JP4372894B2 - Lead-acid battery life judgment device - Google Patents

Description

本発明によれば、基準電圧の精度が±０．７％（標準的な３端子レギュレータの精度）と従来品よりも悪条件であるにも関わらず、取り込み電圧を約２倍に大きく取れるために、測定電圧分解能を約１／２に細かくすることが可能である。
【００３０】
次に、この寿命判定装置１０を用いた劣化状態の検出方法について説明する。まず、試験対象の電池１１をクリップ１２，１３によって接続する。このとき、上述した説明から明らかなように、定電圧回路２４には電力が供給されず、放電用リレーＲＹの接点１４は開いたままである。クリップ１２，１３を接続したことによる火花の発生は抑えられている。クリップ１２，１３による接続後、数秒が経過すると、電源用遅延回路２１の作用により、定電圧回路２４に電力が供給されるようになり、中央演算回路２３などが動作を開始する。次に、スタートボタンＰＢを押下することによって、中央演算回路２３は放電リレー制御回路６１によってリレーＲＹを駆動し、一定の時間（数秒以下）だけ接点１４を閉じ、抵抗１６を介して電池１１を所定電流で放電させる。そして、このとき端子電圧を電圧検出回路２２によって測定し、放電後５秒後のドロップ（低下）電圧（ここでドロップ電圧とは、放電時における電池の端子電圧のことをいう）を求める。中央演算回路２３は、このドロップ電圧に応じて電池１１の劣化状態を判別し、判別結果を発光ダイオード群１７を介して表示するとともに、プリンタ１８によって印字する。
【００３１】
以上、本発明の好ましい実施の形態について説明したが、本発明は、上記の形態のものに限定されるわけではなく、電池の劣化状態を判定するための種々の技術に適用可能である。例えば、放電開始後一定時間後（例えば５秒後）のドロップ電圧のほかに、放電停止から数秒後の回復電圧を測定し、ドロップ電圧と回復電圧の両方から劣化状態を判定するようにしてもよい。
【００３２】
【発明の効果】
以上説明したように本発明は、放電電流を小さく抑えつつ、劣化初期状態の鉛蓄電池を測定する場合のような起電力損失が小さい場合であっても、鉛蓄電池の劣化状態を高精度に検出することができるという効果がある。さらに、寿命判定装置への鉛蓄電池の接続時の火花発生が防止でき、安全性が大幅に向上するという効果がある。
【図面の簡単な説明】
【図１】本発明の実施の一形態の寿命判定装置の構成を示すブロック図である。
【図２】電源用遅延回路および定電圧回路の構成を示す回路図である。
【図３】電圧検出回路の構成を示す回路図である。
【図４】従来の寿命判定装置の要部の構成を示すブロック図である。
【符号の説明】
１０ 寿命判定装置
１１ 電池
１２，１３ クリップ
１６ 抵抗
２１ 電源用遅延回路
２２ 電圧検出回路
２３ 中央演算回路
２４ 定電圧回路
２５ 放電リレー制御回路
４０ Ａ／Ｄ変換器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for determining the life of a lead storage battery used in an automobile or a motorcycle, and in particular, discharges a lead storage battery to be tested for a short time with a predetermined current, and the deterioration state of the lead storage battery from the voltage drop value at that time The present invention relates to a lifetime determination apparatus capable of detecting
[0002]
[Prior art]
Conventionally, as a method for detecting the deterioration state of a lead storage battery, a method of estimating the deterioration state from a discharge voltage after a certain time from the start of discharge has been common. This method utilizes the fact that the discharge voltage after a certain time of a lead storage battery has a correlation with the deterioration state of the lead storage battery. When the lead storage battery deteriorates, the internal resistance and polarization resistance increase, which increases electromotive force loss. As a result, the discharge voltage after a certain time from the start of discharge has a correlation with the deterioration state.
[0003]
FIG. 4 is a block diagram illustrating a configuration of a main part of a conventional life determination apparatus using the above-described method. This apparatus determines the degree of deterioration of the battery 51 to be tested, and includes clips 52 and 53 for connection to the positive terminal and the negative terminal of the battery 51, respectively. Are connected in series with a contact 54 of a relay (discharge relay) RY and a resistor 56. Further, in order to measure the terminal voltage of the battery 51, an A / D (analog / digital) converter 58 is provided as a voltage detection circuit, and the digital output from the A / D converter 58 is supplied to the entire apparatus. It is sent to a microprocessor 59 which is a control circuit for controlling the operation. Each of the A / D converter 58 and the microprocessor 59 requires a power supply voltage, but this life determination device operates by receiving power supply from the battery 51 to be tested. A constant voltage circuit 57 that is supplied with electric power from the battery 51 and supplies a power supply voltage to the A / D converter 58 and the microprocessor 59 is provided. The microprocessor 59 controls the discharge relay control circuit 61 for driving the drive coil 55 of the relay RY.
[0004]
A method of detecting a deterioration state using this life determination device will be described. First, in a state where the contact 54 of the relay RY is opened, the battery 51 to be tested is connected by the clips 52 and 53, and then the relay RY is driven by the discharge relay control circuit 61, and only for a certain time (several seconds or less). The contact 54 is closed and the battery 51 is discharged via the resistor 56. As a result, the battery 51 is discharged at a predetermined current (the terminal voltage of the battery changes depending on the state of charge of the battery 51 and the like. Therefore, the discharge current also varies strictly from a constant value. It is assumed that the discharge through the resistor is included in the discharge at a predetermined current). The terminal voltage at that time is measured by the A / D converter 58, the electromotive force loss is calculated from the measurement result by the microprocessor 59, and the deterioration state of the battery 51 is determined according to the magnitude of the electromotive force loss.
[0005]
Here, attention is paid to the input side of the A / D converter 58. When the battery 51 to be tested is a lead-acid battery with a rating of 12V for in-vehicle use, the voltage between the clips 52 and 53 is about 30V at maximum considering various noises and the possibility of erroneous operation. Conceivable. Therefore, the analog / digital conversion is performed by setting the full range so that the voltage in the range of 0 to 30 V is not overranged. For this purpose, the voltage divided by the resistor 62 and the resistor 63 is converted into an A / D converter. 58 is supplied to the input terminal Vin. Further, as will be described later, since the electromotive force loss is small, it is necessary to ensure the measurement accuracy of analog / digital conversion. For this reason, a reference voltage circuit 60 is provided separately from the driving power supply from the constant voltage power supply 57 to provide a reference voltage. The reference voltage generated by the circuit 60 is supplied to the reference voltage terminal Vref of the A / D converter 58.
[0006]
[Problems to be solved by the invention]
However, in the case of the above-described conventional lifetime determination device, it is difficult to improve the measurement accuracy of the terminal voltage of the battery 51 to a certain level or more, and therefore 100 to 200 A (ampere) is provided for the purpose of securing the electromotive force loss of the lead storage battery. It is necessary to perform such a large current discharge. In addition, since the lead-acid battery does not increase the electromotive force loss unless it is at the end of deterioration, there is a problem that it is impossible to detect the state of the initial stage of deterioration and the middle stage of deterioration. In addition, there is a problem that the power consumption burden on the battery to be tested is large. These problems can be solved by using an A / D converter having a higher resolution, but the high resolution A / D converter is extremely expensive, resulting in an increase in the cost of the lifetime determination device. .
[0007]
Furthermore, since a large current is instantaneously discharged, for example, when a battery to be tested is connected to the life determination device with the contact of the discharge relay closed, there is a possibility that a spark may be generated. There is also. Even when the battery is connected when the contact of the discharge relay is open, the current for supplying to the A / D converter, the microprocessor, etc. in the life determination device flows, so that sparks are also generated. there is a possibility. Such a possibility of occurrence of a spark can be an inconvenient point when performing deterioration diagnosis of a lead storage battery mounted on an automobile in a place such as a gas station where the presence of fire is not preferable.
[0008]
Therefore, the object of the present invention is to detect with high accuracy even when the electromotive force loss is small as in the case of measuring a lead storage battery in the initial stage of deterioration while keeping the discharge current small. An object of the present invention is to provide a lifetime determination device that prevents the occurrence of sparks.
[0009]
[Means for Solving the Problems]
The present inventor limits the input voltage to an A / D converter (A / D conversion element) using a Zener diode or the like in a device that detects a deterioration state by discharging a lead storage battery with a predetermined current for a short time. By setting the full range of the A / D converter within the limited upper limit voltage range, the discharge current is set to 100 A or less, and the electromotive force loss is small, such as when measuring lead acid batteries in the initial stage of deterioration. In addition, the present inventors have found that the deterioration state of the lead storage battery can be detected with high accuracy, and completed the present invention. Further, when configured in this way, even when the driving voltage for the A / D converter is used as the reference voltage in the A / D converter, the deterioration state can be detected with high accuracy even when the electromotive force loss is small. It has been found that a reference voltage circuit that has been separately installed in the past can be omitted, and the circuit configuration can be simplified. Furthermore, the inventor adds a power supply delay circuit that delays the drive power-on of the life determination device by several seconds from the time of connection to the battery, thereby preventing the occurrence of sparks at the time of connection and greatly improving safety. heading, it has led to the completion of the present invention.
[0010]
That is, in the invention according to claim 1, the A / D converter that detects the terminal voltage of the lead storage battery and converts it into a digital value, and the voltage limiting element that limits the upper limit voltage of the input voltage to the A / D converter; Is provided. A Zener diode or the like is preferably used as the voltage limiting element. In this lifetime determination apparatus, conventionally, the input upper limit voltage to the A / D conversion unit having an input withstand voltage of 30 V or higher is limited within a range of 6 to 28 V by a voltage limiting element. As a result, when an A / D converter having a certain number of bits is used, the measurement resolution can be improved by the amount that the input upper limit voltage is limited.
[0011]
Further, in the invention according to claim 1 , the driving power source of the A / D converter is also used as the reference voltage source of the A / D converter. As a result, it is possible to omit a reference voltage circuit that is normally provided separately. By setting the voltage accuracy of the drive power supply to ± 1.0% or less, even when the electromotive force loss is small, it is possible to detect with high accuracy.
[0012]
In the invention which concerns on Claim 2 , 3 , the connection terminal used for electrical connection with a lead storage battery, the A / D converter which detects the terminal voltage of a lead storage battery, and converts it into a digital value, and a connection terminal are used. A constant voltage circuit that receives power from the lead storage battery and supplies operating power to at least the A / D converter, and a time constant circuit including a capacitor, the electrical connection state of the lead storage battery to the connection terminal When a lead storage battery is connected to the connection terminal, the power supply to the constant voltage circuit is started with a delay determined by the time constant circuit, and it is detected that the lead storage battery has been removed from the connection terminal. And a power supply delay circuit for immediately returning the time constant circuit to the initial state. This prevents the occurrence of sparks when connecting the lead storage battery to the connection terminal, and greatly improves safety.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a life determination apparatus according to a preferred embodiment of the present invention.
[0014]
The life determination device 10 is for determining the degree of deterioration of the battery 11 to be tested, and includes clips 12 and 13 for connecting to the positive terminal and the negative terminal of the battery 11, respectively. 13, a contact 14 of the discharge relay RY and a resistor 16 serving as a load during discharge are connected in series. A printed circuit board 20 on which a circuit portion for controlling the discharge relay RY and measuring the terminal voltage of the battery 11 to determine the deterioration state of the battery 11 is provided. Further, a light emitting diode (LED) group 17 for displaying the detection result and a printer 18 for printing the detection result are provided in the life determination apparatus 10.
[0015]
The printed circuit board 20 has a power supply delay circuit 21 and a terminal of the battery 11 for delaying the power-on on the life determination device 10 side by a predetermined time (for example, 2 seconds) when connected to the battery 11 by the clips 12 and 13. A voltage detection circuit 22 that detects a voltage (a voltage between a positive terminal and a negative terminal) and outputs a detection value as a digital value; and a central processing circuit (microprocessor) 23 that controls processing of the entire life determination apparatus 10; A voltage detection circuit 22, a central arithmetic circuit 23, a constant voltage circuit 24 that supplies operating power to the printer 18, a discharge relay control circuit 25 that controls the discharge relay RY, and a light emitting diode in response to a command from the central arithmetic circuit 23. An LED display circuit 26 that drives the group 17 and a printer control circuit 27 that controls printing by the printer 18 are provided. When the battery 11 is connected, the power supply delay circuit 21, the voltage detection circuit 22, and the constant voltage circuit 24 are connected to both ends of the battery 11 via the clips 11 and 12 in parallel with each other. Here, although each circuit on the printer board 20 has been described as a separate circuit using reference numerals 21 to 27, for example, the A / D of the voltage detection circuit 22 using a microprocessor with an A / D converter. It is also possible to realize the converter portion and the central processing circuit 23 with the same semiconductor device, or the circuits 25 to 27 and the central processing circuit 23 with the same semiconductor device.
[0016]
Here, the central processing circuit 23 will be further described. The central processing unit processes the detection voltage value (digital value) from the voltage detection circuit 22 to determine the deterioration state of the battery 11 to be tested, and also the LED display circuit 25, the discharge relay control circuit 26, and the printer control circuit. 27 is controlled. Similarly to the conventional life judging device shown in FIG. 4, this life judging device 10 also drives the discharge relay for a short time to discharge the battery 11 with a predetermined current, and detects the electromotive force loss at that time. By doing so, the deterioration state of the battery 11 is determined. At this time, since the criteria for determining the deterioration state differ depending on the battery standard (size, rated capacity, etc.), the rotary switch SW1 for battery selection is provided here, and the type of the battery 11 to be tested is input. . The central processing circuit 23 determines the deterioration state in accordance with the type of battery input through the rotary switch SW1. Similarly, the determination criterion for the deterioration state may be changed depending on the ambient temperature or whether the battery 11 is measured alone or in a vehicle-mounted state. The life determination device 10 is provided with a start button PB, and when the start button is pressed, the central processing unit 23 closes the contact 14 of the discharging relay RY for a predetermined time (several seconds or less). The discharge relay control circuit 26 is controlled.
[0017]
Next, the configuration of the power supply delay circuit 21 and the constant voltage circuit 24 will be described with reference to FIG.
[0018]
The constant voltage circuit 24 includes a very common + 5V three-terminal voltage regulator circuit REG2, and the input terminal IN of the regulator circuit REG2 is connected to the normally open contact RY1C of the relay RY1 and the clip 12. To the positive terminal of the battery 11. The common terminal COM of the regulator circuit REG2 is connected to the negative terminal of the battery 11 via the clip 13. Therefore, if the battery 11 is simply connected to the life determination device by the clips 12 and 13, power is not supplied to the constant voltage circuit 24, and the circuit such as the central processing circuit 23 is not in an operating state.
[0019]
The power supply delay circuit 21 includes a main body portion 31 of the delay circuit and a discharge circuit 32 for discharging the capacitor C7 of the time constant circuit in the main body portion 31. In the main body portion 31, a three-terminal voltage regulator circuit REG1 is provided, and power from the battery 11 is directly supplied to the input terminal IN of the regulator circuit REG1. Between the output terminal OUT and the common terminal COM of the regulator circuit REG1, the drive coil RY1A of the relay RY1 and the thyristor SCR1 are provided in series. A voltage obtained by dividing the output voltage of the regulator circuit REG1 by the resistor R2 and the resistor R12 is supplied to the gate of the thyristor SCR1. However, the resistor R12 of the common side and the capacitor C7 is connected in parallel, the time constant circuit thus these are configured.
[0020]
The output voltage of the regulator circuit REG1 is supplied to the discharge circuit 32 via another normally open contact RY1B of the relay RY1, and this output voltage is supplied to the base of the transistor TR1 via the diode D3 and the resistor R6. To be supplied. The transistor TR1 is for short-circuiting both ends of the capacitor C7 in the main body circuit 31. A resistor R11 and a capacitor C8 are provided in parallel between the connection point of the diode D3 and the resistor R6 and the emitter of the transistor TR1.
[0021]
Next, operations of the power supply delay circuit 21 and the constant voltage circuit 24 will be described.
[0022]
Assume that the capacitors C7 and C8 are both in a discharged state as an initial state and are connected to the battery by clips 12 and 13 (see FIG. 1). At the time of connection, the regulator circuit REG1 starts operating. However, since the capacitor C7 is in a discharged state, the gate voltage of the thyristor SCR1 is close to 0V, the thyristor TR1 is in a turn-off state, and the relay RY1 is not driven. The voltage from the battery is not supplied to the voltage circuit 24. Thereafter, the voltage across the capacitor C7, that is, the gate voltage of the thyristor SCR1 rises, and after a few seconds (determined by the output voltage of the regulator circuit REG1, the turn-on voltage of the thyristor SCR1, the values of the resistors R2 and R12, the capacitor C7, etc.) The thyristor SCR1 is turned on, the relay RY1 is driven, and power is supplied to the constant voltage circuit 24. At the same time, the output voltage of the regulator circuit REG1 is also supplied to the discharge circuit 32, the transistor TR1 is turned on, the charge stored in the capacitor C7 is discharged, and the gate voltage of the thyristor SCR1 is reduced to almost zero. To do. At this time, since the current flowing through the thyristor SCR1 is equal to or greater than the holding current, the thyristor SCR1 remains on.
[0023]
Here, it is assumed that the battery is removed. As a result, the output voltage of the regulator circuit REG1 drops rapidly, the relay RY1 enters a non-driven state, and the thyristor SCR1 is turned off. As a result, the constant voltage circuit 24 and the discharge circuit 32 are used for connection to the battery. It is cut off from the clip 12 (see FIG. 1). Even if the battery is reconnected due to the chattering phenomenon of the clips 12 and 13 or the like, the capacitor C7 has already been forcibly discharged. Electric power will be supplied.
[0024]
With the above operation, the current flows with a delay from the moment when the clips 12 and 13 are connected to the battery, except for the current flowing in the power supply delay circuit 21 itself and the input current to the voltage detection circuit 22 described later. Therefore, the occurrence of sparks in the clips 12 and 13 including the chattering phenomenon can be suppressed, and the safety at the time of inspection of the lead storage battery is greatly improved.
[0025]
Next, the configuration of the voltage detection circuit 22 will be described with reference to FIG. The voltage detection circuit 22 includes three resistors R41 to R43 for voltage division to be connected in series between the positive terminal and the negative terminal of the battery 11 via the clips 12 and 13 (FIG. 1), and an analog An A / D converter 40 that performs digital conversion and a Zener diode ZD1 for limiting an upper limit value of an input voltage to the A / D converter 40 are provided. Assuming that the negative electrode terminal side of the battery is the ground point, the resistor R43 is disposed on the ground point side among the series-connected resistors R41 to R43. A Zener diode ZD1 is provided between the connection point of the resistor R41 and the resistor R42 and the ground point. The connection point between the resistor R42 and the resistor R43 is connected to the voltage input terminal Vin of the A / D converter 40. The power supply terminal Vdd and the reference voltage terminal Vref of the A / D converter 40 are connected to each other, and a power supply voltage of, for example, +5 V is supplied as a drive power supply from the constant voltage circuit 24 (FIG. 1). Here, the drive power supply to the A / D converter 40 is shared with the reference voltage source, and therefore the reference voltage circuit in the conventional circuit shown in FIG. 4 is not provided.
[0026]
The Zener voltage of the Zener diode ZD1 is appropriately determined according to the rated voltage (open circuit voltage) of the lead storage battery to be tested. However, in the case of a 12V lead storage battery for passenger cars, the Zener voltage is about 16 to 18V. In the illustrated example, the voltage is 18V. When 6V lead-acid storage batteries for motorcycles and 24V lead-acid storage batteries for trucks are to be tested, Zener diodes having a Zener voltage suitable for those test objects are used.
[0027]
The digital output of the A / D converter 40 is sent to the central processing circuit 23 as described above. Here, since the input upper limit voltage is set to 18V by the Zener diode ZD1, the A / D converter 40 is operated with the voltage range of 0 to 18V being the full range.
[0028]
Hereinafter, the result of comparing the voltage detection circuit described here (referred to as an example) with the conventional voltage detection circuit shown in FIG. 4 (referred to as a comparative example) will be described. Here, assuming that the resolution of the A / D converter is 10 bits and the input voltage (before being divided by the resistor) is 12 V, the fluctuation error of the reference voltage, the voltage per 1 LSB, and the A / D converter capture The voltage (the voltage at the input terminal Vin of the A / D converter) and the measured voltage resolution were compared. The results are shown in Table 1.
[0029]
[Table 1]

According to the present invention, since the accuracy of the reference voltage is ± 0.7% (accuracy of a standard three-terminal regulator) and the adverse condition is worse than that of the conventional product, the capture voltage can be increased by about twice. In addition, the measurement voltage resolution can be reduced to about ½.
[0030]
Next, a method for detecting a deterioration state using the lifetime determination apparatus 10 will be described. First, the battery 11 to be tested is connected by the clips 12 and 13. At this time, as is apparent from the above description, no power is supplied to the constant voltage circuit 24, and the contact 14 of the discharging relay RY remains open. Generation of sparks due to the connection of the clips 12 and 13 is suppressed. When several seconds elapse after the connection by the clips 12 and 13, power is supplied to the constant voltage circuit 24 by the action of the power supply delay circuit 21, and the central processing circuit 23 and the like start operating. Next, when the start button PB is pressed, the central processing circuit 23 drives the relay RY by the discharge relay control circuit 61, closes the contact 14 for a certain time (several seconds or less), and connects the battery 11 via the resistor 16. Discharge at a predetermined current. At this time, the terminal voltage is measured by the voltage detection circuit 22 to obtain a drop voltage (reduced voltage) 5 seconds after discharge (here, the drop voltage refers to the terminal voltage of the battery during discharge). The central processing circuit 23 determines the deterioration state of the battery 11 according to the drop voltage, displays the determination result via the light emitting diode group 17, and prints it with the printer 18.
[0031]
As mentioned above, although preferable embodiment of this invention was described, this invention is not necessarily limited to the thing of said form, It can apply to the various technique for determining the deterioration state of a battery. For example, in addition to the drop voltage after a certain time after the start of discharge (for example, after 5 seconds), the recovery voltage after several seconds from the stop of the discharge is measured, and the deterioration state is determined from both the drop voltage and the recovery voltage. Good.
[0032]
【The invention's effect】
As described above, the present invention can detect the deterioration state of the lead storage battery with high accuracy even when the electromotive force loss is small as in the case of measuring the lead storage battery in the initial deterioration state while keeping the discharge current small. There is an effect that can be done. Furthermore, it is possible to prevent the occurrence of sparks when the lead storage battery is connected to the life determination device, and the safety is greatly improved.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a life determination apparatus according to an embodiment of the present invention.
FIG. 2 is a circuit diagram showing configurations of a power supply delay circuit and a constant voltage circuit.
FIG. 3 is a circuit diagram showing a configuration of a voltage detection circuit.
FIG. 4 is a block diagram showing a configuration of a main part of a conventional life judging apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Life determination apparatus 11 Battery 12, 13 Clip 16 Resistance 21 Power supply delay circuit 22 Voltage detection circuit 23 Central processing circuit 24 Constant voltage circuit 25 Discharge relay control circuit 40 A / D converter

Claims (3)

In the life determination device for detecting the deterioration state of the lead storage battery by discharging the lead storage battery at a predetermined current for a short time,
An A / D converter that detects a terminal voltage of the lead storage battery and converts it into a digital value;
Have a, a voltage limiting element that limits the upper limit voltage of the input voltage to the A / D converter,
The lead-acid battery life determination device , wherein the driving power source of the A / D converter is also used as a reference voltage source of the A / D converter . A connection terminal used for electrical connection with the lead-acid battery;
A constant voltage circuit that receives power from the lead storage battery via the connection terminal and supplies operating power to at least the A / D converter;
A time constant circuit including a capacitor; detecting an electrical connection state of the lead storage battery to the connection terminal; when the lead storage battery is connected to the connection terminal, a delay of a predetermined time determined by the time constant circuit A power supply delay circuit that starts supplying power to the constant voltage circuit and immediately returns the time constant circuit to an initial state when it is detected that the lead storage battery has been removed from the connection terminal. life determining apparatus of a lead-acid battery of claim 1, comprising. In the life determination device for detecting the deterioration state of the lead storage battery by discharging the lead storage battery at a predetermined current for a short time,
A connection terminal used for electrical connection with the lead-acid battery;
An A / D converter that detects a terminal voltage of the lead storage battery and converts it into a digital value;
A constant voltage circuit that receives power from the lead storage battery via the connection terminal and supplies operating power to at least the A / D converter;
A time constant circuit including a capacitor; detecting an electrical connection state of the lead storage battery to the connection terminal; when the lead storage battery is connected to the connection terminal, a delay of a predetermined time determined by the time constant circuit A power supply delay circuit that immediately starts supplying power to the constant voltage circuit and immediately returns the time constant circuit to the initial state when it is detected that the lead storage battery has been removed from the connection terminal. The life determination apparatus of the lead storage battery characterized by the above-mentioned.

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