JP3343155B2 - Method and apparatus for monitoring degree of deterioration of Ni-MH battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for monitoring the degree of deterioration of a Ni-MH (nickel-metal hydride) battery.

[0002]

2. Description of the Related Art Alkaline storage batteries, lead storage batteries, Ni-MH
A rechargeable battery (secondary battery) such as a battery is deteriorated by repeated charging and discharging, and when the deterioration progresses to some extent, it is no longer possible to recover the initial capacity even if the battery is charged. .

[0003] For example, in an electric vehicle that runs using this type of battery as an energy source, the performance of the battery directly affects the running performance such as the cruising distance, so that the battery deteriorates to some extent. ,
There is a high need to replace the battery or perform maintenance such as water replenishment, and it is therefore desirable to appropriately determine the degree of deterioration of the battery.

By the way, the degree of deterioration of a battery can be grasped, for example, from the capacity of the battery at full charge (the amount of electricity that can be discharged). This is because, when the battery deteriorates to some extent, even when the battery is fully charged, the capacity of the battery is reduced as compared with the initial capacity (capacity in a new state) or the rated capacity each time the battery is charged. . In fact, when performing battery life and deterioration tests,
The charging and discharging of the battery is repeated under predetermined conditions such as a charging current and a discharging current. At this time, it is customary to measure the capacity of the battery at the time of full charge at an appropriate number of times of charging and discharging.

However, when the degree of deterioration of the battery is grasped from the capacity at the time of full charge of the battery as described above,
There are the following disadvantages.

[0006] That is, when the degree of deterioration of the battery is grasped by the capacity when the battery is fully charged, it is necessary to grasp the capacity when the battery is fully charged.

In this case, as a method of grasping the capacity of the battery, one of the methods is to actually discharge the battery under predetermined conditions, measure the total discharge amount, and calculate the battery discharge amount based on the measured total discharge amount. There is a method of directly grasping the capacity of the device.

However, in general, the capacity of a battery is not only the degree of deterioration of the battery, but also the discharge current, charge current, temperature,
It changes depending on various factors such as the specific gravity of the electrolytic solution. For this reason, as described above, when the battery is actually discharged to grasp the degree of deterioration of the battery and the capacity at the time of full charge of the battery is directly grasped, various parameters such as the discharge current, the charge current, and the temperature are used. Conditions must be properly defined, and since the battery is once fully charged and then actually discharged, a great deal of time and effort is required. Further, it is practically almost impossible to directly grasp the capacity of the battery at the time of full charge in order to grasp the degree of deterioration of the battery in a battery provided in an apparatus such as an electric vehicle. .

For a battery provided in an automobile or the like, as a method of grasping the capacity of the battery, for example, as disclosed in Japanese Patent Application Laid-Open No. 1-143984, an initial state in which the capacity of the battery is known is known. From the battery, the amount of discharge and the amount of charge (time integrated amount of discharge current and charge current), the terminal voltage, the temperature of the battery, etc. are sequentially measured. It is known to obtain (remaining capacity) by analogy and indirectly grasp the capacity (remaining capacity) of the battery.

Therefore, when the deterioration degree of a battery provided in a device such as an electric vehicle is to be grasped, for example, the capacity of the battery immediately after charging of the battery is grasped as disclosed in Japanese Patent Laid-Open No. 1-139884, and It is conceivable to determine the degree of deterioration of the battery from the determined capacity.

However, when charging a battery provided in an apparatus such as an electric vehicle, the battery is not always fully charged. In such a case, the capacity of the battery immediately after charging the battery is determined. However, it is impossible to grasp the degree of deterioration of the battery.

Further, as disclosed in Japanese Patent Application Laid-Open No. 1-143984, when the capacity of the battery is grasped based on the amount of discharge, the amount of charge, the terminal voltage, the temperature of the battery, etc. Even if the capacity of the battery is grasped, the grasped capacity generally tends to fluctuate due to various factors such as the remaining capacity of the battery before charging, the charging current, and the charging time. It is difficult to grasp the degree of deterioration of the steel.

Further, as disclosed in Japanese Patent Application Laid-Open No. 1-139884, when the capacity of a battery is grasped and the degree of deterioration of the battery is grasped from the grasped capacity, a large amount of measurement data is required. The calculation process for obtaining the capacity from the measured data of
There is a disadvantage that a system for grasping the degree of deterioration of the battery becomes complicated.

In view of such a background, the present inventors have conducted various studies. As a result, particularly in the case of a Ni-MH battery, constant current charging or quasi-constant current charging of the battery can be performed without grasping its capacity. At the time of performing, it has been found that the degree of deterioration of the battery can be reliably and easily grasped from the voltage of the battery before the start of charging, the voltage of the battery after the start of charging, and the charging current to the battery.

[0015]

SUMMARY OF THE INVENTION In view of this background, the present invention makes it possible to reliably and easily grasp the degree of deterioration of a Ni-MH battery, and to further maintain the battery in accordance with the state of deterioration of the battery. It is an object of the present invention to provide a method and apparatus for monitoring the degree of deterioration, which can accurately grasp the time of replacement or the remaining capacity of the battery.

[0016]

As a result of various studies, the inventors of the present invention have found that in a Ni-MH battery, when the battery is charged by constant current charging or quasi-constant current charging, The inventors have found that the voltage of the battery increases at the same time as the start of charging, and that a value obtained by dividing the amount of increase in the voltage by the charging current value increases as the battery deteriorates. The value obtained by dividing the amount of increase in the voltage by the charging current is the value of the charging current, the remaining capacity of the battery before charging, the remaining time of the battery before charging, or the value before charging if the deterioration state of the battery is the same. It does not depend on the battery voltage. Furthermore, the value obtained by dividing the increase in the voltage of the battery during charging by the charging current varies depending on the temperature of the battery during charging, but the change has a certain correlation with the temperature of the battery during charging. I found that.

Therefore, a method of monitoring the degree of deterioration of the present invention is a method for grasping and monitoring the degree of deterioration of a Ni-MH battery in order to achieve the above-mentioned object. A step of making the charging current value substantially constant; and a difference (| V _N −V _I |) between the voltage (V _I ) before the start of charging of the battery and the voltage (V _N ) after the start of charging during the charging. And the voltage difference (| V
_N -V _I |) and a substantially constant charging current in the initial stage of the charging (I _C) and the ratio of (| _{a) | V N -V I | /} I C or _{I C} / | V _N -V I Determining the degree of deterioration of the battery based on the value of the ratio.

[0018] The method may further include a step of measuring a temperature of the battery during charging, and a step of correcting the value of the ratio in accordance with the temperature of the battery, wherein the value of the ratio is corrected in accordance with the temperature of the battery. It is characterized in that the degree of deterioration of the battery is grasped and monitored based on the value obtained.

In order to achieve the above object, a deterioration degree monitoring apparatus according to the present invention is an apparatus for grasping and monitoring the deterioration degree of a Ni-MH battery, wherein charging of the battery is performed at least in an initial stage. When the charging current value is made substantially constant, the voltage (V _I ) of the battery before the start of charging
And a voltage detecting means for detecting a voltage (V _N ) after the start of charging, and a difference (|) between the voltage (V _I ) before the start of charging and the voltage (V _N ) after the start of charging, detected by the voltage detecting means. V
_N− V _I |) and a substantially constant charging current value (I _C ) in the initial stage of charging the battery (| V _N −V _I | /
I _C or _{I C / | V N -V I} | and an arithmetic means for obtaining a), characterized in that it identifies and monitors the battery deterioration degree by the obtained values of the ratio by the computing means.

Further, a temperature detecting means for detecting a temperature at the time of charging the battery, and a temperature correcting means for correcting the value of the ratio obtained by the calculating means in accordance with the temperature of the battery detected by the temperature detecting means. Means for compensating and monitoring the degree of deterioration of the battery based on a value obtained by correcting the value of the ratio by the temperature correcting means.

Further, there is provided charging current detecting means for detecting the substantially constant charging current value (I _C ) when the battery is charged, and the calculating means includes a charging current value (I _C ) detected by the charging current detecting means. _C ) is used to determine the value of the ratio.

Further, a notifying means for notifying that the battery needs to be maintained / replaced in accordance with the degree of deterioration of the battery, which is grasped from the value of the ratio, is provided.

[0023] Also, a remaining capacity grasping means for grasping the remaining capacity of the battery, and a remaining capacity for compensating the remaining capacity grasped by the remaining capacity grasping means in accordance with the deterioration degree of the battery grasped by the value of the ratio. It is characterized by comprising a capacity correcting means and a notifying means for notifying the remaining capacity corrected by the remaining capacity correcting means.

[0024]

According to the method for monitoring the degree of deterioration of a Ni-MH battery according to the present invention, when charging the Ni-MH battery, the voltage (V _I ) before the start of charging the battery and the voltage (V _I ) of the battery after the start of charging ( difference _{V N) (| V N -V} I | and), the ratio of the charging current value substantially constant and (I _C) in the initial stage of charging _{(| V N -V I | /} I C or I _C / | V _N -V
_I |) has the value, while varying with the progress of deterioration of the battery as described above, if the deteriorated state is the same, the charging current value (I _C) and the remaining capacity of the pre-charging the battery, before charging It does not depend on the remaining time of the battery or the voltage of the battery before charging. The value of the ratio does not change if the state of deterioration is the same and the temperature at the time of charging the battery is the same.

Therefore, the value of the ratio can be determined by setting the temperature condition of the battery at the time of charging to a specific temperature, the charging current value (I _C ), the remaining capacity of the battery before charging, and the battery before charging. The parameter indicates the degree of deterioration of the battery, regardless of the idle time or the voltage of the battery, and the value can be used to determine the degree of deterioration of the battery.

In this case, as described above, if the temperature of the battery during charging is different, the value of the ratio will be different even in the same deteriorated state, but that value and the temperature of the battery during charging are different. And there is a certain correlation.

Therefore, by measuring the temperature of the battery at the time of charging, and appropriately correcting the value of the ratio according to the measured temperature, the value obtained by the correction is converted to the temperature of the battery at the time of charging. Instead, it can be used as a parameter indicating the degree of deterioration of the battery.

Next, according to the Ni-MH battery deterioration degree monitoring apparatus of the present invention, the ratio (|) obtained by the arithmetic means using the voltages (V _N , V _I ) detected by the voltage detecting means. V _N -V _I | / _{I C} or _{I C} / | V _N -V I
The degree of battery deterioration can be grasped from the value of |) in the same manner as in the method of monitoring the degree of deterioration.

Then, the value of the ratio is corrected by the temperature correction means in accordance with the temperature at the time of charging of the battery detected by the temperature detection means, and the value obtained by the correction is used as the battery at the time of charging. Can be used as a parameter indicating the degree of deterioration of the battery regardless of the temperature of the battery.

In this case, when the charging current value (I _C ) is predetermined to a predetermined value, the value of the ratio can be obtained by using the specified charging current value (I _C ). although, the charging current value (I _C) is, if not always be the same value for each charging of the battery by detecting the charge current value (I _C) by the charging current detecting means , the charging current value detection (I _C)
Is used to determine the value of the ratio.

Further, since the degree of deterioration of the battery can be grasped by the value of the ratio or a value obtained by correcting the ratio by the temperature compensating means, the maintenance / replacement of the battery is performed according to the grasped degree of deterioration. It can be notified at an appropriate timing that the need exists.

The capacity of the battery generally decreases as the battery deteriorates. Therefore, when the remaining capacity grasping means for grasping the remaining capacity of the battery is provided, the remaining capacity grasped by the remaining capacity grasping means is corrected by the ratio value or the temperature compensating means. By performing correction in accordance with the degree of deterioration ascertained based on the value, it becomes possible to report the remaining capacity in consideration of the deterioration of the battery.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One example of the present invention will be described with reference to FIGS. FIG. 1 is a system configuration diagram of a deterioration degree monitoring apparatus of the present embodiment, FIGS. 2 to 7 are diagrams for explaining a method of grasping the degree of deterioration of a battery by the deterioration degree monitoring apparatus, and FIG. FIG. 5 is an explanatory diagram for explaining how a device displays a remaining battery capacity.

In FIG. 1, 1 is a Ni-MH battery,
2 is a voltage sensor (voltage detecting means) for detecting a terminal voltage V of the battery 1; 3 is a current sensor (current detecting means) for detecting a charging / discharging current I of the battery 1;
Are temperature sensors (temperature detecting means) 5 for detecting the degree of deterioration and remaining capacity of the battery 1 based on the detection signals of the sensors 2 to 4. The battery 1 has a rated capacity of 25 Ah, for example.

A load 6 such as a motor is connected to the battery 1, and a charger 7 is detachably connectable via a connection connector 8. The charger 7 supplies a substantially constant constant current to the battery 1 at least at the initial stage of charging, and is, for example, a constant current charging type or a quasi-constant current charging type.

The controller 5 includes a CPU, a RAM, and a ROM.
The controller 5 includes the sensors 2 to 4 and a remaining capacity display 9 (remaining capacity notifying unit) for displaying the remaining capacity of the battery 1.
A warning lamp 10 (notifying means) for notifying that maintenance and replacement of the battery 1 is necessary is connected.

The controller 5 has, as a functional configuration, a deterioration degree grasping means 1 for grasping the degree of deterioration of the battery 1.
1 and a remaining capacity grasping means 1 for grasping the remaining capacity of the battery 1
2 is provided.

In this case, when the battery 1 is charged, the deterioration sensor 11 detects the voltage sensor 2 when the battery 1 is charged.
And a calculation unit 13 for performing a predetermined calculation process using the terminal voltage V and the charging current I of the battery 1 detected through the current sensor 3, and a result obtained by the calculation unit 13.
Temperature correction means 14 for correcting the temperature of the battery 1 during charging detected via the temperature sensor 4, and the degree of deterioration of the battery 1 is determined based on the result obtained through the temperature correction means 14. I try to figure it out. And
The deterioration degree grasping means 11 includes a deterioration degree judging means 11a for judging the degree of deterioration of the battery 1 based on the result obtained through the temperature correcting means 14 as described later. The lamp 10 is turned on or blinks.

The remaining capacity grasping means 12 basically includes a charge / discharge current I / I of the battery 1 detected via the current sensor 3 as disclosed in Japanese Patent Application Laid-Open No. 1-143984. , The amount of discharge and the amount of charge of the battery 1 are detected, and the amount of discharge and the amount of charge are respectively subtracted from and added to the initial capacity (capacity in a new state) of the battery 1. Is corrected according to the temperature T of the battery 1 detected via the temperature sensor 4. Then, the value obtained by the correction is sequentially grasped as the reference remaining capacity of the battery 1. In this case, in this embodiment, the controller 5 further calculates the reference remaining capacity of the battery 1 obtained as described above,
And a remaining capacity correction unit 15 for correcting the reference remaining capacity by the remaining capacity correction unit 15 as a current remaining capacity of the battery 1. The remaining capacity indicator 9 is displayed.

Next, the operation of the apparatus will be described.

In the apparatus of this embodiment, when the battery 1 is charged by the charger 7, the controller 5 determines the degree of deterioration of the battery 1.

That is, when charging the battery 1, the charger 7 is connected to the battery 1 via the connector 8, and in this state, the charger 7 is activated using a commercial power supply or the like.
, The charging current I is supplied to the battery 1. in this case,
As shown in FIG. 2 (a), the charging current I is a constant value I _C in the early stages of at least charging.

On the other hand, at the time of this charging, the deterioration degree grasping means 11 of the controller 5 uses the terminal voltage V
And the charging current I before the charging of the battery 1 is started (for example, when the charger 7 is connected).
And so as to monitor through, as shown in FIG. 2 (b), charging start (energization start of the battery 1) immediately before the terminal voltage V _I (hereinafter referred to as precharge voltage V _I) and start charging immediately the terminal voltage V _N (hereinafter, referred to as the voltage V _N after charging) was detected via the voltage sensor 2 and the charging current value I _C at a given point in time is a charging current I after the start of charging constant
Is detected via the current sensor 3. In this case, FIG.
As shown in (b), the terminal voltage V increases with the start of charging, and therefore, V _N > V _I. The change in the terminal voltage V due to the start of charging is due to the internal resistance of the battery 1.

The pre-charging voltage V _I and the post-charging voltage V _N are not necessarily detected immediately before and immediately after the start of charging. For example, the terminal voltage V before and after a predetermined time from the start of charging may be detected. May be detected.

[0045] Then, the deterioration degree of gripping means 11 of the controller 5, the voltage before charging detected as above V _I and post-charge voltage V _N, as well as the charging current value I _C, precharge voltage V _I and the charging voltage after difference V _N, i.e. obtains the amount of change in the terminal voltage V due to the charging start, the ratio R _C of the charging current value I _C by the following equation. Such calculation is performed by the calculation means 13.

R _C = (V _N −V _I ) / I _C (1) The value of the ratio R _C thus obtained indicates the internal resistance value of the battery 1 in the initial stage of charging. Yes,
Basically the deterioration degree of the battery 1, Sadamari depending on the temperature T of the battery 1 at the initial stage of the charging start time or charged, the remaining capacity before charging of the battery 1 and the charging current value I _C
It does not depend on etc. Here, such characteristics of the ratio R _C will be described with reference to FIGS.

The present inventors have conducted various experiments on the value of the ratio R _C.

Referring to FIG. 3, the inventors of the present invention set the remaining capacity of a Ni-MH battery having the same rated capacity of 25 Ah as
After performing constant-current charging, the ratio R obtained by the above equation (1)
The value of _C was measured and calculated. The result is shown in FIG. Here, two kinds of charging current values of 6 A and 30 A were used. In FIG. 3, the remaining capacity is expressed as a percentage with the fully charged capacity being 100%.

As is apparent from the figure, the value of the ratio R _C is substantially constant regardless of the value of the remaining capacity before charging.
Also, it is almost constant irrespective of the charging current value.

Next, referring to FIG. 4, the inventors of the present invention discharge or charge the above-mentioned battery to various values of the remaining capacity, and then leave the battery for an appropriate period of time. After the elapse of the standing time (rest time), the batteries with the remaining capacity of each value were charged at a constant current. Then, the terminal voltage (open terminal voltage) of the battery immediately before the start of the constant current charging was measured, and the value of the ratio _RC by the constant current charging was measured and calculated. The result is shown in FIG.
It was shown to. Here, the leaving time was of two types, long and short, for the battery having the remaining capacity of each value. The charging current value is 3
0A. In this case, as shown in FIG. 4 (b), the terminal voltage of the charged battery gradually decreases to a certain value with the lapse of the idle time. Therefore, FIG.
The lower terminal voltage of the two measurement points of the battery having the remaining capacity of each value shown in (1) corresponds to the case where the idle time is longer, and the higher terminal voltage corresponds to the case where the idle time is short.

As apparent from FIG. 4 (a), for a battery having the remaining capacity of each value, the value of the ratio _RC does not depend on the value of the remaining capacity, and, of course, the start of constant current charging. It is almost constant regardless of the terminal voltage of the battery just before,
In other words, it is almost constant irrespective of the idle time.

Next, referring to FIG. 5, the inventors of the present invention repeatedly charge / discharge the above-mentioned battery under a predetermined condition such as a charging current and a discharging current from a new state of the battery, and repeat the repetition. After an appropriate number of times (the number of cycles), the remaining capacity of the battery was set to various values, the battery was charged at a constant current, and the value of the ratio _RC was measured and calculated. Here, the charging current value was 6 A. The results are shown in FIG. 5 for a new battery and a battery after 340 cycles of charging and discharging.
It was shown to.

[0053] As is apparent with reference to the figure, in the battery after the charging and discharging of 340 cycles, the value of the ratio R _C is larger than the value of the ratio R _C of the battery of the new state and, The value of the ratio R _C is substantially constant regardless of the value of the remaining capacity before charging. Although not shown in FIG. 5,
The value of the ratio R _C increases as the number of charge / discharge cycles increases, in other words, as the battery deteriorates,
It has grown.

Next, referring to FIG. 6, the inventors of the present invention determined that the temperature of the battery at the time of charging (at the start of charging) for the above-mentioned battery in the same deteriorated state (the same number of charge / discharge cycles). With constant current charging of the battery,
The value of the ratio _RC was measured and calculated. FIG. 6 shows the result.

As can be seen from the figure, the value of the ratio R _C is almost constant when the battery temperature is in the range of 0 ° C. to 30 ° C., but is lower than 0 ° C. Then, the value of the ratio R _C increases as the temperature decreases, and in a range where the temperature is higher than 30 ° C., the value of the ratio R _C increases as the temperature increases.

From the above, the value of the ratio R _C is expressed by Ni
-MH While changing according to the degree of deterioration of the battery, it does not depend on the remaining capacity or charging current value of the battery before charging, the standing time before charging, or the terminal voltage. In addition, if the temperature of the battery at the time of charging is about room temperature, it does not depend on the temperature. Therefore, the value of the ratio R _C is basically a parameter indicating the degree of deterioration of the battery. Hereinafter, the ratio R _{C is referred} to as a deterioration degree reference parameter R _C. However, as described above, when the battery temperature during charging is relatively low or high, the value of the deterioration degree reference parameter R _C changes according to the temperature. The reason that the value of the ratio R _C does not depend on the remaining capacity before charging of the battery, the charging current value, the leaving time before charging, or the like is that the Ni-MH battery has a large influence on the value of its internal resistance. It is conceivable that the composition of the applied electrolyte does not change due to the remaining capacity or the like.

Therefore, in the present embodiment, the deterioration degree grasping means 11 of the controller 5 uses the deterioration degree reference parameter _RC obtained by the above equation (1) to detect the deterioration degree of the battery 1 detected through the temperature sensor 4. By correcting as follows according to the temperature T during charging, a parameter R independent of the temperature T is obtained.

That is, the deterioration degree grasping means 11 detects the temperature T of the battery 1 via the temperature sensor 4 at the start of charging of the battery 1 or at the initial stage of charging.
In accordance with the detected temperature T, for example, the deterioration degree reference parameter _RC is corrected by the following equation (2) to obtain a parameter R.

R = R _C / K _T (2) where K _T is a correction coefficient, the value of which is determined as follows according to the temperature T.

For T <0 (° C.), K _T = −0.02484T + 1 For 10 ≦ T ≦ 30 (° C.), K _T = 1 For T> 30 (° C.), K _T = 0.009317T + 0. 696 The value of the parameter R obtained by the equation (2) basically does not depend on the temperature T when the battery 1 is charged. In fact,
When the parameter R was calculated by the equation (2) for the value of R _C shown in FIG. 6, a substantially constant value was obtained irrespective of the temperature of the battery at the time of charging, as shown by the imaginary line in FIG. .

Accordingly, the value of the parameter R basically changes in accordance with only the degree of deterioration of the battery 1, and the degree of deterioration of the battery 1 can be grasped from the value of the parameter R. Hereinafter, the parameter R is referred to as a deterioration degree parameter R. Note that the above-described correction of the deterioration degree reference parameter R _C is performed by the temperature correction unit 14.

Here, an experiment conducted by the present inventors on the relationship between the deterioration degree parameter R and the state of deterioration of the battery will be described.

The inventors of the present invention have proposed a Ni-
The MH battery was repeatedly charged and discharged under predetermined conditions such as a charging current and a discharging current from its new state, and the full charge capacity of the battery was measured at an appropriate number of times (number of cycles). Here, in charging the battery, the charging current is 3 A and the charging time is 12 hours, and the battery is fully charged. In discharging the battery, the discharging current is 6 A and the terminal voltage of the battery is 1 V (= cut-off voltage). ). Then, at the time of the discharge, the full charge capacity of the battery was measured by integrating the discharge current with time.

In addition, in parallel with the measurement, the charge / discharge
For each appropriate number of cycles, as described above,
Data R_CMeasurement and the degradation degree reference parameter.
R _CIs corrected by the above equation (2), and the deterioration degree parameter
R was determined.

FIG. 7 shows the results of these experiments. As shown in FIG. 7, the full charge capacity of the battery is almost equal to the rated capacity (25) until the number of charge / discharge cycles reaches about 300 times.
Ah), and no significant change is observed, but it rapidly decreases when the number of charge / discharge cycles exceeds 300 times. This indicates that when the number of charge / discharge cycles exceeds 300, due to the deterioration of the battery, the battery cannot recover the initial capacity even if the battery is charged.

On the other hand, the deterioration degree parameter R gradually increases until the number of charge / discharge cycles reaches about 300. However, when the number of cycles exceeds 300, the full charge capacity of the battery is reduced. It rises sharply in response to the decrease in

As described above, the deterioration degree parameter R changes in response to the deterioration state of the battery.
The degree of deterioration of the battery can be grasped from the value of.

Incidentally, the present inventors have determined in the above experiment that
When the battery was rehydrated when the number of charge / discharge cycles reached 380, the full charge capacity of the battery was restored to a value close to the rated capacity, as shown at measurement point P in FIG. In response, the value of the deterioration degree parameter R has decreased to a value close to the new state of the battery as shown by the measurement point Q in FIG. From this, it can be seen that the deterioration degree parameter R can be used as a parameter for grasping the maintenance time such as the replacement of the battery.

As described above, the deterioration degree grasping means 11 of the controller 5, which has obtained the deterioration degree parameter R, compares the deterioration degree parameter R with a predetermined reference value by the deterioration degree judging means 11a. When the value of the parameter R becomes equal to or more than the reference value, the warning lamp 10 is turned on or blinks, thereby notifying that the maintenance or replacement of the water for the battery 1 is necessary.
In this case, as shown in FIG. 7, for example, the reference value indicates that the full charge capacity of the battery 1 is 80% of the rated capacity due to deterioration.
It is set to the value of the deterioration degree parameter R (about 16 mΩ in FIG. 7) corresponding to the case where it has decreased to. Note that the deterioration degree parameter R obtained as described above is
Is stored and held in a RAM (not shown) provided at the same time, and is updated each time the battery 1 is charged.

On the other hand, the remaining capacity grasping means 1 of the controller 5
2 indicates that the battery 1 is operated based on the time integrated value of the charging / discharging current I detected via the current sensor 3 during the operation of the apparatus of the present embodiment (when charging / discharging the battery 1). The reference remaining capacity is obtained, and the obtained reference remaining capacity is updated by the remaining capacity correction means 15 by the latest deterioration degree parameter R obtained by the deterioration degree grasping means 11 as described above.
And the value obtained by the correction is displayed on the remaining capacity display 9 as the current remaining capacity of the battery 1. In this case, the correction in accordance with the deterioration degree parameter R is determined in advance as a characteristic table based on the experimental data as shown in FIG. This is performed by subtracting the decrease in capacity obtained from the characteristic table and the latest deterioration degree parameter R from the reference remaining capacity. As described above, by correcting the reference remaining capacity according to the deterioration degree parameter R, the remaining capacity according to the deterioration state of the battery 1 can be grasped.

The remaining capacity is displayed by the remaining capacity indicator 9.
Is a bar graph using a liquid crystal or the like as shown in FIG. 8, for example.
It is performed by In the figure, the hatched bar graph
B ₁Length obtained by correcting according to the degree of deterioration of the battery 1.
Bar graph B with stippling corresponding to the remaining capacity_Twoof
The length is equivalent to the capacity decrease according to the degree of deterioration of the battery 1.
And bar graph B₁And bar graph B_TwoFor example, liquid crystal
It is displayed by a different color display or the like used. The bar graph
B₁And bar graph B_TwoThe sum of the lengths of
This corresponds to the reference remaining capacity grasped by the gripping means 12. So
Therefore, even if the reference remaining capacity is the same,
Bar graph B showing the degree of deterioration as the process progresses_Two
Of the battery 1
Bar graph B showing remaining capacity₁Becomes shorter.

As described above, according to the apparatus of the present embodiment, the deterioration degree parameter R is obtained when the battery 1 is charged, so that the deterioration degree of the battery 1 can be reliably determined by the value of the deterioration degree parameter R. Can be grasped. Then, since the deterioration degree of the battery 1 can be reliably grasped from the deterioration degree parameter R, it is necessary to accurately notify the necessity of maintenance / replacement of the battery 1 according to the value of the deterioration degree parameter R. By correcting the reference remaining capacity grasped from the charge / discharge current I of the battery 1 and the like according to the value of the deterioration degree parameter R, the battery 1
It is possible to accurately grasp the remaining capacity according to the deterioration state of the battery. Further, when obtaining the deterioration degree parameter R, the terminal voltage V, the charging current I, and the temperature of the battery 1 at the time of charging are simply detected before and after the charging of the battery 1 is started. Since the deterioration degree parameter R can be obtained by a simple calculation, the deterioration degree of the battery 1 can be grasped very easily, and the apparatus configuration for grasping and monitoring the deterioration degree of the battery 1 is simplified. be able to.

In the present embodiment, when determining the deterioration degree parameter R, the charging current value I _C in the initial stage of charging the battery 1 is detected, but the charging current value I _C is predetermined. In such a case, the value may be stored in the RAM or the like of the controller 5, and the deterioration degree parameter R may be obtained using the stored charging current value I _C. In this case, it is possible to omit the current sensor for detecting the charging current value I _C.

In the present embodiment, the deterioration degree reference parameter is used.
R_CIs corrected according to the temperature T of the battery 1 during charging.
Thereby, the deterioration degree parameter R is obtained.
However, when the temperature T of the battery 1 at the time of charging is
Or the deterioration degree reference parameter R_CBut
It is specified in a temperature range that does not change according to the temperature T.
In such a case, the deterioration degree reference parameter R_CThe
It may be used as the deterioration degree parameter R as it is.
No. For example, in the above embodiment, when charging the battery 1
Temperature T is specified in the range of 0 ° C to 30 ° C
If the correction coefficient K _TIs “1”, so the deterioration degree standard
Parameter R_CAnd the value of the degradation parameter R match
Therefore, the deterioration degree reference parameter R_CDeteriorates as it is
It can be used as the degree parameter R. And this
, The temperature sensor for obtaining the degradation parameter R
Can be omitted.

In this embodiment, the degree of deterioration of the battery 1 is
As a parameter to grasp the
The amount of change in voltage V (V_N-V_I) And charging current value I_CAnd the ratio
(V _N-V_I) / I_CBut its reciprocal I_C/ (V
_N-V_I) To determine the degree of deterioration of the battery 1.
It is, of course, possible to do so. this
If the ratio I_C/ (V_N-V_I) Is the value of battery 1
It decreases with the progress of gasification.

[0076]

As is apparent from the above description, according to the method for monitoring the degree of deterioration of a Ni-MH battery according to the present invention, the voltage (V _I ) and the charge before the start of charging of the battery when the battery is charged. The difference of the voltage (V _N ) after the start (| V _N −
V _I |) and a substantially constant charging current value (I _C ) at the initial stage of charging (| V _N −V _I | / I _C or I _C /
| V _N -V _I |)
By monitoring, the degree of deterioration of the battery can be grasped reliably and easily.

Then, the temperature at the time of charging the battery is measured, and the value of the ratio is appropriately corrected according to the measured temperature, so that the value obtained by the correction depends on the temperature of the battery at the time of charging. Therefore, the degree of deterioration of the battery can be reliably grasped from the value obtained by the correction regardless of the temperature at the time of charging the battery. Further, according to the Ni-MH battery deterioration degree monitoring apparatus of the present invention, the voltage (V _I ) before the start of charging and the voltage (V _N ) after the start of charging of the battery are detected by the voltage detecting means. According to the deterioration degree monitoring method, the deterioration degree of the battery can be reliably and easily grasped from the value of the ratio, and the configuration for grasping the degree can be extremely simplified.

Then, the temperature at the time of charging of the battery is detected by the temperature detecting means, and the value of the ratio is corrected in accordance with the detected temperature. It is possible to provide a system with a simple configuration that can reliably ascertain the degree of deterioration and that can reliably and easily ascertain the degree of deterioration of the battery.

[0079] The charging current of the battery includes a current detector (I _C) detects, by finding a value of the ratio using the detected charging current value (I _C), the charging current value ( the system can grasp and monitor the battery deterioration degree regardless of the I _C) can be provided with a simple configuration.

Further, since the degree of deterioration of the battery can be reliably grasped from the value of the ratio or the value obtained by correcting the degree of deterioration according to the temperature of the battery at the time of charging, appropriate notification means can be provided. It is possible to notify the necessity of maintenance / replacement of the battery at an appropriate timing according to the value of the ratio or its correction value.

Further, as described above, the degree of deterioration of the battery can be reliably grasped from the value of the ratio or a value obtained by correcting the ratio according to the temperature of the battery at the time of charging. When you know and inform
By knowing the remaining capacity of the battery according to the value of the ratio and its correction value, it is possible to accurately report the remaining capacity according to the state of deterioration of the battery.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a Ni-MH battery deterioration degree monitoring apparatus to which an example of the present invention is applied.

FIG. 2 is a diagram for explaining a method of ascertaining a degree of battery deterioration by the apparatus of FIG. 1;

FIG. 3 is a diagram for explaining a method of ascertaining the degree of battery deterioration by the apparatus of FIG. 1;

FIG. 4 is a diagram for explaining a method for ascertaining the degree of deterioration of a battery by the apparatus shown in FIG. 1;

FIG. 5 is a diagram for explaining a method of ascertaining the degree of deterioration of the battery by the apparatus of FIG. 1;

FIG. 6 is a diagram for explaining a method of ascertaining the degree of battery deterioration by the apparatus of FIG. 1;

FIG. 7 is a diagram for explaining a method of ascertaining the degree of deterioration of the battery by the apparatus of FIG. 1;

FIG. 8 is an explanatory diagram for explaining the display of the remaining battery capacity by the device of FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ni-MH battery, 2 ... Voltage sensor (voltage detection means), 3 ... Current sensor (current detection means), 4 ... Temperature sensor (temperature detection means), 9 ... Remaining capacity display (remaining capacity notification means), DESCRIPTION OF SYMBOLS 10 ... Warning lamp 10 (notification means), 12 ... Remaining capacity grasping means, 13 ... Calculation means, 14 ... Temperature correction means, 1
5. Remaining capacity correction means.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01M 10/42-10/48 G01R 31/36

Claims (7)

(57) [Claims] 1. Determining and monitoring the degree of deterioration of a Ni-MH battery
At least charging the battery.
In which the charging current value is made substantially constant in the initial stage of
And a voltage (V) before the start of charging of the battery during the charging.
_I) And the voltage (V _N) And the difference (| V_N-V_I
|) And the voltage difference (| V_N-V_I|) And
A substantially constant charging current value in the initial stage of the charging
(I_C) And the ratio (| V_N-V _I| / I_COr I_C/ ｜
V_N-V_I|), And the value of the ratio
Monitoring and monitoring the degree of deterioration of the battery.
A method for monitoring the degree of deterioration of a Ni-MH battery. 2. The method according to claim 1, further comprising the steps of: measuring a temperature of the battery during charging; and correcting the value of the ratio according to the temperature of the battery, wherein the value of the ratio is corrected according to the temperature of the battery. The degree of deterioration of the battery
The method for monitoring the degree of deterioration of a Ni-MH battery according to claim 1, wherein the monitoring is performed. 3. Grasping and monitoring the degree of deterioration of a Ni-MH battery.
Device for charging the battery at least.
When the charging current value is kept almost constant in the initial stage of
In addition, the voltage (V_I) And charging
Voltage after start (V_N) For detecting the voltage,
Voltage before the start of charging (V
_I) And the voltage (V_N) Difference (| V_N-V_I
|) And a substantially constant value in an initial stage of charging the battery.
Charge current value (I_C) And the ratio (| V_N-V_I| / I _CAlso
Is I_C/ | V_N-V_I|), And
Deterioration of the battery by the value of the ratio obtained by the calculating means
Ni-MH battery characterized by grasping and monitoring the degree
Deterioration degree monitoring device. 4. A temperature detecting means for detecting a temperature at the time of charging of the battery, and a temperature correcting means for correcting the value of the ratio obtained by the calculating means, wherein the value of the ratio is corrected by the temperature correcting means. 4. The Ni-MH battery deterioration degree monitoring device according to claim 3, wherein the battery deterioration degree is grasped and monitored by a value obtained by correcting the battery deterioration degree according to the battery temperature detected by the temperature detection means. 5. A charging current detecting means for detecting the substantially constant charging current value (I _C ) during charging of the battery, wherein the calculating means includes a charging current value (I _C ) detected by the charging current detecting means. 5. The deterioration monitoring apparatus for a Ni-MH battery according to claim 3, wherein the value of the ratio is obtained using _C ). 6. A notifying means for notifying that maintenance / replacement of a battery is necessary in accordance with the degree of deterioration of the battery determined by the value of the ratio.
Or the deterioration monitoring device for a Ni-MH battery according to 4. 7. A remaining capacity grasping means for grasping the remaining capacity of the battery, and a remaining capacity for compensating the remaining capacity grasped by the remaining capacity grasping means in accordance with the degree of deterioration of the battery grasped by the value of the ratio. 5. The Ni-MH according to claim 3, further comprising: a capacity correcting unit; and a remaining capacity notifying unit configured to notify the remaining capacity corrected by the remaining capacity correcting unit.
Battery deterioration monitoring device.