JP3458785B2 - Battery life determination apparatus and method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery life determining apparatus and method for determining the life of a battery in use in a battery-powered apparatus.

[0002]

2. Description of the Related Art Batteries are used in various fields and environments such as uninterruptible power supplies, solar power generation, electric vehicles, etc., and play a major role as respective power sources and power storage. Therefore, knowing the battery life is very important in each field and environment.

However, the life of the battery depends on the operating temperature,
It is not constant because it is greatly affected by conditions such as the period of use, charging voltage, state of charge, and number of discharges, and it is not easy to judge them.

Therefore, as a method of determining the life of a battery, there is known a method of determining the life by measuring an internal resistance which increases at the end of the life of the battery or when a defect occurs.

However, in the battery life determination method using this internal resistance, it is necessary to collect in advance the data of the change in the internal resistance over a long period from the state where the battery is new to the state where the battery is exhausted. .

Therefore, as a battery life determination method that does not require such data collection, a battery life determination method using a discharge voltage has been proposed. This is a method for actually determining the life by discharging for a long time with a constant load, measuring the discharge voltage, and determining the life based on the measurement result.

FIG. 6 is a flow chart showing a procedure for determining the life of the battery by actually discharging the battery under a constant load for a long time. First, in step S31, discharging of the battery is started, and at that time, measurement of discharging time is also started. Next, in step S32, it is determined whether the discharge voltage VB is higher than the discharge end voltage Ve. If it is higher, the process proceeds to step S33, and if it is lower, the process proceeds to step S35.

In step S35, a process for determining the life (external output) is performed, and the process proceeds to step S34 to end the discharge of the battery and end the process.

When the process proceeds to step S33, it is determined there whether the discharge time is longer than the determination time TE (backup time). If it is longer, the process proceeds to step S34, the battery discharge is terminated, and the process is terminated. If it is shorter, the process returns to step S32 again, and the battery voltage comparison is repeated. As a result, the discharge end voltage Ve is reached within the determination time.
When the discharge voltage VB is lower than that, the life is determined.

[0010]

However, in the conventional battery life determination method using the discharge voltage described above, the battery is discharged for the actual backup time (the time required for the backup operation performed after the life determination) in the discharge state of a constant current. Since the life is determined by the discharge, the discharge will be for a long time. Therefore, it takes a long time to charge the battery thereafter, which makes the system using the battery unusable for a long time, and has a problem that the battery life is shortened due to the long discharge. .

The present invention has been made in order to solve the above-mentioned conventional problems, and its purpose is to prevent the device from being unusable for a long period of time, without shortening the battery life, and to battery. It is an object of the present invention to provide a battery life determining apparatus and method that can easily determine the life of the battery.

[0012]

In order to achieve the above object, a feature of the invention of claim 1 is that in a battery life judging device for judging the life of a battery, it is judged whether or not the battery is in a fully charged state. If the full charge determination means and the battery is determined to be in a fully charged state, the estimated discharge current of the battery from the amount of electricity supplied to the load before the battery starts discharging for the purpose of determining the life. And a range determining means for determining whether or not the calculated predicted discharge current is within a life determinable range, and it is determined that the predicted discharge current is within a life determinable range. A discharging means for discharging a load from the battery, a timing means for measuring a discharging time from the start of discharging the battery, and a predetermined time from the start of discharging the battery. Discharge voltage Vj of the battery at the time
Voltage detecting means for detecting the temperature of the battery, the temperature detecting means for detecting the temperature T of the battery at the time when the predetermined time has elapsed, and the voltage detecting means for the first time of determining the life of the battery. Holding means for holding the discharge voltage Vj of the battery as an initial voltage Vs;
Calculating means for calculating a difference ΔV between the discharge voltage Vj of the battery detected by the voltage detecting means and the initial voltage Vs held in the holding means, the magnitude of the discharge voltage Vj of the battery, and the difference ΔV. And the temperature T
And determining means for determining the life of the battery.

According to a second aspect of the present invention, the determination means includes data indicating the battery capacity depending on the magnitude of the discharge voltage Vj of the battery and the magnitude of the difference ΔV for each temperature T, and the data obtained this time. From the magnitude of the battery discharge voltage Vj and the magnitude of the difference ΔV, the data corresponding to the temperature T of the battery detected this time is collated to obtain the current battery capacity, and the battery life is determined from this capacity. It is characterized by

According to a third aspect of the present invention, a holding means for holding the temperature detected by the temperature detecting means as Ts at the first time of judging the life of the battery for the first time, and a battery detected by the temperature detecting means. And the temperature Ts held by the holding means,
If different, a correction means for correcting the initial voltage Vs with the battery temperature T is provided, and the calculation means is provided with the initial voltage Vs.
The difference ΔV is calculated using the correction value of s.

[0015]

[0016]

According to a fourth aspect of the present invention, after determining the life of the battery, an arbitrary fixed period is counted, and when this period passes, the discharging means discharges the battery in the predetermined state to a load. The automatic judgment control means for starting the judgment of the life of the battery is provided.

According to a fifth aspect of the present invention, when a determination signal is input from the outside, the discharging means immediately discharges the load from the battery in the predetermined state even if the predetermined period has not passed. To determine the battery life. The feature of the invention of claim 6 is that
In the battery life determination method, a full charge determination process of determining whether or not the battery is in a fully charged state, and when it is determined that the battery is in a fully charged state, the battery starts discharging for life determination. A predictive calculation process of calculating a predicted discharge current of the battery from the amount of electricity supplied to the load before, and a range determination process of determining whether or not the calculated predicted discharge current is within the life determination range. If the predicted discharge current is determined to be within the life determination range by the range determination process, discharge of the battery is started, and the discharge voltage and temperature of the battery at the time when a predetermined time has elapsed from the discharge are measured. Measurement process to, and the discharge voltage measured in the measurement process as an initial voltage at the first time to determine the life of the battery for the first time,
An initial value supplementing process of holding the temperature as an initial temperature,
When the temperature measured in the measurement process and the initial temperature are different, an initial voltage correction process of correcting the initial voltage at the measured temperature, an initial voltage corrected in the initial voltage correction process and the measurement process are performed. Determination of obtaining battery life determination data by a difference calculation process of calculating a difference from the measured discharge voltage and a discharge voltage and temperature of the battery measured in the measurement process and a difference calculated in the calculation process And a process.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a battery life determining device of the present invention. The battery life determining device is added to a device that uses the battery 1 as a power supply source, and includes voltage detecting means 3 for detecting the discharge voltage of the battery 1, temperature detecting means 4 for detecting the temperature of the battery 1, detection voltage of the battery 1, An A / D converter 6 for converting the detected temperature into digital data, and a battery life determining unit 7 for reading the digital data from the A / D converter 6 and determining the life of the battery 1 are provided. The switch 2 turns on / off the connection and disconnection between the battery 1 and the load 5.

The life determining section 7 is a capacity area division diagram (described later).
Is stored in the ROM 9, the RAM 8 in which the detection results of the voltage detection means 3 and the temperature detection means 4 converted into digital values by the A / D converter 6 are recorded, and the discharge voltage difference ΔVj (t) (described later). Discharge voltage V
jt (described later) and the discharge voltage difference ΔVj (t) is represented by R
It is provided with a computing unit 10 that determines the life from a capacity region division diagram corresponding to the temperature Temp (t) recorded in the OM 9. The calculator 10 outputs the life judgment result 11 to the outside.

First, prior to a detailed description of the battery life determining operation of the present embodiment realized by using the battery life determining apparatus having the above-described configuration, the definition of the capacity area division diagram used in the present embodiment, etc. An outline of the battery discharge time prediction method of the present embodiment will be described with reference to FIGS. 3 and 5.

In the present embodiment, the battery life (state in which the battery has run out) means that the capacity of the battery 1 is 5 in the initial state.
It is defined as when it reaches 0%. FIG. 3 is an example for explaining this life. The curve of the solid line 31 in FIG. 3 shows the discharge voltage characteristic when a new battery is discharged at a constant current from the fully charged state, and the curve of the dotted line 32 shows the life. The discharge voltage characteristics when the battery is discharged at a constant current from the fully charged state are shown.

Further, Ve is a discharge end voltage, and Te
Is the time from the fully charged state of a new battery to Ve when discharged at a constant current. Also, Te / 2
Indicates half the time of Te.

Here, when the discharge voltage of a new product is used, the discharge time gradually decreases and the discharge voltage also decreases. That is, the solid line 31 in FIG. 3 changes to a dotted line 32. If the definition of the life is 50% of the initial capacity, it means that the life is reached when the discharge time becomes half of Te, that is, Te / 2, when discharged at a constant current. This also means that the life is reached when the discharge voltage reaches the discharge end voltage Ve before the time Te / 2 is reached. The end-of-discharge voltage Ve is a threshold voltage set to prevent over-discharging of the battery 1, and discharging below this voltage is not performed to protect the battery 1.

Next, a capacitance area division diagram used in this embodiment will be described. FIG. 5 is a diagram showing a capacity region division diagram. As shown in this diagram, the discharge voltage Vj when an arbitrary time has elapsed from the first measured discharge voltage Vs when the battery is fully charged. When (t), the discharge voltage V
s and the difference ΔVj (t) between the discharge voltage Vj (t) and the V
It is shown by dividing the region of the ratio of the initial capacity of the battery to the current capacity based on j (t). However, since this capacity region division diagram differs depending on the battery temperature, it is necessary for each battery temperature {Temp (t)}.

The meaning of this capacitance area division diagram will be described again with reference to FIG. FIG. 3 shows the time-dependent characteristics of the discharge voltage curve (solid line) 31 of a new battery and the discharge voltage curve (dotted line) 32 of a battery that has reached the end of its life.
The discharge was started at that time and discharged until the discharge voltage became Ve. The discharge time until the new battery reaches Ve is Te, the discharge voltage of the new battery is Vs when the time T1 has elapsed after the start of discharge, and the discharge voltage of the battery that has reached the end of life is Vj (t). Is.

Looking at the discharge voltage curves of a battery that has become new and has reached the end of its life, the discharge voltage Ve has a shorter discharge time from Te to Tc as the life has expired, and the capacity has decreased compared to the state of a new product. . In addition, since the discharge voltage is low as a whole, the discharge voltage Vs after the time T1 has elapsed after discharge drops to Vj (t) as the life ends.

Here, Vj (t) is not limited to the discharge voltage when the time T1 elapses after discharging the battery that has reached the end of life,
Assuming that the discharge voltage is when T1 elapses after discharging the battery, Vj (t) gradually decreases from Vs as the battery is used. That is, as the battery is used, the difference ΔVj (t) between the discharge voltage Vs and Vj (t) when T1 elapses after the new battery is discharged.
Means that it will gradually increase.

From the above, the discharge voltage Vj (t) after the elapse of T1 after the discharge decreases as the use period elapses as a feature of the secular change of the discharge voltage, and further, after the discharge, T1 after the discharge of the new product. The difference ΔVj (t) between the discharge voltage Vs after the passage of time and the discharge voltage Vj (t) after the passage of T1 after the discharge increases. From this, Vj (t) and ΔVj
It is understood that the life of the battery Life can be determined by using (t). This life Life
When the capacity of the battery when it is new is 100%, it is shown as a ratio.

Therefore, from the data of the secular change in the discharge voltage of the battery, the life Lif is calculated using Vj (t) and ΔV (0).
FIG. 5 shows e in the figure. FIG. 5 shows Vj vertically
(T), ΔVj (t) is plotted on the side.

From the perspective of this figure, after the start of battery discharge,
Discharge voltage Vj (t) when T1 has elapsed and ΔVj at that time
The intersection of (t) is the ratio of the current battery capacity to the new battery capacity, that is, the life Life.

In the capacity area division diagram shown in FIG. 5, the service life L
The if is divided into six areas A to F of 10 to 20 [%]. Next, this will be described. In general, the characteristics of a battery vary depending on manufacturing variations and differences in operating environment, and even batteries of the same type do not have the same performance. As a result, when a battery life determining method is constructed with a battery having a certain characteristic by the method described above and the method is applied to another battery, the determination error becomes large. Therefore, a method for absorbing the determination error due to the difference in battery performance is needed.

As a method thereof, the life Life is 10 to 20.
[%] Is divided into six areas A to F, and the life judgment is output in six stages. By so doing, it is possible to absorb the determination error due to the difference in battery performance and to determine the life of other batteries.

In this case, the area division method is 10 in this case.
Although it is set to 20%, this may be arbitrarily changed. However, if the area division is made too fine, the determination error becomes large.

Next, the battery life determination operation of the present embodiment shown in FIG. 1 will be specifically described with reference to the flowchart of FIG. First, when there is a life determination request in a certain fixed period, this life determination process is performed by determining the life in each fixed period or by acquiring the discharge voltage at the time of a power failure for a certain fixed time or longer.

The first step S of this process shown in FIG.
In step 11, first, it is determined whether or not the battery 1 is fully charged. In the full charge determination, the battery life determination unit 7 determines whether the voltage of the battery 1 measured by the voltage detection unit 3 is equal to or higher than a certain voltage. Specifically, after the measured voltage is recorded in the RAM 8, the calculator 10 compares the measured voltage with the full charge determination voltage recorded in the ROM 9 in advance. And
If the voltage of the battery 1 is equal to or higher than the full charge determination voltage, it is determined to be full charge.

If it is not determined that the battery is fully charged, the life is not determined. This is because by fixing the state of the battery 1 that is the life determination target to the fully charged state, the life determination is always performed in a constant state.

If the full charge is detected in step S11, the process proceeds to step S12. ROM used here
Although the full charge determination voltage described in No. 9 is set to 13.65 [V] in this embodiment, it can be changed if the charging environment of the battery 1 and the number of batteries are different. There is.

In step S12, it is determined whether or not the discharge current of the battery 1 is in the life determination range. First, the discharge current is calculated from the electric power supplied to the load 5 during the normal operation before the battery 1 starts the discharge for the life determination, and the calculated discharge current is set as the predicted discharge current.
Next, the predicted discharge current and the life determination area pre-recorded in the ROM 9 are compared by the arithmetic unit 10. If the predicted discharge current is within the life determination area, the discharge current of the battery 1 becomes the life determination area. Judge that there is. If it is the life determination area, the process proceeds to step S13, and if it is out of the range, the process returns to step S11 and the life determination is not performed.

Here, the reason why the discharge current is calculated before the battery 1 starts discharging is that wasteful discharging is not performed when the battery 1 is outside the life judgment range after being actually discharged. Although the discharge current is calculated from the electric power supplied to the load 5, other calculation methods may be used. The reason for determining whether or not the discharge current is within the life determination range is that if the discharge rate of the battery 1 is low, a discharge time of several minutes or more is required to reach a stable discharge current.

Step S13 is a process relating to the life judgment of the battery 1 at the time of power failure, and it is judged whether or not the power failure has occurred. When determining the life, the discharge voltage of the battery 1 must be measured, but if the battery 1 is already discharged, that is, if the battery 1 is discharged due to a backup operation during a power failure, etc. This process is performed because it is not necessary to perform the process of starting discharge.

Here, if it is determined that there is a power failure, the process proceeds to step S14, and if it is not determined that there is a power failure, the process proceeds to step S22 where the switch 2 is turned on to start discharging the battery 1, and then step S14. Go to. This allows
It becomes possible to measure the discharge voltage of the battery 1 used in the life determination.

In step S14, a timer counter Count for measuring the discharge voltage and temperature after a fixed time has elapsed.
Initialize tT and start counting. Although not shown, the timer counter CountT is incorporated in the life determining unit 7.

At step S15, the time T
It is determined whether 1 has passed. The reason why the fixed time is measured after the start of the discharge is that the battery 1 is in the charged state or the open state before the start of the discharge and has a relatively high voltage. Therefore, when the discharge is started, there is a transient change in the voltage until it becomes a stable voltage, and it takes some time until it becomes stable. Therefore, in order to measure the discharge voltage when it is stable, the time T1 is measured here. The time T1 recorded in the ROM 9 used here is the time until the battery becomes stable, and this time changes depending on the environment in which the battery is used, etc., so that it can be adjusted. When the timer counter CountT counts T1, the process proceeds to step S16.

In step S16, the discharge voltage Vj (t) of the battery 1 is detected by the voltage detecting means 3 and the temperature detecting means 4.
Measure the temperature Temp (t). The detected value is D /
It is converted into a digital value by the A converter 6 and recorded in the RAM 8.

Step S17 is a process related to the battery life determination at the time of power failure, and it is determined whether or not a power failure has occurred. If the life is judged at the time of power failure,
Since it is not necessary to terminate the discharge in the subsequent processing, it is determined in this processing whether a power failure has occurred. If a power failure has occurred, the process proceeds to step S18. If no power failure has occurred, the process proceeds to step S23, and the switch 2
Is turned off to end the discharge of the battery 1, and then the process proceeds to step S18. Since the discharge voltage of the battery 1 for life determination is measured in step S16, the discharge for life determination is terminated here.

In step S18, it is determined whether this life judgment is the first (first) life judgment of the battery 1. If it is the first life determination, the process proceeds to step S24. If it is not the first life determination, the process proceeds to step S19.

The reason why it is determined whether or not it is the first life judgment here is to obtain Vs necessary for calculating ΔVj (t) used in the life judgment and the temperature Temps for correcting the Vs. Is. Since the life judgment is performed while watching the change from the initial state, the first life judgment,
In other words, the initial state (state where the battery is new) is RAM8
Should be recorded in.

In step S24, in order to record the state of the battery 1 for the first time, the measured Vj (t) is recorded in the RAM 8 as Vs and the Temp (t) is recorded in the RAM 8, and then the process proceeds to step S19.

In step S19, the measured temperature Te
Temperature Temps when mp (t) and initial Vs are measured
To determine if they are equal. If they are equal, step S2
If not equal to 0, the process proceeds to step S25.

Here, the reason for determining the temperature will be described with reference to FIG. As shown in FIG. 4, when the temperature of the discharge characteristic of the battery 1 is high, the discharge characteristic becomes 41, and the discharge time is long and the discharge voltage is high. When the temperature is low, the discharge characteristic becomes 42, and the discharge time is short,
The discharge voltage is also low. Therefore, if the temperature at the time of measuring Vs and the temperature at the time of subsequent life determination are different, ΔVj
Vs, which is the reference when calculating (t), cannot be used as it is. Therefore, the temperature is determined in step S19, and if they are not equal, the process proceeds to step S25 for correcting Vs.

In step S25, a process of correcting Vs is performed. In the correction, the ratio of Vs at each temperature is obtained in advance and recorded in the ROM 9, and this ratio is used for Vs.
To correct.

In step S20, ΔVj (t) used in the life judgment is calculated. This calculates the difference between Vs and Vj (t) recorded in the RAM 8, and the result is Δ
It is recorded in the RAM 8 as Vj (t).

In step S21, Vj (t) and ΔVj which are obtained in the above processing and are recorded in the RAM 8 are recorded.
The life Life is acquired from (t) and Temp (t). The acquisition method is Temp stored in ROM9.
A capacitance area division diagram corresponding to (t) is selected, and the life Life is obtained from the division area of the intersection of Vj (t) and ΔVj (t) in this capacitance area division diagram. For example, when the intersection point reaches the area D in FIG. 5, the life Life is 50 to 70% of the battery capacity of a new battery. At that time,
The obtained life determination result 11 is output from the life determination output unit. The life determination result 11 thus output is used as replacement information for the battery 1, and the battery 1 can be replaced at an appropriate time.

In step S21, the service life Li of the battery 1
After acquiring fe, the process proceeds to step S26, where the life determining unit 7 determines whether or not an arbitrary fixed period (for example, one week or one month later) has elapsed, and if so, the process returns to step S11, Next, the operation of determining the life Life of the battery 1 is started.

If, in step S26, an arbitrary fixed period has not elapsed, the life determining section 7 determines in step S27 whether or not there is a manual determination signal input from the outside. Returning to step S11, the operation of determining the life Life of the battery 1 is started. The manual judgment signal input from the outside is for forcibly starting the life judgment of the battery 1 at an arbitrary time.

If there is no manual determination signal, step S2
The process returns to step 6 and waits for the lapse of an arbitrary fixed period or the input of a manual determination signal.

As described above, in the present embodiment, in the device supplied with the electric power from the battery 1, the voltage Vj (t) and the temperature Temp (t) of the battery 1 after T1 time has elapsed from the start of discharging the battery 1. ), This Vj
The difference ΔV between (t) and the initial voltage Vs when the first life is established
By comparing j (t) with the capacity area division diagram corresponding to the temperature of the battery 1 at that time, the life L of the battery 1 is
The if can be determined.

Moreover, since this determination does not require a long time, the life of the battery 1 can be determined without making the apparatus unusable for a long time and without shortening the life of the battery 1. .

Further, it is not necessary to collect the data necessary for the judgment in advance, and the life of the battery 1 can be judged very easily and in a short time.

[0061]

As described in detail above, according to the inventions of claims 1 to 4 and 8, the discharge voltage, temperature and capacity region division diagram of the battery at one time point after a certain time has passed from the start of discharge of the battery. By using, it is possible to easily determine the life of the battery without making the device unusable for a long time and without shortening the battery life.

According to the fifth aspect of the present invention, when the predicted discharge current is not within the life judgment area, the life judgment is not performed to prevent wasteful battery discharge. According to the invention of claim 6, the life of the battery can be automatically determined at regular intervals.

According to the invention of claim 7, at any time,
It is possible to determine the life of the battery.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a battery life determination device of the present invention.

FIG. 2 is a flowchart showing a battery life determination operation procedure of the device shown in FIG.

FIG. 3 is a discharge voltage characteristic diagram of a new battery and a battery that has reached the end of its life.

FIG. 4 is a discharge characteristic diagram showing the change over time of the discharge voltage of the battery with temperature as a parameter.

5 is a diagram showing a capacity area division diagram recorded in the ROM shown in FIG. 1;

FIG. 6 is a flowchart showing a conventional battery life determination operation procedure.

[Explanation of symbols]

1 battery 2 Switching switch 3 Voltage detection means 4 Temperature detection means 5 load 6 A / D converter 7 Battery life determination unit 8 RAM 9 ROM 10 arithmetic unit

Claims (6)

(57) [Claims] 1. A battery life determining device for determining the life of a battery, comprising full charge determining means for determining whether or not the battery is in a fully charged state, and determining that the battery is in a fully charged state. In this case, a predictive calculation unit that calculates a predicted discharge current of the battery from the amount of electricity supplied to the load before the battery starts discharging for the purpose of determining the life, and the calculated predicted discharge current can determine the life. A range determining means for determining whether or not the range is within the range, a discharging means for discharging the load from the battery to the load when it is determined that the predicted discharge current is within a life determining range, and a discharge start for the battery And a voltage detecting means for detecting a discharge voltage Vj of the battery when a predetermined time has elapsed from the start of discharging the battery, The temperature detecting means for detecting the temperature T of the battery at the time when the predetermined time of the battery has passed, and the discharge voltage Vj of the battery detected by the voltage detecting means for the first time of determining the life of the battery for the first time. Holding means for holding the voltage Vs, calculating means for calculating a difference ΔV between the discharge voltage Vj of the battery detected by the voltage detecting means and the initial voltage Vs held by the holding means, and discharging of the battery A battery life determining device comprising: a determining unit that determines the life of the battery from the magnitude of the voltage Vj, the magnitude of the difference ΔV, and the temperature T. 2. The determination means, data indicating the battery capacity depending on the magnitude of the discharge voltage Vj of the battery and the magnitude of the difference ΔV for each temperature T, and the discharge voltage of the battery obtained this time. The magnitude of Vj and the difference Δ
The battery life is judged from the capacity of the current battery by comparing the data corresponding to the temperature T of the battery detected this time with the data from the magnitude of V to determine the battery life. Battery life determination device. 3. A holding means for holding the temperature detected by the temperature detecting means as Ts at the first time of judging the life of the battery for the first time, a battery temperature T detected by the temperature detecting means and the holding means. Is compared with the temperature Ts held by, and if different, the initial voltage Vs at the battery temperature T
A correction means for correcting the difference is provided, and the calculation means calculates the difference ΔV using a correction value of the initial voltage Vs.
The battery life determination device described. 4. The life of the battery is measured after the battery life is determined, and an arbitrary fixed period is timed, and when this period has elapsed, the discharging means discharges the load from the battery in the predetermined state. 4. The battery life determination device according to claim 1, further comprising an automatic determination control means for starting the determination of. 5. When a determination signal is input from the outside, the battery in the predetermined state is immediately discharged to the load by the discharging means even if the arbitrary fixed period has not passed, and the battery life is extended. The battery life determination device according to claim 4, wherein the determination is started. 6. A full charge determination process for determining whether or not the battery is in a fully charged state, and when it is determined that the battery is in a fully charged state, the battery starts discharging for life determination. A predictive calculation step of calculating a predictive discharge current of the battery from the amount of electricity previously supplied to the load, and a range determination step of determining whether or not the calculated predictive discharge current is within a life determination range. When it is determined by the range determination process that the predicted discharge current is within the life determination range, the discharge of the battery is started, and the discharge voltage and temperature of the battery at the time when a predetermined time has elapsed from the discharge are measured. The discharge voltage measured in the measurement process is set as an initial voltage and the temperature is held as an initial temperature in the measurement process and the first determination of the life of the battery. An initial value correction process, an initial voltage correction process of correcting the initial voltage at the measured temperature when the temperature measured in the measurement process is different from the initial temperature, and an initial voltage corrected in the initial voltage correction process. Battery life based on a difference calculation process for calculating the difference between the voltage and the discharge voltage measured in the measurement process, and the discharge voltage and temperature of the battery measured in the measurement process and the difference calculated in the calculation process. A battery life determination method comprising: a determination process of obtaining determination data;