the example of  FIG.  1   ; 
         FIG.  8    is a schematic diagram of a state of switches according to the example of  FIG.  3   ; and 
         FIG.  9    is a flowchart of a control method for a charging device according to an example of the present application. 
     
    
    
     DETAILED DESCRIPTION 
     Examples of the present application are described below in detail in conjunction with drawings, from which the object, technical solutions and advantages of the present application are more apparent. 
     Referring to  FIG.  1    which is a schematic diagram of a charging device according to an example of the present application, a charging device  100  includes a first power output module  110 , a second power output module  120 , a first charging interface  130 , a second charging interface  140 , and a controller  200 . 
     The charging device  100  refers to a device for charging a battery pack of a power tool. The power tool may include, but is not limited to, a string trimmer, a blower, a pruner, a chainsaw, a lawn mower, an angle grinder, and an electric drill. Of course, the power tool may also include another type of tool, which is not limited in the examples of the present application. The battery pack includes a housing, the housing at least partially forms an outer surface of the battery pack and is used for accommodating at least a cell group, and the cell group includes multiple cells which are electrically connected to form the cell group. The housing is further formed with a plugging interface for connecting the battery pack to the power tool, and the battery pack can be connected to the power tool along a plugging direction. As a power source for the power tool, the battery pack may be used for supplying power to the power tool. Exemplarily, the charging device  100  may be a charger or an adapter, which is not limited in the examples of the present application. 
     A first switch  150  is coupled between the first power output module  110  and the first charging interface  130 . The first power output module  110  refers to a module outputting power, and the first charging interface  130  refers to an interface for supplying power of the charging device  100  to the battery pack of the power tool. In the case where the first switch  150  is on, the first power output module  110  supplies power to the first charging interface  130 ; and in the case where the first switch  150  is off, the first power output module  110  does not supply power to the first charging interface  130 . 
     A second switch  160  is coupled between the first power output module  110  and the second charging interface  140 . The second charging interface  140  refers to an interface for supplying the power of the charging device  100  to the battery pack of the power tool. In the case where the second switch  160  is on, the first power output module  110  supplies power to the second charging interface  140 ; and in the case where the second switch  160  is off, the first power output module  110  does not supply power to the second charging interface  140 . 
     In a possible example, the first switch  150  and the second switch  160  are single pole, single throw switches, that is, an end of the first switch  150  is coupled to the first power output module  110  and the other end of the first switch  150  is coupled to the first charging interface  130 . An end of the second switch  160  is coupled to the first power output module  110  and the other end of the second switch  160  is coupled to the second charging interface  140 . 
     In a possible example, the first switch and the second switch may be provided as one switch, where the switch may be used for making the first power output module supply power to the first charging interface or making the first power output module supply power to the second charging interface or making the first power output module not supply power to the first charging interface and the second charging interface. Exemplarily, the switch may be a single pole, triple throw switch, or the switch may be a two-way metal-oxide-semiconductor field-effect transistor (MOSFET) switch, or the switch may be a two-way single pole, double throw switch. The type of the switch is not limited in the examples of the present application, and the switch may be replaced with any type of switch capable of implementing the preceding functions. 
     A third switch  170  is coupled between the second power output module  120  and the first charging interface  130 . The second power output module  120  refers to a module outputting power. The power outputted by the first power output module  110  may or may not be consistent with the power outputted by the second power output module  120 , which may be set by a technician according to actual requirements. In the case where the third switch  170  is on, the second power output module  120  supplies power to the first charging interface  130 ; and in the case where the third switch  170  is off, the second power output module  120  does not supply power to the first charging interface  130 . 
     A fourth switch  180  is coupled between the second power output module  120  and the second charging interface  140 . In the case where the fourth switch  180  is on, the second power output module  120  supplies power to the second charging interface  140 ; and in the case where the fourth switch  180  is off, the second power output module  120  does not supply power to the second charging interface  140 . 
     In a possible example, the third switch  170  and the fourth switch  180  are single pole, single throw switches, that is, an end of the third switch  170  is coupled to the second power output module  120  and the other end of the third switch  170  is coupled to the first charging interface  130 ; and an end of the fourth switch  180  is coupled to the second power output module  120  and the other end of the fourth switch  180  is coupled to the second charging interface  140 . 
     In a possible example, the third switch and the fourth switch may be provided as one switch, where the switch may be used for making the second power output module supply power to the first charging interface or making the second power output module supply power to the second charging interface or making the second power output module not supply power to the first charging interface and the second charging interface. Exemplarily, the switch may be a single pole, triple throw switch, or the switch may be a two-way MOSFET switch, or the switch may be a two-way single pole, double throw switch. The type of the switch is not limited in the examples of the present application, and the switch may be replaced with any type of switch capable of implementing the preceding functions. As shown in  FIG.  2   ,  FIG.  2    is a schematic diagram of switches according to an example of the present application. In  FIG.  2   , the charging device  100  uses single pole, triple throw switches. 
     The controller  200  is used for controlling the first switch  150 , the second switch  160 , the third switch  170  and the fourth switch  180  to be turned on or off. 
     In a possible example, the controller  200  acquires a load state of the first charging interface  130  and a load state of the second charging interface  140  and controls the first switch  150 , the second switch  160 , the third switch  170  and the fourth switch  180  to be turned on or off, where the load state of the first charging interface  130  is used for indicating whether the first charging interface  130  is connected to a first battery pack. The load state of the first charging interface  130  is also used for indicating a state of charge of the first battery pack when the first charging interface  130  is connected to the first battery pack, and the load state of the second charging interface  140  is used for indicating whether the second charging interface  140  is connected to a second battery pack and a state of charge of the second battery pack. The controller  200  controls, according to the load state of the first charging interface  130  and the load state of the second charging interface  140 , the first switch, the second switch, the third switch and the fourth switch to be turned on or off so that the power supply output of the charging device  100  to the battery pack is more in line with the charging requirements of the battery pack, thereby improving the charging efficiency of the charging device  100 . 
     In the examples of the present application, the charging device  100  includes the first charging interface  130  and the second charging interface  140 , the first switch  150  is coupled between the first power output module  110  and the first charging interface  130 , the second switch  160  is coupled between the first power output module  110  and the second charging interface  140 , the third switch  170  is coupled between the second power output module  120  and the first charging interface  130 , the fourth switch  180  is coupled between the second power output module  120  and the second charging interface  140 , and the switches are controlled by the controller  200 . In this manner, the output capacity and parallel function of the charging device  100  are increased so that the battery pack can be charged fast at high power. 
     To sum up, in the technical solutions provided in the examples of the present application, two charging interfaces are provided in the charging device  100  so that two battery packs can be charged at the same time, thereby improving the charging efficiency. 
     In addition, the first switch  150  is coupled between the first power output module  110  and the first charging interface  130 , the second switch  160  is coupled between the first power output module  110  and the second charging interface  140 , the third switch  170  is coupled between the second power output module  120  and the first charging interface  130 , the fourth switch  180  is coupled between the second power output module  120  and the second charging interface  140 , and the switches are controlled by the controller  200  so that the charging device  100  can control the switches to be turned on or off according to an actual application situation, thereby improving the charging efficiency and achieving high flexibility. 
     In an illustrative example, as shown in  FIG.  3   , the charging device  100  further includes a first detection device  131  and a second detection device  141 . The first detection device  131  is used for determining the load state of the first charging interface  130 , where the load state of the first charging interface  130  is used for indicating whether the first charging interface  130  is connected to the first battery pack and the state of charge of the first battery pack. The state of charge of the first battery pack is used for indicating the current charge of the first battery pack. 
     The first detection device  131  is coupled to the first charging interface  130 . The first detection device  131  may determine whether the first charging interface  130  is connected to the first battery pack by detecting whether a voltage exists across the first charging interface  130 . In a possible example, to more accurately detect whether the first charging interface  130  is connected to the first battery pack, and the first detection device  131  is also coupled to a first communication interface  132  on the charging device  100 . The first detection device  131  determines a voltage across the first charging interface and a voltage across the first communication interface  132  at the same time and determines. Based on the voltage across the first charging interface  130  and the voltage across the first communication interface  132 , determine whether the first charging interface  130  is connected to the first battery pack. In the case where the first detection device  131  determines that a voltage exists across the first charging interface  130  and a voltage exists across the first communication interface  132 , the first detection device  131  determines that the first charging interface  130  is connected to the first battery pack. In the case where the first detection device  131  determines that no voltage exists across the first charging interface  130  and no voltage exists across the first communication interface  132 , the first detection device  131  determines that the first charging interface  130  is not connected to the first battery pack. In the case where the first detection device  131  determines that a voltage exists across the first charging interface  130  and no voltage exists across the first communication interface  132 , the first detection device  131  determines that the first charging interface  130  is not connected to the first battery pack. In the case where the first detection device  131  determines that no voltage exists across the first charging interface  130  and a voltage exists across the first communication interface  132 , the first detection device  131  determines that the first charging interface  130  is not connected to the first battery pack. Exemplarily, the first charging interface  130  includes a positive interface and a negative interface, and the first battery pack includes a positive terminal and a negative terminal. When the positive interface of the first charging interface  130  is coupled to the positive terminal of the first battery pack and the negative interface of the first charging interface  130  is coupled to the negative terminal of the first battery pack, the first charging interface  130  may supply power to the first battery pack. 
     The first communication interface  132  is used for the charging device  100  to communicate with the first battery pack. The first battery pack further includes a communication port. When the first communication interface  132  of the charging device  100  is coupled to the communication port of the first battery pack, the first battery pack may communicate with the charging device  100 . 
     In a possible example, the first battery pack sends its state of charge to the charging device  100  through the communication port. In an example, the charging device  100  automatically detects the charge of the first battery pack to obtain the state of charge of the first battery pack. 
     The second detection device  141  is used for determining the load state of the second charging interface  140 , where the load state of the second charging interface  140  is used for indicating whether the second charging interface  140  is connected to the second battery pack and the state of charge of the second battery pack. The state of charge of the second battery pack is used for indicating the current charge of the second battery pack. 
     The second detection device  141  is coupled to the second charging interface  140 . The second detection device  141  may determine whether the second charging interface  140  is connected to the second battery pack by detecting whether a voltage exists across the second charging interface  140 . In a possible example, to more accurately detect whether the second charging interface  140  is connected to the second battery pack, the second detection device  141  is also coupled to a second communication interface  142  on the charging device  100 , and the second detection device  141  determines a voltage across the second charging interface  140  and a voltage across the second communication interface  142  at the same time and determines, based on the voltage across the second charging interface  140  and the voltage across the second communication interface  142 , whether the second charging interface  140  is connected to the second battery pack. In the case where the second detection device  141  determines that a voltage exists across the second charging interface  140  and a voltage exists across the second communication interface  142 , the second detection device  141  determines that the second charging interface  140  is connected to the second battery pack. In the case where the second detection device  141  determines that no voltage exists across the second charging interface  140  and no voltage exists across the second communication interface  142 , the second detection device  141  determines that the second charging interface  140  is not connected to the second battery pack. In the case where the second detection device  141  determines that a voltage exists across the second charging interface  140  and no voltage exists across the second communication interface  142 , the second detection device  141  determines that the second charging interface  140  is not connected to the second battery pack. In the case where the second detection device  141  determines that no voltage exists across the second charging interface and a voltage exists across the second communication interface  142 , the second detection device  141  determines that the second charging interface  140  is not connected to the second battery pack. Exemplarily, the second charging interface  140  includes a positive interface and a negative interface, and the second battery pack includes a positive terminal and a negative terminal. When the positive interface of the second charging interface  140  is coupled to the positive terminal of the second battery pack and the negative interface of the second charging interface  140  is coupled to the negative terminal of the second battery pack, the second charging interface may supply power to the second battery pack. 
     The second communication interface  142  is used for the charging device  100  to communicate with the second battery pack. The second battery pack further includes a communication port. When the second communication interface  142  of the charging device  100  is coupled to the communication port of the second battery pack, the second battery pack may communicate with the charging device  100 . 
     In a possible example, the second battery pack sends its state of charge to the charging device  100  through the communication port; or the charging device  100  automatically detects the charge of the second battery pack to obtain the state of charge of the second battery pack. 
     The controller  200  is configured to control the first switch  150 , the second switch  160 , the third switch  170  and the fourth switch  180  to be turned on or off based on the load state of the first charging interface  130  and the load state of the second charging interface  140 . 
     The controller  200  controls the first switch  150 , the second switch  160 , the third switch  170  and the fourth switch  180  to be turned on or off according to the load state of the first charging interface  130  and the load state of the second charging interface  140 , so that the power supply output of the charging device  100  to the battery pack is more in line with the charging requirements of the battery pack, thereby improving the charging efficiency of the charging device  100 . 
     In a possible example, the first detection device  131  is used for determining that the load state of the first charging interface  130  is that the first charging interface  130  is connected to the first battery pack and the first battery pack is not fully charged. The second detection device  141  is used for determining that the load state of the second charging interface  140  is that the second charging interface  140  is not connected to the second battery pack. The controller  200  is used for turning on the first switch  150  and the third switch  170  and turning off the second switch  160  and the fourth switch  180 . 
     In this case, the charging device  100  supplies power to the first battery pack through the first power output module  110  and the second power output module  120  at the same time, shortening the time for charging the first battery pack and improving the charging efficiency. At the same time, the second switch  160  and the fourth switch  180  are turned off so that the first power output module  110  and/or the second power output module  120  do not supply power to the second charging interface, thereby avoiding energy waste. 
     As shown in  FIG.  4   ,  FIG.  4    is a schematic diagram of states of switches according to an example of the present application. The second charging interface  140  is not connected to the second battery pack, and the first power output module  110  and the second power output module  120  supply power to the first battery pack. 
     Exemplarily, as shown in  FIG.  5   , using an example in which the first switch and the second switch are implemented as a first single pole, triple throw switch and the third switch and the fourth switch are implemented as a second single pole, triple throw switch, the first single pole, triple throw switch and the second single pole, triple throw switch are set to be in the states shown in  FIG.  4    so that the first power output module  110  and the second power output module  120  charge the first battery pack at the same time. 
     It is to be noted that, in the example of the present application, only an example in which the first charging interface  130  is connected to the first battery pack and the second charging interface  140  is not connected to the second battery pack is used for description, and a charging control logic in the case where the first charging interface  130  is not connected to the first battery pack and the second charging interface  140  is connected to the second battery pack is similar to that in the preceding case. That is, in the case where the first charging interface  130  is not connected to the first battery pack, the second charging interface  140  is connected to the second battery pack, and the second battery pack is not fully charged, the controller  200  turns on the second switch  160  and the fourth switch  180  and turns off the first switch  150  and the third switch  170 . 
     In a possible example, the first detection device  131  is used for determining that the load state of the first charging interface  130  is that the first charging interface  130  is connected to the first battery pack and the first battery pack is not fully charged. The second detection device  141  is used for determining that the load state of the second charging interface  140  is that the second charging interface  140  is connected to the second battery pack and the second battery pack is fully charged. The controller  200  is used for turning on the first switch  150  and the third switch  170  and turning off the second switch  160  and the fourth switch  180 . 
     In this case, the charging device  100  supplies power to the first battery pack through the first power output module  110  and the second power output module  120  at the same time, shortening the time for charging the first battery pack and improving the charging efficiency. At the same time, in the case where the second battery pack is fully charged, the second switch  160  and the fourth switch  180  are turned off so that the first power output module  110  and/or the second power output module  120  do not supply power to the second charging interface, thereby avoiding energy waste. 
     It is to be noted that, in the example of the present application, only an example in which the first battery pack is not fully charged and the second battery pack is fully charged is used for description, and a charging control logic in the case where the first battery pack is fully charged and the second battery pack is not fully charged is similar to that in the preceding case. That is, in the case where the first charging interface  130  is connected to the first battery pack, the first battery pack is fully charged, the second charging interface is connected to the second battery pack, and the second battery pack is not fully charged, the controller  200  turns on the second switch  160  and the fourth switch  180  and turns off the first switch  150  and the third switch  170 . 
     When no battery pack exists or when a battery pack exists but the battery pack is fully charged, the corresponding power output module is disconnected from the charging interface, and the idle power output module is connected in parallel to charge the battery pack that needs to be charged. 
     In a possible example, the first detection device  131  is used for determining that the load state of the first charging interface  130  is that the first charging interface  130  is not connected to the first battery pack. The second detection device  141  is used for determining that the load state of the second charging interface  140  is that the second charging interface  140  is not connected to the second battery pack. The controller  200  is used for turning off the first switch, the second switch, the third switch and the fourth switch. 
     In the case where neither the first charging interface  130  nor the second charging interface  140  is connected to the battery pack, the charging device  100  turns off the first switch  150 , the second switch, the third switch  170  and the fourth switch  180  so that the first power output module  110  and the second power output module  120  do not supply power to the outside, thereby avoiding energy waste. 
     Exemplarily, as shown in  FIG.  6   , using an example in which the first switch and the second switch are implemented as a first single pole, triple throw switch and the third switch and the fourth switch are implemented as a second single pole, triple throw switch, the first single pole, triple throw switch and the second single pole, triple throw switch are set to be in the null connection states shown in  FIG.  6    so that the first power output module  110  and the second power output module  120  do not supply power to the charging interfaces. 
     In a possible example, the first detection device  131  is used for determining that the load state of the first charging interface  130  is that the first charging interface  130  is connected to the first battery pack and the first battery pack is fully charged. The second detection device  141  is used for determining that the load state of the second charging interface  140  is that the second charging interface  140  is connected to the second battery pack and the second battery pack is fully charged. The controller  200  is used for turning off the first switch  150 , the second switch  160 , the third switch  170  and the fourth switch  180 . 
     In the case where the first charging interface  130  is connected to the first battery pack, the first battery pack is fully charged, the second charging interface  140  is connected to the second battery pack, and the second battery pack is fully charged, the charging device  100  turns off the first switch  150 , the second switch  160 , the third switch  170  and the fourth switch  180  so that the first power output module  110  and the second power output module  120  do not supply power to the outside, thereby avoiding energy waste. 
     In a possible example, the first detection device  131  is used for determining that the load state of the first charging interface  130  is that the first charging interface  130  is connected to the first battery pack and the first battery pack is not fully charged. The second detection device  141  is used for determining that the load state of the second charging interface  140  is that the second charging interface  140  is connected to the second battery pack and the second battery pack is not fully charged. The controller  200  is used for turning on the first switch  150  and the fourth  180  switch and turning off the second switch  160  and the third switch  170 . 
     In the case where neither the first battery pack nor the second battery pack is fully charged, the first power output module  110  supplies power to the first battery pack and the second power output module  120  supplies power to the second battery pack, thereby improving the charging efficiency. 
     When both the first charging interface  130  and the second charging interface  140  are connected to the battery packs and neither of the battery packs is fully charged, each of the first power output module  110  and the second power output module  120  independently charges a respective battery pack. 
     As shown in  FIG.  7   ,  FIG.  7    is a schematic diagram of states of switches according to another example of the present application. When both the first charging interface  130  and the second charging interface  140  are connected to the battery packs and neither of the battery packs is fully charged, each of the first power output module  110  and the second power output module  120  independently supplies power to a respective charging interface. 
     Exemplarily, as shown in  FIG.  8   , using an example in which the first switch and the second switch are implemented as a first single pole, triple throw switch and the third switch and the fourth switch are implemented as a second single pole, triple throw switch, the first single pole, triple throw switch and the second single pole, triple throw switch are set to be in the states shown in  FIG.  8    so that each of the first power output module  110  and the second power output module  120  independently supplies power to its respective charge interface. 
     Referring to  FIG.  9   ,  FIG.  9    is a flowchart of a control method for a charging device according to an example of the present application. The charging device includes a first power output module, a second power output module, a first charging interface, a second charging interface, and a controller. A first switch is coupled between the first power output module and the first charging interface, a second switch is coupled between the first power output module and the second charging interface, a third switch is coupled between the second power output module and the first charging interface, and a fourth switch is coupled between the second power output module and the second charging interface. The method may include the steps described below. 
     In step  801 , a load state of the first charging interface is determined, where the load state of the first charging interface is used for indicating whether the first charging interface is connected to a first battery pack and a state of charge of the first battery pack. 
     In step  802 , a load state of the second charging interface is determined, where the load state of the second charging interface is used for indicating whether the second charging interface is connected to a second battery pack and a state of charge of the second battery pack. 
     In step  803 , based on the load state of the first charging interface and the load state of the second charging interface, the first switch, the second switch, the third switch and the fourth switch are controlled to be turned on or off. 
     Step  801  and step  802  may be performed simultaneously; or step  801  may be performed before step  802  is performed; or step  802  may be performed before step  801  is performed, which is not limited in the examples of the present application. 
     In an illustrative example, step  801  includes determining that the load state of the first charging interface is that the first charging interface is connected to the first battery pack and the first battery pack is not fully charged. 
     Step  802  includes determining that the load state of the second charging interface is that the second charging interface is not connected to the second battery pack. 
     Step  803  includes turning on the first switch and the third switch and turning off the second switch and the fourth switch. 
     In an illustrative example, step  801  includes determining that the load state of the first charging interface is that the first charging interface is connected to the first battery pack and the first battery pack is not fully charged. 
     Step  802  includes determining that the load state of the second charging interface is that the second charging interface is connected to the second battery pack and the second battery pack is fully charged. 
     Step  803  includes turning on the first switch and the third switch and turning off the second switch and the fourth switch. 
     In an illustrative example, step  801  includes determining that the load state of the first charging interface is that the first charging interface is not connected to the first battery pack. 
     Step  802  includes determining that the load state of the second charging interface is that the second charging interface is not connected to the second battery pack. 
     Step  803  includes turning off the first switch, the second switch, the third switch and the fourth switch. 
     In an illustrative example, step  801  includes determining that the load state of the first charging interface is that the first charging interface is connected to the first battery pack and the first battery pack is fully charged. 
     Step  802  includes determining that the load state of the second charging interface is that the second charging interface is connected to the second battery pack and the second battery pack is fully charged. 
     Step  803  includes turning off the first switch, the second switch, the third switch and the fourth switch. 
     In an illustrative example, step  801  includes determining that the load state of the first charging interface is that the first charging interface is connected to the first battery pack and the first battery pack is not fully charged. 
     Step  802  includes determining that the load state of the second charging interface is that the second charging interface is connected to the second battery pack and the second battery pack is not fully charged. 
     Step  803  includes turning on the first switch and the fourth switch and turning off the second switch and the third switch. 
     To sum up, in the technical solutions provided in the examples of the present application, two charging interfaces are provided in the charging device so that two battery packs can be charged at the same time, thereby improving charging efficiency. 
     In addition, the first switch is coupled between the first power output module and the first charging interface, the second switch is coupled between the first power output module and the second charging interface, the third switch is coupled between the second power output module and the first charging interface, the fourth switch is coupled between the second power output module and the second charging interface, and the switches are controlled by the controller based on the load states of the charging interfaces so that the charging device can control the switches to be turned on or off according to an actual application situation, thereby improving the charging efficiency and achieving high flexibility. 
     It is to be noted that the method example and the product example provided in the preceding examples belong to the same concept, and for the specific implementation process of the method example, see the product example, and details are not repeated here. 
     It is to be noted that, in the examples of the present application, only an example in which the charging device includes two charging interfaces is used for description. In other possible examples, the charging device may include three or more charging interfaces, which is not limited in the examples of the present application. 
     It is to be understood that “multiple” mentioned herein means two or more. “And/or” describes an association relationship between associated objects and indicates that three relationships may exist. For example, A and/or B may indicate the following three cases: A exists alone; A and B exist at the same time; and B exists alone. The character “/” generally indicates an “or” relationship between associated objects before and after the character. In addition, the numbering of the steps described herein only exemplarily shows a possible execution sequence of the steps. In some other examples, the preceding steps may not be executed according to the numbering, for example, two steps with different numbers are performed at the same time, or two steps with different numbers are performed in an order reverse to the order shown in the figure, which is not limited in the examples of the present application. 
     Those of ordinary skill in the art can understand that all or part of the steps for implementing the preceding examples may be performed by hardware or may be performed by relevant hardware instructed by a program, where the program may be stored in a computer-readable storage medium. The preceding storage medium may be a read-only memory, a magnetic disk, an optical disk or the like. 
     The above are only exemplary examples of the present application and not intended to limit the present application. Any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present application are within the scope of the present application