JP5424033B2 - Charger - Google Patents

Description

  The present invention relates to a charging device for charging a battery pack made of a secondary battery.

  As a power source for driving a cordless electric tool, a battery pack including a secondary battery having a relatively high capacity such as a nickel metal hydride battery or a nickel cadmium battery (hereinafter referred to as a nickel cadmium battery) is used. In addition, lithium ion batteries are being put into practical use as secondary batteries with high capacity and light weight. Lithium ion batteries are characterized by a nominal voltage that is relatively higher than that of nickel metal hydride batteries and nickel-cadmium batteries, and that they are small and lightweight. Further, the lithium ion battery has characteristics that it has a good discharge efficiency, can be discharged even in a relatively low temperature environment, and can obtain a stable voltage in a wide temperature range. However, when a lithium ion battery is in an overdischarged state, there is a possibility that the copper foil of the negative electrode may be dissolved or a short circuit may occur between the electrodes. Therefore, it is essential to prevent unnecessary discharge. On the other hand, nickel hydride batteries and nickel cadmium batteries, when left in an overdischarged state for a long time, have a large number of cells, especially when multiple battery cells are connected in series to form a battery set. In some cases, the voltage variation in the battery becomes large, which may affect the life of the battery pack.

  The battery pack has a configuration that prevents unnecessary discharge or charging in order to ensure the battery life. For example, if a switch is provided in the discharge path between the battery set and the output terminal and power is supplied from the charging device, the switch is turned on, and if power is not supplied from the charging device, the switch is turned off. It is configured to be in a state. Thus, there has been proposed a charging device having a configuration in which the battery is not discharged even if the battery is left in the charging device for a long period of time (Patent Document 1).

JP 2008-187791 A

When charging a battery pack made of a secondary battery, it is necessary to manage the charging voltage and the charging current. Therefore, the charging device, in order to detect the batteries voltage has a voltage detecting means for detecting a battery voltage dividing resistors. In order to suppress unnecessary discharge of the battery set, this voltage detection means has a switch between the battery set and the switch is turned on as necessary to detect the battery voltage. .

  However, when such a switch is composed of an FET, if the FET itself malfunctions or a disconnection occurs between the battery set, the voltage detection means will not be able to detect the battery voltage, which will hinder the charge control of the battery pack. Will come.

  In view of the above problems, an object of the present invention is to provide a charging device that prevents overcharging of a battery pack even when an abnormality occurs in voltage detection means.

The charging device of the present invention includes a charging unit that charges a secondary battery, a voltage detection unit that detects a battery voltage of the secondary battery, a temperature detection unit that detects a battery temperature of the secondary battery, and the voltage detection. Full charge determination means for determining full charge of the secondary battery based on at least one of the battery voltage detected by the means and the battery temperature detected by the temperature detection means, and the full charge determination means is the secondary battery A charging device comprising: control means for stopping charging of the secondary battery by the charging means when the full charge is determined; and an abnormality determining means for determining whether or not the voltage detecting means is abnormal. The full charge determination means is a case where the voltage detection means is normal, and the temperature change value per unit time of the battery temperature detected by the temperature detection means is set to a first predetermined value. The secondary battery is determined to be fully charged, and the voltage detection means is abnormal, and the temperature change value is set to a second predetermined value smaller than the first predetermined value. When it reaches, the secondary battery is determined to be fully charged.

  With the above configuration, the secondary battery is charged by the charging means. During charging, the battery voltage of the secondary battery is detected by the voltage detection means, and the battery temperature of the secondary battery is detected by the temperature detection means. The abnormality determination unit determines whether or not the voltage detection unit is abnormal. When abnormality has occurred in the voltage detection means, the second predetermined value in which the temperature change value per unit time of the battery temperature detected by the temperature detection means is smaller than the first predetermined value when the voltage detection means is normal. When reaching the value, the secondary battery is determined to be fully charged and charging is terminated. Therefore, even when an abnormality occurs in the voltage detection means, the secondary battery can be charged without affecting the characteristics of the secondary battery.

  The charging device according to claim 4, wherein the secondary battery is charged based on the battery voltage detected by the charging means for charging the secondary battery, the voltage detection means for detecting the battery voltage of the secondary battery, and the voltage detection means. A charging apparatus comprising: a charging control unit that controls charging of a battery; and an abnormality determination unit that determines whether or not the voltage detection unit is abnormal. The charging control unit is configured such that the voltage detection unit is abnormal. In this case, the charging time is shorter than when the voltage detecting means is normal.

  With the above configuration, the secondary battery is charged by the charging means. During charging, the battery voltage of the secondary battery is detected by voltage detection means. The abnormality determination unit determines whether or not the voltage detection unit is abnormal. When the voltage detection means is abnormal, the charging time of the secondary battery is shortened more than when the voltage detection means is normal, thereby reliably preventing overcharge of the secondary battery.

  According to the charging device of the first aspect, when the voltage detection means is abnormal, the secondary battery is charged in a shorter time than when the voltage detection means is normal. To ensure the battery life of the battery pack.

  According to the charging device of the second aspect, it is possible to reliably determine whether the voltage detection means is normal or abnormal.

  According to the third aspect of the present invention, when the voltage detection means is abnormal, the temperature change value per unit time of the battery temperature detected by the temperature detection means is compared with that when the voltage detection means is normal. Since the secondary battery is fully charged using a small value, the secondary battery is reliably prevented from being overcharged and the battery life of the battery pack is ensured.

  According to the charging device of the fourth aspect, when the voltage detecting means is abnormal, the charging time of the secondary battery is shortened compared with the case where the voltage detecting means is normal. Securely prevent and ensure the battery life of the battery pack.

It is a circuit diagram which shows the charging device which shows one embodiment of this invention. It is a flowchart explaining operation | movement of the charging device of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a charging device 100 that charges the battery pack 2.

  The battery pack 2 includes a battery set 2A in which a plurality of secondary batteries such as a nickel cadmium battery and a nickel hydride battery are connected in series, a temperature sensitive element 2a such as a thermistor for detecting the battery temperature of the battery set 2A, and two A discrimination resistor 2b for discriminating the type of the secondary battery is provided. The charging device 100 includes an AC power source 1, a primary side smoothing circuit 10, a switching circuit 20, a secondary side smoothing circuit 30, a charging current control unit 60, a charging voltage control unit 70, a power supply unit 6, and a power supply control unit 7. Have Further, the charging device 100 includes a battery temperature detection unit 3, a battery type determination unit 4, a battery voltage detection unit 5, a signal transmission unit 8, a switching control IC stop unit 9, a constant voltage circuit 40, a microcomputer 50, an LED 80, and a discharge path. A blocking means 90 is provided.

  The primary-side rectifying / smoothing circuit 10 is a circuit that rectifies an alternating current supplied from the alternating-current power supply 1 and includes a full-wave rectifying circuit 11 and a smoothing capacitor 12.

  The switching circuit 20 includes a high-frequency transformer 21, a MOSFET 22, a switching control IC 23, a starting resistor 24, a switching control IC constant voltage circuit 25, and a switching control IC stop circuit 26.

  The high-frequency transformer 21 includes a primary winding 21a, a secondary winding 21b, a tertiary winding 21c, and a quaternary winding 21d. A DC input voltage is applied to the primary winding 21a, the secondary winding 21b is an output winding for the switching control IC 23, a tertiary winding 21c is an output winding for charging the battery pack 2, The quaternary winding 21d is an output winding for a control system power source such as the microcomputer 50. The secondary winding 21b and the quaternary winding 21d have the same polarity with respect to the primary winding 21a, and the tertiary winding 21c has a reverse polarity.

  The switching control IC 23 is a switching power supply IC that changes the drive pulse width of the MOSFET 22 in order to adjust the output voltage of the switching circuit 20. The switching control IC constant voltage circuit 25 includes a diode 25a, a capacitor 25b, a resistor 25c, a transistor 25d, and a Zener diode 25e. During normal operation, a voltage corresponding to the sum of the Zener diode 25e and the base-emitter voltage of the transistor 25d of about 0.6 V is applied to the switching control IC 23, and switching is performed using this voltage as a power source. The zener diode 25e is selected to have an appropriate value as the power supply voltage of the switching control IC 23.

  The switching control IC stop circuit 26 includes a resistor 26a, a photocoupler receiver 26b paired with a transmitter 9a described later, a Zener diode 26c, a P-channel FET 26d, and N-channel FETs 26e and 26f. During normal operation, the switching control IC stop circuit 26 is not operating, but when the photocoupler 26b is turned on by a signal from the switching control IC stop means 9, the voltage of the AC line rectified by the rectifier diode 11 causes the resistor 26a to be turned on. Via the zener diode 26c. Since a value corresponding to the Zener voltage of the Zener diode 26c is applied to the gate of the FET 26e, the FET 26e is turned on. When the FET 26e is turned on, the FET 26d is turned on due to the potential difference between the gate and drain of the FET 26d. At the same time, a voltage corresponding to the Zener voltage of the Zener diode 26f is applied to the gate of the FET 26f, and the FET 26f is turned on. During normal operation, the switching control IC 23 is in an operating state by applying a voltage corresponding to the sum of about 0.6 V between the base-emitter voltage of the Zener diode 25e and the transistor 25d. However, when the FET 26f is turned on, the Zener diode 26f is short-circuited, and the applied voltage drops to about 0.6V.

  When the applied voltage falls below the voltage necessary for the operation of the switching control IC 23, the switching control IC 23 stops the switching operation. When the switching control is stopped, the signal from the transmission side 9b of the photocoupler is not transmitted, so the FET 26f is turned off again, and the switching control IC 23 has a voltage of about 0.6 V between the Zener diode 25e and the base-emitter of the transistor 25d. A voltage corresponding to the sum of the two is applied, and an operating state is entered. However, in this embodiment, after the photocoupler receiving side 26b is once turned on, the AC line voltage is used to turn on the FET 26d, the FET 26e, and the photocoupler regardless of whether the photocoupler receiving side 26b is on or off. The FET 26f is turned on. Therefore, as long as the voltage on the AC line is not lost, the FET 26f is kept on, so that the switching control IC 23 cannot operate.

  The secondary side rectifying / smoothing circuit 30 includes a diode 31, a smoothing capacitor 32, and a resistor 33, and charges the battery pack 2.

  The charging current control means 60 includes resistors 60a, 60b, 60c, 60d, 60e, 60f, an operational amplifier 60g, a diode 60h, and a shunt resistor 60i. The charging current controls the charging current of the battery pack 2 based on the value of the voltage drop of the shunt resistor 60i due to the flowing of the charging current with the value obtained by dividing the power supply voltage Vcc by the resistors 60a and 60b as a reference value. Further, the charging current control means 60 controls the charging current by feeding back a control signal to the switching control IC 23 via the signal transmission means 8.

  The charging voltage control means 70 includes a resistor 70a and a Zener diode 70b. The charging voltage of the battery pack 2 is determined by the value of the Zener diode 70b. Like the charging current, the charging voltage is controlled by feeding back a control signal to the switching control IC 23 via the signal transmission means 8.

  The power supply means 6 supplies power from the switching circuit 20 to the battery pack 2 and is constituted by a relay. However, not only the relay but also an appropriate power supply means can be used. The power supply control means 7 controls the power supply means 6. The presence / absence of power supply from the switching circuit 20 to the battery pack 2 is controlled via the power supply means 6 under the control of the power supply control means 7.

  Furthermore, the battery temperature detection means 3 is comprised from resistance 3a and 3b. When the battery pack 2 is mounted on the charging device 100, the temperature sensitive element 2a and the battery temperature detecting means 3 are connected via the battery side and charging device side terminals. At this time, in the battery temperature detection means 3, the voltage Vcc is divided by the resistor 3a and the parallel resistance of the resistor 3b and the temperature sensing element 2a, and this voltage value is input to the A / D port of the microcomputer 50. Thus, the microcomputer 50 detects the battery temperature.

  Before the battery pack 2 is mounted on the charging device 100, the battery temperature detection means 3 detects a value obtained by dividing the voltage Vcc by the resistors 3 a and 3 b by the microcomputer 50. Next, when the battery pack 2 is mounted, a value corresponding to the battery temperature is detected by the microcomputer 50. That is, by the mounting of the battery pack 2, the detection result in the microcomputer 50 changes to a value corresponding to the battery temperature. Therefore, when the detection result of the battery temperature detection means 3 changes from the value before the battery is mounted, the microcomputer 50 determines that the battery pack 2 is mounted.

  The battery type discriminating means 4 includes a resistor 4a. When the battery pack 2 is mounted on the charging device 100, a voltage value obtained by dividing the voltage Vcc by the resistor 4 a and the discrimination resistor 2 b in the battery pack 2 is input to the A / D port of the microcomputer 50. Therefore, the microcomputer 50 can identify the battery type. For example, if the discrimination resistor 2b is a resistance X, the battery type indicates that the secondary battery is a nickel cadmium battery, and if the resistance is Y, the secondary battery is a nickel metal hydride battery.

  The battery voltage detection means 5 includes resistors 5a and 5b as voltage detection means. The battery voltage is detected by dividing the battery voltage of the battery set 2A by the resistors 5a and 5b and inputting the voltage value to the A / D port of the microcomputer 50.

  The signal transmission means 8 is composed of a photocoupler or the like, and feeds back the charging voltage control signal and the charging current control signal of the secondary side rectifying and smoothing circuit 30 to the switching control IC 23.

  The switching control IC stop means 9 includes a photocoupler transmitter 9a and an FET 9b for stopping the switching control IC 23 itself. The transmitter 9a is paired with the receiver 26b. The FET 9b is controlled by a signal from the output port of the microcomputer 50. When the FET 9b is turned on, a signal is transmitted to the switching control IC stop circuit 26 via the transmission unit 9a and the reception unit 26b.

  The constant voltage circuit 40 includes a diode 41, capacitors 42 and 44, a three-terminal regulator 43, and a reset IC 45. The voltage Vcc is a power source for the microcomputer 50. The reset IC 45 outputs a reset signal to the reset input port 54 to put the microcomputer 50 in an initial state.

  The microcomputer 50 includes a CPU 51, an A / D port 52, output ports 53a and 53b, and a reset port 54, and functions as a full charge determination unit, a control unit, or an abnormality determination unit.

  The LED 80 displays the state of charge of the battery pack 2. The LED 80 is turned on and off by a signal from the output port of the microcomputer 50. In the present embodiment, when the LED is turned on, the battery pack 2 is being charged, and when the LED is turned off, the battery pack 2 is not being charged.

  The discharge path blocking means 90 is composed of a P-channel FET 91, an N-channel FET 92, and resistors 93, 94, 95, 96, and is used to disconnect the battery voltage detection means 5 from the discharge line from the battery set 2A. It is. When electric power is supplied to the charging device 100, the FET 91 is in an on state and the FET 92 is also in an on state, so that the battery voltage detection unit 5 is connected to the battery set 2A and can detect the battery voltage. On the other hand, when power is not supplied to the charging apparatus 100, the P-channel FET 91 is in the off state and the N-channel FET 92 is also in the off state, so that the battery voltage detecting means 5 is electrically connected to the battery set 2A. Not connected. Therefore, even if the battery pack 2 is left in the state where it is mounted on the charging device 100 for a long period of time, the discharge through the resistors 5a and 5b of the battery set 2A can be suppressed.

  As described above, the charging apparatus 100 is configured.

  The determination of the full charge of the battery pack 2 charged by the charging device 100 is usually performed using both the battery temperature detection means 3 and the battery voltage detection means 5 in order to prevent overcharging of the secondary battery. Is called. One of the full charge detection methods based on the battery voltage is a -ΔV detection method. In this detection method, it is determined that the battery is fully charged by detecting that a predetermined amount has dropped from the peak voltage detected near the end of charging based on the detection output of the battery voltage detecting means 5. The second-order differential detection method detects the time when the second-order differential value according to the battery voltage time becomes negative and determines that the battery is fully charged, thereby stopping charging before the battery voltage reaches the peak and overcharging. It is a method to prevent.

  As a method for determining whether the battery pack 2 is fully charged based on the output of the battery temperature detecting means 3, the charging of the battery pack 2 is started by utilizing the phenomenon that the battery temperature rapidly rises when the battery pack 2 approaches the fully charged state. A method of detecting ΔT that the battery temperature rise value from the battery has reached a predetermined value or more to determine full charge, or the battery temperature rise rate per unit time during charging of the battery pack 2 (hereinafter referred to as battery temperature gradient) There is a dT / dt detection method in which it is determined that the battery is fully charged by detecting that the value exceeds a predetermined value.

  However, when the battery voltage cannot be detected by the battery voltage detection means 5, the full charge of the battery pack 2 is determined only by the battery temperature. In this case, for example, when the environmental temperature for charging the battery pack 2 is low, an increase in the battery temperature may be suppressed by the environmental temperature. Therefore, in the full charge determination using only the battery temperature, it is determined that the battery is fully charged. There is a possibility that the secondary battery will be overcharged before. Therefore, in this embodiment, when the battery voltage detection unit 5 is abnormal and cannot detect the battery voltage, the battery voltage detection unit 5 functions normally by reducing the value of the battery temperature gradient for determining full charge. Compared with the case where it carries out, full charge is discriminate | determined early and charge of the battery pack 2 is complete | finished. Note that the microcomputer 50 does not charge the battery pack 2 when the battery temperature detection unit 3 does not operate due to an abnormality such as a disconnection in the charging device 100 or the battery pack 2 or a mounting failure or contact failure of the battery pack 2.

  Next, full charge determination of the battery pack 2 by the charging device 100 will be described using the flowchart of FIG. Note that the full charge determination based on the battery temperature is performed based on the battery temperature gradient, and a reference value of the battery temperature gradient for determining full charge is a.

  First, when the charging device 100 starts to be turned on, the microcomputer 50 initializes the output ports 53a and 53b. Next, it is determined whether or not the battery pack 2 is mounted on the charging device 100 (step 201). When the battery pack 2 is mounted, for example, when the value of the A / D port of the microcomputer 50 to which the detection result of the battery temperature detecting means 3 is input is changed, the microcomputer 50 causes the battery pack 2 to be connected to the charging device 100. It is determined that it has been implemented. If it is determined in step 201 that the battery pack 2 is mounted, the microcomputer 50 turns on the LED 80 according to a signal from the output port and displays that the battery pack 2 is being charged (step 202). Next, the microcomputer 50 starts charging the battery pack 2 (step 203). The microcomputer 50 starts charging by controlling the power supply means 6 from the output port via the power supply control means 7 and starting power supply to the battery pack 2.

  Next, the microcomputer 50 determines whether or not a predetermined time has elapsed since the start of charging (step 204). In this case, the predetermined time is, for example, a time between 30 seconds and 1 minute. In the battery set 2A, the battery voltage may become 0V in a fully discharged state, so it is necessary to wait for the battery voltage to recover by charging before the battery voltage is detected. Therefore, when a predetermined time has elapsed from the start of charging of the battery pack 2 (step 204: YES), the microcomputer 50 proceeds to step 205 and determines whether or not a battery voltage is detected.

  The microcomputer 50 determines whether or not the battery voltage is detected as follows. In general, until the battery pack 2 is fully charged, the battery voltage gradually increases as the charging time elapses. Therefore, if there is a fluctuation in the voltage value input to the A / D port of the microcomputer over a predetermined period, the microcomputer 50 indicates that the battery voltage of the battery set 2A is normally input to the battery voltage detection means 5, that is, The battery voltage detection means is determined to be normal (step 205: YES), and the process proceeds to step 207. On the other hand, if the voltage value input to the A / D port of the microcomputer does not change over a predetermined period, that is, if the voltage value maintains a constant value over the predetermined period, the microcomputer 50 does not detect the battery voltage. That is, it is determined that the battery voltage detection means is abnormal (step 205: NO), and the process proceeds to step 206. The phenomenon in which the battery voltage is not detected includes disconnection of the electrical connection between the battery set 2A and the battery voltage detection means 5 due to the failure of the discharge path interruption means 90, and a metal piece between the battery set 2A and the battery voltage detection means 5. This may be caused by an electrical short circuit due to mixing or an abnormal operation of the A / D port of the microcomputer 50.

  When the battery voltage detection means 5 is abnormal, the full charge detection of the battery pack 2 cannot be performed using the battery voltage, but is performed using only the battery temperature. When full charge is determined only by the battery temperature, the determination accuracy is lowered, and in some cases, the secondary battery may be overcharged. Accordingly, in step 206, the reference value for determining full charge from the temperature gradient of the battery temperature is changed to a value b (b <a) smaller than the initial value a. The battery pack 2 tends to increase in the battery temperature gradient when the battery is fully charged. Therefore, by reducing the reference value, the battery pack 2 is determined to be fully charged at an earlier stage than usual, and the charging is finished. To do. After changing the battery temperature gradient reference value, the process proceeds to step 207.

  In step 207, the battery temperature is detected by the battery temperature detecting means 3 and stored. Next, the latest battery temperature gradient is calculated and stored from the battery temperature detected last time and the current battery temperature detected in step 207 (step 208). Next, if the latest battery temperature gradient calculated in step 208 becomes a minimum value compared with the already calculated battery temperature gradient, the latest battery temperature gradient is updated as the minimum battery temperature gradient (step 209). ). Next, when the difference between the latest battery temperature gradient and the minimum battery temperature gradient is equal to or greater than the reference value (step 210: YES), it is determined that the battery pack 2 is fully charged, and the process proceeds to step 212. As the reference value in step 210, the initial value a is used when it is determined that the battery voltage can be detected in step 205, and the value b (a> b) is used when it is determined that the battery voltage cannot be detected. On the other hand, when the difference between the latest battery temperature gradient and the minimum value of the battery temperature gradient is not equal to or greater than the reference value (step 210: NO), the process proceeds to step 211.

  In step 211, the battery voltage is detected, and full charge of the battery pack 2 is detected based on the detected battery voltage. After determining that the battery pack 2 is fully charged based on the battery voltage (step 211: YES), the process proceeds to step 212 and the charging is terminated. If it is determined in step 205 that the battery voltage detection means is abnormal, the battery voltage cannot be detected (step 211: NO), and the process returns to step 204. Even when it is determined in step 205 that the battery voltage detection means is normal, when it is determined that the battery pack 2 is not fully charged based on the battery voltage (step 211: NO), the process returns to step 204.

  In step 212, the microcomputer 50 controls the power supply unit 6 from the output port via the power supply control unit 7, and stops charging by stopping the power supply to the battery pack 2.

  After completing the charging, in step 213, the microcomputer 50 outputs a signal from the output port and turns off the LED 80 to indicate the end of charging. Next, when the battery pack 2 is removed from the charging device 100 in step 214 (step 214: YES), the process returns to step 201.

  As described above, when the battery voltage cannot be detected by the battery voltage detection means 5, the full charge of the battery pack 2 is determined only by the battery temperature. In this case, since the determination accuracy of the full charge is not good, the reference value of the battery temperature gradient for determining the full charge is changed to a value smaller than the reference value when the battery voltage can be detected. Overcharge can be reliably prevented.

  In addition, the battery voltage detection means 5 is normal, and the time required from the start of charging the battery pack 2 until full charge is determined based on the battery voltage in step 311 is the first predetermined time, and the battery voltage detection means 5 If the time required to determine full charge in step 210 is the second predetermined time when the battery voltage detection means 5 is abnormal, if the battery voltage detecting means 5 is abnormal, the step 210 is compared with the normal case. Since the reference value at is small, it is predicted that the charging will be completed early and the charging will be finished. Accordingly, the second predetermined time is shorter than the first predetermined time. That is, when an abnormality has occurred in the battery voltage detection means 5, the charging time of the battery pack 2 is shortened compared with the case where the battery voltage detection means 5 is normal, and is completed in a short time. Conversely, when the charging of the battery pack 2 by the charging device 100 ends earlier than the initially predicted time, it can be considered that some abnormality has occurred in the battery voltage detection means 5.

  Note that the determination of the full charge based on the battery temperature is performed based on the rate of change of the battery temperature gradient, but it is also possible to determine the full charge based on the battery temperature gradient itself.

  The secondary battery constituting the battery pack 2 is not limited to a nickel cadmium battery or a nickel metal hydride battery, and an appropriate secondary battery can be used.

  The charging device of the present invention can be used for charging a battery pack having a secondary battery of an appropriate type.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Battery pack 3 Temperature detection means 5 Voltage detection means 20 Switching circuit 50 Microcomputer 100 Charging apparatus

Claims (1)

A charging means for charging the secondary battery;
  Voltage detection means for detecting a battery voltage of the secondary battery;
  Temperature detecting means for detecting a battery temperature of the secondary battery;
  Full charge determination means for determining full charge of the secondary battery based on at least one of the battery voltage detected by the voltage detection means and the battery temperature detected by the temperature detection means;
  Control means for stopping charging of the secondary battery by the charging means when the full charge determining means determines that the secondary battery is fully charged;
  Abnormality determination means for determining whether or not the voltage detection means is abnormal;
A charging device comprising:
  The full charge determination means includes
    When the voltage detection means is normal and the temperature change value per unit time of the battery temperature detected by the temperature detection means reaches a first predetermined value, the secondary battery Determine that the battery is fully charged,
    When the voltage detection means is abnormal, and the temperature change value reaches a second predetermined value smaller than the first predetermined value, the secondary battery is determined to be fully charged. A charging device characterized by that.

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