Abstract: Disclosed are an apparatus and method for estimating an available time of a battery relatively accurately in consideration of a driving pattern of a user. The apparatus for estimating an available time of a battery includes a current measuring unit for measuring an output current of the battery, a SOC estimating unit for estimating SOC (State Of Charge) of the battery, and a controller for estimating an available time of the battery by using a measured current value obtained by the current measuring unit, an estimated SOC value obtained by the SOC estimating unit and an entire capacity of the battery.

Abstract: Embodiments of the present invention include circuits and methods for sensing resistance. In one embodiment the present invention includes a method comprising detecting a voltage at an input of a regulator received from a power adapter, determining a maximum current capability of the power adapter, and charging a battery coupled to an output of the regulator using said detected voltage and said maximum current as inputs to said regulator. In one embodiment, the detected voltage is used to configure a voltage used to determine if or when a voltage received from a power adapter drops below some threshold.

Abstract: A portable device charger is disclosed, which is able to charge portable devices whether it is connected to an external power supply or not. The charger connects to household AC power as well as USB DC power, and further has a photovoltaic cell. It manages the input power from these three sources to charge a portable device and/or recharge the charger's battery, by supplementing the input power with battery power if the device demands more power than the input source, and charging the battery with remaining power if the device demands less power than is provided by the input source. The charger turns off the AC/DC converter and draws no power from the AC source if the battery is full and there is no attached device.

Abstract: A system for protecting a power consuming circuit, the system comprising two terminals for receiving power and two terminals for providing received power. Between one of the receiving terminals and a providing terminal, a transistor is provided which is controlled by a Zener diode and to break the connection between one of the receiving terminals and a providing terminal, if a voltage over the providing terminals or the receiving terminals exceeds the breakdown voltage of the Zener diode.

Abstract: Circuitry and techniques to measure, at the battery's terminals, characteristic(s) of the charging signal applied to the battery/cell during the recharging operation and, in response to feedback data which indicates the charging signal is out-of-specification, control or instruct the charging circuitry to adjust characteristic(s) of the recharging signal (e.g., the amplitude of the voltage of and/or current applied to or removed from the battery during the charging operation). For example, a rechargeable battery pack comprising a battery, and controllable switch(es), a current meter and voltmeter, all of which are fixed to the battery. Control circuitry generates control signal(s) to adjust a current and/or voltage of the charging signal using the feedback data from the current meter and/or voltmeter, respectively.

Abstract: Various embodiments of a battery detector are provided. In one aspect, a battery detector of a portable electronic device is applied to a battery module without an identification (ID) terminal. When the portable electronic device receives a direct current (DC) voltage provided by an external transformer to conduct a startup procedure, the battery detector detects whether the battery module is connected to the portable electronic device or not, and prevents the portable electronic device from conducting erroneous operations.

Abstract: A control circuit for use in a battery charger circuit that includes a switching voltage regulator, with the control circuit having a constant current charging mode and a constant voltage charging mode. A switcher controller is provided which configured to control a state of a top side switching transistor and a low side transistor of the switching voltage regulator in response to at least one error signal. A power path transistor switch is disposed intermediate an output of the switching voltage regulator and a first node for receiving a first terminal of a battery to be charged.

Abstract: A charge control circuit supplies power from an external power source to a first common node and charges a second common node. A regulator circuit is coupled between the external power source and the first common node, and a transistor is coupled between the first common node and the second common node. A current sensing and control device senses the current from the first common node to the second common node and generates a first control signal. A first voltage sensing and control device senses a voltage at the first common node, and generates a conduction control signal to control the transistor. A second voltage sensing and control device senses a voltage at the second common node, and generates a second control signal. The regulator circuit provides system power to the first common node according to the first control signal and the second control signal.

Abstract: The method for charging or discharging a battery comprises measurement of the voltage at the terminals of the battery and comparison of the measured voltage with an end of charging or discharging voltage threshold. The method also comprises measurement of a temperature representative of the temperature of the battery and measurement of the current flowing in the battery to form a pair of measurements. The voltage threshold is then determined according to the pair of measurements. Charging or discharging of the battery is stopped when the voltage threshold is reached.

Abstract: In one embodiment the present invention includes a system and method of charging a battery using a switching regulator. In one embodiment, a switching regulator receives an input voltage and input current. The output of the switching regulator is coupled to a battery to be charged. The switching regulator provides a current into the battery that is larger than the current into the switching regulator. As the voltage on the battery increases, the current provided by the switching regulator is reduced. The present invention may be implemented using either analog or digital techniques for reducing the current into the battery as the battery voltage increases.

Abstract: A charging controlling system includes an input terminal, an output terminal, a battery terminal, and a switch terminal. The charging controlling system includes a coil connected to the switch terminal at a first end thereof. The charging controlling system includes a resistor connected to a second end of the coil at a first end thereof and to the battery terminal at a second end thereof. The charging controlling system includes a capacitor connected between the second end of the coil and the ground. The charging controlling system includes a diode connected to the switch terminal at a cathode thereof and to the ground at an anode thereof. The charging controlling system includes a charging controlling circuit that controls charging of the battery.

Abstract: Stated is a charging-current regulating device for charging an energy storage device for a field device, and for regulating a charging current for the energy storage device, wherein regulating the charging current for the energy storage device takes place in such a manner that a limiting value relating to an input current of the field device is not exceeded. Regulating the charging current may take place in such a manner that energy storage takes place as quickly as possible and without overloading an input protection circuit of the field device.

Abstract: An inductively-heated applicator system including a heating module and applicator or applicator pen. The heating module includes a dock for seating the applicator. The heating module includes circuitry to selectively generate an electromagnetic field to wirelessly provide energy to the applicator when it is positioned in the dock. The heating module may also include temperature control circuitry to at least one of monitor and control the temperature of the applicator. The applicator pen includes a heating element that may be heated through energy provided by the electromagnetic field. The heating element may be directly inductively heated by the electromagnetic field. The heating element may be a roller element that heats and applies the product. Alternatively, the applicator may include a secondary in which electrical power is induced when the electromagnetic field is present. In this alternative, the power may be applied to the heating element to produce resistive heat.

Abstract: A control circuit is provided which includes a pre-charge circuit connected in parallel with a solid state switching device of, for example, a power distribution network. The pre-charge circuit pre-charges a load capacitance at a load side of the switching device prior to activation of the switching device. The pre-charge circuit includes a threshold waveform generation circuit and an over-current detect circuit. The threshold waveform generation circuit synthesizes a maximum acceptable charging waveform for the pre-charge circuit in charging the load capacitance, and the over-current detect circuit signals an over-current fault condition upon a charging current through the pre-charge circuit exceeding the synthesized, maximum acceptable charging waveform. The pre-charge circuit includes a sense resistor coupled to a power input side of the solid state switching device, with charging current through the pre-charge circuit being monitored via the sense resistor.

Abstract: A charging circuit includes a transistor, a current regulating resistor, a field effect transistor (FET) and a main controller. The transistor includes an emitter, a base and a collector, the FET includes a source, a gate and a drain. The emitter is connected to the battery charger; the drain is connected to the battery. The main controller includes a current control unit, a charge control unit and a voltage detection unit. The current control unit transmits current signals to the base of the transistor to turn on the transistor and regulate the current values of the collector, the voltage detection unit detects the voltage of the battery and controls the charge control unit according to detection result, and the charge control unit sends a command signal to the gate to switch the FET on or off.

Abstract: A battery management method and apparatus. In one embodiment of the method, a source current is divided into Ic and Icr. Ic is transmitted to and charges a battery. A first voltage is generated that is related to Icr. The first voltage is converted into a first digital signal. A processing unit receives and processes the first digital signal in accordance with instructions stored in a memory. The transmission of Ic to the battery is interrupted in response to the processing unit processing the first digital signal. Current provided by the battery is divided into Idc and Idcr. Idc is transmitted to a device. A second voltage is generated that is related to Idcr. The second voltage is converted into a second digital signal. The processing unit receives and processes the second digital signal in accordance with instructions stored in the memory. The transmission of Idc to the battery is interrupted in response to the processing unit processing the second digital signal.

Abstract: A charger calibrating device and a calibrating method thereof. The device comprises a control module and a processing module. The control module controls a charger to be calibrated to perform a first stage charging and a second stage charging on an electronic device. The processing module performs an adjusting process according to the second stage charging time for adjusting the high level period of the PWM signal in the charging circuit of the charger. In the adjusting process, generating an updated high level period by adding or decreasing a preset adjusting amplitude, and decrease the preset adjusting amplitude by half to generate an updated adjusting amplitude. The processing module terminates the calibrating process after repeating the aforementioned calibrating loop a preset number of times.

Abstract: A charger circuit comprising: a charging path coupled between an input voltage and a battery; a power switch on the charging path; a switch control circuit controlling the power switch; a timer counting a charging period; and a low current control circuit issuing a signal to the switch control circuit to control the power switch such that a charging current is maintained to be a predetermined low current when the timer counts to a predetermined maximum charging period.

Abstract: A battery voltage monitoring circuit includes a first power supply terminal to be connected to the positive terminal of a battery pack having rechargeable cells connected in series; a first supply voltage sensing terminal to be connected to the positive terminal of the battery pack; a first resistor connected between the first power supply terminal and the first supply voltage sensing terminal; a second supply voltage sensing terminal to be connected to the negative terminal of a first rechargeable cell of the rechargeable cells, the first rechargeable cell being on the positive terminal side of the battery pack and connected to the positive terminal of the battery pack; a second resistor connected between the second supply voltage sensing terminal and the first power supply terminal; and a first comparator configured to compare a voltage at the first power supply terminal and a voltage at the first supply voltage sensing terminal.

Abstract: A method of determining a charger of a mobile terminal, and which includes receiving, via a controller of the mobile terminal, a connection signal indicating the charger is connected to the mobile terminal; setting, via the controller, a charging current of the charger for charging the mobile terminal and increasing the set charging current in predetermined current units; measuring, via the controller, an actual current received from the charger and applied to the mobile terminal; comparing, via the controller, the set charging current with the measured actual current; determining, via the controller, a charging sector of the charger when the set charging current is larger than the measured actual current for a first predetermined amount of time; and calculating a charging current capacity of the charger using the determined charging sector.

Abstract: A battery system includes multiple battery cells having multiple cell voltages, and a balancing module.

Abstract: A method and apparatus for controlling a composite battery charger including a switching regulator and a linear charger charging a battery connected to it, whereby the switching regulator provides the supply voltage for the linear charger and Device Circuits. The control method and circuit fully turns on the pass device of the linear charger in a constant current operating mode and the switching regulator is controlled to maintain a constant charge current through the pass device while also supplying device current to the Device Circuits. The device current may vary. The method and circuit limits the dissipation of the pass device of the linear charger by reducing the supply voltage as a function of the charge current in the CC/CV transition region of the battery charger and by reducing the charge current as a function of the battery voltage if the battery voltage is below a predetermined value related to a predetermined minimum supply voltage value.

Abstract: A charging device to charge a secondary battery that includes a DC/DC circuit to generate a charging current supplied to the secondary battery, an impedance measurement circuit to measure an impedance of the secondary battery, a first control circuit to output a duty-cycle decrease signal in accordance with the measured impedance, a charging-current monitor circuit to detect the charging current outputted from the DC/DC circuit when the duty cycle of the pulses generated by the DC/DC circuit is decreased by the duty-cycle decrease signal, and, a second control circuit to compare the charging current detected by the charging-current monitor circuit and a charging-current threshold and to output to the DC/DC circuit a frequency change signal that increases a switching operation frequency in the DC/DC circuit.

Abstract: A current compensation module, a charging apparatus, and a charging apparatus controlling method are disclosed. The current compensation module is used for controlling an outputted charging current in order to charge a battery module. The current compensation module includes a transition unit, a proportional controlling unit, and an integral controlling unit. The transition unit allows an internal signal of the current compensation module increasing from a first voltage. When the internal signal attains to a second voltage, the proportional controlling unit will output a proportional controlling signal to adjust the charging current. When the charging current attains to a rated output current, the integral controlling unit incorporates with the proportional controlling unit to output a proportional-integral controlling signal in order to control and adjust the charging current for the battery module, and to suppress the output overshoot current of the charging apparatus.

Abstract: A charging circuit that prevents a system abnormality caused by removal of a battery. The charging circuit includes a constant voltage charge controller which detects charge voltage and performs a constant voltage charging operation. A constant current charge controller detects charge current and performs a constant current charging operation. A controller controls the constant voltage charge controller to perform the constant voltage charging operation during a period from when the charge voltage reaches a fully charged voltage to when the charge current decreases to a charge completion current. The controller suspends charging the battery when the constant voltage charging operation is being performed and detects whether or not the battery is coupled to the charging circuit based on the charge voltage during the charging suspension.

Abstract: A solid state circuit breaker includes a first terminal; a second terminal; a first wide-band gap field effect transistor coupled to the first terminal; a second wide-band gap field effect transistor coupled to the second terminal, wherein the first wide-band gap field effect transistor and the second wide-band gap field effect transistor are common-source connected to one another; and a bi-directional snubber device coupled to the first wide-band gap field effect transistor and the second wide-band gap field effect transistor. Such a solid state circuit breaker may also include a gate drive circuit coupled to the first wide-band gap field effect transistor and the second wide-band gap field effect transistor, where the gate drive circuit may comprise a voltage regulation stage and a drive stage.

Abstract: A battery charging system is disclosed. The battery charging system includes a battery charger, a switching circuit and a control circuit. The battery charger receives electric power from a DC power supply and charges a rechargeable battery based on a setting current. The switching circuit is capable of switching between a first charging mode and a second charging mode. In the first charging mode, the battery charger charges the rechargeable battery while the DC power supply is supplying electric power to the battery charger in a state where the DC power supply is able to supply electric power to a load. In the second charging mode, the DC power supply charges the rechargeable battery in a state where the DC power supply is able to supply electric power to the load.

Abstract: A computer system includes multiple ports to which at least one external device is connected and which are connectable to multiple power supplying lines branched from a power supplying line for supplying electric power to the at least one external device; a switching unit which controls connections between the power supplying lines and the ports; and a controller which controls the switching unit so that two or more power supplying lines among the power supplying lines are connected to a first port, to which one of the at least one external device is connected, among the ports.

Abstract: A method of charging a battery pack, the battery pack including at least one battery cell. The method includes comparing a battery cell voltage to a first voltage; comparing the battery cell voltage to a second voltage that is greater than the first voltage; and controlling a current amplifying unit coupled to the at least one battery cell to amplify a current from a charger to the at least one battery cell if the battery cell voltage is between the first voltage and the second voltage.

Abstract: A plurality of current control MOS transistors and a plurality of current detection systems are provided, each of the current detection systems including a current detection transistor current-mirror connected to the current control MOS transistor and a current-voltage converter connected in series to the current detection transistor. The current detection systems are switched between one another for operation in response to the intensity of a charging current flowing through the current control transistors.

Abstract: An overcharge protection device (OPD) is provided that may be used alone, or in combination with conventional charging protection systems, to protect a battery pack from the occurrence of a potentially damaging overcharging event. The OPD is designed to be coupled to, and interposed between, the terminals of the battery pack. During normal system operation, the OPD has no effect on the operation of the charging system or the battery pack. During an overcharging event, if overcharging is not prevented by another conventional system, the OPD of the invention creates a short across the terminals of the battery pack causing a battery pack fuse designed to provide battery pack short circuit protection to blow, thereby interrupting the current path from the charger to the battery pack and preventing the battery pack from being overcharged.

Abstract: A device for charging number of cells connected together in a row and create a battery voltage, the charging is done in such a way that every single cell in a battery (or several small cells together) is charged separately by the computer control and moves automatically to the next cell until all cells comprising the battery are full.

Abstract: An apparatus and method for charging a battery. The disclosed apparatus includes a battery to be charged, a power delivery path configured for delivering power to the battery, and an integrated switching battery charger configured for charging a battery by delivering output power to the battery via the power delivery path based on input power from an input power source. In the disclosed apparatus for charging a battery, the integrated switching battery charger includes an output voltage regulation loop and an input voltage regulation loop, both of which are configured to control the output current flowing out of the integrated switching battery charger to the battery. The input or output voltage regulation loops are further enhanced by adding a current source which is proportional to absolute temperature from the regulated voltage to the control voltage for the purpose of either regulating peak power from the source or to maximize energy storage in the battery as a function of temperature.

Abstract: A method for controlling charging and discharging of a battery pack for an electric or hybrid vehicle to prevent overheating damage. Current flowing into or out of the battery pack is monitored, and root mean square (RMS) current is integrated over a time window and compared to a threshold to determine if power needs to be regulated in order to prevent damage to the cells in the battery pack. If the time-integrated RMS current exceeds the threshold, a closed-loop proportional-integral (PI) controller is activated to regulate power input or output. The controller will continue to regulate power until the time-integrated RMS current drops below the threshold. Various thresholds can be defined for different time windows. The gains used in the PI controller can also be adjusted to scale the amount of power regulation.

Abstract: Some embodiments of the present invention provide a system that charges a lithium-ion battery. During operation, the system monitors: a current through the battery, a voltage of the battery, and a temperature of the battery. Next, the system uses the monitored current, voltage and temperature to control a charging process for the battery. In some embodiments, controlling the charging process involves: inferring electrode lithium surface concentrations for the battery from the monitored current, voltage and temperature; and applying the charging current and/or the charging voltage in a manner that maintains the inferred electrode lithium surface concentrations for the battery within set limits.

Abstract: A charging circuit that prevents a system abnormality caused by removal of a battery. The charging circuit includes a constant voltage charge controller which detects charge voltage and performs a constant voltage charging operation. A constant current charge controller detects charge current and performs a constant current charging operation. A controller controls the constant voltage charge controller to perform the constant voltage charging operation during a period from when the charge voltage reaches a fully charged voltage to when the charge current decreases to a charge completion current. The controller suspends charging the battery when the constant voltage charging operation is being performed and detects whether or not the battery is coupled to the charging circuit based on the charge voltage during the charging suspension.

Abstract: The present invention provides an apparatus for easily detecting an abnormal status of power generation of a solar cell panel in a solar cell power generation system having the power generation of 1 MW or higher. The present invention provides an abnormality detecting apparatus for a solar cell power generation system including a plurality of solar cell strings each having a plurality of solar cell modules connected to each other in series and a backflow preventing diode connected to a power output terminal of each of the solar cell strings, characterized in that the abnormality detecting apparatus further includes measuring means for measuring a current flowing in the backflow preventing diode; and that the measuring means is supplied with electric power from both terminals of the backflow preventing diode.

Abstract: Provided is a secondary battery system including: a battery controller which controls charge and discharge of a secondary battery; a total controller which controls the entire system; an ammeter which detects a charge current and a discharge current of the secondary battery; and a voltmeter which detects a voltage of the secondary battery, in which a direct current resistance of the secondary battery at the time of charge and a direct current resistance of the secondary battery at the time of discharge are obtained on the basis of a current value and a voltage value detected by the ammeter and the voltmeter, to thereby determine a temporary increase in the direct current resistance of the secondary battery caused by charge and discharge with a large current on the basis of a relation between the two obtained direct current resistances.

Abstract: A portable apparatus includes a system configured to receive a system current and perform a function, a charging battery configured to be charged with a charging battery current and supply power to the system, and a power management circuit configured to receive an externally supplied power, supply the system current to the system, and supply the charging battery current to the charging battery based on a sensed level of the system current, wherein the charging battery current decreases in proportion to the system current.

Abstract: A switch embedded integrated circuit for battery protection includes a first pin to be connected with one terminal of a battery, a second pin to be connected with a load or charger, a third pin to be connected with another terminal of the battery, a MOSFET having a body diode thereof and connected between the first and second pins, a control logic circuit and a detection circuit. The detection circuit monitors the voltage between the first pin and the third pin to determine a detection signal for the control logic circuit to turn on or off the MOSFET and switch the direction of the body diode, thereby providing an over charging and an over discharging protection functions.

Abstract: The disclosed embodiments provide a system that manages use of a battery in a portable electronic device. The system includes a monitoring mechanism that monitors one or more battery-usage parameters of the battery during use of the battery with the portable electronic device. The battery-usage parameters may include a battery age, a resting time, a swell rate, a temperature, a cell balance, a voltage, a current, usage data about how the battery has been cycled, and/or user input. The system also includes a management apparatus that adjusts a charge-termination voltage or a discharge-termination voltage of the battery based on the battery-usage parameters to manage a cycle life of the battery, the swell rate, and/or a runtime of the battery.

Abstract: According to one embodiment, the economical load dispatcher calculates a discharging threshold value and a charging threshold value based on a discharging unit price of and a charging and discharging efficiency of the secondary battery and further calculates output allocations of the generators and secondary battery such that the secondary battery is discharged when incremental fuel costs of the generators are higher than the discharging threshold value, whereas the secondary battery is charged when incremental fuel costs of the generators are lower than the charging threshold value.

Abstract: An exemplary charging system and method for controlling a fast charging process involving an external power source (e.g., a high-voltage charging station providing 10 kW-300 kW of power) and a plug-in electric vehicle. In one embodiment, the charging method uses a costing function to estimate the negative impact each fast charging session has on battery life. If the overall negative impact of past and/or present charging sessions has exceeded some threshold, then the charging method may reduce charging parameters (e.g., limit the charging amperage, voltage, power, duration, etc.) in an effort to avoid further diminishing the battery life. Thus, the charging system and method enable a user to frequently engage in fast charging sessions with an external power source, yet minimize the impact that such sessions have on the battery.

Abstract: A battery charger voltage control method dynamically adjusts the system voltage generated by a battery charger circuit based on the operating conditions to ensure that sufficient power is supplied to power up the circuitry of the electronic device when the battery charger circuit is connected to a current-limited power source and the battery of the electronic device is deeply depleted or is missing. In embodiments of the present invention, the battery charger voltage control method sets the system voltage to an elevated voltage value to maximize the energy transfer from the power source to the circuitry of the electronic device. In this manner, the battery charger voltage control method enables a near instant boot-up of the electronic device, even under the operating conditions where the battery of the electronic device is deeply depleted or missing and the switching battery charger circuit can only receive power from a current-limited power source.

Abstract: An overcurrent protection circuit of a rechargeable battery includes a current detection terminal and an overcurrent return resistor connecting part. A voltage converted from a discharge current of the rechargeable battery is detected at the current detection terminal. The overcurrent return resistor connecting part connects the current detection terminal to overcurrent detection resistors having different resistances in accordance with a level of the voltage detected at the current detection terminal when the voltage detected at the current detection terminal is equal to or greater than a discharge overcurrent detection voltage and a discharge overcurrent state in which an overcurrent flows from the rechargeable battery is detected.

Abstract: A power management control circuit controls a first power transistor to convert a input voltage to an output voltage and controls a second power transistor to charge a battery from the output voltage. The first power transistor is coupled between the input voltage and the output voltage, and the second power transistor is coupled between the output voltage and the battery. The power management control circuit includes: a detection transistor detecting a current through the second power transistor and generating a charging reference voltage; an amplifier comparing the output voltage with the voltage of the battery to generate an amplified signal for controlling the charging reference voltage; a comparator comparing a reference voltage with the charging reference voltage to generate an EOC (End of Charge) signal for determining whether to stop charging the battery; and an offset voltage compensation device compensating an input offset voltage of the amplifier.

Abstract: An ECU executes a program including a step of determining that a pilot wire for transferring a pilot signal CPLT, which is output when a charging cable is connected to a plug-in hybrid vehicle and an external power source, to the ECU is broken, when output of the pilot signal CPLT is currently stopped and a voltage VAC of the external power source (absolute value of voltage VAC) detected by a voltmeter provided within the plug-in hybrid vehicle is greater than zero.

Abstract: A storage battery system includes a battery module including nonaqueous electrolyte secondary batteries. The storage battery system further includes a temperature sensor which measures a temperature of the battery module, a voltmeter which measures a voltage of each of the nonaqueous electrolyte secondary batteries and a charge control unit which controls a maximum end-of-charge voltage V1 (V) of the nonaqueous electrolyte secondary batteries to fall within the range defined in formula (1) given below when the temperature of the battery module is not lower than 45° C. and is not higher than 90° C.: 0.85×V0?V1?0.

Abstract: In one embodiment the present invention includes a system and method of charging a battery using a switching regulator. In one embodiment, a switching regulator receives an input voltage and input current. The output of the switching regulator is coupled to a battery to be charged. The switching regulator provides a current into the battery that is larger than the current into the switching regulator. As the voltage on the battery increases, the current provided by the switching regulator is reduced. The present invention may be implemented using either analog or digital techniques for reducing the current into the battery as the battery voltage increases.

Abstract: A charge circuit is composed of a first circuit and a second circuit. Said second circuit is provided at a battery pack in which a secondary battery is comprised. Said first circuit is provided at a charger for charging said secondary battery. Said charge circuit comprises: an output power supply section; a control section configured to control said output power supply section to perform a charging operation; a memory provided at said second circuit and storing a number of charging; and a threshold current setting section. Said control section is configured to, in said charging operation, perform firstly a constant current charging operation, and then perform a constant voltage charging operation, and finish the charging operation when a charging current reaches a charge stop current value. Said threshold current setting section is configured to decrease said charge stop current value along with the increase of said number of charging.