Charging device and charging method

Abstract

[Problem] To achieve both operation of a battery with improved charging efficiency, and operation of the battery in a fully charged state. [Solution] This charging device comprises: X charging slots into which repeatedly chargeable / dischargeable batteries are inserted; Y (where, Y ≤ X) charging circuits for charging the batteries inserted into the charging slots; and a control unit for controlling the charging circuits so as to preferentially charge, among the batteries inserted into the charging slots, a battery determined to have a state of charge less than a first target state of charge lower than a full charge.

Description

Charging device and charging method

[0001] The present disclosure relates to a charging device and a charging method.

[0002] In recent years, with the evolution of batteries such as lithium-ion secondary batteries, it has become common to use batteries as a power source for mobile objects such as drones. It has also become common to use mobile objects such as drones to perform tasks such as inspection, surveying, delivery, and pesticide spraying.

[0003] However, there is a limit to the capacity of the batteries that can be installed on drones, so if a drone is used for an extended period of time, it will need to stop operation and return to its original location to charge or replace the battery.

[0004] The following Patent Literature 1 discloses a technology for generating a charging plan for efficiently charging the total amount of power required for drone work in one or more cycles. Patent Literature 1 discloses charging the battery within a charging rate range that provides good hourly charging efficiency.

[0005] International Publication No. 2020 / 153316

[0006] However, with the technology disclosed in Patent Document 1, the battery is charged within a predetermined charging rate range, and charging ends before the battery is fully charged. Therefore, with the technology disclosed in Patent Document 1, it is difficult to fully utilize the capacity of the battery.

[0007] Therefore, there was a need to achieve both battery operation with improved charging efficiency and operation of a fully charged battery.

[0008] According to the present disclosure, a charging device is provided that includes X charging slots into which repeatedly chargeable and dischargeable batteries are inserted, Y (where Y≦X) charging circuits that charge the batteries inserted into the charging slots, and a control unit that controls the charging circuits to preferentially charge batteries, among the batteries inserted into the charging slots, that are determined to have a charging rate below a first target charging rate that is lower than a full charge.

[0009] The present disclosure also provides a charging method including inserting repeatedly chargeable and dischargeable batteries into X charging slots, and charging the batteries inserted into the charging slots using Y (where Y≦X) charging circuits, wherein the charging circuits are controlled to preferentially charge batteries, among the batteries inserted into the charging slots, whose charging rate is determined to be less than a first target charging rate that is lower than a full charge.

[0010] FIG. 1 is a perspective view showing an example of the appearance of a charging device according to an embodiment of the present disclosure; FIG. 2 is a block diagram showing a functional configuration of the charging device according to the embodiment; FIG. 3 is a graph diagram for explaining a first target charging rate at which constant current charging is switched to constant voltage charging; FIG. 4 is a table diagram showing examples of notification patterns by a charging notification unit and a battery notification unit; FIG. 5 is a flowchart diagram showing a determination flow when determining a battery to be charged; and FIG. 6 is a schematic diagram showing a specific example of battery charging.

[0011] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0012] The explanation will be given in the following order: 1. Appearance example 2. Configuration example 3. Control example

[0013] 1. Exterior Appearance Example An exterior appearance of a charging device 100 according to an embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a perspective view showing an exterior appearance example of the charging device 100 according to this embodiment.

[0014] 1 , the charging device 100 includes a power input unit 131, a plurality of charging slots 120, and a plurality of charging notification units 110. The charging device 100 can charge batteries 200 inserted into each of the plurality of charging slots 120.

[0015] Battery 200 is a secondary battery such as a lithium-ion secondary battery that can be repeatedly charged and discharged. Battery 200 is a large battery that is mounted on a mobile object such as a drone that operates for long periods of time and used as a power source for the mobile object. Battery 200 may have a rectangular parallelepiped shape, for example. A connector (not shown) is provided on the underside of battery 200 for connecting to charging device 100 or the mobile object on which battery 200 is mounted.

[0016] The battery 200 is provided with a battery notification unit 210 that roughly indicates the state or charging rate of the battery 200. The battery notification unit 210 may be configured, for example, with a plurality of LED (Light Emitting Diode) lamps arranged in one direction. The battery notification unit 210 may indicate an approximate charging rate of the battery 200 by the number of lit LED lamps among the plurality of LED lamps. The battery notification unit 210 may also indicate the state of the battery 200 or an error notification by the light emission pattern or light emission color of the plurality of LED lamps.

[0017] Charging slot 120 is an opening into which battery 200 is inserted. Charging slot 120 may be, for example, a rectangular opening that corresponds to the rectangular parallelepiped outer shape of battery 200. A connector (not shown) is provided inside the opening of charging slot 120 to supply power for charging to battery 200. When battery 200 is inserted into the opening of charging slot 120, the connector inside the opening and the connector provided on battery 200 are connected, and power is supplied from charging device 100 to battery 200.

[0018] The charge notification unit 110 is provided corresponding to each charge slot 120 and notifies the charge state of the battery 200 inserted in the corresponding charge slot 120. The charge notification unit 110 may be configured, for example, with an LED lamp provided near the corresponding charge slot 120. The charge notification unit 110 may notify the charge state of the battery 200 inserted in the corresponding charge slot 120 by, for example, the light emission pattern or light emission color of the LED lamp. Details of the notification by the charge notification unit 110 will be described later.

[0019] The power input unit 131 is a connection port through which power is input from an external source. The power input unit 131 may be, for example, an outlet into which a plug that supplies alternating current (AC) power is inserted. The charging device 100 converts the AC power input from the outside into direct current (DC) power, thereby enabling the charging device 100 to charge the battery 200 inserted in the charging slot 120 with the power input from the outside.

[0020] The charging device 100 is provided with at least one charging circuit. The charging circuit prevents overcurrent, overvoltage, or overcharging by controlling the current or voltage when charging the battery 200. For example, the charging circuit may control the current or voltage while monitoring the charge capacity or voltage of the battery 200, thereby switching the charging of the battery 200 from constant current charging to constant voltage charging or stopping the charging of the battery 200. The charging device 100 can simultaneously charge a number of batteries 200 corresponding to the number of charging circuits provided in the charging device 100.

[0021] For example, if the number of charging circuits provided in the charging device 100 is Y, the number of charging slots 120 may be X (X≧Y). When the charging device 100 is provided with X charging slots 120, which is equal to or greater than the number (Y) of charging circuits, the charging device 100 can reduce the loss of charging opportunities when replacing a fully charged battery 200 with another battery 200. Specifically, by inserting a battery 200 in a charging standby state into a charging slot 120 in advance, the charging device 100 can reduce the loss of charging opportunities when switching the charging target from the fully charged battery 200 to a battery 200 in a charging standby state. In such a case, the charging device 100 can further improve the charging efficiency of the multiple batteries 200 inserted into the charging slots 120.

[0022] As described above, the battery 200 is mounted on a mobile object, such as a drone, that operates for long periods of time and is used to power the mobile object. In such a case, the batteries 200 may be operated in groups of N (e.g., N is 2 or greater). When operating the batteries 200 in groups of N, it is desirable that the charging rates of the batteries 200 in a group be approximately the same to prevent current backflow and the like. The charging device 100 can equalize the charging rates of all batteries 200 inserted into the charging slots 120 to the first target charging rate by preferentially charging the batteries 200 to the first target charging rate. Furthermore, when the number of charging circuits (Y) is the same as the number of batteries 200 in a group (N), the charging device 100 can simultaneously charge the N batteries 200, whose charging rates have been adjusted to the first target charging rate, using the N charging circuits to equalize the charging rates. Furthermore, in order to insert multiple sets of N batteries 200 into the charging device 100, it is desirable that the number of charging slots 120 (X) be an integer multiple of the number of charging circuits (Y = N).

[0023] For example, when batteries 200 are operated in pairs (N=2), the number of charging circuits (Y) may be two (Y=2), which is the same as the number (N) of batteries 200 in the pair. Also, the number of charging slots 120 (X) may be four (X=4), which is twice the number (Y) of charging circuits.

[0024] 2. Configuration Example An example of the configuration of the charging device 100 according to this embodiment will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the functional configuration of the charging device 100 according to this embodiment.

[0025] As shown in FIG. 2 , the charging device 100 includes a power supply unit 130 , a control unit 150 , a plurality of charging circuits 140 , a plurality of charging notification units 110 , and a plurality of charging slots 120 .

[0026] The power supply unit 130 is a power source for charging the batteries 200 inserted into the multiple charging slots 120. For example, the power supply unit 130 may convert externally input AC power into DC power and supply the DC power to each of the batteries 200 inserted into the multiple charging slots 120 via the charging circuit 140. The power supply unit 130 may not only convert the externally input AC power into DC power, but may also adjust the voltage, adjust the current, or stabilize the DC power.

[0027] The control unit 150 controls the charging of the batteries 200 inserted into the charging slots 120. Specifically, the control unit 150 detects the insertion and removal of the batteries 200 in each charging slot 120 and controls the connection between the charging slot 120 into which the battery 200 is inserted and the charging circuit 140, thereby controlling which battery 200 is to be charged. The control unit 150 also controls the supply of power to the battery 200 to be charged by detecting the charge capacity (i.e., charging rate) and voltage of the battery 200 to be charged. The connection between the charging slot 120 and the charging circuit 140 is controlled, for example, by turning on and off a switch in an electronic circuit. The battery 200 inserted into the charging slot 120 connected to the charging circuit 140 receives power from the power supply unit 130 and is being charged. On the other hand, the battery 200 inserted into the charging slot 120 not connected to the charging circuit 140 is in a charging standby state.

[0028] In this embodiment, the control unit 150 controls the connection between the charging slot 120 and the charging circuit 140 so as to preferentially charge the battery 200 inserted into the charging slot 120 whose charging rate is determined to be less than the first target charging rate.

[0029] The first target charging rate is a charging rate that is lower than a full charge and that allows efficient charging of the battery 200. Specifically, the first target charging rate may be a charging rate at which charging of the battery 200 switches from constant current charging to constant voltage charging.

[0030] Such a first target charging rate will be described with reference to Fig. 3. Fig. 3 is a graph for explaining the first target charging rate at which charging is switched from constant current charging to constant voltage charging.

[0031] As shown in FIG. 3 , when the charge capacity of battery 200 is low and the charge rate is low or medium, battery 200 is charged at a constant current to prevent overcurrent. On the other hand, when the charge capacity of battery 200 is high and the charge rate is high, battery 200 has a high resistance to charging. Therefore, battery 200 is charged to full charge at a constant voltage to prevent overvoltage and overcharging. This charging method is also called a constant current, constant voltage (CCCV) charging method. Note that in the CCCV charging method, the timing to switch from constant current charging to constant voltage charging is determined, for example, by determining whether the voltage of battery 200 has reached a predetermined voltage value.

[0032] That is, the battery 200 is charged at a high rate by constant current charging when the charging rate is low or medium, and charged at a low rate by constant voltage charging when the charging rate is high. Therefore, the control unit 150 can efficiently charge the battery 200 to a charging rate that is usable in a mobile object by preferentially charging the battery 200 to a first target charging rate that allows high-speed charging. Thereafter, the control unit 150 can charge the battery 200 to a full charge by slow charging if there is time.

[0033] According to this, the control unit 150 can preferentially charge the batteries 200 inserted into the charging slots 120 whose charging rates are determined to be less than the first target charging rate to the first target charging rate by constant current charging. Thereafter, the control unit 150 can sequentially charge the batteries 200 inserted into the charging slots 120 to full charge by constant voltage charging. Therefore, the charging device 100 can charge the batteries 200 by using both efficient charging to the first target charging rate and full charge.

[0034] However, the first target charging rate may be a charging rate arbitrarily set by the user who operates the battery 200, instead of the charging rate at which constant current charging is switched to constant voltage charging.

[0035] In addition to the first target charging rate, a second target charging rate may also be set.

[0036] When the second target charging rate is set lower than the first target charging rate, the control unit 150 may preferentially charge the batteries 200 inserted into the charging slots 120 whose charging rates are lower than the second target charging rate to the second target charging rate by constant current charging. Thereafter, the control unit 150 may preferentially charge the batteries 200 inserted into the charging slots 120 whose charging rates are lower than the first target charging rate to the first target charging rate by constant current charging. Thereafter, the control unit 150 may sequentially charge all the batteries 200 to full charge by constant voltage charging.

[0037] Conversely, when the second target charging rate is set higher than the first target charging rate, the control unit 150 may preferentially charge, by constant current charging, batteries 200 inserted into the charging slots 120 whose charging rates are lower than the first target charging rate to the first target charging rate. Thereafter, the control unit 150 may preferentially charge, by constant voltage charging, batteries 200 inserted into the charging slots 120 whose charging rates are lower than the second target charging rate to the second target charging rate. Thereafter, the control unit 150 may sequentially charge all of the batteries 200 to full charge by constant voltage charging.

[0038] As described above, the charging circuit 140 is a control circuit that controls the current or voltage when charging the battery 200. The charging circuit 140 monitors the charge capacity or voltage of the battery 200, and can switch the charging method for the battery 200 (constant current charging or constant voltage charging) or stop charging the battery 200.

[0039] In the charging device 100, the number of batteries 200 corresponding to the number of charging circuits 140 are simultaneously charged. The number (Y) of charging circuits 140 may be the same as the number (N) of batteries 200 operated as a set. In this manner, the charging device 100 can adjust the charging rates of all batteries 200 inserted into the charging slots 120 to a first target charging rate, and then simultaneously charge the N batteries 200 that have been adjusted to the first target charging rate using the charging circuits 140 while adjusting their charging rates.

[0040] As described above, the charging slot 120 has an opening into which the battery 200 is inserted, and is a connection port that supplies power from the charging device 100 to the battery 200 by connecting with the inserted battery 200 .

[0041] The number (X) of charging slots 120 may be equal to or greater than the number (Y) of charging circuits. By inserting batteries 200 in a charging standby state into charging slots 120 in advance, charging device 100 can immediately start charging batteries 200 in a charging standby state when charging of the battery 200 is completed. Furthermore, the number (X) of charging slots 120 may be an integer multiple of the number (N) of batteries 200 operated as a set. By doing so, charging device 100 can insert multiple sets of batteries 200, each set consisting of N batteries, into charging slots 120 in advance.

[0042] As described above, the charging notification unit 110 includes a light-emitting unit such as an LED lamp, and notifies the charging state of the battery 200 inserted into the corresponding charging slot 120 by the light-emitting pattern or light-emitting color of the light-emitting unit. Specifically, the charging notification unit 110 may cause the light-emitting unit to emit light in a light-emitting pattern or light-emitting color corresponding to the charging state (e.g., charging standby state, charging in progress, charging complete, etc.) of the battery 200 inserted into the corresponding charging slot 120.

[0043] For example, the charge notification unit 110 may notify the charging state of the battery 200 using the light emission pattern or light emission color of an LED lamp shown in Fig. 4. Fig. 4 is a table showing examples of notification patterns by the charge notification unit 110 and the battery notification unit 210.

[0044] As shown in FIG. 4 , the charging notification unit 110 may change the light emission pattern of the LED lamp depending on whether the battery 200 is in a charging standby state, is being charged, is fully charged, or is not inserted. For example, the charging notification unit 110 may turn off the LED lamp when the battery 200 is not inserted. The charging notification unit 110 may turn on the LED lamp when the battery 200 is fully charged. Furthermore, the charging notification unit 110 may flash the LED lamp twice quickly and repeatedly when the battery 200 is in a charging standby state, and flash the LED lamp slowly and continuously when the battery 200 is being charged. In this way, the charging notification unit 110 can notify the charging state of the battery 200 using the light emission pattern of the LED lamp.

[0045] The charge notification unit 110 may change the light color of the LED lamp to a first light color (e.g., orange) when the charging rate of the battery 200 is less than a first target charging rate. On the other hand, the charge notification unit 110 may change the light color of the LED lamp to a second light color (e.g., green) when the charging rate of the battery 200 is equal to or greater than the first target charging rate. In this way, the charge notification unit 110 can notify, by the light color of the LED lamp, whether the charging rate of the battery 200 is equal to or greater than the first target charging rate.

[0046] Meanwhile, the battery notification unit 210 may change the light emission pattern of the LED lamps depending on whether the battery 200 is in a charging standby state, charging, or a charging-completed state. For example, the battery notification unit 210 may turn off the LED lamps when the battery 200 is in a charging standby state. When the battery 200 is charging, the battery notification unit 210 may turn on the LED lamps in a number corresponding to the charging rate of the battery 200. When the battery 200 is in a charging-completed state, the battery notification unit 210 may turn on all the LED lamps.

[0047] The charging device 100 having the above configuration can efficiently charge the battery 200 to a charging rate that is usable for a mobile object or the like by preferentially charging the battery 200 to a first target charging rate that allows high-speed charging. Thereafter, the charging device 100 can charge the battery 200 to a full charge by slow charging over time. Therefore, the charging device 100 can efficiently charge the battery 200 to the first target charging rate and fully charge the battery 200 at the same time.

[0048] 3. Control Examples A specific control example of the charging device 100 according to this embodiment will be described with reference to FIGS. 5 and 6. FIG.

[0049] For example, when a new battery 200 is inserted into the charging slot 120 of the charging device 100, the charging device 100 may determine the battery 200 to charge according to the flowchart shown in Fig. 5. Fig. 5 is a flowchart showing the flow of judgment when determining the battery 200 to charge.

[0050] 5, first, the insertion of the battery 200 into the charging slot 120 is detected (S101). At this time, the charging device 100 determines whether the charging rate of the inserted battery 200 is less than a first target charging rate (S102).

[0051] If the charging rate of the inserted battery 200 is less than the first target charging rate (S102 / YES), the charging device 100 determines whether the charging device 100 is charging a battery 200 with a charging rate less than the first target (S103).

[0052] If the charging device 100 is charging batteries 200 whose charging rate is less than the first target (YES in S103), the charging device 100 further determines whether the number of batteries 200 being charged is less than the number of charging circuits 140 (S104). If the number of batteries 200 being charged is less than the number of charging circuits 140 (YES in S104), the charging device 100 starts charging the inserted batteries 200 (S108). On the other hand, if the number of batteries 200 being charged is the same as the number of charging circuits 140 (NO in S104), the charging device 100 puts the inserted batteries 200 into a charging standby state (S109).

[0053] If it is determined in step S103 that the charging device 100 is not charging a battery 200 whose charging rate is less than the first target (S103 / NO), the charging device 100 stops charging the battery that is being charged (S105) and then starts charging the inserted battery 200 (S108).

[0054] Also, if the judgment in step S102 is that the charging rate of the inserted battery 200 is equal to or higher than the first target charging rate (S102 / NO), the charging device 100 judges whether the charging device 100 is charging a battery 200 whose charging rate is lower than the first target charging rate (S106).

[0055] If the charging device 100 is not charging a battery 200 whose charging rate is less than the first target (S106 / NO), the charging device 100 determines whether the number of batteries 200 being charged is less than the number of charging circuits 140 (S107).

[0056] If the number of batteries 200 being charged is less than the number of charging circuits 140 (S107 / YES), the charging device 100 starts charging the inserted batteries 200 (S108). On the other hand, if the number of batteries 200 being charged is the same as the number of charging circuits 140 (S107 / NO), the charging device 100 puts the inserted batteries 200 into a charging standby state (S109). Also, if the charging device 100 is charging a battery 200 whose charging rate is less than the first target (S106 / YES), the charging device 100 puts the inserted batteries 200 into a charging standby state (S109).

[0057] When it is determined that charging of the inserted battery 200 has started (S108) or that the inserted battery 200 has transitioned to a charging standby state (S109), the charging device 100 controls the connection between the charging circuit 140 and the charging slot 120 based on the determination, and charges the battery 200 inserted in the charging slot 120. Thereafter, the charging device 100 continues charging the battery 200 until it detects insertion or removal of a battery 200, or until charging of any battery 200 has finished (S110).

[0058] When insertion or removal of a battery 200 is detected, or when charging of any battery 200 is completed (S110), the charging device 100 again determines the battery 200 to be charged, following the flow from step S102.

[0059] The above-mentioned determination flow is summarized in Table 1 below as a matrix of the insertion / removal of the battery 200 and the state of the charging device 100. In Table 1, the charging device 100 is equipped with two charging circuits 140. In other words, the charging device 100 can charge up to two batteries 200 inserted into the charging slots 120.

[0060]

[0061] According to Table 1, the charging device 100 can determine whether to charge the inserted battery 200 or put it into a charging standby state based on the charging rate of the inserted battery 200 and the number and charging rate of the batteries 200 being charged when the battery 200 is inserted.

[0062] Furthermore, in addition to prioritizing the charging of batteries 200 whose charging rate is determined to be less than the first target, charging device 100 may determine which battery 200 to charge in accordance with the order in which batteries 200 were inserted into charging slots 120. When batteries 200 are inserted into charging slots 120 at the same time, charging device 100 may determine which battery 200 to charge in accordance with the numbers assigned to the charging slots 120. The case in which batteries 200 are inserted into charging slots 120 at the same time refers to a case in which a battery 200 to be charged is determined when multiple batteries 200 waiting to be charged are inserted into charging slots 120. That is, when multiple batteries 200 are inserted into charging slots 120, external power is input to power input unit 131, a battery 200 being charged is removed from charging slot 120, or charging of a battery 200 being charged is completed, etc.

[0063] A specific example of charging of battery 200 by charging device 100 will be described with reference to Fig. 6. Fig. 6 is a schematic diagram showing a specific example of charging of battery 200. Fig. 6 illustrates charging device 100 equipped with four charging slots 120 and two charging circuits 140. The four charging slots 120 equipped in charging device 100 shown in Fig. 6 are assigned slot numbers 1 to 4 in order from the left when facing Fig. 6.

[0064] First, as shown in Fig. 6A, assume that four batteries 200 with charging rates less than the first target charging rate are inserted into four charging slots 120. Assume that the four batteries 200 are inserted into the four charging slots 120 in the order of slot numbers 2, 4, 3, and 1. In this case, the charging device 100 starts charging the batteries 200 inserted into the charging slots 120 with slot numbers 2 and 4, which were inserted earlier, in order to charge the batteries 200 up to the first target charging rate.

[0065] 6B, it is assumed that the charging rate of the battery 200 inserted into the charging slot 120 with slot number 4 has reached the first target charging rate. In this case, the charging device 100 ends charging of the battery 200 inserted into the charging slot 120 with slot number 4, and starts charging of the battery 200 inserted into the charging slot 120 with slot number 1 in the order of slot numbers.

[0066] Subsequently, after the charging rate of the battery 200 inserted into the charging slot 120 with slot number 2 reaches the first target charging rate, charging of the battery 200 inserted into the charging slot 120 with slot number 3 begins. After that, as shown in (C) of Fig. 6, it is assumed that the charging rate of the battery 200 inserted into the charging slot 120 with slot number 1 reaches the first target charging rate. In this case, the charging device 100 charges only the battery 200 inserted into the charging slot 120 with slot number 3, in order to charge the battery 200 to the first target charging rate with priority.

[0067] 6(D), it is assumed that the charging rates of the four batteries 200 inserted into the four charging slots 120 have reached the first target charging rate. In this case, the charging device 100 starts charging the batteries 200 inserted into the charging slots 120 with slot numbers 1 and 2 in the order of slot number in order to fully charge the batteries 200.

[0068] 6(E), it is assumed that the battery 200 inserted into the charging slot 120 with slot number 2 is removed from the charging slot 120. In such a case, the charging device 100 charges the batteries 200 inserted into the charging slots 120 with slot numbers 1 and 3 in the order of slot number, excluding slot number 2, to fully charge the battery 200.

[0069] 6(F), suppose that a battery 200 with a charging rate lower than the first target charging rate is inserted into the charging slot 120 with slot number 2. In this case, the charging device 100 stops charging the batteries 200 inserted into the charging slots 120 with slot numbers 1 and 3, and starts charging the battery 200 inserted into the charging slot 120 with slot number 2, in order to prioritize charging up to the first target charging rate.

[0070] As described above, the charging device 100 according to this embodiment can automatically switch between charging up to a first target charging rate and charging up to full charge, based on the charging rate of the battery 200 inserted in the charging slot 120. As a result, the charging device 100 according to this embodiment can efficiently charge the battery 200 up to the first target charging rate and fully charge the battery 200 at the same time.

[0071] Although the preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the technical scope of the present disclosure is not limited to such examples. It is clear that a person skilled in the art of the present disclosure can conceive of various modified or altered examples within the scope of the technical idea described in the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure.

[0072] Furthermore, the effects described herein are merely descriptive or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that will be apparent to those skilled in the art from the description of this specification, in addition to or in place of the above-described effects.

[0073] The following configurations also fall within the technical scope of the present disclosure. (1) A charging device comprising: X charging slots into which repeatedly chargeable and dischargeable batteries are inserted; Y charging circuits (where Y≦X) that charge the batteries inserted into the charging slots; and a control unit that controls the charging circuits to preferentially charge batteries, among the batteries inserted into the charging slots, whose charging rate is determined to be less than a first target charging rate that is lower than a full charge. (2) The charging device described in (1), wherein the first target charging rate is a charging rate at which charging of the batteries is switched from constant current charging to constant voltage charging. (3) The charging device described in (1), wherein the control unit controls the charging circuits to charge the batteries further based on the order in which the batteries were inserted into the charging slots. (4) The charging device described in (3), wherein, if the batteries were inserted into the charging slots simultaneously, the control unit controls the charging circuits to charge the batteries based on identification numbers assigned to the charging slots. (5) The charging device according to any one of (1) to (4), wherein the batteries are used in sets of N (where N<X). (6) The charging device according to (5), wherein the number of charging circuits is N (i.e., Y=N). (7) The charging device according to (5) or (6), wherein the number of charging slots is an integer multiple of N. (8) The charging device according to any one of (1) to (7), further comprising a charging notification unit that notifies of the charging state of the battery inserted in the charging slot. (9) The charging device according to (8), wherein the charging notification unit notifies whether the charging rate of the battery has reached the first target charging rate. (10) The charging device according to (8) or (9), wherein the charging notification unit notifies whether the charging rate of the battery is fully charged. (11) The charging device according to any one of (8) to (10), wherein the charging notification unit notifies whether the battery is being charged or is waiting to be charged.(12) The charging device according to any one of (8) to (11), wherein the charging notification unit includes a light emitting unit, and the charging notification unit notifies the charging state of the battery by the light emitting pattern or light color of the light emitting unit. (13) A charging method including: inserting repeatedly chargeable and dischargeable batteries into X charging slots; and charging the batteries inserted in the charging slots by Y charging circuits (where Y≦X), wherein the charging circuits are controlled to preferentially charge batteries, among the batteries inserted in the charging slots, whose charging rate is determined to be less than a first target charging rate that is lower than a full charge.

[0074] REFERENCE SIGNS LIST 100 Charging device 110 Charging notification unit 120 Charging slot 130 Power supply unit 131 Power supply input unit 140 Charging circuit 150 Control unit 200 Battery 210 Battery notification unit

Claims

1. A charging device comprising: X charging slots into which repeatedly chargeable and dischargeable batteries are inserted; Y (where Y≦X) charging circuits that charge the batteries inserted into the charging slots; and a control unit that controls the charging circuits to preferentially charge batteries, among the batteries inserted into the charging slots, that are determined to have a charging rate below a first target charging rate that is lower than a full charge.

2. The charging device according to claim 1, wherein the first target charging rate is a charging rate at which charging of the battery switches from constant current charging to constant voltage charging.

3. The charging device of claim 1, wherein the control unit controls the charging circuit to charge the batteries further based on the order in which the batteries are inserted into the charging slots.

4. The charging device according to claim 3, wherein, when the batteries are inserted into the charging slots in the same order, the control unit controls the charging circuit to charge the batteries based on the identification numbers assigned to the charging slots.

5. The charging device according to claim 1, wherein the batteries are used in groups of N (where N<X).

6. The charging device according to claim 5, wherein the number of the charging circuits is N (i.e., Y=N).

7. The charging device according to claim 5, wherein the number of the charging slots is an integer multiple of N.

8. The charging device according to claim 1, further comprising a charging notification unit that notifies the charging state of the battery inserted in the charging slot.

9. The charging device according to claim 8, wherein the charging notification unit notifies whether the charging rate of the battery has reached the first target charging rate.

10. The charging device according to claim 8, wherein the charging notification unit notifies whether the charging rate of the battery is fully charged or not.

11. The charging device according to claim 8, wherein the charging notification unit notifies whether the battery is being charged or is waiting to be charged.

12. The charging device according to claim 8, wherein the charging notification unit includes a light emitting unit, and the charging notification unit notifies the charging state of the battery by the light emitting pattern or light emitting color of the light emitting unit.

13. A charging method comprising: inserting repeatedly chargeable and dischargeable batteries into X charging slots; and charging the batteries inserted into the charging slots by Y (where Y≦X) charging circuits, wherein the charging circuits are controlled to preferentially charge batteries, among the batteries inserted into the charging slots, whose charging rate is determined to be less than a first target charging rate that is lower than a full charge.

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