JPH08329989A - How to charge a sealed lead acid battery - Google Patents

Abstract

(57) [Summary] [Purpose] A multi-stage constant current that detects the charging voltage of a sealed lead-acid battery using lead-calcium-tin alloy in the grid of the electrode plate and changes the current value to end charging with a timer. The charging system reduces the influence of charge acceptance and the difference between cell chambers, stabilizes the amount of electricity charged at each stage, and enables longer battery life and higher reliability. [Configuration] In the charging method of sealed lead acid battery, the charging current of the first stage and less 0.4CA, the second and subsequent stages charge current _{(i n) i 1> i} n + 1> i n + 2 and then , And the charging period (T
_In the multi-stage constant current charging in which _n ) is T ₁ <T _{n + 1} <T _{n + 2} (n> 1), the detected charging voltage of the battery is set to 2.32 V / cell to 2.37 V / cell.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for charging a sealed lead-acid battery used for cycling such as a power source for portable consumer appliances.

[0002]

2. Description of the Related Art In recent years, sealed lead-acid batteries have come to be used in a wide range of applications from consumer portable power supplies to electric vehicles. Among these applications, constant-voltage charging, constant-current charging, V-taper charging, two-step constant-current charging and the like have been proposed as charging methods for applications in which charge / discharge cycles are repeated. Among them, the two-stage constant current charging method is widely used in applications such as electric vehicles because of its ease of handling.

The conventional two-stage constant current system is a system in which the charging voltage of the battery is detected, the current value at the end of charging is changed to a small value, and charging is terminated by a timer. It was set to 0.40V to 2.45V / cell.

[0004]

In this two-stage constant current charging, the time until the charging battery voltage rises to the detection voltage determines the charge electric quantity of the first step, and the charge electric quantity of the first step is determined. It depends. Normally, the amount of electricity in the first stage occupies about 80% of the total amount of electricity charged, so that proper charging can be performed regardless of the amount of discharge.

However, the amount of electricity charged in the first stage is not always constant even if the amount of electricity discharged is the same, and there are cases where the overall amount of electricity charged is different.

It is considered that the factor is the charge acceptability on the lead storage battery side. The battery charging voltage of a lead storage battery rises sharply when hydrogen gas is generated from the negative electrode. The lead of the negative electrode active material is sponge-like, has a large number of pores and has a large surface area of the active material, and is designed so that the charge / discharge reaction can smoothly occur.

However, lead particles tend to gradually aggregate due to repeated charging and discharging, and their surface area becomes smaller.
When the surface area is small, the apparent current density is large, and as a result, the efficiency of the charge / discharge reaction is decreased, hydrogen is easily generated, and the charging battery voltage is easily increased. Therefore, the amount of electricity charged in the first stage decreases. That is, even if the same battery is charged and discharged under the same conditions, the amount of electricity charged in the first stage is different between the initial stage and after repeating the charge and discharge cycle.

As described above, the quantity of electricity charged in the first stage does not always correlate with the quantity of discharge, and is unstable. In addition, a lead-acid battery usually has a 3-cell chamber or a 6-cell chamber connected in series.
Since each battery is configured, the voltage is detected by a value obtained by adding the three cell chambers or the six cell chambers, and a difference between the cell chambers is likely to occur. Depending on the operating conditions such as the ambient temperature or continuous charge and discharge, there is a large difference in the charge acceptability of the negative electrode, which may lead to an early battery life without proper charging.

The present invention solves the above-mentioned conventional problems, and provides a charging method capable of extending the service life and increasing the reliability of a sealed lead-acid battery in applications in which charge and discharge cycles are repeated. To aim.

[0010]

In order to solve the above-mentioned problems, the present invention comprises a positive electrode plate, a negative electrode plate and a separator, and a sealed lead acid battery using a lead-calcium-tin alloy in the grid of the electrode plate. Controls the charging current, charging time, and detection voltage with the multi-stage constant current charging method that detects the charging voltage of the battery in the first step of charging and changes the current value and terminates the charging of the second and subsequent steps with a timer. to is intended, first-stage charging current (i ₁₎ the 0.4CA following, the second and subsequent stages charge current _{(i n) i 1> i} n + 1> i n + 2 (n> 1) And the charging time (T _n ) by the timer is T ₁ <T _{n + 1} <T
It is a charging method in which the detected voltage is detected at 2.32 V / cell to 2.37 V / cell as _{n + 2} (n> 1).

[0011]

[Operation] 2.4 which is a normal charging voltage in a lead storage battery
0V / cell to 2.45V / cell is the voltage at which hydrogen starts to be generated, but since 2.37V / cell is before the hydrogen generation, it is given in the time until the charge acceptability of the negative electrode reaches the detection voltage. There is little effect, and the effect of differences in each cell room is also small. That is, it is possible to suppress a decrease in current efficiency due to hydrogen generation. By lowering the detection voltage in this way, the influence of charge acceptability and the difference between the cell chambers are reduced, the amount of electricity charged in the first stage is stabilized, and the battery life can be extended and reliability can be increased. Become.

[0012]

EXAMPLES Examples of the charging method of the present invention will be described below.
This will be described with reference to the drawings.

As the battery, a voltage, nominal capacity 12V 38Ah type battery was used. The appearance of the battery 1 is as shown in FIG.
It has a monoblock structure in which six cell chambers 2 of VI are lined up in a row. A lead-calcium-tin alloy was used as the grid of the electrode plate. As the charging specification, n = 1, that is, a two-stage constant current system is used, and the first stage is 0.2 CA, that is, 7.6 A,
The second stage is set to 0.05 CA, that is, 1.9 A, and the second stage charging is completed by a timer. As a preliminary test before determining the detection voltage and the timer time, the battery was discharged to 9.6 V with a constant current of 38 A and then charged with constant current at 7.6 A, and the charging voltage of each cell chamber, the amount of hydrogen generation, and the amount of charge electricity Was measured.

FIG. 2 shows the relationship between the charging voltage and the amount of hydrogen generated in each cell chamber, and FIG. 3 shows the relationship between the charging voltage and the charging time / charge amount.
Shown in

From the result of FIG. 2, the charging voltage of the cell is 2.4.
It was found that hydrogen evolution was measured when rising to 0V. Moreover, from FIG. 3, it was found that the charging voltage of the cell gradually increased from 2.32V. This allows
The detection voltage to be examined is (a) 2.30 V / cell, (b)
2.32 V / cell, (c) 2.37 V / cell, (d)
There were five types, 2.40 V / cell and (e) 2.45 V / cell.

The timer time is 120% of the discharged electricity quantity, which is the sum of the charged electricity quantity that reaches each detection voltage in the first-stage charging and the second-stage charge electricity quantity, and the timer time is T ₁
It was calculated to be <T _{n +1} (n> 1). The amount of electricity discharged was 25 Ah, so each timer time
It was set to 5.4H, 5.0H, 4.6H, 4.3H, and 4.2H.

Under these five types of charging conditions, 12V38
A charge / discharge cycle test of an Ah battery was performed. The discharge condition was a constant current discharge of 38 A and a termination of 9.6 V, 0 minutes from the end of discharge to the start of charge, and 10 minutes from the end of charge to the start of discharge.
The continuous charge / discharge cycle is defined as minutes. The ambient temperature was 25 ± 2 ° C. The charge / discharge cycle test result is shown in FIG.

As is clear from FIG. 4, in the case of the battery under the condition of the detection voltage of 2.30 V / cell shown in FIG.
After 50 cycles, the capacity had dropped to 80% of the initial capacity. When this capacity-decreased product was analyzed, the capacity was decreased in all 6 cells, and the discharge capacity was dominated by the positive electrode active material.

Next, this battery is used (e) with a detection voltage of 2.45.
When the charge condition of V / cell was changed and charging / discharging was repeated 5 cycles, the capacity recovered to 95% of the initial value. From this, it is estimated that the cause of the capacity decrease is insufficient charging of the positive electrode plate. This is because the switching voltage at the first stage is too low and the amount of charge at a small current at the second stage is large, so the amount of charge forcibly performed on the positive electrode is insufficient, resulting in a decrease in the charging efficiency of the positive electrode. This is probably because the amount of highly reactive positive electrode active material produced was reduced. It is considered that since the number of times of charge and discharge is large in the continuous charge and discharge cycle, the amount of the positive electrode active material having high reactivity gradually decreases, and reaches about 80% of the initial value in about 250 cycles.

Further, in the battery under the charging condition of (d) the detection voltage of 2.40 V / cell and (e) of 2.45 V / cell,
In both cases, the capacity of the negative electrode was reduced, and in particular, the deterioration of cell 3 or cell 4 in FIG. 1, that is, the cell located in the center of the battery case was large. In addition, comparing the amount of sulfuric acid retained in the negative electrode active material of the battery with reduced capacity with the initial product,
Approximately 12% with the battery of detection voltage 2.40V / cell of (d),
It was about 15% less in the battery with the detection voltage of 2.45 V / cell in (e). From this, it is considered that the cause of the capacity decrease is the decrease in reactivity due to the decrease in the surface area of the negative electrode active material and the decrease in the amount of sulfuric acid retained. Further, the surface area of the negative electrode active material was more likely to decrease as the temperature was higher, and the deterioration of the cell 3 or cell 4 having poor heat dissipation was higher than the others.

On the other hand, regarding the amount of electricity charged in the first stage,
(D) For the 2.40 V / cell battery, the initial discharge amount was 87%, whereas at 200 cycles, the discharge amount was 83%, and for the 2.45 V / cell battery, the initial discharge amount was 87%. While it was 88%, it decreased to 80% of the discharge amount at the time of 200 cycles. Also, in (b) 2.
In the case of the battery of 32V / cell, the discharge amount was 82% in the initial stage, but it was 78% of the discharge amount at the time of 500 cycles.
In the case of the 2.37 V / cell battery of (c), it was 85% of the discharge amount at the beginning, but 8 at the time of 500 cycles.
It was 1%, and the decrease in the amount of electricity charged in the first step was small. For the 2.30 V / cell battery of (a), the discharge amount was 79% in the initial stage, but was 78% at the time of 200 cycles, which is an improvement in terms of preventing reduction in the surface area of the negative electrode active material. It is thought to have been done.

As is clear from the above embodiments, under the charging conditions of the detection voltage of 2.30 V / cell, 2.40 V / cell, and 2.45 V / cell, the capacity decreases relatively early and the life is reached. However, in a battery under the charging conditions of 2.32 V / cell and 2.37 V / cell, sufficient charge / discharge cycle life characteristics could be obtained.

Further, in a battery under the condition that the detection voltage is 2.45 V / cell, the surface temperature of the central portion of the battery gradually rises as the charging / discharging cycle progresses, and the maximum temperature is 43 ° C.
Became. Along with this, it was observed that the rising speed of the charging voltage slowed down immediately before the detection voltage. This is probably because the gas absorption reaction was promoted.

In the sealed lead-acid battery, oxygen generated during charging reacts with lead, which is the negative electrode active material, to absorb oxygen gas. Since this reaction is an exothermic reaction, the temperature of the battery rises during charging. Depending on the ambient temperature and the frequency of charging / discharging, the temperature of the battery increases significantly, the overvoltage decreases, and the increase in the battery voltage decreases. Therefore, it may take a long time to reach the detection voltage. In such a case, the amount of electricity charged in the first stage and the amount of electricity charged as a whole increase. When the ambient temperature is high and the detection voltage is high, the charging voltage may not reach the detection voltage, and the charging current may not change to cause overcharging. However, if the detected voltage is in the range of 2.32 V / cell to 2.37 V / cell, it is estimated that there is no possibility as described above.

Further, the battery voltage at the stage of starting hydrogen generation varies depending on the charging current at that time, but it is confirmed that hydrogen will not be generated at 2.37 V / cell at 0.4 CA or less. Therefore, as the charging current value,
0.4 CA or less is suitable.

Further, for the charging current of the first stage, two stages
Charging current after the eye (i_n) I₁> I _{n + 1}> I_{n + 2}(N>
1) and the battery voltage does not reach the hydrogen generation voltage.
Control the charging current to prevent the charging efficiency from decreasing.
It is essential to control to. At the same time, by timer
Charging time is T₁<T_{n + 1}<T_{n + 2}(N> 1), hydrogen generation
Reduces charging efficiency due to raw material and uniform heat generation of battery between cells
By doing so, the effect of the above charging method is improved.
Will be clear.

That is, by detecting the charge detection voltage at 2.32 V / cell to 2.37 V / cell and controlling the charge current and the charge time, it is possible to provide a battery having excellent cycle life characteristics. .

The detection voltage of the present invention is not applied when lead-antimony alloys having different hydrogen overvoltages are used for the electrode plate grid.

[0029]

As described above, according to the method for charging a sealed lead-acid battery of the present invention, the influence of charge acceptance and the difference between cell chambers are reduced, and the amount of electricity charged in the first stage is stabilized. Therefore, it is possible to extend the life of the battery and increase its reliability.

[Brief description of drawings]

FIG. 1 is an external view of a battery according to an embodiment of the present invention.

[Fig. 2] Relationship between charging voltage and hydrogen generation amount

[Fig. 3] Relationship diagram between charging voltage and charging time / charge quantity

FIG. 4 is a diagram showing a capacity change in a charge / discharge cycle test.

[Explanation of symbols]

 1 lead acid battery 2 cell room

Claims (1)

[Claims] 1. A battery comprising a positive electrode plate, a negative electrode plate and a separator, wherein the grid of the electrode plate uses lead-calcium-tin alloy to detect the charging voltage of the battery by first-stage charging. In the multi-stage constant current charging method in which the current value is changed and the charging in the second and subsequent stages is terminated by a timer, the charging current (i ₁ ) in the first stage is 0.4 CA or less and the charging current in the second and subsequent stages (i _n ) is i ₁ > i _{n + 1} > i _{n + 2} (n> 1), and the charging time (T _n ) by the timer is T ₁ <T _{n + 1} <T
_{n + 2} (n> 1), and the detection voltage is 2.32V to 2.
A method for charging a sealed lead-acid battery, which is characterized by detecting at 37 V / cell.