JP2012137297A - Battery degradation detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery degradation detecting apparatus capable of detecting a degradation state of a battery with a simple configuration.SOLUTION: A battery degradation detecting apparatus 100 detects a battery voltage +B at the time a start switch SW1 is turned on, and if the battery voltage +B is below a predetermined lower limit value V2 of normal voltage, turns on an alarm LED 13. Therefore, it is possible to accurately and quickly notify a user of degradation of the battery VB. In addition, because it does not require complex calculation as in the case of measuring internal resistance of the battery VB, the circuit configuration can be simplified, and therefore miniaturization and cost reduction of the apparatus can be achieved.

Description

  The present invention relates to a battery deterioration detection device that issues a warning and notifies a user when a battery mounted on a vehicle such as a vehicle deteriorates.

  Generally, a battery is mounted on a vehicle to supply power for starting a start motor and driving power for various devices such as a motor and a lamp mounted on the vehicle. In recent years, a battery is provided for supplying power to a vehicle driving motor mounted in a hybrid vehicle, an electric vehicle, or the like.

  Since a battery mounted on a vehicle may be deteriorated due to overdischarge, change with time, etc., it is desired to detect the deterioration of the battery before the battery is completely deteriorated and becomes unusable. . As a conventional example of a battery deterioration detection device, for example, one described in Japanese Patent Application Laid-Open No. 11-109004 (Patent Document 1) is known. In Patent Document 1, it is disclosed that an internal resistance calculation unit or the like is provided to constantly detect the state of the battery.

JP-A-11-109004

  However, in the conventional example disclosed in Patent Document 1 described above, although the deterioration state of the battery can be detected, there is a problem that the system configuration is complicated and the cost is increased, and it is difficult to mount on a general gasoline vehicle. There is a drawback.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a battery deterioration detection device capable of detecting a battery deterioration state with a simple configuration. It is in.

  In order to achieve the above object, the invention according to claim 1 of the present application is a battery deterioration detection device that detects a deterioration state of a battery mounted on a vehicle. ), Temperature detection means (for example, thermistor Th1) for detecting the ambient temperature of the battery, and lower limit value setting means (for example, the CPU 11) for setting a normal voltage lower limit value that defines the minimum voltage for judging the deterioration of the battery voltage. And a normal voltage lower limit value correcting means (for example, CPU 11) for correcting the normal voltage lower limit value based on the temperature detected by the temperature detecting means, and the battery immediately after the vehicle start switch is turned on. Battery deterioration determination means (for example, determining that the battery has deteriorated when the voltage falls below the normal voltage lower limit value) If, battery deterioration detecting apparatus characterized by comprising a, a CPU 11).

  The invention according to claim 2 further includes a timer for measuring an elapsed time after the start switch is turned on, and the battery deterioration determining means is configured such that the battery voltage immediately after the start switch is turned on is the normal value. Even when the voltage is lower than the lower voltage limit, if the threshold voltage (T) set in advance after the start switch is turned on becomes equal to or higher than the normal voltage lower limit, the battery has deteriorated. It is characterized by determining that it is not present.

  The invention according to claim 3 further includes storage means (for example, EEPROM 14) for storing a voltage correction table indicating a correspondence relationship between the ambient temperature of the battery and the correction voltage with respect to the normal voltage lower limit value, and the normal voltage The lower limit correction means corrects the normal voltage lower limit with reference to the voltage correction table.

  According to a fourth aspect of the present invention, the lower limit value setting means sets a normal operating voltage lower limit value that defines a minimum voltage required for the battery to drive a load, in addition to the normal voltage lower limit value, When it is determined that the battery has deteriorated, the battery deterioration determination means outputs an alarm signal when the battery voltage subsequently exceeds the normal operating voltage lower limit value.

  According to a fifth aspect of the present invention, there is further provided alarm means (for example, an alarm LED 13) which is turned on when the alarm signal is output to notify the deterioration of the battery.

  In the battery deterioration detection device according to the present invention, the output voltage of the battery when the start switch is turned on is detected, and the battery is deteriorated when the output voltage falls below a preset normal voltage lower limit value. Is determined. Therefore, it is possible to detect the deterioration of the battery with high accuracy and speed, and it is not necessary to perform complicated calculations such as measuring the internal resistance of the battery as in the conventional case, so the circuit configuration is simplified. This makes it possible to reduce the size and cost of the apparatus.

It is a block diagram which shows the structure of the battery deterioration detection apparatus which concerns on embodiment of this invention. It is a characteristic view which shows the change of a battery voltage when starting the start switch mounted in a vehicle. It is a flowchart which shows the process sequence of the battery deterioration detection apparatus which concerns on 1st Embodiment of this invention. It is a flowchart which shows the process sequence of the battery deterioration detection apparatus which concerns on 2nd Embodiment of this invention. It is a characteristic view which shows the relationship between ambient temperature, a normal voltage lower limit, and the correction value of a normal operating voltage lower limit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing a configuration of a battery deterioration detection device 100 and peripheral devices thereof according to an embodiment of the present invention. As shown in FIG. 1, this battery deterioration detection device 100 is connected to the positive pole (voltage + B) of a battery VB mounted on the vehicle and has a function of detecting the deterioration of the battery VB. A constant voltage IC 12, an EEPROM 14 (storage means), an alarm LED 13 for informing the user of deterioration of the battery VB, a timer 17, resistors R1 to R4, and a thermistor Th1 (temperature detection means).

  The constant voltage IC 12 is a positive electrode of the battery VB, generates a stabilized DC voltage (for example, 5 V) by inputting the battery voltage + B, and outputs the DC voltage to the Vcc terminal of the CPU 11. The CPU 11 operates with this stabilized voltage. The constant voltage IC 12 is connected to the anode of the alarm LED 13 via the resistor R4, and the cathode of the alarm LED 13 is connected to the terminal P01 of the CPU 11. Then, the constant voltage IC 12 generates a voltage VH and supplies it to the alarm LED 13.

  The resistors R1 and R2 are connected in series, one end of the resistor R1 is connected to the positive electrode of the battery VB, and one end of the resistor R2 is connected to the ground. Furthermore, the connection point between the resistors R1 and R2 is connected to the A / D converter 15 of the CPU 11. Therefore, the A / D converter 15 is supplied with a voltage obtained by dividing the battery voltage + B by the resistors R1 and R2.

  The resistor R3 and the thermistor Th1 are connected in series, one end of the resistor R3 is connected to the VH output section of the constant voltage IC 12, and one end of the thermistor Th1 is connected to the ground. A connection point between the resistor R3 and the thermistor Th1 is connected to the A / D converter 16 of the CPU 11. The thermistor Th1 is provided in the vicinity of the battery VB. Therefore, the A / D converter 16 is supplied with a voltage obtained by dividing the voltage VH by the resistance of the resistor R3 and the thermistor Th1, and the resistance value of the thermistor Th1 changes depending on the ambient temperature of the battery VB. The A / D converter 16 receives a voltage signal corresponding to the ambient temperature of the battery VB. That is, the thermistor Th1 has a function as temperature detection means.

  In the present embodiment, a normal voltage lower limit value (indicated by reference symbol V2) and a normal operating voltage lower limit value (indicated by reference symbol V3) of the battery VB are set, and the EEPROM 14 sets the lower limit values V2, V3. Is remembered. The normal operating voltage lower limit value V3 indicates the lowest voltage at which the load connected to the battery VB operates normally, and the normal voltage lower limit value V2 indicates the lowest voltage voltage that determines whether or not the battery VB is deteriorated.

  Further, the EEPROM 14 stores a voltage correction table indicating the relationship between the ambient temperature of the battery VB and the voltage correction value. FIG. 5 is a characteristic diagram showing an example of a voltage correction table, in which a voltage correction value corresponding to the ambient temperature is recorded. Then, the normal voltage lower limit value and the normal operating voltage lower limit value are corrected using values corrected with respect to the reference temperature (in this example, the ambient temperature of 25 ° C.). For example, when the ambient temperature is −10 ° C., 0.55 volts is added to the normal voltage lower limit value and the normal operating voltage lower limit value.

  The timer 17 measures the elapsed time after the start switch SW1 is turned on. The timer 17 is used in a second embodiment to be described later, and can be omitted in the first embodiment.

  The CPU 11 has an operation lower limit voltage set to, for example, 3.3 volts (the voltage V1 shown in FIG. 2), the battery voltage (obtained from the connection point between the resistors R1 and R2), the ambient temperature of the battery VB (obtained from the thermistor Th1). ) And the time measurement data output from the timer 17 (in the case of the second embodiment), it is determined whether or not the battery VB has deteriorated, and if it has deteriorated, an alarm signal is output. The alarm LED 13 is turned on to notify the user that the battery VB has deteriorated.

  Further, the positive electrode of the battery VB is connected to the starter solenoid 21 via the start switch SW1, and when the start switch SW1 is turned on, the starter solenoid 21 is operated to turn on the ignition. it can.

  Next, the processing operation by the CPU 11 of the battery deterioration detection device 100 according to the first embodiment of the present invention will be described with reference to the flowchart shown in FIG.

  First, in step S11, the CPU 11 acquires the battery voltage + B after the start switch SW1 is turned on. In this process, since the voltage at the connection point between the resistors R1 and R2 is supplied to the A / D converter 15, the CPU 11 can acquire digitized voltage data.

  In step S12, the CPU 11 acquires lower limit data of the voltage when the battery VB is normal (when it is not deteriorated). In this process, the normal voltage lower limit value V2 and the normal operating voltage lower limit value V3 of the battery VB stored in the EEPROM 14 are acquired (see FIG. 2).

  In step S13, the CPU 11 acquires temperature data in the vicinity of the battery VB based on the voltage generated in the thermistor Th1. In this process, the voltage generated in the thermistor Th1 is supplied to the A / D converter 16, so that the CPU 11 can acquire digitized temperature data. Further, referring to the voltage correction table (FIG. 5) stored in the EEPROM 14, the normal voltage lower limit value V2 and the normal operating voltage lower limit value V3 acquired in the process of step S12 are corrected. For example, when the ambient temperature of the battery VB is −10 ° C., 0.55 volts is added to V2 and V3 when the ambient temperature is 25 ° C.

  In step S14, the CPU 11 determines whether or not the battery voltage + B acquired in the process of step S11 is within a normal range. In this process, when the battery voltage + B is higher than the normal voltage lower limit value V2, it is determined that it is within the normal range, and when it is lower than the normal voltage lower limit value V2, it is determined that it is not within the normal range. FIG. 2 is a characteristic diagram showing the ON operation of the start switch SW1 and the change in the battery voltage + B. When the start switch SW1 is turned on at time t1, the battery voltage + B rapidly decreases and the battery normal voltage lower limit is set. When it is below the value V2, it is determined that it is not within the normal range (NO determination), and when it is not below the battery normal voltage lower limit value V2, it is determined that it is within the normal range (YES determination).

  If the battery voltage + B falls below V2, in step S15, the CPU 11 turns on the battery voltage abnormality flag. The battery voltage abnormality flag may be stored in the EEPROM 14 or may be stored in other storage means (not shown).

  On the other hand, when the battery voltage + B does not fall below V2, in step S16, the CPU 11 turns off the battery voltage abnormality flag.

  In step S <b> 17, the CPU 11 acquires the battery voltage + B.

  In step S18, the CPU 11 determines whether or not the acquired battery voltage + B is within the operating range. That is, it is determined whether or not the battery voltage + B exceeds the normal operating voltage lower limit value V3.

  If the battery voltage + B does not exceed the normal operating voltage lower limit value V3, the process returns to step S17, and if it exceeds, the process proceeds to step S19. That is, as shown in FIG. 2, when the start switch SW1 is turned on at time t1, the battery voltage + B suddenly decreases and then increases, so that after a while, the normal operating voltage lower limit value V3 is exceeded. Become. In the processes of steps S17 and S18, the acquisition of the battery voltage + B is repeated until the battery voltage + B exceeds the normal operating voltage lower limit value V3.

  In step S19, the CPU 11 determines whether or not the battery voltage abnormality flag is on. That is, it is determined whether the battery voltage abnormality flag is turned on in step S15 or whether the battery voltage abnormality flag is turned off in step S16.

  If it is determined that the battery voltage abnormality flag is on (YES in step S19), in step S20, the CPU 11 transmits an alarm signal to the alarm LED 13 to turn on the alarm LED 13, and the battery VB is The user is informed that an abnormality has occurred. On the other hand, when it is determined that the battery voltage abnormality flag is off (NO in step S19), in step S21, the CPU 11 turns off the alarm LED 13 to cancel the alarm.

  In this way, the battery deterioration detection device 100 according to the first embodiment of the present invention detects the battery voltage + B when the start switch SW1 is turned on, and the battery voltage + B is set to the normal voltage lower limit value V2 set in advance. When the value is lower than, the alarm LED 13 is turned on to notify the user that an abnormality has occurred in the battery VB.

  Therefore, it is possible to notify the user that the battery VB has deteriorated with high accuracy and speed. Further, unlike the conventional example, since complicated calculation such as measuring the internal resistance of the battery VB is not required, the circuit configuration can be simplified, and the apparatus can be reduced in size and cost. it can.

  Even when the battery voltage + B falls below the normal voltage lower limit value V2, the CPU 11 is driven at a voltage lower than the lower limit value V2 (operating lower limit voltage V1; for example, 3.3 V), so the battery VB deteriorates. Even in such a case, the CPU 11 can be reliably operated, and the deterioration of the battery VB can be detected with high accuracy.

  Furthermore, a voltage correction table is set in the EEPROM 14, and the normal voltage lower limit value V2 and the normal operating voltage lower limit value V3 are corrected based on the ambient temperature of the battery VB, so that the deterioration of the battery VB is not affected by the ambient temperature. Can be detected.

  Further, when the battery voltage + B falls below the normal voltage lower limit value V2, the alarm LED 13 is turned on after the battery voltage + B exceeds the normal operating voltage lower limit value V3. Later, the user can be surely notified of the deterioration of the battery VB.

  Further, when the deterioration of the battery VB is detected, the alarm LED 13 is turned on, so that the user can easily notice the deterioration of the battery VB.

  Next, a second embodiment of the battery deterioration detection device 100 according to the present invention will be described. Since the apparatus configuration is the same as that shown in FIG. Hereinafter, the operation of the battery deterioration detection apparatus 100 according to the second embodiment will be described with reference to the flowchart shown in FIG.

  First, in step S31, the CPU 11 acquires the battery voltage + B after the start switch SW1 is turned on. In this process, since the voltage at the connection point between the resistors R1 and R2 is supplied to the A / D converter 15, the CPU 11 can acquire digitized voltage data.

  In step S <b> 32, the CPU 11 acquires the lower limit value data of the voltage when the battery VB is normal (when it is not deteriorated). In this process, the normal voltage lower limit value V2 and the normal operating voltage lower limit value V3 of the battery VB stored in the EEPROM 14 are acquired (see FIG. 2).

  In step S33, the CPU 11 acquires temperature data in the vicinity of the battery VB based on the voltage generated in the thermistor Th1. In this process, the voltage generated in the thermistor Th1 is supplied to the A / D converter 16, so that the CPU 11 can acquire digitized temperature data. Further, referring to the voltage correction table (FIG. 5) stored in the EEPROM 14, the normal voltage lower limit value V2 and the normal operating voltage lower limit value V3 acquired in the process of step S32 are corrected.

  In step S34, the CPU 11 determines whether or not the battery voltage + B acquired in the process of step S31 is within a normal range. In this process, when the battery voltage + B is higher than the normal voltage lower limit value V2, it is determined that it is within the normal range, and when it is lower than the normal voltage lower limit value V2, it is determined that it is not within the normal range. As shown in FIG. 2, when the start switch SW1 is turned on at time t1, if the battery voltage + B decreases rapidly and falls below the battery normal voltage lower limit value V2, it is determined that it is not within the normal range ( NO determination), when it is not less than the battery normal voltage lower limit V2, it is determined that it is within the normal range (YES determination).

  If the battery voltage + B does not fall below the normal voltage lower limit value V2, the battery voltage abnormality flag is turned off in step S37. On the other hand, when the battery voltage + B falls below the normal voltage lower limit value V2, in step S35, the CPU 11 activates the timer 17 and continues the time during which the battery voltage + B is lower than the normal voltage lower limit value V2. It is determined whether or not it is less than or equal to a preset threshold time T (see FIG. 2).

  When the time when the battery voltage + B is lower than the normal voltage lower limit value V2 is equal to or shorter than the threshold time T (when + B exceeds V2 before reaching the time t2), the battery voltage abnormality flag is determined by the process of step S37. Turn off. On the other hand, when the time during which the battery voltage + B is lower than the normal voltage lower limit value V2 exceeds the threshold time T (when + B is lower than V2 at time t2), in step S36, the CPU 11 determines that the battery voltage is abnormal. Turn on the flag.

  In step S38, the CPU 11 acquires the battery voltage + B.

  In step S39, the CPU 11 determines whether or not the corrected battery voltage + B is within the operating range. That is, it is determined whether or not the battery voltage + B exceeds the normal operating voltage lower limit value V3.

  If the battery voltage + B does not exceed the normal operating voltage lower limit value V3, the process returns to step S38, and if it exceeds, the process proceeds to step S40. That is, as shown in FIG. 2, when the start switch SW1 is turned on at time t1, the battery voltage + B suddenly decreases and then increases, so that after a while, the normal operating voltage lower limit value V3 is exceeded. Become. In the processes of steps S38 and S39, the acquisition of the battery voltage + B is repeated until the battery voltage + B exceeds the normal operating voltage lower limit value V3.

  In step S40, the CPU 11 determines whether or not the battery voltage abnormality flag is on. That is, it is determined whether the battery voltage abnormality flag is turned on in step S36 or whether the battery voltage abnormality flag is turned off in step S37.

  If it is determined that the battery voltage abnormality flag is on (YES in step S40), in step S41, the CPU 11 transmits an alarm signal to the alarm LED 13 to turn on the alarm LED 13, and the battery VB is The user is informed that an abnormality has occurred. On the other hand, when it is determined that the battery voltage abnormality flag is off (NO in step S40), in step S42, the CPU 11 turns off the alarm LED 13 to cancel the alarm.

  In this way, the battery deterioration detection device 100 according to the second embodiment can achieve the same effect as that of the first embodiment described above, and the battery voltage + B when the start switch SW1 is turned on is reduced. Thus, when the time that is lower than the battery normal voltage lower limit value V2 and further lowers exceeds the threshold time T, the battery voltage abnormality flag is turned on and the alarm LED 13 is turned on.

  Accordingly, it is possible to prevent a false alarm from being issued due to a sudden drop in the battery voltage + B or due to the influence of noise or a detection error.

  As described above, the battery deterioration detection device of the present invention has been described based on the illustrated embodiment, but the present invention is not limited to this, and the configuration of each part is replaced with an arbitrary configuration having the same function. be able to.

  The present invention can be used for easily detecting a battery mounted on a vehicle.

11 CPU
12 Constant voltage IC
13 Alarm LED
14 EEPROM
15, 16 A / D converter 17 Timer 21 Starter solenoid 100 Battery deterioration detection device SW1 Start switch VB Battery + B Battery voltage R1 to R4 Resistance Th1 Thermistor

Claims (5)

In a battery deterioration detection device that detects a deterioration state of a battery mounted on a vehicle,
Voltage detecting means for detecting the output voltage of the battery;
Temperature detecting means for detecting the ambient temperature of the battery;
Lower limit value setting means for setting a normal voltage lower limit value that defines a minimum voltage for judging deterioration of the battery voltage;
Normal voltage lower limit correction means for correcting the normal voltage lower limit value based on the temperature detected by the temperature detection means;
Battery deterioration determination means for determining that the battery has deteriorated when the battery voltage immediately after the start switch of the vehicle is turned on falls below the normal voltage lower limit;
A battery deterioration detection device comprising: A timer for measuring an elapsed time after the start switch is turned on;
Even when the battery voltage immediately after the start switch is turned on falls below the normal voltage lower limit value, the battery deterioration determination means, after elapse of a preset threshold time from turning on the start switch, The battery deterioration detection device according to claim 1, wherein when the battery voltage becomes equal to or higher than the normal voltage lower limit value, it is determined that the battery has not deteriorated.   The apparatus further comprises storage means for storing a voltage correction table indicating a correspondence relationship between the ambient temperature of the battery and the correction voltage for the normal voltage lower limit value, and the normal voltage lower limit value correction means refers to the voltage correction table. The battery deterioration detection device according to claim 1, wherein the normal voltage lower limit value is corrected. The lower limit setting means sets a normal operating voltage lower limit value that defines a minimum voltage required for the battery to drive a load, in addition to the normal voltage lower limit value,
The battery deterioration determining means, when determining that the battery has deteriorated, outputs an alarm signal when the battery voltage subsequently exceeds the normal operating voltage lower limit value. The battery deterioration detection device according to claim 3.   The battery deterioration detection device according to claim 4, further comprising alarm means that turns on when the alarm signal is output and notifies the deterioration of the battery.

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