JP2001169474A - Secondary battery charging device and battery pack with charge-controlling function using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reasonable charging device that integrates a current controlling circuit for pulse-charging with a constant current as switching control systems including pulse width modulation PWM and pulse frequency modulation PFM, and to provide a battery pack with a charge-controlling function using the device. SOLUTION: A switching converter in a charging circuit operates in accordance with both pulses outputted from the PWM or PFM means and from a pulse-charging on/off controlling means. The PWM or PFM means controls the charging current value so that it becomes a given value. The pulse-charging on/off controlling means keeps the pulse charging turned on until the battery voltage reaches a charge-stopping voltage, turns off the pulse charging when it reaches the charge-stopping voltage, and turns on the pulse charging again when it drops to a charge-resuming voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device for a secondary battery and a battery pack having a charge control function using the same, and more particularly to a charging device in which pulse current control and battery voltage control in a pulse charging device are integrally controlled. .

[0002]

2. Description of the Related Art As a method of rapidly charging a secondary battery, there is generally known a method of charging a constant current up to a predetermined upper limit voltage and then charging the battery at a constant voltage while regulating the upper limit voltage. In this method, in principle, the time required for full charging can be reduced by increasing the charging current for constant current charging, but in practice, the charging current cannot be increased so much from the viewpoint of avoiding deterioration of battery performance. We cannot expect a significant reduction in time.

As a method for improving this, a pulse charging method in which charging and charging suspension are repeated is disclosed in Japanese Patent Laid-Open No. 7-105983.
No. 6,086,045. According to the publication, in this method, a charging suspension period is provided after charging, so that even if charging is performed with a relatively large charging current, deterioration of battery performance hardly occurs,
As a result, charging can be completed in a short time. The publication further discloses that such a pulse charging circuit can be simply configured by using a switch element for switching between charging and charging pause also as an overcharge protection switch originally built in the battery pack.

[0004]

In the above-mentioned prior art, the effect can be expected by the pulse charging system from the viewpoint of shortening the charging time. However, from the viewpoint of simplification of the charging circuit,
Although there is an effect by using the switch element for pulse charging also as the overcharge protection switch, a current control circuit for pulse charging with a constant current is separately required, and further improvement is required.

[0005] Therefore, an object of the present invention is to provide a current control circuit for pulse-charging with a constant current in addition to the above-mentioned conventional technology, in which a switching control method such as pulse width modulation (PWM) or pulse frequency modulation (PFM) is used. The present invention is to provide a more streamlined charging device by integrating and constructing a switch control for pulse charging, and to further provide a battery pack with a charge control function using the same.

[0006]

A charging apparatus according to the present invention comprises a secondary battery, a switching converter, a battery current detecting means, a battery voltage detecting means, a pulse width modulation or a pulse frequency modulation means, and a pulse charging ON. / Off control means and switch driving means. The switching converter is a converter of a type in which a voltage supplied from a DC power supply is converted to a voltage suitable for charging the secondary battery by a switch element. The pulse width modulation or pulse frequency modulation means outputs pulses subjected to pulse width modulation or pulse frequency modulation such that the battery current value detected by the battery current detection means becomes a predetermined value. The pulse charge on / off control means outputs a pulse level for turning on the pulse charge until the battery voltage value detected by the battery voltage detection means reaches a predetermined charge stop voltage. When the battery voltage reaches the stop voltage, the output is shifted to a pulse level for turning off the pulse charging, and when the battery voltage value falls to a predetermined charging restart voltage, a pulse level for turning on the pulse charging is output again. The switch driving unit is configured to switch the switching converter according to both a pulse output from the pulse width modulation or pulse frequency modulation unit and a pulse charging on / off pulse output from the pulse charging on / off control unit. Drive the element.

A battery pack with a charge control function according to the present invention has a secondary battery, a pulse charge control function, an overdischarge protection function, and an overcharge protection function. The pulse charge control function includes a switching converter that supplies a charging current;
Pulse width modulation or pulse frequency modulation means for controlling the charging current by pulse driving the switching converter; and turning off charging when the voltage of the secondary battery reaches the charging stop voltage, until the battery voltage reaches the charging restart voltage. Pulse charge on / off control means operable to turn on the charge when it has dropped. At least one of the switch element having the overdischarge protection function and the switch element having the overcharge protection function is also used as a switch element of the switching converter.

[0008] The repetition cycle of pulse charging on / off is
It is usually a long cycle of 1 second or more, and the pulse charge ON period is as long as about 0.1 second or more.
Pulse frequency is usually several tens kHz to several hundred kHz
, A large number of PWM or PFM pulses on the order of 10,000 are generated during one pulse charging ON period. Therefore, the charging current can be made to converge to a predetermined value within each pulse charging ON period.

This makes it possible to provide the switching converter for both charging current control and pulse charging on / off control, making it extremely rational without the need for a constant current power supply circuit or a low voltage power supply circuit. A charging device is realized. The DC power supply only needs to maintain a voltage higher than the target charging voltage of the battery, and a simple power supply that is not controlled at a constant voltage is sufficient.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments.

FIG. 1 is a view showing a first embodiment of a secondary battery charging apparatus according to the present invention. In the figure, 1 is a battery, 2 is a DC power supply, 3 is a switching converter, 4 is a battery current detecting means, 5 is a PWM or PFM means, 6 is a battery voltage detecting means, 7 is a pulse charge on / off control means,
8 is a switch driving means. Also, 31, 32, 33
Is a component of the switching converter 3, which is a switch element, a choke coil, and a flywheel diode, respectively. Further, reference numerals 41 and 42 denote components of the battery current detecting means 4, which are a current detecting resistor and an amplifying means, respectively. In addition,
The battery 1 may be a single cell or a plurality of cells stacked in series.

The switching converter 3 includes a DC power supply 2
Is a so-called switching regulator type converter for converting the voltage of the battery 1 into an appropriate voltage for charging the battery 1. The switch driving means 8 is driven by a pulse output from the PWM or PFM means 5 and the pulse charge on / off control means 7. Is controlled via

The battery current detecting means 4 comprises a current detecting resistor 41 inserted in series with the battery 1 and a current detecting voltage amplifying means 42 for amplifying a current detecting voltage generated at both ends thereof. The battery current value detected here is given to the PWM or PFM means 5, and the PWM or PFM means 5 performs feedback control of the switching converter 3 by PWM or PFM pulses so that the battery current value becomes a predetermined value.

The battery voltage value detected by the battery voltage detecting means 6 is supplied to a pulse charge on / off control means 7, which controls the pulse charge on / off control means 7 until the battery voltage value reaches a predetermined charge stop voltage. Outputs a pulse level for turning on pulse charging, and when the battery voltage value reaches a predetermined charging stop voltage, transitions the output to a pulse level for turning off pulse charging, until the battery voltage value drops to a predetermined charging restart voltage. Persist level.

The switch driving means 8 is a PWM or PFM
The switching element 31 of the switching converter 3 is driven according to both the PWM or PFM pulse output from the means 5 and the pulse charging on / off pulse output from the pulse charging on / off control means 7.

The repetition cycle of pulse charging on / off is
It is usually a long cycle of 1 second or more, and the pulse charge ON period is as long as about 0.1 second or more.
Pulse frequency is usually several tens kHz to several hundred kHz
, A large number of PWM or PFM pulses on the order of 10,000 are generated during one pulse charging ON period. Therefore, the charging current can be made to converge to a predetermined value within each pulse charging ON period.

This makes it possible to use the switching converter for both the purpose of charging current control and pulse charging on / off control, and it is possible to use a very rational power supply circuit or a constant voltage power supply circuit. A charging device is realized.

FIG. 2 shows an example of a switch driving pulse for driving the switching converter and a corresponding charging current waveform. A switch drive pulse is obtained by inverting the AND logic result of the charge current control PWM pulse and the pulse charge on / off pulse. As described above, there are actually many PWM or PFM pulse pulses on the order of 10,000 during one pulse charging ON period, but this is schematically illustrated by about ten pulses in the figure. It is expressed in a typical way. The charging current flows only during the pulse charging ON period. The current waveform becomes dull until the control of the converter by PWM converges, but the time required for convergence remains within a few percent of the ON period. When the dullness of the current waveform in the rising portion becomes a problem, it can be improved by storing the pulse width at the last time of the pulse charging ON period and using the initial value of the pulse width in the next pulse charging ON period. .

When the charging current waveform in the region where the current is stable is enlarged, a ripple having a triangular waveform is recognized for each PWM pulse. This ripple can be reduced by increasing the inductance of the choke coil 32 of the switching converter. However, for the purpose of charging the battery, a small amount of ripple does not usually hinder the charging. The control of the charging current may be performed with an average value including the ripple.

FIG. 3 shows the waveforms of the pulse charging current and voltage in a relatively long time range from the start of charging.
In the figure, 4.4 V on the voltage axis is the charge stop voltage,
0V is a charging restart voltage. The figure shows a case where the battery voltage before the start of charging is about 3.6 V.
The voltage increases starting from 6V. The charge current waveform is shown by omitting the waveform blunting at the rise of the current as shown in FIG. 2, and is shown by a rectangular waveform of the constant current (Ic). The charging current (Ic) flows during the pulse charging ON period, and the battery voltage increases. When the battery voltage reaches the charging stop voltage (4.4 V), the charging current is turned off. In the pulse charge off period,
The battery voltage gradually decreases as the chemical change of the battery progresses. When the battery voltage drops to the charging restart voltage, pulse charging is turned on again, and the battery voltage starts to rise. Thereafter, this repetition continues, but as the charging progresses, the pulse charging ON period gradually becomes shorter, while the OFF period becomes longer. When the pulse charging ON period is shorter than a predetermined value, or when the OFF period is longer than a predetermined value, the pulse charging is terminated, and a transition is made to a constant voltage charging mode not shown in FIG. It is assumed that charging is completed. Such charge mode switching control and charge completion control are performed by executing a program of a microcomputer (not shown).

FIG. 4 shows an example of the PWM means for controlling the charging current. 4A shows an example of implementation by an analog circuit, FIG. 4B shows an example of implementation by software processing, and FIG. 4C shows an example of software processing. In the figure, reference numeral 7 denotes a PWM means, and its components include a comparison amplifier 71, a comparator 72, a triangular wave generator 73, a loop phase compensation capacitor 74, and an A / A
The D converter 76 is a microcomputer.

In FIG. 4A, the comparison amplifier 71 includes:
The difference voltage between the voltage corresponding to the battery current detected by the current detection means 4 and the reference voltage (Vr) corresponding to the target current is converted into a current (Id) and output. The current (Id) is integrated by the loop phase compensation capacitor 74, and is provided as a pulse width control voltage to the negative input terminal of the comparator 72. The triangular wave generator 73 has a frequency of about 100 kHz as shown in the figure.
Is generated and applied to the positive input terminal of the comparator 72. The comparator 72 outputs a high level only during a period when the voltage of the triangular wave is higher than the pulse width control voltage. As can be seen from the figure, when the pulse width control voltage decreases, the high level width increases. As a result, when the charging current is equal to the target current, the pulse width control voltage keeps a constant value, so that the pulse width also keeps the same value, and the switching converter controlled by the same changes the current value to the same value. To maintain.
When the charging current becomes smaller than the target current, the comparison amplifier 71 supplies a current in a direction to decrease the pulse width control voltage, whereby the pulse width is widened, and the switching converter works to increase the current value. When the charging current becomes larger than the target current, the opposite operation is performed to reduce the charging current. By repeating this, the charging current converges to the target current.

In FIG. 4B, a voltage corresponding to the battery current detected by the current detecting means 4 is converted to an A / D converter 75.
The microcomputer 76 converts the digital value into a digital value and takes it into the microcomputer 76. The microcomputer 76 executes software processing as shown in FIG.

In the above two examples, the target current has been described as a fixed value, but this is not always an essential condition. For example, it is possible to consider a variable control that lowers the target current as the charging progresses, or to variably control a proper charging current while detecting the temperature of the battery.

FIG. 5 shows a second embodiment of the charging device according to the present invention.
An embodiment will be described. In the figure, 38 is a newly added switch element, 8 is a switch means, 81 is a drive 1 for driving the switch element 31, and 82 is a drive 2 for driving the newly added switch element 38. PWM / P
The output pulse of the FM means 5 drives the switch element 31 via the drive 1, and the output pulse of the pulse charging on / off control means 7 drives the newly added switch element 38 via the drive 2. . That is, PWM for charging current control
A / PFM pulse and a pulse for pulse charging on / off control are added to separate switch elements connected in series to control opening and closing. The function of the charge control obtained by this embodiment is equivalent to that of the first embodiment, but these two switch elements are also used as overdischarge protection switch elements and overcharge protection switch elements, respectively. The feature is that it can be done. The switch element 38
Can be regarded as one of the components of the switching converter 3. In this case, the switch element 31
And the switch element 38 may be interpreted as one switch having two control terminals.

FIG. 6 shows an embodiment of a battery pack according to the present invention. In FIG. 6, 100 is a battery pack, 2
Reference numeral 00 denotes a portable device or a charging DC power supply. 101,1
02 and 103 are external terminals of the battery pack 100, 101 is a power supply terminal, 102 is a ground terminal, and 103 is a communication terminal. In the battery pack, 9 is an overdischarge protection switch element, 10 is overdischarge or overcharge protection control means, 11 is a battery remaining amount calculation means, 12 is communication means, and 43 is a current integrated value generation means. Other symbols are the first
This is the same as the embodiment.

The feature of this embodiment is that the charging device of the first embodiment is incorporated in the battery pack, and is integrated with the overdischarge / overcharge protection function and the remaining battery level detection function originally provided in the battery pack. It is a point that has been constructed. As a result, the charge control function is built into the battery pack without increasing the number of components, and when charging, the battery can be charged simply by connecting a simple DC power supply without any special control function outside the battery pack. Is obtained.

The operation will be described below. The switch element 31 in the switching converter 34 also has a function as a switch element for overcharge protection,
When the overcharge protection control means 10 detects that the voltage obtained from the battery voltage detection means 6 exceeds the overcharge protection voltage and issues an overcharge protection command, the switch drive means turns off the switch based on the command. Can be The overdischarge protection switch element 9 is inserted in series between the battery 1 and the power supply terminal 101 of the battery pack, and the overdischarge / overcharge protection control means 10 controls the voltage obtained from the battery voltage When an over-discharge protection command is issued upon detecting that the voltage has dropped below the discharge protection voltage, the over-discharge protection command is turned off by the command.
At the time of charging, the overdischarge protection switch element 9 is on. The switch element 31 and the switch element 9 are
One is used as an overdischarge protection switch element and the other is used as an overcharge protection switch element, and a combination reverse to that described above is also possible.

The current integrated value generating means 43 generates a time integrated value of the current in order to accurately detect the remaining battery level. As an example thereof, a device that outputs a time integration value of a current as a pulse number as described later can be used. Since the current value can be obtained from the value of the number of pulses per unit time, the current value can be taken into the PWM / PFM means 5 to control the pulse width. The battery remaining amount calculating means 11
The battery remaining amount is calculated from the integrated current value during discharging and charging, and the result is reported to the portable device via the communication unit 12.

The PWM / PFM means 5 and the pulse charging ON / OFF
The operation of the off control means 7 is basically the same as that of the first embodiment. However, the PWM / PFM means 5 operates so as to switch from the current control mode to the voltage control mode when the charging is almost completed.

FIG. 7 shows an example in which the integrated current value generating means 43 and the remaining battery power calculating means 11 are integrated. In the figure, 431 is an input inverter, 432 is an integrator, 4321 is a voltage-current conversion amplifier, 4322 is an operational amplifier, 433 is an integration capacitor, 434 is an integration capacitor inversion means,
35 is an integration reset means, 436 and 437 are comparators, 438 is an OR gate, 439 is an up / down inversion means, 440 is a pulse counter, 441 is a counter value latch means, and 444 is a unit time average current calculation means.

The integrator 432 integrates a current proportional to the voltage between both ends of the current detection resistor 2 by Miller integration by the operational amplifier 4322 and the integration capacitor 433. When the integrated voltage reaches a predetermined voltage plus or minus from the reference voltage, the integration reset means 4
Activate 35 to clear the integrated charge. While the current is flowing through the current detection resistor, the current integration and the integration reset are repeated, and the number of times of the integration is counted by the pulse counter 440 to obtain the current integrated value. The counter value of the pulse counter 440 is latched by the counter value latch means 441 according to a read command issued from the microcomputer, and is taken into the microcomputer. The microcomputer calculates the integrated current value or the average current value per unit time from the counter value. Note that the input inverter 431, the integrating capacitor inverting means 434, and the up-down inverting means 439 operate synchronously and switch between the state a and the state b at equal intervals. This cancels out the influence of the offset of the integrator, and has the ability to accurately integrate current in a current range of approximately 10 milliamps to 10 amps.

The details of this embodiment (FIG. 7) are described in Japanese Patent Application No. 11-49645 filed earlier by the applicant of the present invention.

[0034]

According to the present invention, the switching converter can be used for both the purpose of charging current control and pulse charging ON / OFF control, and requires a constant current power supply circuit, a low voltage power supply circuit, and the like. A very reasonable charging device is realized, and the DC power supply only needs to be able to maintain a voltage higher than the charging target voltage of the battery, and a simple device without constant voltage control is sufficient. The effect of is obtained.

Further, in the battery pack in which the charging device according to the present invention is incorporated, since the battery pack is constructed integrally with the overdischarge / overcharge protection function and the battery remaining amount detection function originally provided, the number of components is increased significantly. The charging control function is built in the battery pack without charging, and at the time of charging, the charging can be performed simply by connecting a simple DC power supply having no special control function to the outside of the battery pack.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a charging device according to the present invention.

FIG. 2 is a diagram showing an example of a switch driving pulse for driving the switching converter in FIG. 1 and a charging current waveform corresponding thereto.

FIG. 3 is a diagram showing waveforms of current and voltage of pulse charging in FIG. 2;

FIG. 4 is a diagram showing an example of a charging current control PWM unit in FIG. 1;

FIG. 5 is a diagram showing a second embodiment of the charging device according to the present invention.

FIG. 6 is a diagram showing an embodiment of a battery pack according to the present invention.

FIG. 7 is a diagram illustrating an example of a current integrated value generation unit in FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Battery, 2 ... DC power supply, 3 ... Switching converter, 31 ... Switch element, 32 ... Choke coil, 33
... Flywheel diode, 38 ... Switch element, 4
... Battery current detection means, 41 ... Current detection resistance, 42 ... Amplification means, 5 ... PWM or PFM means, 6 ... Battery voltage detection means, 7 ... Pulse charge on / off control means, 71 ... Comparison amplifier, 72 ... Comparator , 73: triangular wave generator, 74: loop phase compensation capacitor, 75: A / D converter, 76: microcomputer, 8: switch driving means, 100: battery pack,
200: DC power supply for portable equipment or charging, 101: power terminal, 102: ground terminal, 103: communication terminal, 9: switch element for overdischarge protection, 10: overdischarge or overcharge protection control means, 11: remaining battery level Arithmetic means, 12 communication means, 4
3 ... Current integrated value generation means, 431 ... Input inverter, 432
... Integrator, 4321 ... Voltage-current conversion amplifier, 4322 ...
Operational amplifier, 433: integrating capacitor, 434: integrating capacitor inverting means, 435: integrating reset means, 43
6,437 comparator, 438 OR gate, 43
9 ... Up-down inversion means, 440 ... Pulse counter,
441: counter value latch means, 444: unit time average current calculation means.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02J 7/04 H02J 7/04 FF term (Reference) 5G003 AA01 BA01 CA02 CA14 CC02 DA13 EA05 GA01 GB03 GC05 5H030 AA03 AS06 BB06 DD01 FF42 FF43

Claims (6)

[Claims] An apparatus for charging a secondary battery, wherein a charging current control and a pulse charging on / off control are performed using a common switching converter. 2. A secondary battery, a switching converter,
A rechargeable battery charger comprising: battery current detection means; battery voltage detection means; pulse width modulation or pulse frequency modulation means; pulse charge on / off control means; Is a converter that converts a voltage supplied from a DC power supply into a voltage suitable for charging the secondary battery by a switch element. The pulse width modulation or pulse frequency modulation means includes a battery current detection unit. Means for outputting a pulse subjected to pulse width modulation or pulse frequency modulation so that the battery current value detected by the means becomes a predetermined value. The pulse charge on / off control means is detected by the battery voltage detection means. Until the battery voltage value reaches a predetermined charge stop voltage, outputs a pulse level that turns on pulse charging, and the battery voltage value reaches the charge stop voltage The output is shifted to a pulse level for turning off the pulse charging, and when the battery voltage value falls to a predetermined charging restart voltage, a pulse level for turning on the pulse charging is output again. Driving the switching element of the switching converter in accordance with both the pulse output from the modulation or pulse frequency modulation means and the pulse charging ON / OFF pulse output from the pulse charging ON / OFF control means. A charging device for a secondary battery. 3. A secondary battery, a switching converter,
A secondary battery comprising: a battery current detection unit; a battery voltage detection unit; a pulse width modulation or pulse frequency modulation unit; a pulse charge on / off control unit; a pulse charge on / off switch element; A charging device, wherein the switching converter is a converter that converts a voltage supplied from a DC power supply to a voltage suitable for charging the secondary battery by a switch element, and the pulse width modulation or the pulse. The frequency modulation means outputs a pulse width-modulated or a pulse frequency-modulated pulse so that the battery current value detected by the battery current detection means becomes a predetermined value. The pulse charging on / off control means Outputting a pulse level for turning on pulse charging until the battery voltage value detected by the battery voltage detecting means reaches a predetermined charging stop voltage, When the battery voltage value reaches the charge stop voltage, the output is shifted to a pulse level that turns off pulse charging, and when the battery voltage value falls to a predetermined charging restart voltage, a pulse level that turns on pulse charging again is output. The switch driving means drives a switch element of the switching converter according to a pulse output from the pulse width modulation or pulse frequency modulation means, and turns on / off a pulse charge output from the pulse charge on / off control means. A charging device for a secondary battery, wherein the pulse charging on / off switch element is driven according to an off pulse. 4. A battery pack with a charge control function having a secondary battery, a pulse charge control function, an overdischarge protection function, and an overcharge protection function, wherein the pulse charge control function reduces a charging current. A switching converter to be supplied, pulse width modulation or pulse frequency modulation means for controlling the charging current by pulse-driving the switching converter, and turning off the charging when the voltage of the secondary battery reaches a charging stop voltage. Pulse charging on / off control means operable to turn on charging when the voltage drops to the charging restart voltage, and at least one of the overdischarge protection function switch element and the overcharge protection function switch element. And a switching element of the switching converter. 5. A secondary battery, a switching converter,
Battery current detection means, battery voltage detection means, pulse width modulation or pulse frequency modulation means, pulse charge on / off control means, switch driving means, overdischarge / overcharge protection control means, and overdischarge protection switch A battery pack having a charge control function comprising an element and an overcharge protection switch element, wherein the switching converter switches a voltage supplied from a DC power supply to a voltage suitable for charging the secondary battery. Wherein the pulse width modulation or the pulse frequency modulation means performs pulse width modulation or pulse frequency modulation so that the battery current value detected by the battery current detection means becomes a predetermined value. The pulse charge on / off control means adjusts the battery voltage value detected by the battery voltage detection means to a predetermined charge stop voltage. Until the battery voltage value reaches the charge stop voltage, the output level shifts to a pulse level that turns off the pulse charge until the battery voltage value reaches the charge stop voltage, and the battery voltage value reaches a predetermined charge restart voltage. The switch driving means outputs a pulse level for turning on pulse charging again when the pulse charging is lowered. The switch driving means outputs a pulse output from the pulse width modulation or pulse frequency modulation means and an output from the pulse charging on / off control means. The switching element of the switching converter is driven in accordance with both ON / OFF pulses of the pulse charging. The overdischarge / overcharge protection control means, when the battery voltage value falls below the overdischarge protection voltage. An over-discharge protection command is issued to turn off the over-discharge protection switch element, and when the battery voltage value exceeds the over-charge protection voltage, A charge protection command is issued to turn off the overcharge protection switch element, and at least one of the overdischarge protection switch element and the overcharge protection switch element is also used as a switch element of the switching converter. Battery pack with charge control function. 6. The battery pack with a charge control function according to claim 5, further comprising: a current integrated value generating means for detecting a remaining amount of the secondary battery, wherein the battery current detecting means includes the current integrated value. A battery pack with a charge control function, wherein a value corresponding to the battery current is detected from the current integrated value obtained by the value generating means.