JPH05211728A - Power control system - Google Patents

Abstract

PURPOSE:To maintain reliability by changing the connection or disconnection of a battery through turning OFF the battery discharge switch of the battery starting the connection or disconnection, when the connection or disconnection of the battery is detected in a state where power is supplied to an apparatus, and by continuing the supply of power. CONSTITUTION:The battery discharge switches SW21-SW23 of any of a plurality of batteries l are turned ON so that power is supplied to an apparatus. Then, when tone start of the connection or disconnection of the battery 1 is detected in this state by a signal from a battery detection terminal 2, any of the battery discharge switches SW21-SW23 of other battery 1 is turned ON if power can be supplied from the battery 1, thereafter the battery discharge switches SW21-SW23 of the battery 1 starting the connection or disconnection is turned OFF so that the connection or disconnection of the battery is changed, and the supply of power is continued. Thus, it is possible to maintain the reliability of a power supply system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply control system for controlling power supply from a plurality of batteries to a device.

[0002]

2. Description of the Related Art Conventionally, in a device provided with a main power source for supplying power and a battery for backing up when the main power source is off, when a battery (battery cassette) is attached to or detached from the device, the device is slid for a certain distance. There is a device which has an electrode for maintaining the connection state of the battery and performs a data saving process when the attachment / detachment detecting unit detects the detachment start of the battery.

[0003]

The above-mentioned conventional device has the following problems because the data saving process is performed when the battery removal start is detected.

(1) In a device that can be supplied from a plurality of batteries, if the battery being discharged is attached or detached, the data saving process may be performed each time the start of attachment or detachment of the battery is detected. However, there is a problem that the operation cannot be continuously performed without performing the battery evacuation process and the operation is interrupted. For this reason,
It is desired to continue the operation without interruption when switching to another battery.

(2) In a device which can be supplied from a plurality of batteries, when the discharging battery is switched to another battery to continue the operation as it is, the voltage is dropped at the time of switching. There is a problem that reliability is reduced because it is not checked. For this reason, when switching batteries and supplying power to the device, it is desirable to automatically perform reset processing and initialization processing when voltage drop is detected even temporarily to maintain reliability. There is.

The present invention solves these problems.
When switching the power supply from multiple batteries and supplying it to the device, if a battery that can be supplied is installed, the battery is switched and the operation is continued if a voltage lock is not detected, and a voltage drop is detected. Reset to
Initialization, on the other hand, if the battery is not installed, data saving processing is performed, and operation of the device is continued without interruption as much as possible at the time of battery switching, and reset when a voltage drop is detected at the time of switching, The purpose is to maintain reliability by performing initialization.

[0007]

[Means for Solving the Problems] Means for solving the problems will be described with reference to FIG. In FIG. 1, a battery detection terminal 2 detects the start of attachment / detachment of a battery.

Battery discharge switches SW21 to SW
Reference numeral 23 is a switch for supplying power from the battery to the device. The voltage detection unit 6 detects whether or not the voltage drops below a predetermined threshold value when the battery is switched.

Battery charging switches SW11 to SW1
A switch 3 supplies a charging current to the battery.

[0010]

According to the present invention, as shown in FIG. 1, the battery discharge switches SW21 to SW of any one of a plurality of batteries are provided.
When the power supply to the apparatus is turned on by turning on 23 and the start of the attachment / detachment of the battery is detected by the signal from the battery detection terminal 2, when the power can be supplied from another battery, this battery Battery discharge switch S
After turning on any one of W21 to SW23, the battery discharge switch of the battery that has started to be attached / detached is turned off and switched.

At this time, when the voltage detection unit 6 switches the battery, it is detected whether or not the voltage drops below a predetermined threshold value, and when the voltage drop is detected, the device is reset or initialized. I'm trying to do it.

Further, when the battery is to be switched to another battery, the data saving process is performed when there is no battery that can be supplied with power. Also,
When the start of attachment / detachment of the battery being charged among the plurality of batteries is detected by the signal from the battery detection terminal 2, the battery charging switches SW11 to SW of the battery being charged when there are other uncharged batteries
13 is turned off and the battery charging switches SW11 to SW13 of the uncharged battery are turned on to switch the battery.

Therefore, when the power is switched from a plurality of batteries and supplied to the apparatus, if a battery that can be supplied is installed, the battery is switched and the operation is continued if the voltage drop is not detected, and the voltage drop is continued. When the battery is switched, the device is reset and initialized, and if the battery is not installed, the data saving process is performed to continue the operation of the device without interrupting the battery switching and to detect the voltage drop when switching the battery. It is possible to maintain reliability by performing a reset etc. Further, it is possible to supply the power generated from the AC power source to the device and automatically switch to another uncharged battery to charge the battery when the attachment / detachment of the battery being charged is detected while the battery is being charged. Becomes

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the construction and operation of an embodiment of the present invention will be described in detail with reference to FIGS.

FIG. 1 is a configuration diagram (1) of an embodiment of the present invention. In FIG. 1, a battery 1 is a battery that supplies power to a device such as a computer system (not shown), and turns on a battery discharge switch of any one battery to supply power to the device.
Here, it is composed of three of a battery (1), a battery (2) and a battery (3), and any one supplies power (system power) to a device (not shown).

The battery detection terminal 2 includes a battery (1),
The battery detection signals C1 and C are provided on the battery (2) and the battery (3), respectively, when the battery starts to be attached / detached.
2 and C3 are terminals for detecting the start of attachment / detachment of the battery by setting, for example, zero. This battery detection terminal 2 is
When the attachment / detachment of the battery (battery pack) is started, the contact of the battery detection terminal 2 comes off and the battery detection signal C
When 1, C2, C3 become zero and the battery is further attached and detached, the power supply from the battery is cut off. Therefore, this battery detection signal C1, C
2, when C3 becomes zero, the battery is switched to another battery, or when there is no battery to be switched, data saving processing is performed (FIGS. 3 and 4).
reference).

The battery discharge switch SW21 to the battery discharge switch SW23 are switches for supplying power from the battery (1) to the battery (3) to the device. Here, any one of the battery discharge switches SW21 to SW23 is turned on (temporarily overlapped and turned on when the batteries are switched), and the battery (1)
Power is generated from the corresponding one of (3) to (3).
Is supplied to the DC-DC converter 42 constituting the
The predetermined voltage DC-DC converted by the C-DC converter 42 is supplied to a device (not shown) as a system power supply. Battery discharge switch SW21 to SW2
To turn on 3, the battery discharge switch signal OUT
The corresponding signals of 1 to OUT3 are turned on.

The diode 3 is for supplying the power source generating circuit 4 from the power source having the higher voltage when the plurality of battery discharge switches SW21 to SW23 of the battery (1) to the battery (3) are turned on. Is.

The battery charging switch SW11 to the battery charging switch SW13 supply the power from the AC adapter 41 and the DC-DC converter 42 constituting the power generation circuit 4 to any one of the batteries (1) to (3). And a switch for sequentially charging. When any one of the batteries (1) to (3) is started to be attached / detached, one battery charging switch SW1 of any of the other uncharged batteries (1) to (3) is started.
1 to SW13 are turned on for charging. To turn on the battery charge switches SW11 to SW13, turn on the corresponding signals of the battery charge switch signals IN1 to IN3.

The power supply generation circuit 4 supplies a DC power supply (system power supply) generated from an AC power supply to a device (not shown) or supplies the power supply to the battery (1) to the battery (3) for charging. It is composed of an AC adapter 41 and a DC-DC converter 42.

The AC adapter 41 is an AC power source (commercial 1
A predetermined DC voltage is generated based on (00 VAC, 200 VAC, etc.). DC-DC converter 42
When the DC voltage is supplied from the AC adapter 41, the DC-DC converted predetermined DC voltage is supplied to a device (not shown) as a system power source, and the predetermined DC voltage is supplied to the battery (1) to the battery (3). 1) to charge the battery, or when the DC voltage from the AC adapter 41 is not supplied, the voltage from the battery (1) to the battery (3) is converted from DC to DC. The predetermined DC voltage is supplied to a device (not shown) as a system power supply.

The consumption current detector 7 is a load from any one of the battery (1) to the battery (3), in this case D
The current supplied to the C-DC converter 42 is detected as a voltage. The voltage corresponding to the detected current is input to the A / D converter 8 in FIG. 2 and converted into a digital value.

FIG. 2 is a configuration diagram (2) of another embodiment of the present invention. In FIG. 2, the one-chip microcomputer 9 performs processing such as battery switching, reset processing, and data saving based on various signals (various signals shown on the left end) detected by the configuration of FIG. 1 (see FIG. 3). From FIG. 6), and the battery mounting check 1
0, battery remaining amount calculation 11, battery charge / discharge control 1
2, data save processing 13, battery charge SW / discharge SW
Control 14, error handling 15, and microcomputer initialization 16
It is composed of etc.

The battery mounting check 10 detects the mounting of the battery based on the battery detection signals C1, C2 and C3 from the battery detection terminals 2 of the batteries (1), (2) and (3). is there. For example, when it is detected that the battery detection signal C1 becomes zero potential, it is detected that the attachment / detachment of the battery (1) is started. In response to detection of the start of attachment / detachment of the battery (1), the battery is switched when there is a battery to be switched, and the data saving process is performed when there is no battery to be switched (see FIG. 4). Use later).

The battery remaining amount calculation 11 is performed by using the batteries (1), (2) and (3) to calculate the DC-DC converter 42.
The current supplied to the battery is detected by the consumption current detector 7, which is converted into a digital value by the A / D converter 8 and taken in, for example, based on the discharge current from full charge, time, etc. It is to calculate the quantity.

The battery charging / discharging control 12 controls charging and discharging of the battery based on the battery mounting state from the battery mounting check 10 and the battery remaining amount state from the battery remaining amount calculation 11. (Fig. 3
To FIG. 6).

The data saving process 13 is a process of saving the data of the device when the battery mounting check 10 notifies that the battery is started to be removed and there is no other battery that can supply power to the device. Is performed (described later with reference to FIG. 4).

The battery charge SW / discharge SW control 14 is
In response to an instruction from the battery charge / discharge control 12 or the like, the battery charge switch signals IN1 to IN3 for turning on / off the battery charge SW11 to SW13 are generated, or the battery discharge switches SW21 to SW2.
Battery discharge switch signal OUT1 for turning on / off 3
Through OUT3.

The error processing 15 indicates that the voltage of the power supply (system power supply) supplied from the DC-DC converter 42 to the device that is the load drops below a predetermined threshold value, particularly when the battery is switched, the voltage drops below the predetermined threshold value. The voltage detection unit 6 detects the voltage, and performs error processing in response to the notification to that effect. As the error processing, a system reset is sent to a device (computer system) not shown for resetting, or the microcomputer initialization 16 is started.

The microcomputer initialization 16 initializes the one-chip microcomputer 9 in response to the activation from the error processing 15. The sub battery 17 is a one-chip microcomputer 9
This is a battery for operating the one-chip microcomputer 9 when the power supplied to the device is cut off.

Next, the operation of the configuration shown in FIGS. 1 and 2 at the time of discharging (when supplying power from the battery to the apparatus) will be described in detail with reference to FIGS. 3 and 4. FIG. 3 shows a time chart (during discharge) of the present invention. Where C1 and C
2, C3: Battery detection signal (a signal for detecting that the battery has been attached / detached) OUT1, OUT2, OUT3: Battery discharge switch signals for turning on / off the battery discharge switches SW21 to SW23 IN1, IN2, IN3: Battery charge switch SW1
Battery charge switch signal for turning on / off 1 to SW13 Voltage detection: voltage detected by system power supply by voltage detection unit 6 System reset: Signal for error processing 15 to send to device in response to voltage drop to reset system Supplies the battery discharge switch signal OUT1 in which the battery charge SW / discharge SW control 14 is turned on to the battery discharge switch SW21 to turn it on, and the battery (1) to S
DC-DC converter 4 via W21 and diode 3
2. Shows a state in which power is supplied to a device (not shown) through the system power supply route.

In the state of, the battery mounting check 10 detects that the battery detection signal C1 is OFF in response to the user starting the attachment / detachment of the battery (1). In response to this, the battery charge / discharge control 12
The battery (2) is selected here as another battery that can be supplied with power. Corresponding to this selection, the battery charge SW / discharge SW control 14 turns on the battery discharge switch signal OUT2 and turns on the battery discharge switch SW22, and the battery (2) passes through the diode 3 and D
Supply of power to the C-DC converter 42 is started. After starting the power supply, the battery charge / discharge control 12
In response to the instruction from, the battery charge SW / discharge SW control 14 turns off the battery discharge switch signal OUT1 of the battery (1) whose desorption is started, turns off the battery discharge switch SW21, and outputs from the battery (1). Stop the power supply.

When the battery (1) is being switched to the battery (2), the voltage detecting section 6 causes the DC-
The voltage of the system power supply supplied from the DC converter 42 to a device (not shown) is monitored, and it is detected here that the voltage has dropped below a predetermined voltage, and the error processing 15 is notified of that fact. Upon receiving this notification, the error processing 15 supplies a system reset to a device (not shown), resets the system of the device, and displays an error. The microcomputer initialization 16 also performs initialization.

As described above, under the configuration of FIGS. 1 and 2, the system power is supplied from the battery (1) among the batteries (1), (2) and (3) (), The user starts attaching / detaching the battery (1), and C1
In response to the battery mounting check 10 detecting that the battery has become zero potential, the battery discharge switch SW22 of the battery (2) capable of supplying power is turned on to start supplying power, and then attachment / detachment is started. Battery (1)
The battery discharge switch SW21 is turned off to switch the battery (1) to the battery (2). At the time of this switching, the voltage detection unit 6 monitors the voltage supplied as the system power supply, and since it has been detected here that the voltage has dropped below the predetermined voltage, the error processing 15 performs system reset and initialization of the device. As a result, it becomes possible to automatically switch the battery, and it is also possible to automatically reset and restart the system when a voltage drop of the system power source should occur.

The discharge operation of the configuration shown in FIGS. 1 and 2 will be described in detail according to the order shown in the flow chart of FIG. 4 (during discharge). In FIG. 4, S1 determines whether or not discharging is in progress. If yes, then continue with S2. In the case of NO, there is no need to perform the process at the time of discharging, so the process ends.

In step S2, it is determined whether the battery (1) is discharging. If yes, then continue with S3. If no,
Proceed to S5. In S3, since the battery (1) is determined to be discharging in YES in S2, C1 (battery detection signal) is checked. When it is ON (when the voltage of the battery detection terminal 2 is equal to that of the battery (1) and the attachment / detachment of the battery (1) has not been started), it is determined in S13 whether the power source is normal, the process ends when YES, and NO. At this time, an abnormal process (system reset, initialization) is performed in S14, and the process ends.
On the other hand, in the case of OFF (when the voltage of the battery detection terminal 2 is lower than that of the battery (1), for example, when the battery (1) is attached / detached due to zero potential), the battery switching is performed in S4. Proceed to.

In step S4, it is determined whether discharge switching, that is, switching from the battery (1) to another battery is possible (whether there is a dischargeable battery). In the case of OK, discharge switching (switching from the battery (1) to another battery (2) or battery (3) capable of supplying power) is performed in S11, and it is determined in S13 whether the power is normal, and YES.
When NO, the process ends, and when NO, the abnormal process (system reset, initialization) is performed in S14, and the process ends. On the other hand, NO
In case of (when there is no battery to be switched), S12
After performing the data saving process in step S13, it is determined whether the power source is normal in step S13. If YES, the process ends. If NO, the error process (system reset, initialization) is performed in step S14, and the process ends.

As described above, when the battery (1) is discharging (YES in S2), when the battery detection signal C1 is ON, the power supply is normal, and when abnormal, the abnormal processing is performed. On the other hand, when it is detected that the battery detection signal C1 is turned off and the user has started the attachment / detachment of the battery (1), if there is a battery capable of supplying power among the other batteries (2) and (3), The power is switched to supply power, and if there is no battery to switch to, data saving processing is performed. Also in this case, when a power supply abnormality is detected, abnormality processing (system reset, initialization, etc.) is performed. As a result, it becomes possible to switch to another battery while power is being supplied from any one of the plurality of batteries (1), (2), and (3), and when there is no battery to switch to. It becomes possible to save the data by performing the data saving process. Further, when a power supply abnormality occurs during switching of these batteries, abnormality processing (system reset, initialization, etc.) is automatically performed, so that the reliability of the device can be improved.

S5 to S7 are for the battery (2), and S8 to S10 are for the battery (3), which are the same as those for the battery (1) at S2 to S4, and therefore their explanations are omitted. Next, with reference to FIGS. 5 and 6, during charging of the configuration of FIGS. 1 and 2 (power is supplied to the device from the AC adapter 41 and the DC-DC converter 42 and the battery (1),
The operation in the case of supplying to any one of (2) and (3) for charging will be described in detail.

FIG. 5 shows a time chart (at the time of charging) of the present invention. Here, C1, C2, C3: Battery detection signal OUT1, OUT2, OUT3: Battery discharge switch signal IN1, IN2, IN3: Battery charge switch signal Voltage detection: Detected voltage supplied to system power supply System reset: System reset The signal to be supplied is that the battery charge SW / discharge SW control 14 supplies the battery charge switch signal IN1 to the battery charge switch SW11 to turn it on, and the AC adapter 41, DC
A state in which the battery (1) is being charged via the DC converter 42 and SW11.

In the state, the battery mounting check 10 detects that the battery detection signal C1 is OFF in response to the user starting the attachment / detachment of the battery (1). In response to this, in response to an instruction from the battery charge / discharge control 12, the battery charge SW / discharge SW control 1
Reference numeral 4 supplies the battery charging switch signal IN1 for turning off the battery (1) to the SW11 to turn it off to stop charging the battery (1). Next, the battery charge / discharge control 12 selects the battery (2) here as another uncharged battery. In response to this selection, the battery charge SW / discharge SW control 14 turns on the battery charge switch signal IN2 and turns on the battery charge switch SW12, and the AC adapter 41 and the DC-DC converter 4
2, charging of the battery (2) is started via the SW 21.

As described above, under the configuration shown in FIGS. 1 and 2, the battery (1) among the batteries (1), (2) and (3) is charged and power is supplied to the device. (), The user starts attaching / detaching the battery (1), and C1
In response to the battery mounting check 10 detecting that the battery has become zero potential, the battery charging switch SW12 for the uncharged battery, here the battery (2), is stopped after the charging of the battery (1) is stopped. Turn on to start charging. As a result, it becomes possible to automatically switch the battery and charge the battery while supplying system power to the device from the AC adapter 41 and the DC-DC power supply 42. When the battery is fully charged during charging, the charging is switched to another uncharged battery.

The charging operation of the configuration shown in FIGS. 1 and 2 will be described in detail according to the order shown in the flowchart (charging) of FIG. In FIG. 6, S21 determines whether or not charging is in progress. If YES, the process proceeds to S22. In the case of NO, there is no need to perform the process at the time of charging, so the process ends.

In step S22, it is determined whether the battery (1) is being charged. If YES, the process proceeds to S23. If NO, the process proceeds to S25. In S23, since it is determined that the battery (1) is being charged in YES in S22, C1 (battery detection signal) is checked. When it is ON (when the voltage of the battery detection terminal 2 is equal to that of the battery (1) and the attachment / detachment of the battery (1) has not been started), the process ends (the charging is continued). On the other hand, when the battery (1) is OFF (when the voltage of the battery detection terminal 2 is lower than that of the battery (1) and becomes zero, for example, and the attachment / detachment of the battery (1) is started), the battery (1) is charged in S24. Is stopped (IN1 of OFF is supplied to SW11 to turn off SW11 to stop charging), and the process proceeds to S31.

In S31, since the attachment / detachment of the battery (1) is started (S23 is OFF), the battery (1) is attached in S24.
Stop charging and determine if there is an uncharged battery and you can switch. If YES, switch to an uncharged battery in S32, for example uncharged battery (2)
The ON IN2 is supplied to the SW12 to turn on the SW12, and the AC adapter 41 and the DC-DC converter 4
2. Power is supplied to the battery (2) via SW12 to start charging. On the other hand, in the case of NO, there is no uncharged battery to be switched, so the process ends (END).

As described above, when the battery (1) is being charged (YES in S22), the battery detection signal C1
When is ON, charging continues. On the other hand, when the battery detection signal C1 is turned off and it is detected that the user has started the attachment / detachment of the battery (1), another battery (2),
If there is an uncharged rechargeable battery in (3), it is switched to that to restart charging, and if there is no battery to be switched, it ends. As a result, when any one of the plurality of batteries (1), (2) and (3) is attached / detached during charging, it is possible to automatically switch to another uncharged battery for charging. In addition, when fully charged, it is possible to switch to another uncharged battery for charging. When charging these, AC adapter 41,
It is also possible to supply the system power together from the DC-DC converter 42 to the device.

S25 to S27 are the battery (2) and S2
8 to S30 are for the battery (3) and are the same as the battery (1) for S22 to S24, and therefore the description is omitted.

[0048]

As described above, according to the present invention,
When switching the power supply from multiple batteries and supplying it to the device, if a battery that can be supplied is switched, the operation is continued when the voltage drop is not detected and the voltage lock is detected. On the other hand, if the battery is not installed, data saving processing is performed, and since the configuration that allows charging of the battery and supply of power to the device is adopted at the same time, the device can be operated at the time of battery switching. The reliability can be maintained by continuing without interruption and resetting when a voltage drop is detected at the time of switching. Further, the battery can be charged and the power can be supplied to the device at the same time. Due to these, (1) When power is supplied to the device from a plurality of batteries, when the discharging battery is started to be attached / detached, if there is another battery that can supply power, it is switched to this and the power is continued. If there is no battery that can be supplied and can be supplied, data saving processing can be performed.

(2) In addition, the power supply is monitored during the process of (1) and the like, and when a voltage drop below a predetermined voltage is detected, the system is automatically reset and initialized, and a device for supplying power ( System) reliability can be improved.

(2) Also, while the power is being supplied from the AC power source to the apparatus, the battery is also charged, and when the attachment / detachment of the battery being charged is detected, the charging of the battery is stopped and other battery is not charged. It is possible to automatically switch the charging battery and sequentially perform charging.

[Brief description of drawings]

FIG. 1 is a configuration diagram (1) of an embodiment of the present invention.

FIG. 2 is a configuration diagram (part 2) of the embodiment of the present invention.

FIG. 3 is a time chart of the present invention (during discharge).

FIG. 4 is a flowchart for explaining the operation of the present invention (during discharge).

FIG. 5 is a time chart of the present invention (during charging).

FIG. 6 is a flowchart for explaining the operation of the present invention (during charging).

[Explanation of symbols]

1: Battery 2: Battery detection terminal 3: Diode 4: Power supply generation circuit 41: AC adapter 42: DC-DC converter 6: Voltage detection unit 7: Current consumption detection unit 8: A / D converter 9: 1 chip microcomputer 10 : Battery mounting check 11: Battery remaining amount calculation 12: Battery charge / discharge control 13: Data save processing 14: Battery charge SW / discharge SW control 15: Error processing 16: Microcomputer initialization 17: Sub-batteries C1, C2, C3: Battery detection signal IN1, IN2, IN3: Battery charge switch signal OUT1, OUT2, OUT3: Battery discharge switch signal SW11, SW12, SW13: Battery charge switch SW21, SW22, SW23: Battery discharge switch

Claims (4)

[Claims] 1. A power supply control method for controlling the supply of power from a plurality of batteries to a device, a battery detection terminal (2) for detecting the start of attachment / detachment of a battery, and a battery discharge switch for supplying power from the battery to the device. And the start of attachment / detachment of the battery is detected by a signal from the battery detection terminal (2) in a state in which the battery discharge switch of any of the plurality of batteries is turned on to supply power to the device. When the power can be supplied from another battery, turn on the battery discharge switch of this battery, and then turn off the battery discharge switch of the battery that started the attachment / detachment to switch the power so that the power supply is continued. Power control method characterized by being configured. 2. A voltage detection unit (6) for detecting whether or not the voltage drops below a predetermined threshold value when switching the battery according to claim 1, and the voltage detection unit (6) is provided. A power supply control method characterized in that when a voltage drop is detected, a device that supplies power is reset. 3. When switching the battery according to claim 1 to another battery, when there is no battery capable of supplying power, data saving processing of a device which supplies power is performed. Power control method characterized by being configured. 4. A power supply control method for controlling the supply of power from a plurality of batteries to a device, a battery detection terminal (2) for detecting the start of attachment / detachment of a battery, and a battery charging switch for supplying a charging current to the battery. A power supply generation circuit (4) for generating power to the battery and the device, the power supply generation circuit (4) supplying power to the device and starting attachment / detachment of a battery being charged among the plurality of batteries. Is detected by the signal from the battery detection terminal (2), the battery charge switch of the battery being charged is turned off and the battery charge switch of the uncharged battery is turned on when there is another uncharged battery. The power supply control method according to any one of claims 1 to 3, wherein the power supply control method is configured to be switched and charged.