JP5519853B1 - Electronic equipment and electronic equipment system - Google Patents

Abstract

An electronic device and an electronic device system that obtain resistance values in a charging terminal and a battery pack, obtain an appropriate current value suitable for the resistance values, and achieve both rapid charging and safety.
An electronic device system includes an electronic device and a charger. The electronic device includes a battery pack and a terminal main body. The battery pack 20 includes a housing 21, a battery cell 22, a charging terminal 27, and a data terminal 28. The terminal body 30 includes a current / voltage control unit 31, a current measurement unit 33, a voltage difference calculation unit 34, a resistance value calculation unit 35, a current value calculation unit 36, a charging terminal 37, and a data terminal 38. It has. Based on the terminal-cell voltage difference ΔV between the charging terminal 37 and the battery cell 22 and the current value I _INP , the resistance value R is calculated by the resistance value calculator 35 and supplied to the battery pack 20 based on the resistance value R. The appropriate current value I is calculated by the current value calculation unit 36.
[Selection] Figure 1

Description

  The present invention relates to an electronic device and an electronic device system with improved charging safety.

  Various types of shapes are used for electronic devices, including portable chargers, and charging to a battery pack (secondary battery) provided in the electronic device is performed by connecting the charger and the electronic device. Proposals have been made in consideration of safety during charging (see, for example, Patent Documents 1 to 4).

  In Patent Document 1, a constant current stabilizing circuit, a constant voltage stabilizing circuit, a control unit, and the like are provided in a charger, and a thermal cutoff temperature based on the temperature of the secondary battery is provided for rapid charging of the secondary battery to generate heat of the battery. The risk due to is reduced.

  Patent Document 2 relates to a mobile terminal device, an authentication circuit, a built-in power supply that supplies power to the authentication circuit, and an authentication circuit that cuts off power supply from the external power supply to the terminal body while authenticating the external power supply. Power management means for supplying power to the power source. And the portable terminal main body can be protected by not using the external power source for authentication, and the power consumption of the built-in battery used for authentication can be reduced by supplying power only during the authentication period.

  In Patent Document 3, the power supply device includes a receiving unit that receives internal temperature data of the charging / discharging device, a temperature measuring unit that measures its own internal temperature, and power supplied to the charging / discharging device based on the temperature data. Power supply mode switching means for switching the power supply mode. And by measuring the temperature, the battery pack can be charged in an appropriate charging mode corresponding to the temperature condition, so charging due to overcurrent that occurs when charging the battery pack in a state that is not within the temperature appropriate range It is possible to suppress a decrease in capacity.

  Patent Document 4 discloses a secondary battery charging method in which a battery cell of a secondary battery pack is charged by a charger. The method includes a step of detecting a voltage of a battery cell of the secondary battery pack, and a step of controlling charging of the battery cell by a charger according to the voltage of the battery cell detected by the step.

JP-A-8-308139 JP 2007-195021 A JP 2007-325500 A Japanese Patent Laid-Open No. 11-187586

  As shown in Patent Documents 1 to 4, various proposals have been made for safety during charging. By the way, since the battery pack is usually detachable from the terminal main body of the electronic device, deterioration of the contact may occur at the contact between the charging terminal of the battery pack and the charging terminal of the terminal main body due to aging. is there. As a result, there is a risk that the resistance at the contact increases, heat is easily generated, and charging becomes unstable. However, Patent Documents 1 to 4 do not disclose a technique corresponding to the above-described problem.

  The present invention has been made in view of the above-mentioned reasons, and its purpose is to obtain a resistance value in the charging terminal and the battery pack, obtain an appropriate current value suitable for the resistance value, and achieve both rapid charging and safety. It is an object to provide an electronic device and an electronic device system that achieve the above.

An electronic apparatus according to the present invention is an external detachable battery pack including at least a protection circuit, a first charging terminal, and a battery cell, wherein the battery cell passes through at least a part of the protection circuit. A current measuring unit for measuring a value of a charging current supplied to a battery pack connected to one charging terminal; a data terminal capable of receiving a charging voltage applied to the battery cell itself from the battery pack; second charging terminal, the second value to the terminal by comparing the value of the charging voltage of the terminal voltage applied to the charging terminal connected to one charging terminal - voltage for calculating a voltage difference between the cells Based on the difference calculation unit, the terminal-cell voltage difference and the value of the charging current , at least a resistance value generated from the protection circuit and a voltage drop between the second charging terminal and the battery cell. Calculate the resistance value to be generated And anti-value calculating unit, and a current value calculator for calculating an appropriate current value to be supplied to the battery pack based on the resistance value, and a control unit for controlling the value of the charging current so that the appropriate current value, the I have.
Moreover, the electronic device of the present invention is an electronic device comprising a terminal body and a battery pack,
1) The battery pack includes a housing detachable with respect to the terminal body portion, exposed from the housing, first charging power transmitted from the external charger via the terminal body section is supplied A terminal, a protection circuit housed in the housing and connected to the first charging terminal, and a housing housed in the housing and connected to the first charging terminal via at least a part of the protection circuit. A battery cell, a battery cell voltage detection unit for detecting a charging voltage applied to the battery cell itself, and a data terminal capable of transmitting the value of the charging voltage to the terminal body unit,
2) The terminal main body includes a second charging terminal connected to the first charging terminal, a current measuring unit that measures a value of a charging current supplied to the battery pack, and the second charging terminal. compared value of the terminal voltage applied between the value of the charging voltage to the terminal - the voltage difference calculation unit for calculating a voltage difference between the cells, the terminal - on the basis of the value of the charging current and the voltage difference between the cells A resistance value calculation unit for calculating a resistance value generated at least from the protection circuit and causing a voltage drop between the second charging terminal and the battery cell; and the battery pack based on the resistance value A current value calculation unit that calculates an appropriate current value to be supplied to the battery, and a control unit that controls the value of the charging current to be the appropriate current value .

  As one aspect of the electronic device of the present invention, for example, the resistance value corresponds to at least a resistance value generated from the charging terminal and the protection circuit.

  As one aspect of the electronic apparatus of the present invention, for example, the terminal main body further includes a current voltage control unit that controls the current value to be the appropriate current value.

  As one aspect of the electronic apparatus of the present invention, for example, the current / voltage control unit performs constant current control for controlling the current value to be substantially constant and constant voltage control for controlling the terminal voltage to be substantially constant, thereby performing the constant voltage control. In the current control, the current value is controlled to be the appropriate current value.

  As one aspect of the electronic apparatus of the present invention, for example, the terminal main body further includes an allowable power consumption storage unit that stores allowable power consumption allowed in the battery pack corresponding to the resistance value, and the resistance value is When R and the allowable power consumption are W, the current value calculation unit calculates the appropriate current value I based on the following equation.

  As one aspect of the electronic apparatus of the present invention, for example, the battery cell voltage detector is an A / D converter that outputs the detected value of the charging voltage in the form of a digital signal, and the data terminal is the charging voltage. Can be transmitted to the terminal body in the form of a digital signal, and the voltage difference calculation unit is applied to the charging terminal and is in the form of a digital signal and a terminal voltage value. The charging voltage value is compared, and the terminal-cell voltage difference is calculated.

  The electronic device system of the present invention includes an electronic device and a charger.

  According to the electronic device and the electronic device system of the present invention, the battery cell voltage detector constantly monitors the value of the charging voltage applied to the battery cell itself, and determines the resistance value based on the value of the current supplied to the charging terminal. The appropriate current value is calculated. By performing current control with this appropriate current value, heat generation that may occur at the charging terminal or the like can be suppressed, and it is possible to achieve both charging safety of the electronic device and continuation of rapid charging.

1 is a block diagram showing an example of a first embodiment of an electronic device and an electronic device system according to the present invention. The block diagram which shows an example of 2nd Embodiment of the electronic device and electronic device system which concern on this invention. The graph which shows an example of the charge condition of the electronic device and electronic device system which concern on this invention.

  Hereinafter, preferred embodiments of an electronic device and an electronic device system according to the present invention will be described in detail with reference to FIGS.

  FIG. 1 is a block diagram showing an example of a first embodiment of an electronic device and an electronic device system according to the present invention.

  The electronic device system includes an electronic device 10 and a charger 50, and the electronic device 10 includes a battery pack 20 and a terminal main body 30. The battery pack 20 is detachable from the terminal main body 30, but may be configured integrally with the terminal main body 30. The charger 50 is electrically connected to the electronic device 10 via a cable such as a USB.

  The battery pack 20 is a secondary battery, and includes a housing 21, a battery cell 22 housed in the housing 21, a protection circuit 23, a battery cell voltage detection unit 24, a protection circuit information output unit 25, An authentication circuit 26, a charging terminal 27, and a data terminal 28 are provided.

  The battery cell 22 is, for example, a lithium ion battery, a nickel metal hydride battery, or the like. The battery cell 22 is charged by power supplied from the charger 50, and operates various configurations provided in the terminal main body 30 by the charged power. The protection circuit 23 is mounted between the battery cell 22 and the charging terminal 27 and is electrically connected to the battery cell 22 and the charging terminal 27 so that an excessive voltage or current is not applied to the battery cell 22 during charging. Protected by monitoring. The battery cell voltage detection unit 24 is directly connected to the battery cell 22 and serves as voltage detection for directly detecting (monitoring) a charging voltage applied to the battery cell 22 itself.

  The protection circuit information output unit 25 receives the protection circuit information generated by the protection circuit 23 and outputs it to the terminal body 30 in the form of a digital signal. The protection circuit information generated by the protection circuit 23 includes the temperature information of the battery cell 22, and the protection circuit information output unit 25 indicates status information indicating a normal state or an abnormal state of the battery cell 22 based on the temperature information. Is transmitted to the terminal body 30 in the form of a digital signal. Inclusion of temperature information in addition to protection information for abnormal current and voltage that may be supplied to the battery cell 22 may lead to improved protection of the battery pack 20. Although the protection circuit 23 and the protection circuit information output unit 25 have been described as independent configurations, the protection circuit information output unit 25 may be mounted in the protection circuit 23.

  When the battery pack 20 and the terminal body 30 are electrically connected, the authentication circuit 26 generates an authentication signal indicating the regular battery pack 20 with respect to the terminal body 30, and the terminal body in the form of a digital signal To the unit 30. The terminal main body 30 determines whether or not the battery pack 20 connected to the terminal main body 30 is a legitimate connection device based on the transmitted authentication signal. Charging is not performed unless current is supplied and the battery pack 20 is normal. By performing the determination based on the authentication signal, it is possible to guarantee the safety in use for the user and to electrically protect the entire electronic device system.

A plurality of charging terminals 27 are provided in the battery pack 20, are exposed from the casing 21 and are electrically connected to a charging terminal 37 of the terminal main body 30 described later, and the terminal main body 30 is connected from an external charger 50. The electric power sent via is supplied. The data terminal 28 that is electrically connected to the battery cell voltage detection unit 24 is exposed from the housing 21 and is electrically connected to a data terminal 38 of the terminal body 30 that will be described later. Then, the data terminal 28 transmits the charge voltage value V _CELL detected by the battery cell voltage detection unit 24 to the terminal body 30 in the form of a digital signal, for example. The data terminal 28 also transmits protection circuit information, status information, an authentication signal, and the like, which will be described later, to the terminal main body 30.

  The electronic device 10 is, for example, a mobile phone such as a smartphone, a tablet, a mobile terminal with a camera, a digital camera, an information terminal such as a measuring instrument or a detector, or the like. The terminal main body 30 of the electronic device 10 includes a current / voltage control unit 31, a current measurement unit 33, a voltage difference calculation unit 34, a resistance value calculation unit 35, a current value calculation unit 36, and a plurality of charging terminals 37. A data terminal 38 and an allowable power consumption storage unit 39 are provided. Furthermore, in addition to the above-described configuration, various types of circuits and the like for controlling the terminal main body 30 are mounted in the terminal main body 30, and an internal load 40 generated by operating during charging of the battery pack 20 is provided. Exists.

The current / voltage control unit 31 controls the charging current supplied to the battery pack 20 based on the value V _CELL of the charging voltage received from the battery cell voltage detection unit 24, so that the charging terminal 37 of the terminal main body unit 30 and the battery pack 20 A charging current is supplied to the battery pack 20 via the charging terminal 27. The current measuring unit 33 measures a current value I _INP (analog value) corresponding to the power supplied to the charging terminal 37 of the terminal main body unit 30 and outputs it in the form of a digital signal. In the case of this form, the current measuring unit 33 also functions as an A / D converter.

The voltage difference calculation unit 34 includes a terminal voltage value V _BATT applied to the charging terminal 37 of the terminal body 30 and a terminal-cell voltage difference ΔV (= V _BATT −V _CELL between the charging terminal 37 and the battery cell 22. ) Is calculated. The resistance value calculator 35 calculates a resistance value R that causes a voltage drop between the charging terminal 37 and the battery cell 22 based on the terminal-cell voltage difference ΔV and the current value I _INP . The current value calculation unit 36 calculates an appropriate current value I to be supplied to the battery pack 20 based on the resistance value R. The allowable power consumption storage unit 39 stores the allowable power consumption W allowed in the battery pack 20 corresponding to the resistance value R.

  The charger 50 is electrically connected to the terminal main body 30, applies a charging voltage to the battery pack 20 via the terminal main body 30, and supplies a charging current. The charger 50 also includes a rectifier 51 that is an AC / DC converter, a power output unit 52 that outputs power to the terminal body 30 based on the power converted by the rectifier 51, and an output or stop of the power output unit 52 And an output control unit 53 for controlling the control and the like.

<Relationship and operation of each component>
The battery cell voltage detection unit 24 uses the data terminal 28 of the battery pack 20 and the data terminal 38 of the terminal main body unit 30 as the voltage of the charging voltage V _CELL of the battery cell 22 detected by the battery cell voltage detection unit 24. It transmits to the difference calculation part 34. The transmission may be in the form of a digital signal or an analog signal. In this embodiment, the data terminal 28 is in the form of a digital signal, and is combined with the protection circuit information generated by the protection circuit 23, the status information generated by the protection circuit information output unit 25, and the authentication signal generated by the authentication circuit 26 in a time-sharing manner. To the terminal main body 30. For output in the form of a digital signal, the battery cell voltage detector 24 is also an A / D converter.

The voltage difference calculation unit 34 compares the received charging voltage value V _CELL with the terminal voltage value V _BATT applied to the charging terminal 37, and calculates the terminal-cell voltage difference ΔV (= V _BATT −V _CELL ). The calculation is performed and the terminal-cell voltage difference ΔV is transmitted to the resistance value calculation unit 35. Note that the voltage difference calculation unit 34 also functions as an A / D converter, and obtains a terminal voltage value V _BATT applied to the charging terminal 37 as an analog value and then converts it into a digital value. The value V _CELL can be compared. The resistance value calculation unit 35 is based on the received terminal-cell voltage difference ΔV (digital value) and the current value I _INP (digital value) received from the current measurement unit 33, and is connected between the charging terminal 37 and the battery cell 22. A resistance value R (= ΔV / I _INP ) that causes a voltage drop is calculated.

In particular, the resistance value R can be calculated because the charging current value I _INP is constant in the “constant current charging” section described later. The resistance value R described above is a circuit resistance generated from the terminal resistance value R _TER generated by at least the charging terminal 27 of the battery pack 20 and the charging terminal 37 of the terminal body 30 being electrically connected to the protection circuit 23. The sum of the values R _CER . The terminal resistance value R _TER is a resistance loss between the charging terminals 27 and 37. For example, the circuit resistance value R _TER becomes large due to deterioration of the charging terminals 27 and 37 due to the number of insertions and removals of both. On the other hand, the circuit resistance value R _TER changes because the loss increases due to, for example, heat generation of the protection circuit 23.

The above-described changing resistance value R changes to heat loss when a large charging current (for example, 4.0 A) flows (W _LOSS = I ² R). By setting a permissible range for the heat generation amount W _LOSS and calculating the appropriate current value I by the current value calculation unit 36 and controlling it by the current voltage control unit 31, heat generation between the charging terminals and the protection circuit 23 is suppressed. Is possible. That is, the current value calculation unit 36 calculates the appropriate value based on the following equation (1) using the resistance value R transmitted from the resistance value calculation unit 35 and the allowable power consumption W stored in the allowable power consumption storage unit 39. The current value I is calculated. The resistance value R is a digital value, and the appropriate current value I is also obtained as a digital value. The allowable power consumption W is an arbitrary value determined by the type of the electronic device 10.

The appropriate current value I in the above equation (1) means that the allowable power consumption W is a predetermined value, so that the resistance value R increases as the resistance value R increases. The current / voltage control unit 31 performs constant current control for controlling the charging current value I _INP to be substantially constant and constant voltage control for controlling the terminal voltage value V _BATT to be substantially constant. In the constant current control in the “constant current charging” section, control is performed so that the current value I _INP becomes the appropriate current value I transmitted from the current value calculation unit 36.

The terminal body 30 and the battery pack 20 are detachable, and the charging terminals 27 and 37 are rusted due to, for example, moisture in the long term, and the terminal resistance value R _TER of the charging terminals 27 and 37 increases. On the other hand, there is a possibility that the circuit resistance value R _CER increases in the protection circuit 23 due to heat generation due to long-time use of the electronic device 10 or an increase in the terminal resistance value R _TER . If a constant charging current continues to flow when the amount of heat generation is large, the amount of heat generation will increase further, for example, a dangerous state such as ignition will occur, and depending on the electronic device 10, rapid charging is stopped by the protection circuit 23 or the like. Sometimes. By setting the allowable power consumption W, rapid charging with the appropriate current value I is continued even if heat is generated, so that it is possible to achieve both safety of the electronic device 10 and continued rapid charging.

The current voltage control unit 31 controls the charging current supplied to the battery pack 20 based on the charging voltage value V _CELL of the battery cell 22 sent from the battery cell voltage detection unit 24. If the value V _{CELL of the} charging voltage is, for example, 3.4 V or less, “complementary charging” control with a small current (for example, 0.1 A) is performed. Further, if the value V _{CELL of the} charging voltage is between 3.4 V and 4.25 V, for example, “constant current charging” control is performed at a constant current (for example, 4.0 A). Then, if the charging voltage value V _CELL is, for example, 4.25 V or more, “constant voltage charging” control is performed to decrease the charging current (for example, 1 A → 50 mA). Moreover, it is good also as a structure which outputs the capacity | capacitance of the battery cell 22 to a display means etc. like a liquid crystal monitor, and notifies a user as needed.

  Further, the current / voltage control unit 31 receives the protection circuit information generated by the protection circuit 23, the status information generated by the protection circuit information output unit 25, and the authentication signal generated by the authentication circuit 26, and simultaneously controls the output of the charger 50. The data is also transmitted to the unit 53. The current / voltage control unit 31 controls the start, continuation, stop, and the like of supply of the charging current from the terminal main body unit 30 to the battery pack 20 according to the received content.

  In the embodiment, it has been described that the current / voltage control unit 31 is in the terminal main body unit 30, but it may be provided on the charger 50 side. Furthermore, although it has been described that the allowable power consumption W is stored in the allowable power consumption storage unit 39, it may be stored in the current value calculation unit 36. And when heat_generation | fever more than the allowable power consumption W generate | occur | produces, it is also possible to stop charge.

  FIG. 2 is a block diagram illustrating an example of a second embodiment of a battery pack, an electronic device, and an electronic device system according to the present invention. The difference from the first embodiment is that the protection circuit 23 is shown in more detail.

  In the protection circuit 23 of the battery pack 20, a control unit 23a that performs control in the protection circuit, a SW 23b that continues or stops charging of the battery cell 22 in response to a signal from the control unit 23a, and an abnormal temperature in the battery pack A thermal fuse 23c that detects and breaks is mounted. In the first embodiment, the negative charge terminal 27 is directly connected to the battery cell 22, but in the second embodiment, the positive charge terminal 27 is directly connected to the battery cell 22.

  That is, the battery cell 22 is electrically connected to at least one of the charging terminals 27 exposed from the housing 21 through at least a part of the protection circuit 23. Further, since the battery cell 22 is not arranged so as to be directly connected to both the positive side charging terminal 27 and the negative side charging terminal 27, there is no danger of a short circuit or the like.

  FIG. 3 is a graph illustrating an example of a state of charge of the battery pack, the electronic device, and the electronic device system according to the present invention. The vertical axis represents voltage and current values, and the horizontal axis represents time.

The current / voltage control unit 31 performs “constant current charging” control at a constant current (for example, 4.0 A) if the value V _CELL of the charging voltage of the battery cell 22 is between 3.4 V and 4.25 V, for example. (Refer to “Constant current charging section” in the figure). In “constant current charging”, the current value I _INP corresponding to the power supplied to the charging terminal 37 is constant, and the terminal voltage value V _BATT applied to the charging terminal 37 and the battery cell 22 itself are applied. The terminal-cell voltage difference ΔV from the charging voltage value V _CELL can be calculated. Since the voltage difference ΔV can be expressed by ΔV = R × I _INP , the resistance value R that is the sum of the terminal resistance value R _TER and the circuit resistance value R _CER can be calculated (R = ΔV / I _INP ). An example in which the appropriate current value I is calculated by the equation (1) using the calculated resistance value R and controlled by the current / voltage control unit 31 is indicated by a thick line in the drawing. The change of the appropriate current value I may be continuous or stepwise. In the above embodiment, the process in which the resistance value R and the appropriate current value I are obtained as digital values has been described. However, the conversion mode from an analog value to a digital value is not limited to that in the above embodiment.

As described above, the battery cell voltage detection unit 24 is electrically connected directly to the battery cell 22 and always directly detects the value V _{CELL of the} charging voltage applied to the battery cell 22 itself. The terminal-cell voltage difference ΔV based on the charging voltage value V _CELL and the terminal voltage value V _BATT applied to the charging terminal 37, and the current value I _INP corresponding to the power supplied to the charging terminal 37, Thus, the resistance value R is calculated by the resistance value calculation unit 35. Then, the current value calculation unit 36 calculates an appropriate current value I to be supplied to the battery pack 20 based on the formula (1), and the current / voltage control unit 31 performs appropriate “constant current charging” for the battery pack 20. Control is performed. As a result, rapid charging is continued while constantly monitoring the heat generation between the charging terminals 27 and 37, and it is possible to achieve both safety of the electronic device 10 and continued rapid charging.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. In addition, the material, shape, dimension, numerical value, form, number, arrangement location, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved.

  The battery pack, the electronic device, and the electronic device system according to the present invention include a charging terminal for rapidly charging a battery pack such as a mobile phone such as a smartphone, a mobile terminal such as a tablet, a digital camera, a portable personal computer, and a measuring instrument. It can be applied to applications that can prevent heat generation due to deterioration of the material.

DESCRIPTION OF SYMBOLS 10: Electronic device 20: Battery pack 21: Case 22: Battery cell 23: Protection circuit 24: Battery cell voltage detection part 25: Protection circuit information output part 26: Authentication circuit 27: Charging terminal 28: Data terminal 30: Terminal main body Unit 31: Voltage / current control unit 33: Current measurement unit 34: Voltage difference calculation unit 35: Resistance value calculation unit 36: Current value calculation unit 37: Charging terminal 38: Data terminal 39: Allowable power consumption storage unit 50: Charger I _INP : current value V _BATT : terminal voltage value V _CELL : charge voltage value

Claims (6)

Electronic equipment,
An external removable battery pack comprising at least a protection circuit, a first charging terminal and a battery cell, wherein the battery cell is connected to the first charging terminal via at least a part of the protection circuit. A current measuring unit for measuring the value of the charging current supplied to the battery pack;
A data terminal capable of receiving a charging voltage applied to the battery cell itself from the battery pack;
A second charging terminal connected to the first charging terminal;
A voltage difference calculation unit for calculating a voltage difference between the cells, - the terminal compares the value of the value and the charging voltage of the terminal voltage applied to the second charging terminals
Based on the voltage difference between the terminal and the cell and the value of the charging current , at least a resistance value generated from the protection circuit and a resistance value causing a voltage drop between the second charging terminal and the battery cell. A resistance value calculation unit to be calculated;
A current value calculation unit for calculating an appropriate current value to be supplied to the battery pack based on the resistance value;
A control unit for controlling the value of the charging current to be the appropriate current value;
With electronic equipment. The electronic device according to claim 1,
An allowable power consumption storage unit that stores the allowable power consumption allowed in the battery pack corresponding to the resistance value ;
When the resistance value is R and the allowable power consumption is W, the current value calculation unit calculates the appropriate current value I based on the following equation.

An electronic device comprising a terminal body and a battery pack,
1) The battery pack
A housing removable from the terminal body,
A first charging terminal exposed from the housing and supplied with power sent from an external charger via the terminal main body; and
A protection circuit housed in the housing and connected to the first charging terminal;
A battery cell housed in the housing and connected to the first charging terminal via at least a part of the protection circuit;
A battery cell voltage detector for detecting a charging voltage applied to the battery cell itself;
A data terminal capable of transmitting the value of the charging voltage to the terminal main body,
2) The terminal body is
A second charging terminal connected to the first charging terminal;
A current measuring unit for measuring a value of a charging current supplied to the battery pack ;
A voltage difference calculation unit for calculating a voltage difference between the cells, - the terminal compares the value of the value and the charging voltage of the terminal voltage applied to the second charging terminals
Based on the voltage difference between the terminal and the cell and the value of the charging current , at least a resistance value generated from the protection circuit and a resistance value causing a voltage drop between the second charging terminal and the battery cell. A resistance value calculation unit to be calculated;
A current value calculation unit for calculating an appropriate current value to be supplied to the battery pack based on the resistance value;
A control unit for controlling the value of the charging current to be the appropriate current value;
With electronic equipment. The electronic device according to claim 3,
The terminal main body further includes an allowable power consumption storage unit that stores allowable power consumption allowed in the battery pack corresponding to the resistance value,
When the resistance value is R and the allowable power consumption is W, the current value calculation unit calculates the appropriate current value I based on the following equation.

The electronic device according to claim 3 or claim 4,
The battery cell voltage detection unit is an A / D converter that outputs the value of the detected charging voltage in the form of a digital signal,
The data terminal can transmit the value of the charging voltage to the terminal body in the form of a digital signal,
The voltage difference calculation unit compares the value of the second applied Ru terminal voltage to the charging terminal, the value of the charging voltage in the form of digital signals, the terminal - for calculating a voltage difference between the cells, Electronics.   The electronic device system containing the electronic device of any one of Claim 1 to 5, and a charger.

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