JP2003348765A - Charger and charging control circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charger for keeping a storage battery in a condition close to full charge, while preventing over-charging. <P>SOLUTION: This charger, which is provided with a charging means of charging a battery with constant voltage and constant current, in response to a power input and which supplies discharging current from the battery to a load when the power input stops, comprises a charge control means of instructing the stopping and resuming operations of the charging means; a temperature measuring means of measuring the temperature of the battery; and a voltage detection means, which compares the reference voltage value corresponding to the measured result by the temperature measuring means with the voltage between battery terminals and detects that the voltage between terminals is lower than the reference voltage value, and a counting means of instructing the charging control means for perform resumption at a prescribed time, after counting starts corresponding to the detected result by the voltage detection means. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device and a charging control circuit for charging a battery provided in an electronic computer or the like. In recent years, to preserve data,
Computers equipped with a backup battery are increasing. In such applications, the lead storage battery is often used for continuous trickle charging. However, lead storage batteries are vulnerable to overcharging, and the life of the battery may be shortened depending on the use conditions such as the charging method and the environmental temperature. In such a case, it is necessary to frequently replace the battery, and the burden on the user increases. For this reason, there is a need for a charging method capable of charging a battery without excess or shortage and making full use of the life of the battery.

[0002]

2. Description of the Related Art FIG. 7 shows a configuration example of a power supply unit of an electronic computer to which a conventional charging circuit is applied. In FIG. 7, a power supply device inputs an AC power supply to an AC / DC conversion unit 203 via a filter 201 and a circuit breaker 202 to convert the AC power supply into a DC power, and converts the obtained DC power supply into a DC / DC conversion unit 2.
The battery 101 is supplied to the load 205 via the power supply circuit 04 and to the charging circuit 210 to charge the battery 101 provided therein.

In FIG. 7, a power control unit 206
Is configured to control operations of the AC / DC conversion unit 203, the DC / DC conversion unit 204, and the charging circuit 210 according to ON / OFF of an AC power supply. In FIG. 7, when the AC voltage is applied, the charging circuit 210 turns off the transistor 212 in response to the instruction from the power supply control unit 206, and supplies the DC current from the AC / DC conversion unit 203. In response, the battery 101 is charged via the constant voltage circuit 213, the constant current circuit 214, and the diode 215. On the other hand, when the AC voltage is off,
Conversely, the above-described transistor 212 is turned on, and the discharge current from the battery 101 is supplied to the load 205 via the DC / DC converter 204 via the diode 216.

As described above, the charging circuit 210 configured to charge the lead storage battery 211 via the constant voltage circuit 213 and the constant current circuit 214 does not need to particularly control the charging current, and the charging circuit 210 has a simple configuration. Because it can be realized, it is often used in laptop computers and the like. The reason is that when the charging circuit 210 having this configuration is used, the battery 101 is charged with a constant current when the voltage between the terminals of the battery 101 is low.
This is because, when 1 approaches full charge, as the impedance of the battery 101 increases, it automatically switches to trickle charge with a small current, and the battery 101 can always be kept fully charged.

[0005]

When the charging circuit having the above configuration is used, the battery 101 is trickle-charged as long as an AC voltage is applied to the power supply device. Therefore, if the charge current at the time of trickle charge exceeds the self-discharge current of battery 101, battery 101 will be in an overcharged state. Therefore, conventionally, the capacity of each part of the charging circuit 210 is designed so that the charging current at the time of trickle charging is substantially equal to the discharging current due to self-discharge.

However, the operating characteristics of a lead-acid battery greatly depend on its own temperature. For example, when the lead-acid battery is used at a temperature different from the environmental temperature assumed at the time of design, the charge current during trickle charge exceeds the discharge current. As a result, there is a possibility that the life of the lead storage battery is shortened. On the other hand, as a technique for preventing overcharging due to trickle charging, Japanese Patent Laid-Open No.
There is a technique disclosed in Japanese Unexamined Patent Publication No. 70239 “Automatic charging method for unmanned vehicles”.

This technique monitors the charging current flowing into the lead-acid battery from the charging circuit having the above-described structure and the voltage between the terminals of the lead-acid battery, and when the charging current falls below a predetermined threshold value, the lead-acid battery is fully charged. The charging is stopped when it is determined that the voltage has become zero, and the charging is restarted when the voltage between the terminals of the lead storage battery falls below a predetermined threshold.

As described above, overcharging can be prevented by stopping / restarting charging in accordance with the state of charge of the lead storage battery, and the lead storage battery can be kept almost fully charged. However, since the charging current flowing during trickle charging is a very small current of, for example, about 1 mA, it is very difficult to measure such a very small current with high accuracy. In addition, this technique does not consider the temperature dependence of the operating characteristics of the lead storage battery.

For this reason, even when the above-described technique is applied, the overcharged state is overlooked due to a measurement error of the charging current or a difference in the charging current due to a difference in the environment in which the battery is used. There was a possibility.
An object of the present invention is to provide a charging device that keeps a storage battery close to full charge while preventing overcharge.

[0010]

According to a first aspect of the present invention, there is provided a charging means for charging a battery with a constant voltage and a constant current in accordance with a power supply input, and a discharge current from the battery is supplied when the power supply input is stopped. Charging device for supplying
Charge control means for instructing stop and restart of the operation of the charging means, temperature measuring means for measuring the temperature of the battery, and a reference voltage value according to the measurement result by the temperature measuring means and a voltage between the terminals of the battery, Voltage detecting means for detecting that the voltage between terminals has fallen below the reference voltage value, and time measuring means for starting a time measuring operation in accordance with a detection result by the voltage detecting means and instructing the charging control means to restart after a predetermined time has elapsed. It is characterized by having.

According to a second aspect of the present invention, there is provided a charging device comprising a charging means for charging a battery with a constant current in response to a power input, and supplying a discharge current from the battery to a load when the power input is stopped. Comparing the voltage between the terminals of the battery with a predetermined reference voltage value, and detecting the fully charged state of the battery when the terminal voltage reaches the reference voltage value Assuming that, the charge detection means for instructing the charge control means to stop, and a time measurement means for starting a timekeeping operation in response to the output of the stop instruction by the charge control means, and instructing the charge control means to restart after the elapse of the stop time. It is characterized by having.

According to a third aspect of the present invention, a charging means for charging a battery with a constant voltage and a constant current in accordance with a power supply input, a temperature measuring means for measuring a temperature of the battery, and a measurement result obtained by the temperature measuring means. A voltage detecting means for comparing the reference voltage value with the voltage between the terminals of the battery and detecting that the voltage between the terminals has fallen below the reference voltage value. A charging control circuit that controls a charging device that supplies a discharge current to a load includes a charging control unit that instructs stop and restart of the operation of the charging unit, and starts a timing operation according to a detection result by the voltage detection unit. In addition, the charging control means restarts the operation of the charging means in response to a restart instruction of the timer means for instructing restart of the charging operation after a predetermined time has elapsed.

According to a fourth aspect of the present invention, a charging means for charging a battery with a constant current in accordance with a power supply input, and a voltage between terminals of the battery and a predetermined reference voltage value are compared. And a charge detecting means for instructing a stop of charging when the full charge state of the battery is detected when the power supply input is stopped, and when the power input is stopped, a discharge current from the battery is supplied to the load. A charging control circuit for controlling the charging device, the charging control circuit having an instruction to stop and restart the operation of the charging device, and starting a timing operation in response to the output of the stop instruction by the charging control device, The charging control means is provided with a means for restarting the operation of the charging means in response to a restart instruction of the timing means for instructing the restart of the charging operation after the lapse of the time.

[0014]

According to the first aspect of the present invention, the voltage detecting means compares the reference voltage according to the result of measurement by the temperature measuring means with the voltage between the terminals of the battery, thereby taking into account the temperature dependence of the characteristics of the battery. By accurately evaluating the discharge state of the battery and detecting the elapse of a predetermined time by the timing means, it is possible to detect the point at which charging of the battery should be restarted and restart the charging.

According to the second aspect of the present invention, the charging control means stops the operation of the charging means in response to an instruction from the charging detecting means, so that the charging means is stopped when the battery is fully charged. it can. Thereafter, by detecting the elapse of a predetermined stop time by the timing means, a point in time at which charging of the battery should be restarted is detected, and charging is restarted.
As a result, the battery 101 can always be kept close to full charge.

According to the third aspect of the present invention, the time counting means starts the time counting operation in accordance with the detection result by the voltage detecting means, and after the elapse of a predetermined time, the restart instruction is output by the time counting means. After the voltage falls below the reference voltage according to the measurement result by the temperature measuring means, the charging of the battery is started after a lapse of a predetermined time. This allows
The discharge state of the battery can be accurately evaluated in consideration of the temperature dependence of the characteristics of the battery, the point in time at which charging of the battery should be restarted can be detected, and the charging can be restarted.

According to the fourth aspect of the present invention, the charge control means stops the operation of the charge means in response to an instruction from the charge detection means,
Thereafter, the charging control means restarts the operation of the charging means according to the elapse of the predetermined stop time by the timing means. In this way, when the battery is fully charged, the charging means is stopped, a point in time at which charging of the battery should be restarted is detected, and charging is restarted, so that the battery 101 is always in a state close to full charge. Can be held.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a configuration example of a charging device to which the present invention is applied. In FIG. 1, the same components as those of the power supply device shown in FIG. 7 are denoted by the same reference numerals. 1, the charging apparatus includes a current detection circuit 220, a timer 231 and a charging control unit 232 added to the charging circuit 210 shown in FIG. 7, and the charging control unit 232 operates according to a detection result by the current detection circuit 220. The charging control unit 232 controls the operation of the charging unit including the constant voltage circuit 213 and the constant current circuit 214 in response to the notification from the timer 231.

The above-described current detection circuit 220 includes a resistor 22
1 is amplified by the amplifier 222, and the result of the comparator 224 comparing the output of the amplifier 222 with the reference voltage Vf1 from the voltage generator 223 is sent to the charge controller 232 as a detection result. I have. Here, as described above, the charging current when the lead-acid battery is charged at a constant voltage and a constant current has a constant value ic until the terminal voltage of the lead-acid battery reaches a predetermined value V1 as shown in FIG. And then
It decreases monotonically as the impedance of the lead storage battery increases, and becomes a very small current of about 1 mA after being fully charged (indicated by a dotted line in FIG. 2).

Since the change in the charging current shown in FIG. 2 is due to the operating characteristics of the lead storage battery, if a point in time when the charging current falls below a predetermined value (for example, 50 mA) is detected, a predetermined time from that point is detected. It can be estimated that the battery is fully charged at the point in time when elapses. In this case, the above-described voltage generation unit 223 generates a voltage value corresponding to a current value (for example, 50 mA) larger than the charging current at the time of trickle charging as the reference voltage Vf1, and inputs the reference voltage Vf1 to the comparator 224. May be configured to output a logic "1" when the output of the amplifier 222 falls below the reference voltage Vf1 to indicate that the corresponding current has been detected.

The charge control section 232 corresponds to a charge control means, and sets a predetermined time T1 in the timer 231 in response to an input of a detection result indicating that the corresponding current has been detected, 231 is started, and when a notification that the time T1 has elapsed is received from the timer 231,
What is necessary is just to set it as the structure which instruct | indicates the stop of operation | movement of the constant voltage circuit 213 and the constant current circuit 214.

As shown in FIG. 2, the charging time is the current value i _th corresponding to the above-described threshold value Vf1.
It may be set a value corresponding to the time required for a change up to a minute current i _tr during trickle charged from. In this way, the charging control unit 232 and the timer 231 operate according to the detection result of the current detection circuit 220,
The time at which the battery is fully charged can be estimated based on the combination of the value of the charging current and the elapsed time, and the charging of the battery can be stopped. Therefore, it is possible to prevent the battery from being overcharged. In this case, as shown by the solid line in FIG. 2, the current value of the charging current becomes “0” when the time T1 has elapsed since the charging current became the current value i _th .

Here, in general, a current value of about 50 mA can be accurately detected, and, as shown in FIG. The detection circuit 220 can detect the relevant point in time with high accuracy and reliability. Therefore,
The time when the battery is fully charged can be estimated with high accuracy and can be reliably detected.

After the charging is stopped in this way, the charging control unit 232 sets another time T2 in the timer 231 and starts the timer 231 again, and the timer 231
In response to the notification indicating the elapse of the time T2 from 31, the charge control unit 232 instructs the constant voltage circuit 213 and the constant current circuit 214 to restart the operation.

Thus, the charge controller 232 and the timer 2
The function of the clock means is realized by the function of the battery 31 and the charging of the battery 101 can be restarted after a predetermined time has elapsed since the charging was stopped. As the time T2 described above, for example,
If the time required for the inter-terminal voltage to drop to about 95% of the fully charged state by the self-discharge of the battery 101 is set, the battery 101 can be kept almost fully charged.

As described above, by intermittently charging the battery 101, it is possible to keep the battery 101 almost fully charged and prevent overcharging. In this case, as if trickle charge was continued,
Although it is not always possible to keep the battery fully charged, it is sufficient for normal use if the battery is charged to about 95% of the battery capacity. On the other hand, according to this technique, overcharging can be reliably prevented, so that there is an effect that it is possible to make full use of the life of the battery. The cost burden can be reduced.

Further, by controlling the stop / restart of charging in accordance with the temperature of the battery, overcharging can be more reliably prevented in consideration of the operating environment of the battery. FIG.
FIG. 1 shows an embodiment of a charging device according to the present invention. FIG.
, The charging device includes a voltage detection circuit 240 and a temperature measurement unit 25 instead of the timer 231 of the charging device shown in FIG.
0 is added, and the reference voltages Vf1 and Vf2 used in the current detection circuit 220 and the voltage detection circuit 240 are changed according to the value measured by the temperature measurement unit 250. The charge control unit 232 controls the operations of the constant voltage circuit 213 and the constant current circuit 214 in accordance with the detection results of the current detection circuit 220 and the voltage detection circuit 240.

The voltage detection circuit 240 compares the voltage between the terminals of the battery 101 with the reference voltage Vf2 from the voltage generator 242 by the comparator 241 and determines that the voltage between the terminals is equal to the reference voltage Vf2.
Outputs a logic “1” when the charge control unit
32. This voltage detection circuit 2
At 40, one end of the above-described voltage generation unit 242 is grounded, and the other end outputs a reference voltage Vf2 to
41. Further, a voltage value corresponding to the measurement result by the temperature measurement unit 250 is applied to the ground point of the voltage generation unit 242, and the value of the reference voltage Vf2 is changed by changing the potential of this ground point. It has a configuration.

The voltage generator 2 of the current detection circuit 220
The output of the above-described temperature measuring unit 250 is also applied to the 23 ground points, and similarly, the value of the above-described reference voltage Vf1 is varied. Also, in FIG.
The temperature measuring section 250 amplifies the difference between the output of the thermistor 251 and a predetermined reference voltage Vf3 by the differential amplifier 252, and outputs the output of the differential amplifier 252 to the current detection circuit 220.
And the voltage is sent to the voltage detection circuit 240.

As the reference voltage Vf3, for example, a voltage value corresponding to the output voltage of the thermistor 251 at normal room temperature (about 20 degrees Celsius) may be set. In addition, when the voltage of 0 V is applied to the ground point, the voltage generation unit 242 of the voltage detection circuit 240 determines the reference voltage Vf2 as a reference voltage Vf2, for example, a voltage between terminals corresponding to 95% of full charge at normal room temperature. May be generated.

On the other hand, the voltage generator 2 of the current detection circuit 220
23, in a state where the potential of 0V is applied to the ground, as the reference voltage Vf1, for example, may generate a voltage value corresponding to the charging current i _tr during trickle charging at normal room temperature. In this case, the output voltage of differential amplifier 252 monotonically decreases as the temperature of battery 101 rises, and reference voltages Vf1 and Vf2 both increase accordingly. On the other hand, the output voltage of the differential amplifier 252 increases in accordance with the decrease in the temperature of the battery 101, and accordingly, the reference voltages Vf1, Vf
f2 decreases conversely.

As described above, the current detection circuit 220 and the voltage detection circuit 240 can maintain the full charge even when the charge current value during trickle charge and the inter-terminal voltage that can be determined to be full charge change due to the change in the temperature of the battery 101. It is possible to reliably detect the point in time when charging is performed and the point in time when recharging is required.

The charge control section 232 responds to the input of a detection result indicating that the charge current during trickle charge has been detected.
If the stop of the operations of the constant voltage circuit 213 and the constant current circuit 214 is instructed, and the restart of the operations of the constant voltage circuit 213 and the constant current circuit 214 is instructed in response to the input of the detection result indicating that the inter-terminal voltage has dropped. Good.

As described above, by changing the thresholds for the charge detection and the discharge detection by the current detection circuit 220 and the voltage detection circuit 240 in consideration of the temperature dependence of the operation characteristics of the battery 101, various environments can be achieved. Adaptively, it is possible to appropriately control the charging operation of the battery 101. This ensures that regardless of the battery usage environment,
Since the battery can always be kept close to full charge and overcharge can be reliably prevented, the life of the battery can be fully utilized.

When the battery is charged only by the constant current circuit 214, it is indispensable to control the stop and restart of the charging operation. Hereinafter, a case where the battery 101 is charged only by the constant current circuit 214 will be described.
FIG. 4 shows a configuration example of a charging device to which the present invention is applied.

In FIG. 4, the charging apparatus removes the constant voltage circuit 213 from the conventional charging circuit 210 shown in FIG. 7 and adds a timer 231, a charge control unit 232 and a voltage detection circuit 240 instead. The charge control unit 232 controls the operation of the constant current circuit 214 according to the detection result by the detection circuit 240 and the notification from the timer 231.

In this case, the voltage generator 242 of the voltage detection circuit 240 generates a voltage value Vm corresponding to the fully charged state of the battery 101 as the reference voltage Vf2,
For example, when the voltage between the terminals of the battery 101 reaches the reference voltage Vf2, a logic “1” may be output to notify the charge control unit 232.

In response to this notification, the charge control unit 232
Instructs the constant current circuit 214 corresponding to the charging means 104 to stop the charging operation, sets a predetermined time T2 in the timer 231 and starts the timer 231. In response to the notification from the timer 231, the constant current circuit 214 May be instructed to restart the charging operation.

Here, the time T2 set in the timer 231 is the same as that of the embodiment shown in FIG.
The time required for the voltage between terminals to decrease to a value at which charging should be started (for example, 95% of full charge) may be set. In this case, the constant current im flows into the battery 101 as shown by the dotted line in FIG. 5, and accordingly, as shown by the thick solid line in FIG. When it increases and reaches the above-described voltage value Vm, it is determined that the battery is fully charged, and charging is immediately stopped. Thereafter, when the time T2 has elapsed and the inter-terminal voltage has decreased due to the self-discharge of the battery 101, charging is started again.

As described above, the charging control section 232 restarts the charging operation by the constant current circuit 214 in response to the notification from the voltage detection circuit 240, so that the battery 101 can be charged without excess or shortage. By controlling the constant current circuit in this way, the battery can always be kept close to full charge and overcharge can be prevented, so that the life of the battery can be fully utilized and the user's life can be fully utilized. The cost burden can be reduced.

Further, by controlling the charging operation in consideration of the temperature of the battery, overcharging can be more reliably prevented. FIG. 6 shows another embodiment of the charging device according to the present invention. 6, the charging device includes a temperature measuring unit 250 added to the charging device shown in FIG. 4, changes the reference voltage Vf2 of the voltage detection circuit 240 according to the output of the temperature measuring unit 250, and changes the charging control unit 232. Changes the value of the time T2 set in the timer 231.

That is, similarly to the embodiment shown in FIG.
The output of the temperature detection unit 250 is applied to the ground point of the voltage generation unit 242 of the voltage detection circuit 240, and the output of the temperature detection unit 250 is notified to the charge control unit 232. Further, the charge control unit 232 controls the temperature of the battery 10 by the temperature measurement unit 250 as in the embodiment shown in FIG.
The time T2 may be shortened when it is notified that the temperature 1 is higher than the normal room temperature, and conversely, the time T2 may be extended when it is notified that the temperature is low.

Thus, the time when charging is stopped and the length of time during which charging is stopped can be adjusted according to the difference between the terminal voltage and the discharge current depending on the temperature.
In this way, by controlling the charging operation of the battery according to the temperature of the battery, overcharging can be reliably prevented and the battery can always be kept close to full charge. This allows the battery life to be fully utilized irrespective of the operating environment of the battery, so even when using the computer in a harsh environment, the number of times of battery replacement can be reduced and the user's life can be reduced. The cost burden can be reduced.

[0044]

As described above, according to the present invention, by intermittently charging the battery, it is possible to prevent the battery from being left in an overcharged state and to maintain the battery in a state close to full charge. As a result, it is possible to make full use of the life of the battery and reduce the burden on the user. Furthermore, the state of charge of the battery is evaluated by examining the voltage and temperature between the terminals of the battery, and the stop and restart of the charging operation are controlled in accordance with the evaluation result, thereby reliably preventing overcharge of the battery and fully charging the battery. Can be kept very close to

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a charging device to which the present invention is applied.

FIG. 2 is a diagram showing a change in a charging current.

FIG. 3 is a diagram showing an embodiment of a charging device according to the present invention.

FIG. 4 is a diagram showing a configuration example of a charging device to which the present invention is applied.

FIG. 5 is a diagram showing changes over time of a voltage between terminals of a battery and a charging current.

FIG. 6 is a diagram showing another embodiment of the charging device according to the present invention.

FIG. 7 is a configuration diagram of a power supply device of a computer to which a conventional charging circuit is applied.

[Explanation of symbols]

101 Battery 201 Filter 202 circuit breaker 203 AC / DC converter 204 DC / DC converter 206 power control unit 210 charging circuit 212 transistor 213 Constant voltage circuit 214 constant current circuit 215,216 diode 220 Current detection circuit 221 resistance 222 amplifier 223,242 Voltage generation unit 224,241 comparator 231 timer 232 charge control unit 240 Voltage detection circuit 250 Temperature measurement unit 251 Thermistor 252 differential amplifier

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hirohide Kageyama             4-1-1 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             No. 1 Inside Fujitsu Limited (72) Inventor Takashi Sato             4-1-1 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             No. 1 Inside Fujitsu Limited (72) Inventor Kihiko Yuhiko             4-1-1 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             No. 1 Inside Fujitsu Limited (72) Inventor Toshiaki Yamamoto             4-1-1 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             No. 1 Inside Fujitsu Limited (72) Inventor Hiroshi Yamaki             4-1-1 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             No. 1 Inside Fujitsu Limited F term (reference) 5G003 AA01 BA01 CA03 CA14 CB01                       CB06 CC02 DA05 DA07 DA18

Claims (4)

[Claims] 1. A charging device, comprising: charging means for charging a battery with a constant voltage and a constant current in accordance with a power input, and supplying a discharge current from the battery to a load when the power input is stopped. Charge control means for instructing stop and restart of the operation of the means, temperature measuring means for measuring the temperature of the battery, and a reference voltage value according to the measurement result by the temperature measuring means and a voltage between terminals of the battery. A voltage detecting means for detecting that the inter-terminal voltage has fallen below the reference voltage value; and starting a timing operation in accordance with a detection result by the voltage detecting means, and after a lapse of a predetermined time, the charging control means A charging device comprising: a timer for instructing restart. 2. A charging device, comprising: charging means for charging a battery with a constant current in response to a power input, wherein the charging device supplies a discharge current from the battery to a load when the power input stops. Charge control means for instructing stop and restart of the battery, comparing the terminal voltage of the battery and a predetermined reference voltage value, when the terminal voltage reaches the reference voltage value,
Charge detection means for instructing the charge control means to stop, assuming that the battery has been fully charged, and starting a timing operation in response to the output of the stop instruction by the charge control means; A charging device, comprising: a timer for instructing the charging controller to restart. 3. A charging means for charging a battery with a constant voltage and a constant current according to a power supply input, a temperature measuring means for measuring a temperature of the battery, and a reference voltage value according to a measurement result by the temperature measuring means. And a voltage detecting means for comparing the terminal voltage of the battery with the voltage of the battery, and detecting that the terminal voltage is lower than the reference voltage value. A charging control circuit that controls the charging device that supplies the discharge current from the load to a load, comprising: a charging control unit that instructs a stop and a restart of the operation of the charging unit, according to a detection result by the voltage detection unit. In response to the restart instruction of the timer means for instructing the resumption of the charging operation after the elapse of a predetermined time, the charging control means starts the timekeeping operation, and the charging control means Charging control circuit, characterized in that to resume the work. 4. A charging means for charging a battery with a constant current according to a power input, comparing a voltage between terminals of the battery with a predetermined reference voltage value, wherein the voltage between terminals reaches the reference voltage value. A charging detection means for instructing a stop of charging when detecting a full charge state of the battery, wherein a discharge current from the battery is supplied to a load when the power input is stopped. A charging control circuit that controls the charging device to be supplied; a charging control unit that instructs stop and restart of the operation of the charging unit; and starts a timing operation in response to an output of a stop instruction from the charging control unit. In addition, the charging control unit has a function of restarting the operation of the charging unit in response to the restart instruction of the timing unit for instructing the restart of the charging operation after the elapse of the stop time. Charge control circuit according to claim.