JPH0974610A - Battery overcharge prevention device for electric vehicles - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a battery overcharge prevention device for an electric vehicle capable of preventing damage to the battery due to overcharge. A battery 10 that can be repeatedly used by charging and a charging device 2 that charges the battery 10.
0, abnormality detecting means 30 and 40 provided on the wall surface of the battery case of the battery 10 for detecting abnormality of the battery, and when the abnormality detecting means 30 and 40 detect abnormality of the battery 10, the charging current of the charging device 20 is limited. Charging control means 50 for

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery overcharge prevention device for an electric vehicle.

[0002]

[Related Art] In recent years, exhaust gas regulations for internal combustion engines have become stricter due to environmental problems, and many new technologies have been researched and developed in order to comply with these regulations. One of such new technologies is an electric vehicle. This electric vehicle has no exhaust gas and has great expectations as a next-generation vehicle.

An electric vehicle is driven by an electric motor, which is basically powered by a battery. Since driving of such an electric vehicle requires a very large amount of energy, it is desired to employ a battery having a high energy density as a battery for supplying power to the electric motor of the electric vehicle. As a battery that meets such a demand, for example, a high energy density,
The adoption of nickel-hydrogen storage batteries is under consideration.

A typical nickel-metal hydride storage battery mounted on an electric vehicle is formed as a module having a rectangular parallelepiped outer shape as a whole by connecting a plurality of rectangular parallelepiped single cells 11 as shown in FIG. To be done. Here, the single cell 11 is formed by stacking a plurality of nickel positive electrode plates 12a and hydrogen storage alloy electrode plates (negative electrode plates) 12b in a rectangular parallelepiped resin case 13 with a separator 12c interposed therebetween. The formed electrode plate group 12 is housed together with an alkaline electrolyte and is hermetically formed by a lid 14 having a positive electrode terminal 14a and a negative electrode terminal 14b. still,
The respective unit cells 11 are electrically connected to each other and have a structure capable of securing a required electric power.

By the way, when charging the above nickel-hydrogen storage battery, it is desirable to avoid overcharging as much as possible. This overcharging is to continue charging even after the charge is over, and when such overcharging is performed, the charging energy becomes heat and is released.
The battery will generate heat abnormally. When the nickel-hydrogen storage battery generates heat and is exposed to a high temperature as described above, the battery capacity is reduced, and the battery is deteriorated to have a shorter life. Therefore, the battery needs to be replaced in a short period of time. For this reason, it is not preferable for the nickel-hydrogen storage battery to be in a high temperature state, and it is particularly desirable to avoid overcharging as much as possible during charging.

A method of avoiding overcharge during charging is as follows.
Since the nickel-hydrogen storage battery has the characteristic that the battery temperature rises when overcharged as described above,
Temperature-controlled charging, which detects the battery temperature, determines that the battery has entered the overcharge region when the temperature becomes equal to or higher than a predetermined value, and terminates the charging, is generally adopted. Here, although it varies depending on the charging condition, in the charging of the nickel-hydrogen storage battery, normally, the temperature-controlled charging that stops the charging when the temperature of the battery surface becomes 45 ° C. or higher is performed.

[0007]

By the way, in the case of the temperature-controlled charging, external influences such as the influence of the outside temperature, the heat generation due to the internal resistance of the battery itself, the heat generation due to the contact failure of the terminal, the heat generation due to the flow of a large current, etc. Due to such factors, it may not be possible to accurately grasp the heat generated by charging the battery.

For example, when the outside air temperature is low, the surface temperature of the battery may not reach a predetermined value (45 ° C.) or more even after the charging is completed. In such a case, the charging current continues to be supplied even after the charging is completed, so that the battery is overcharged. On the other hand, when the outside air temperature is high, or when the battery is generating heat due to the internal resistance of the battery or is generating heat due to the flow of a large current, the temperature of the battery surface has reached the predetermined value (45 ℃) or higher. In such a case, the charging current is stopped even though the charging is not completed. Then, of course, the battery becomes insufficiently charged.

As described above, the conventional temperature-controlled charging is easily affected by external factors, so it may not be possible to accurately determine whether or not the battery is actually overcharged. In addition, in the nickel-hydrogen storage battery, when charging and discharging are repeated for several cycles (200 to 300 cycles), between the individual cells that form the nickel-hydrogen storage battery,
The capacity may vary.

As described above, when a nickel-hydrogen storage battery having a variation in capacity is charged, a single cell with a reduced capacity will have an initial capacity until the surface temperature of the battery exceeds a predetermined value. Similarly, the charging current is applied to the single cell that maintains. In this case, charging unbalance occurs between the unit cells, and there are cells that are in an overcharged state or cells that have not reached full charge. That is, in order to avoid overcharge, even if the battery as a whole is charged at a predetermined value (45 ° C.) or less, a single cell may be overcharged.

As described above, the battery temperature is the predetermined value (45
Even if the temperature is less than or equal to ℃), the battery may be overcharged due to the influence of the outside temperature and the variation in capacity. Here, the nickel-hydrogen storage battery has a characteristic that the positive electrode and the negative electrode in the single cell expand when overcharged due to the above reasons, and such overcharge progresses and excessive Further, if the positive and negative electrode plates expand, the battery case may be damaged and the electrolytic solution inside may leak out.

An object of the present invention is to provide an overcharge preventing device for an electric vehicle battery, which can solve the above-mentioned problems in the electric vehicle battery and prevent damage to the battery due to overcharging.

[0013]

In order to achieve the above object, the present invention provides a battery that can be repeatedly used by charging, and a charging device that charges the battery.
An abnormality detecting unit provided on a wall surface of the battery case of the battery for detecting an abnormality of the battery, and a charging control unit for limiting a charging current of the charging device when the abnormality detecting unit detects an abnormality of the battery. An overcharge prevention device for an electric vehicle battery is provided.

When the battery is charged, the overcharge prevention device determines that the battery is in an overcharged state when detecting an abnormality in the battery, and limits the charging current at that time. According to claim 2 of the present invention, in the overcharge preventing device for an electric vehicle battery according to claim 1,
In the charge control means, the detection value of the abnormality detection means is the first
Is stopped when the detected value is equal to or less than a second predetermined value lower than the first predetermined value, and the charging is restarted.

According to another aspect of the present invention, there is provided an overcharge prevention device, wherein when charging the battery, when the detected value of the abnormality detecting means becomes equal to or higher than the first predetermined value, the battery is charged due to overcharge or heat generation due to internal resistance. Judge that it is in an abnormal state. Then, in order to return the battery to a normal state,
At that point, charging is stopped once. After that, when the detected value becomes equal to or lower than the second predetermined value which is lower than the first predetermined value, charging is started again.

According to a third aspect of the present invention, in the overcharge preventing device for a battery for an electric vehicle according to the first aspect, the charge control means is configured to detect when the detection value of the abnormality detection means is equal to or more than a first predetermined value. Provides a charging current which increases the charging current when the detection value of the abnormality detecting means becomes equal to or lower than a second predetermined value which is lower than the first predetermined value. The overcharge prevention device according to claim 3 is in an abnormal state of the battery due to factors such as overcharge or heat generation due to internal resistance when the detection value of the abnormality detection means becomes equal to or higher than a first predetermined value during battery charging. It is judged that it is placed in. Then, in order to return the battery to the normal state, the charging current is once reduced at that time. After that, when the detected value becomes equal to or lower than a second predetermined value lower than the first predetermined value, the charging current is increased to return to the current value before the reduction.

According to a fourth aspect of the present invention, in the electric vehicle battery overcharge prevention device according to the second or third aspect, the abnormality detecting means includes at least a temperature detecting means for detecting the temperature of the battery. Is provided. The overcharge prevention device according to claim 4, when charging the battery, detects the temperature of the battery case wall surface of the battery by the temperature detecting means, and when the temperature becomes equal to or higher than a first predetermined value, overcharge Alternatively, it is determined that the battery is in a high temperature state due to factors such as heat generation due to internal resistance. Then, since it is not preferable to expose the battery to high temperature, the charging is once stopped or the charging current is reduced in order to lower the temperature. After that, when the temperature of the battery decreases and the temperature of the battery becomes equal to or lower than a second predetermined value, charging is started again or the charging current is increased to return to the current value before the reduction.

According to a fifth aspect of the present invention, in the electric vehicle battery overcharge prevention device according to the second or third aspect, the abnormality detecting means detects the deformation amount of the battery case wall surface of the battery. What is provided is characterized in that it comprises detection means. In the overcharge prevention device according to claim 5, when the battery is charged, the deformation amount detecting means detects the deformation amount of the battery case wall surface of the battery, and the battery is in the overcharge state based on the deformation amount. If it is in the overcharged state, the charging is controlled at that time.

Further, according to a sixth aspect of the present invention, the abnormality detecting means in the overcharge preventing device for an electric vehicle battery according to the fourth aspect further includes a deformation amount detecting means for detecting a deformation amount of a battery case wall surface of the battery. Is provided. The overcharge prevention device according to claim 6 is provided with temperature detection means and deformation amount detection means as abnormality detection means, and when charging the battery, the overcharge prevention device is determined from the temperature of the battery and the deformation amount of the battery case wall surface. Determine if the battery is overcharged.

Incidentally, in the overcharge prevention device according to claim 6,
If the electrode expands and the wall surface of the battery case is deformed, the battery is directly damaged. Therefore, even if the charge control is performed such that the charging is stopped when the deformation amount of the battery becomes equal to or more than the first predetermined value. I do not care. According to a seventh aspect of the present invention, in the electric vehicle battery overcharge prevention apparatus according to the first aspect, the charging control means includes a battery abnormality warning means for warning the abnormality of the battery, There is provided a device which, when the detected value is equal to or higher than the first predetermined value, stops the charging current and operates the battery abnormality warning means to issue an abnormality warning.

The overcharge prevention device according to claim 7 is provided with a battery abnormality warning means, and when the abnormality detection means detects an abnormality of the battery when charging the battery, the battery is brought into an overcharged state. It is determined that there is, and at that time, the charging current is stopped and the battery abnormality warning means is activated to warn the driver of the battery abnormality.

As the abnormality detecting means in the overcharge prevention device according to claim 7, at least one of a temperature detecting means for detecting the temperature of the battery and a deformation amount detecting means for detecting the deformation amount of the battery case wall surface. Is adopted. For this reason, when the temperature of the battery rises abnormally and exceeds a specified value, or when the battery case wall surface deforms abnormally and the amount of deformation exceeds a specified value, or when the temperature and amount of deformation It is determined that the battery is in an overcharged state when both of them have exceeded a predetermined value. Then, at this point, the charging current is stopped and an abnormality warning is given. Examples of the battery abnormality warning means for warning the abnormality of the battery include a warning lamp and an alarm.

Further, placing the battery in a high temperature state
Since it causes deterioration of the battery, it is preferable to cool the battery during charging. Therefore, in the overcharge prevention device according to the present invention as described above,
When the temperature detecting means detects a temperature equal to or higher than a predetermined value,
It is preferable to have a configuration including a cooling means for cooling the battery. With such a configuration, when the temperature of the battery becomes equal to or higher than a predetermined value, the battery can be cooled by the cooling means.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an overcharge preventing device for an electric vehicle battery according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of an electric vehicle battery overcharge prevention device 1 according to the present invention.

The overcharge prevention device 1 includes a battery 10, a charging device 20 for charging the battery 10, a deformation amount detecting means 30 for detecting the deformation amount of the battery 10, and a battery 10.
Temperature detecting means 40 for detecting the temperature of the battery, and charging control means (hereinafter referred to as C / U) 50 for controlling the charging device.
And an abnormality warning means 60 for warning the abnormality of the battery 10.
And a cooling means 70 for cooling the battery 10.

The battery 10 is a device for supplying electric power to the traveling motor of the electric vehicle in order to drive the traveling motor. As the battery 10, for example, a nickel-hydrogen storage battery, which has a higher energy density than a conventional lead storage battery and is suitable for driving an electric vehicle, is used. As the nickel-hydrogen storage battery 10, the same nickel-hydrogen storage battery as conventionally used is adopted, and as shown in FIG.
A plurality of rectangular parallelepiped single cells 11 are connected to each other to form a nickel-metal hydride storage battery module. Here, the resin battery case 13 is preferably made of polypropylene because it is easy to detect the amount of deformation and has a required strength.

The charging device 20 is a device for injecting a charging current into the battery 10, and may be one conventionally used. The deformation amount detecting means 30 detects the positive electrode plate 12 in the single cell 11 when the battery is in an overcharged state.
a and the negative electrode plate 12b expand, and the battery case 13 also expands accordingly, so that the battery case 13 at that time
The amount of deformation of is detected.

As this deformation amount detecting means 30, a strain sensor capable of detecting the deformation amount of the battery case 13 as strain is used. The strain sensor 30 is installed in the battery case 13 at a location where it is easy to detect the amount of deformation. As such a place, for example, the battery case 1
Of the three wall surfaces, the electrode plate 1 located on the outermost side of the electrode plate group 12
It is preferable that the central portion of the wall surface 13a, which is a portion facing 2b, be substantially centered. The strain sensor 30 is preferably installed in the resin-made battery case case 13 of each single cell 11, but if installation is difficult due to problems such as wiring, the single cell located in the center of the nickel-hydrogen storage battery 10 will be described. In the gap between 11a and 11b, it may be installed only on the wall surface on the single cell 11a side.

The temperature detecting means 40 is used for the battery 1 being charged.
The temperature of the battery case wall surface of 0 is detected, and for example, a temperature sensor is used. It is preferable that the temperature sensor 40 be installed in each battery case 13 like the strain sensor 30, but if it is difficult to install the temperature sensor 40 due to a problem such as wiring, the temperature sensor 40 is located substantially in the center of the nickel-hydrogen storage battery 10. Cell 11
You may make it install only in the side surface 13b which faces the outer side of a.

The C / U 50 includes an input / output device (not shown), a storage device containing a control program, a central processing unit,
It is provided with a timer counter and the like, and controls charging of the battery 10. On the input side of the C / U 50, a strain sensor 3 for detecting the amount of deformation of the battery case 13 of the battery 10
0 and a temperature sensor 40 that detects the surface temperature of the battery are connected. In addition to the charging device 20, a warning lamp 60 and a cooling fan 70, which will be described later, are connected to the output side of the C / U 50.

The C / U 50 senses the output voltage of the strain sensor 30 and the output voltage of the temperature sensor 40, and when the output voltage of the temperature sensor 40 exceeds a predetermined value or when the output voltage of the strain sensor 30 exceeds a predetermined value. Then, the control is performed to limit the charging current flowing from the charging device 20 to the battery 10. The C / U 50 also turns on the warning lamp 60 when the strain sensor 30 detects expansion of the case 13 of the battery 10. Further, the C / U 50 operates the cooling fan 70 to cool the battery 10 when the temperature sensor 40 detects that the temperature of the battery 10 exceeds a predetermined value.

The abnormality warning means 60 is means for displaying a warning to the driver that the battery 10 has expanded due to overcharging. For example, a warning lamp provided in the instrument panel, an alarm for issuing a warning sound, and the like are provided. can give. The abnormality warning means 60 may give a warning that the battery 10 is in an abnormal state even when the temperature of the battery 10 rises abnormally.

The cooling means 70 has a high temperature due to external factors such as overcharging or heat generation due to internal resistance.
It cools 0, and examples thereof include a cooling fan. Next, the operation procedure of the overcharge prevention device 1 will be described with reference to the flowchart of FIG.

When the driver turns on the charging device, first, in step S1, the C / U 50 determines whether or not the charging of the battery 10 is completed. It should be noted that the completion of charging is determined by measuring the terminal voltage of the battery and using that value. If this determination is Yes, the charge control subroutine is ended. On the other hand, in the case of No, a predetermined charging current is supplied to the battery 10 in step S2. Then, step S3
Then, the output voltage of the temperature sensor 40 is sensed to detect the temperature of the battery 10. Then, in step S4, the temperature of the battery 10 is the first predetermined temperature (for example, 45 ° C.).
It is determined whether or not the following. If this determination is Yes, the charging is further continued in step S5. Then, the deformation amount of the case 13 of the battery 10 is detected by sensing the output voltage of the strain sensor 30, and step S
At 6, it is determined whether the deformation amount is equal to or less than a predetermined value, that is, whether the battery 10 is inflated. This judgment is N
In the case of o, the battery has not expanded and is in a normal state, so the process returns to step S1 and it is determined whether or not the charging is completed. Then, if the charging is completed, the charging control subroutine is ended, and if the charging is not completed, the charging control subroutine is repeatedly executed again.
On the other hand, if the determination in step S6 is Yes, the battery 10 is in an overcharged state and the battery case 13 is inflated, so charging is stopped in step S7. Then, in step S8, the warning lamp 60 is turned on to warn the driver of the overcharged state, and then the charging control subroutine is ended.

If the determination in step S4 is No, the battery temperature is 45 ° C. or higher due to external factors such as overcharging, the influence of the outside air temperature, heat generation due to internal resistance, or heat generation due to the flow of a large current. Therefore, in order to lower the battery temperature, the charging current is limited in step S9. Further, in step S10, the cooling fan 70 is operated to accelerate the temperature decrease of the battery 10 that has generated heat.
After that, in step S11, it is determined whether or not the temperature of the battery has dropped to a second predetermined value (for example, 30 ° C.) or less. In the case of this determination being No, the procedure returns to Step S11, and again it is determined whether or not the temperature of the battery has dropped below the second predetermined value. On the other hand, in the case of Yes, the process returns to step S1 and it is determined whether or not the charging is completed. If this determination is No, the charging is not completed and the temperature of the battery 10 exceeds the first predetermined value (45 ° C.).
It can be seen that this is due to the external factors. In this case, the process proceeds to step S2, the charging current is supplied again, and this charging control subroutine is repeatedly executed until the charging is completed. On the other hand, when the determination in step S2 is Yes and charging is completed, the battery 10 is charged to the predetermined value (45
It can be seen that the reason why the temperature was above (° C) was due to overcharge. That is, in this state, the charging is completed, so the charging control subroutine ends.

Here, when the charging current is limited in step S9, the battery temperature becomes equal to or lower than the second predetermined value in step S11, and it is determined in step S1 that the charging is not completed, the subsequent step S2. In the present invention, when flowing the charging current again, as a method of limiting and restarting the charging current, for example, the charging current is stopped and the current is supplied again.
On / off control or a method of reducing the charging current and then returning the current value to the value before the reduction is adopted.

As described above, the charging control subroutine is repeatedly executed until the charging of the battery 10 is completed or the expansion of the battery case of the battery is detected. As described above, in the overcharge prevention device for an electric vehicle of the present invention, the temperature sensor detects the temperature, the charging status of the battery is grasped from this temperature, and charging is performed while preventing the battery from being overcharged. Can be expired. Furthermore, the strain sensor keeps track of the deformation state of the battery, and even if the battery expands due to overcharging at a temperature below a certain temperature due to variations in capacity, etc., it is possible to detect that an abnormality has occurred in the battery. be able to. For this reason, a predetermined value (4
The expansion of the battery due to overcharging that progresses even at a temperature of 5 ° C. or less can be detected at an early stage, and the battery can be replaced before it is damaged.

Although only the nickel-hydrogen storage battery has been described in the present invention, the overcharge prevention device of the present invention can be used for preventing overcharge of other storage batteries such as conventional lead storage batteries and lithium storage batteries. I do not care.

[0039]

According to the first aspect of the present invention, the overcharge preventing device for an electric vehicle battery is provided with an abnormality detecting means for detecting an abnormality of the battery when the battery is charged. Limits charging current when detected. Therefore, it is possible to prevent the battery from becoming abnormal and causing inconvenience such as damage.

According to a second aspect of the present invention, there is provided an overcharge preventing device for an electric vehicle battery, which is overcharged or generates heat due to internal resistance when the detected value of the abnormality detecting means exceeds a first predetermined value during battery charging. It is determined that the battery is in an abnormal state due to a factor. Then, in order to return the battery to the normal state, the charging is once stopped at that time. Then, the second detected value is lower than the first predetermined value.
When it becomes less than or equal to the predetermined value of, charging is started again. Therefore, due to an external factor, the charging is restarted even when the battery is not actually charged, so that the maximum capacity of the battery can be charged.

According to another aspect of the present invention, there is provided an overcharge prevention device, wherein when charging the battery, when the detected value of the abnormality detecting means becomes equal to or higher than the first predetermined value, the battery is charged due to overcharge or heat generation due to internal resistance. Judge that it is in an abnormal state. Then, in order to return the battery to a normal state,
At that point, the charging current is once reduced. After that, when the detected value becomes equal to or lower than a second predetermined value lower than the first predetermined value, the charging current is increased to return to the current value before the reduction. For this reason, even if the battery is not actually charged due to an external factor, charging is restarted, so that the battery can be charged to the maximum capacity.

In the overcharge prevention device for a battery for an electric vehicle according to a fourth aspect of the present invention, the temperature of the battery is the first when charging the battery.
When it exceeds the specified value of, charging is stopped at that point,
Then, when the temperature of the battery decreases and the battery temperature becomes equal to or lower than the second predetermined value, charging is started again.
Therefore, the temperature of the battery rises due to external factors such as the influence of the outside air temperature, heat generation due to internal resistance, heat generation due to the flow of a large current, and the like, even if the battery is not actually charged. Since the charging is restarted, the battery can be charged to the maximum capacity.

In the overcharge prevention device of the fifth aspect, when the battery is charged, the deformation amount detecting means detects the deformation amount of the battery case wall surface of the battery. It is possible to detect that the case has expanded. The overcharge prevention device according to claim 6 is provided with temperature detection means and deformation amount detection means as abnormality detection means, and when charging the battery, the overcharge prevention device is determined from the temperature of the battery and the deformation amount of the battery case wall surface. Determine if the battery is overcharged. Therefore, it is possible to detect the overcharge of the battery more accurately, limit the charge before the battery is damaged, and avoid the inconvenience that the electrolyte leaks.

The overcharge prevention device according to claim 7 is provided with a battery abnormality warning means, and when the abnormality detection means detects a battery abnormality when charging the battery, the battery is brought into an overcharged state. When it is determined that the battery is present, the charging is stopped and the battery abnormality warning means is activated to warn the driver of the battery abnormality.
Therefore, it is possible to prevent the battery from expanding due to overcharging and to suppress the deterioration of the battery. Further, maintenance can be performed before the battery is damaged, which contributes to prevention of leakage of the electrolytic solution.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an overcharge prevention device for an electric vehicle battery.

FIG. 2 is an exploded perspective view of a nickel-hydrogen storage battery for an electric vehicle.

FIG. 3 is a flowchart showing a procedure for preventing overcharging of a battery in an electric vehicle battery overcharging prevention device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Overcharge prevention device 10 Battery 20 Charging device 30 Deformation amount detection means 40 Temperature detection means 50 Charge control means 60 Abnormality warning means 70 Cooling means

Claims (7)

[Claims] 1. A battery that can be repeatedly used by charging, a charging device that charges the battery, an abnormality detection unit that is provided on a wall surface of a battery case of the battery and that detects an abnormality of the battery, and the abnormality detection unit. Is provided with a charging control means for limiting the charging current of the charging device when an abnormality is detected in the battery. 2. The charging control means stops charging when the detection value of the abnormality detecting means is equal to or more than a first predetermined value,
The overcharge prevention device for an electric vehicle battery according to claim 1, wherein the charging is restarted when the detected value becomes equal to or lower than a second predetermined value which is lower than the first predetermined value. 3. The charging control means reduces the charging current when the detection value of the abnormality detection means is equal to or higher than a first predetermined value, and the detection value of the abnormality detection means is lower than a first predetermined value. 2. The overcharge prevention device for an electric vehicle battery according to claim 1, wherein the charging current is increased when the value becomes equal to or less than a predetermined value of 2. 4. The overcharge prevention device for an electric vehicle battery according to claim 2, wherein the abnormality detecting means includes at least temperature detecting means for detecting the temperature of the battery. 5. The overcharge prevention for an electric vehicle battery according to claim 2, wherein the abnormality detecting means includes a deformation amount detecting means for detecting a deformation amount of a battery case wall surface of the battery. apparatus. 6. The overcharge prevention device for an electric vehicle battery according to claim 4, wherein the abnormality detection means further includes deformation amount detection means for detecting the deformation amount of the battery case wall surface of the battery. . 7. The charging control means includes a battery abnormality warning means for warning the abnormality of the battery, and when the detection value of the abnormality detection means is equal to or more than a first predetermined value, charging is stopped and the battery is The overcharge prevention device for an electric vehicle battery according to claim 1, wherein the abnormality warning means is operated to issue an abnormality warning.