Charging of storage battery

[Technical Field to which the Invention Affiliates] The present invention relates to a storage battery, particularly a method for charging a lead storage battery.

PROBLEM TO BE SOLVED: To use various charging methods as a charging method of a lead storage battery. In charging, the amount of charging electricity corresponding to the amount of discharging electricity is required, but if charging is performed with an amount of electricity exceeding the necessary amount, overcharging occurs and the capacity of the battery decreases. In lead-acid batteries, deterioration progresses due to oxidative corrosion of the positive electrode lattices constituting the positive electrode plate and reduction of water content in the electrolytic solution due to overcharging. In order to suppress such deterioration due to overcharging, a constant voltage charging method has been conventionally used in which charging control is performed at a charging voltage of a certain value or less. In such a constant voltage charging method, by setting the charging control voltage to be equal to or lower than the voltage at which hydrogen gas is generated from the negative electrode plate, it is possible to suppress the decrease in water content during charging and also to suppress the terminal current of charging, so that the positive electrode lattice is formed. Since it can suppress oxidative corrosion of lead-acid batteries, it has been widely and generally used as a charging method for lead-acid batteries. In particular, in a closed-type lead-acid battery, this method is mostly used because it is not possible to replenish the electrolyte.

[0003] In recent years, electric vehicles such as electric tricycles and electric wheelchairs have begun to spread widely from the viewpoint of environment and welfare. Since lead-acid batteries are relatively inexpensive, they are being adopted as the main power source for these electric vehicles. As a charging method for lead-acid batteries used for such cycle applications, the constant voltage charging method as described above has been generally used.

[0004] However, when the constant voltage charging method is used for lead-acid batteries for electric vehicles, the short life of the storage batteries has begun to be scattered in some vehicles. It has been found that the occurrence of such a short-life phenomenon is deeply related to the usage pattern of vehicle users. It was found that there is a high probability that the life will be short, especially if the usage time is short and the charging time is long. In such a case, it is conceivable to lower the charging control voltage or limit the charging time to a short time, but if such a change is made, the amount of electricity to be charged will be secured if the usage time is long and the charging time is short. It does not have a short life at an early stage. In this way, it is necessary to select the optimum charging method according to the usage pattern of the user. However, the electric vehicle as described above is widely used by general consumers, and it is practically impossible to select a charging method according to one's usage pattern.

[0005] An object of the present invention is to provide an optimum charging method for a storage battery even in various usage forms as described above.

[0006] In order to solve the above-mentioned problems, the invention of claim 1 of the present invention is a method of charging a storage battery, in which the storage battery voltage Vba1 after precharging the storage battery is measured, and the storage battery voltage Vba1 is the first set voltage. When it is lower than V1 and higher than the second set voltage V2, which is lower than the first set voltage V1, charging 1 is performed by the first charge control, and the storage battery voltage Vba1 is higher than the second set voltage V2. When the charge 2 is performed by the second charge control when the voltage is lower than the second set voltage V2 and higher than the third set voltage V3, and when the storage battery voltage Vba1 is lower than the third set voltage V3. After performing active charging, charging 2 by the second charge control is performed, and in the charging 1, the storage battery is charged at a constant voltage with the first charging voltage Vch1, and the storage battery is charged after the charging current drops to a predetermined value Ia. After constant voltage charging with the second charging voltage Vch2, which is lower than the first charging voltage Vch1, and constant voltage charging of the storage battery with the third charging voltage Vch3 in charging 2, the charging current drops to a predetermined value Ib. It shows a method of charging a storage battery characterized by performing constant current charging with a predetermined charging current Ic for a predetermined time and then charging with a constant voltage at a fourth charging voltage Vch4 lower than the third charging voltage. According to the second aspect of the present invention, in the configuration of the first aspect, the storage battery voltage Vba2 sets the second set voltage V2 and the third setting in the cycle of measuring the active charge and the storage battery voltage Vba2 subsequently. It is repeated up to a predetermined number of times N until it reaches a value between the voltage V3, and when the storage battery voltage Vba2 becomes between the second set voltage V2 and the third set voltage V3, the storage battery is put into the first position. It is characterized in that charging 2 is performed by charging control of 2. Further, in the invention of claim 3 of the present invention, in the configuration of claim 1 or 2, the storage battery voltage Vba1 measured after precharging is higher than the first set voltage V1 or higher than the third set voltage V3. It is characterized in that the subsequent charging operation of the storage battery is suspended when the voltage is lower than the lower fourth set voltage V4. Further, the invention of claim 4 of the present invention is claimed.<u style="single">Lower than</u>In this case, when the charging current Ip at the time of pre-charging is Imax or less and Imin (Imin&gt; 0) or more, the storage battery voltage Vba1 after pre-charging is measured, and when Ip&gt; Imax, the charger abnormality is displayed. The subsequent charging operation is stopped, and when Ip &lt;Imin, the battery is abnormal and the subsequent charging operation is stopped, and the Vba0 value is the fifth set voltage V5.<u style="single">that's all</u>In the case of, the charger abnormality is displayed when the charging current Ip&gt; Imax, the subsequent charging operation is stopped, and when the charging current Ip is within Imax, the storage battery voltage Vba1 after precharging is measured. It is a thing. The invention of claim 5 of the present invention is a method of charging a storage battery, in which the storage battery voltage Vba1 after precharging the storage battery is measured, and the storage battery voltage Vba1 is lower than the first set voltage V1 and the first When the set voltage V1 of 1 is lower than the second set voltage V2, charging 1 is performed by the first charge control, and the storage battery voltage Vba1 is lower than the second set voltage V2 and the second After charging 2 by the second charge control when it is higher than the third set voltage V3, which is lower than the set voltage V2, and after performing active charging when the storage battery voltage Vba1 is lower than the third set voltage V3. Charge 2 is performed by the second charge control, and the storage battery voltage Vba0 is measured prior to precharging the storage battery, and this Vba0 value is the fifth set voltage V5.<u style="single">Lower</u>In this case, when the charging current Ip at the time of pre-charging is Imax or less and Imin (Imin&gt; 0) or more, the storage battery voltage Vba1 after pre-charging is measured, and when Ip&gt; Imax, the charger abnormality is displayed. The subsequent charging operation is stopped, and when Ip &lt;Imin, the battery is abnormal and the subsequent charging operation is stopped, and the Vba0 value is the fifth set voltage V5.<u style="single">that's all</u>In the case of, the charger abnormality is displayed when the charging current Ip&gt; Imax, the subsequent charging operation is stopped, and when the charging current Ip is within Imax, the storage battery voltage Vba1 after precharging is measured. It shows a method of charging a storage battery. The invention of claim 6 of the present invention measures the atmospheric temperature T of the storage battery in the configuration of claims 1, 2, 3, 4 or 5, and Vch1, Vch2, Vch3 and Vch4 with respect to the atmospheric temperature T. The value is characterized by having a negative characteristic.

[Embodiments of the Invention] A method of charging a storage battery according to the present invention will be described with reference to the drawings.

[0008] FIG. 1 is a flow chart showing a method of charging a storage battery according to the present invention. The battery to be charged is a sealed lead-acid battery.

[0009] First, the storage battery voltage Vba0 in the open circuit state of the storage battery is measured, and the ambient temperature Ta around the storage battery is measured. This temperature measurement is performed using, for example, a thermistor. After the battery voltage Vba0 is measured, precharging is performed at the charging current Ip for a predetermined time. In the present invention, the charging current Ip at this time can be measured to detect a charger abnormality or a battery abnormality. That is, the storage battery voltage Vba0 measured prior to precharging is the fifth set voltage V5.<u style="single">Less than</u>If the charging current Ip at the time of pre-charging is larger than Imax or smaller than Imin, the subsequent charging operation is not performed. As a result, it is possible to detect a storage battery that is short-circuited internally or a storage battery that has deteriorated due to remarkable over-discharging. Similarly, the storage battery voltage Vba0 measured prior to precharging is the fifth set voltage V5.<u style="single">More than</u>In that case, the storage battery itself is judged to be normal, but when the charging current Ip becomes larger than Imax, it is judged that the charger is abnormal and the subsequent charging operation is stopped.

[0010] After the pre-charging is completed, the storage battery voltage Vba1 at the time of opening is measured at a certain time interval. In the present invention, the state of the storage battery, particularly the discharged state, is determined by using the value of the storage battery voltage Vba1. Here, it is preferable that the storage battery voltage Vba1 is measured after a certain time interval has passed from the precharging. For example, a method of charging the storage battery and determining the discharge state based on the charging voltage value at that time can be considered, but if the storage battery is over-discharged or left for a long period of time, the charging voltage of the storage battery rises and the battery is charged. There is a risk of determining it as a state. Further, it is also conceivable to consider a method of determining only by the storage battery voltage in the open circuit state without performing precharging. However, for example, even if the storage batteries are in the same discharged state, the opening voltage of the storage battery varies depending on the subsequent storage state, and as a result, the determination of the discharged state becomes large. Further explaining this phenomenon, when a lead-acid battery in a certain discharged state is left unattended, the surface of the negative electrode active material is particularly covered with a very thin layer of lead sulfate by self-discharge. This is because such a layer has a small amount of self-discharge itself, and as a result, although the discharge state before and after being left unattended does not change so much, the potential of the negative electrode itself shifts to anodic and lowers the storage battery voltage. In such a case, if the discharge state is simply determined by the opening voltage of the storage battery, it is determined that the discharge depth is deeper than the actual discharge state, and proper charging cannot be performed. Further, immediately after the discharge, the storage battery voltage is not stable due to the concentration polarization of the electrolytic solution, and if the discharge state is discriminated by this unstable voltage, the discrimination accuracy is significantly lowered. According to the present invention, by measuring the storage battery voltage Vba1 in the open circuit state at intervals after precharging, it is possible to suppress the variation in the determination and accurately determine the discharge state. By this pre-charging, the thin layer of lead sulfate generated by the minute self-discharge is reduced, and the elimination of the concentration polarization immediately after the discharge is promoted, so that the storage battery voltage in the open circuit state reflecting the actual discharge state can be obtained.

[0011] In the present invention, the subsequent charging operation is controlled by the value of the storage battery voltage Vba1 after precharging. That is, when the storage battery voltage Vba1 is between the first set voltage V1 and the second set voltage V2 lower than the first set voltage V1, it is determined that the discharge state of the storage battery is shallow and suitable for it. Charge 1 by charge control of 1. When the storage battery voltage Vba1 is between the second set voltage V2 and the third set voltage V3 lower than this second set voltage V2, it is determined that the discharge state of the storage battery is deep and the second set suitable for it. Charge 2 by charge control. When the storage battery voltage Vba1 is further lower than the third set voltage V3, the storage battery is determined to be in a state where the charge acceptability is lowered due to over-discharging or the like, and is actively charged. By performing this active charging at a constant current for a short time, for example, the passive layer of the positive electrode generated by over-discharging and the coarsened lead sulfate having poor charge acceptability formed by being left for a long period of time can be charged and recovered. .. After this active charging, charging 2 is performed by the second charge control as a storage battery with deep discharge. Also, depending on the degree of over-discharge or neglect, it may not recover with one active charge, so measure the storage battery voltage Vba2 in the open circuit state after active charge until this storage battery voltage Vba2 becomes the third set voltage V3 or higher. After repeating active charging and subsequent measurement of the storage battery voltage Vba2 up to a predetermined number of times (N times), the storage battery is charged by charging 2 by the second charge control. If the number of repetitions of active charging is a predetermined number (N times) and the storage battery voltage Vba2 is less than the third set voltage V3, it is determined that the battery has reached the end of its life or the battery has reached the end of its life, and the subsequent charging operation is stopped. is there. When the storage battery voltage Vba1 after pre-charging becomes higher than the first set voltage V1 or the storage battery voltage Vba1 is lower than the third set voltage V1 in consideration of safety during charging, the fourth set voltage V4 If it is lower than that, it is desirable to determine that the charger is abnormal or the storage battery is abnormal or has reached the end of its life, and stop the subsequent charging operation.

[0012] Next, preferred embodiments of charging 1 by the first charge control and charging 2 by the second charge control described above are shown in FIGS. 2 and 3.

[0013] FIG. 2 is a diagram showing a charging pattern of charging 1 by the first charging control. In charging 1, constant voltage charging (initial charging current: Ii (A)) is initially performed by the first control voltage Vch1. After the charging voltage of the storage battery reaches the control voltage Vch1, constant voltage control is performed and the charging current is attenuated. When the charging current value drops to a predetermined value Ia, the charging control voltage Vch1 is lowered to Vch2, which is lower than this. As a result, it is possible to prevent overcharging due to charging following shallow discharge and suppress a decrease in the life of the storage battery.

FIG. 3 is a diagram showing a charging pattern of charging 2 by the second charging control. In charging 2, constant voltage charging (initial charging current: Ii (A)) is initially performed by the third control voltage Vch3. During this constant voltage charging, after the charging voltage of the storage battery reaches the control voltage Vch3, constant voltage control is performed and the charging current is attenuated. After the charging current drops to a predetermined value Ib, constant current charging is performed at the current value Ic for a predetermined time. Of course, it is also possible to make the Ib value and the Ic value the same value here. By constant current charging at this current value Ic, it is possible to suppress insufficient charging during deep charging and effectively bring out the life performance of the storage battery. After this constant current, charging is performed at a fourth control voltage Vch4, which is lower than the third control voltage Vch3.

[0015] Here, the initial control voltage value Vch1 and the control voltage Vch3 in the first charge control and the second charge control can both have the same value. Further, in consideration of the charge acceptability due to the atmospheric temperature at the time of charging, it is necessary to control the Vch1 value and the Vch3 value so as to have negative characteristics with respect to the atmospheric temperature Ta measured before the start of charging, in order to obtain the effect of the present invention. Is preferable. It is also possible to set the second control voltage Vch2 and the fourth control voltage Vch4 to the same value and share the charge control unit of this part between the first charge control and the second charge control. It is very effective in reducing the cost of. Further, it is preferable to control the second control voltage Vch2 and the fourth control voltage Vch4 so as to have a negative characteristic with respect to the ambient temperature Ta.

[Example] &lt;Example 1&gt; Examples of the present invention will be described.

A charge / discharge cycle life test of a sealed lead-acid battery having a nominal voltage of 24 V and a rated capacity of 28 Ah at a 10-hour rate was performed using the charging method according to the embodiment of the present invention. Here, the various setting values are as follows.

【0018】<img file="JP3678045B2_D0001.tif" /> 【0019】<img file="JP3678045B2_D0002.tif" />Here, as the discharge conditions, condition A: discharge 1 (discharge for 2.4 hours at a constant current of 7A (discharge 60% of the rated capacity)) (reference numeral A in FIG. 4) and condition B: discharge 2 ((7A constant current for 22 minutes (10% discharge of rated capacity)) 2 types (reference code B in Fig. 4)). Condition C: Discharge of odd cycle discharge 1 A test was also conducted in which an even cycle of discharge was performed with discharge 2 (reference numeral C in Fig. 4).

Next, for the same 24V28Ah battery, as a comparative example, after discharging under condition D: discharge 1 , charging by charge control 1 in the embodiment of the invention is performed independently (reference numeral D in FIG. 4). ) And condition E: discharge according to discharge 1 and then charge by charge control 2 independently (reference numeral E in Fig. 4), condition F: discharge according to discharge 2 and then carry out the invention. In the form of, charging by charge control 1 is performed independently (reference numeral F in FIG. 4) and condition G: charging by discharge 2 and then charging by charge control 2 is performed independently (in FIG. 4). The test of code G) was also performed. The charging time was 12 hours in each case. The capacity of the storage battery was measured by completely discharging the storage battery to 21V at 7A every 20 cycles. These results are shown in Fig. 4.

[0022] From the result of FIG. 4, according to the charging method of the present invention, even if the discharge depth of the sealed lead-acid battery changes, it can be detected and appropriately charged at all times, and the life of the sealed lead-acid battery can be extended. It was confirmed that it can be effectively exhibited stably and without variation in 450 to 500 cycles. On the other hand, according to the comparative example, the life was greatly affected by the discharge depth and the charging method, and the variation was very large, 150 to 500 cycles, and it was not stable. This indicates that a short life occurs due to variations in usage patterns of device users.

&lt;Example 2&gt; Next, for the 24V 28Ah sealed lead-acid battery in Example 1, an over-discharged battery was created by connecting a constant resistance of 2Ω for 24 hours and then leaving it at 25 ° C for 1 month. Then, a cycle of repeating charging according to the embodiment of the present invention in Example 1 and 7A constant current discharge (final voltage 21V) was performed 5 times (condition H, reference numeral H in FIG. 5). Condition I of the comparative example is a cycle of repeating charging of the same over-discharged battery as described above by independently performing charge control 2 and 7A constant current discharge (terminating voltage 21V) from the charging method according to the embodiment of the present invention. This was done (reference numeral I in FIG. 5). These results are shown in Fig. 5. From the results shown in FIG. 5, a sufficient discharge capacity is obtained from the first cycle according to the charging method of the present invention, while in the comparative example, the discharge at the level of the first cycle in the present invention is finally reached in the third cycle. Capacity was obtained. As described above, according to the charging method of the present invention, a sufficient recovery capacity can be obtained with a relatively small number of times by detecting the over-discharged state of the storage battery and performing active charging. This is very useful because it can prevent an unintended capacity reduction for the user of the device.

[Effect of the Invention] As described above, according to the charging method of the present invention, even if the discharge depth varies depending on the user of the storage battery, particularly the sealed lead-acid battery, it is detected and the discharge depth is matched. Appropriate charging is performed, and as a result, the life characteristics of the sealed lead-acid battery can be enhanced, which is extremely effective industrially.

BRIEF DESCRIPTION OF THE DRAWINGS [Fig. 1] Fig. 1 is a diagram showing a charging flow of a storage battery according to an embodiment of the present invention. FIG. 2 is a charging pattern by a first charge control during a charging flow of a storage battery according to an embodiment of the present invention. FIG. 3 is a diagram showing a charging pattern by the second charge control during the charging flow of the storage battery according to the embodiment of the present invention. FIG. 4 is a charging method according to the embodiment of the present invention and a charging method of a comparative example. FIG. 5 shows the cycle life characteristics of the sealed lead-acid battery when the above-mentioned is used. [Fig. 5] Capacity of the over-discharged sealed lead-acid battery when the charging method according to the embodiment of the present invention and the charging method of the comparative example are used. Diagram showing recovery characteristics