Electric vehicle lead-acid battery failure mode and its repair

Awdur: Iflowpower - Proveedor de centrales eléctricas portátiles

Electric vehicle lead-acid battery failure mode and its repair method are now calculated by the battery, or the lead-acid battery is the largest. The advantage of lead-acid battery capacity is that other batteries are still unsubstituted. In addition, the characteristics of its large current discharge also determine its advantages in starting the battery.

But lead as heavy metals, in addition to cost, there is still a certain toxicity, and there is a different degree of harm to the environment and human body. So extend the life of the lead acid battery, not only can reduce operating costs, but also environmental protection, it is a desiration problem for expanding the use of lead-acid batteries. Therefore, study the problem of repairing lead-acid batteries, extending its life, but the sales of lead-acid batteries will not be reduced, but will increase, but the environmental pollution can not increase.

To understand the repair of lead-acid batteries, first understand the failure mode of lead-acid batteries. Then talk about different failure mode. First, the failure mode of the lead-acid battery is different due to the species, manufacturing conditions, and the method of use, and ultimately leads to different batteries.

Incident, the failure of lead-acid batteries has several cases: 1, corrosion deformation of the positive electrode plate. There are three types of alloys used on the current processing: the traditional lead antimony alloy, the content of antimony is 4% -7% mass fraction; low bismuth or ultra-low antimony alloy, the content of antimony is 2% mass fraction or less than 1% quality Fractal, containing tin, copper, cadmium, sulfur and other variant crystals; lead calcium series, actual lead-calcium-tin-aluminum quadriendline, calcium content at 0.06% -0.

10% mass fraction. The above-mentioned positive plate grid is cast in the battery charging process to be oxidized into a lead of sulfate and neutral, and finally causes the use of the support of the active material to fail; or due to the formation of the lead-corrosion layer of the nest The alloy is born, so that the board gate is largely deformed. When this deformation exceeds 4%, the total plate will be destroyed, and the active substance is poor contact with the grid, or short circuit at the bus stop.

2, the positive plate active substance is falling off, softened. In addition to the reactive substances of the rending, the rending and discharge is repeated, the binding between the particles of the neutral particles is loose, softened, from the grid to fall off. A series of factors such as manufacturing, equipped tight and charge and discharge conditions, etc.

3, irreversible sulfate. When the battery is over discharged and the negative electrode will form a coarse, difficult to accept charging of lead crystals, this phenomenon is referred to as irreversible sulfate. Mild irreversible sulfate, can still be recovered by some ways; when severe, the electrode is faded, charged.

4, the capacity is premature loss. When low bismuth or lead calcium is a grid alloy, the capacity of the battery has suddenly declined in the initial (about 20 cycles), so that the battery is invalid. 5, severe accumulation of antimony in active substances.

The bismuth on the positive electrode plate is transferred to the surface of the negative electrode plate active material as the circulatory portion is transferred from the H + lower than the lower electrode of the lead than the lower electrical potential of the lead, so that the charging voltage is lowered during the accumulation of antimony, most current Both are used for water analysis, the battery cannot be charged normally, thus failing. The antirectarid content of the lead-acid battery negative substance that is only 2.30 V is only 2.

30V, and it is produced to the surface layer of the negative electrode active substance, and the content of antimony is 0.12% -0.19% mass fraction.

For some batteries, such as submarines, batteries, have certain restrictions on battery hydrogen. Testing of hydrogen-proof cellular electrode active substances, uniform bismuth content reached 0.4% mass fraction.

6, heat failure. About less maintenance batteries, requires no charging voltage to not exceed single 2.4V.

In actual use, for example, in the car, the pressure regulating device may be out of control, the charge voltage is too high, so that the charging current is too large, the heat of the inclusions will increase the temperature of the battery electrolyte, resulting in a decrease in the internal resistance of the battery; Enhanced charging current. The temperature rise and current of the battery are enhanced, and it is ultimately uncontrollable, so that the battery is deformed, cracking. Although thermal out-of-control is not the failure mode of lead-acid batteries, it is not uncommon.

Pay attention to the phenomenon of the charging voltage and the heat generation of the battery. 7, corrosion of negative general convolution. Under normal circumstances, the negative plate gate and the bus row do not have corrosion problems, but in the valve-controlled sealed battery, when the oxygen circulation is established, the upper space of the battery is substantially perfringed, and the bus bar is in the diaphragm.

Climb on the ear to the bus. The alloy of the bus bar will be oxidized, and the lead of sulfate is further formed. If the bus bar alloy is selected improperly, the flow of residual inclusions and gaps are arranged.

The corrosion will deepen along these gaps, resulting in venting, negative plate failure. 8, the diaphragm perforation causes short circuit. The diaphragm of individual varieties, such as PP (polypropylene) diaphragm, large pore diameter, and the PP fuse can cause displacement, resulting in large holes, active substances can pass through the large holes during charge and discharge, resulting in micro short circuit , Make battery failure.

Second, the failure of factors that affect lead-acid battery life is the result of many factors, which are determined in the internal factors of the plate, such as composition, crystal form, porosity, plate size, grid material, and Structure, etc., also depends on a series of external factors, such as discharge current density, electrolyte concentration and temperature, discharge depth, maintenance conditions, and storage time, etc. An important external factor is analyzed here.

1, discharge depth. The discharge depth begins to stop when discharging during the process. 100% depth pointing all capacity.

Lead-acid battery life is very affected by discharge depth. The focus of design consideration is to use cycle, shallow cycle or floating use. If the battery used by the shallow cycle is used in deep cycle, the lead-acid battery will quickly fail.

Since the binding of the positive electrode active substance is not strong, the lead is generated by the lead, and the charging is restored to the lead, the molecular moisture of the lead in the lead of sulfate is larger, and the active material volume expansion is expanded when discharged. If 1 mole of lead-converted leads into 1 mole of lead, the volume added 95%. Thus repeated contraction and expansion, the mutual binding between the particles of the neutral particles is gradually loophore, easy to fall off.

If the active substance of 1 mole of the elixir is only 20% discharge, the degree of expansion is greatly reduced, and the combination force is broken slowly, so the deeper the discharge depth, the shorter the life of the circulation. 2, over charge. There is a large amount of gas precipitation at the time of overcharge.

At this time, the active material is hit by the gas, which causes the active substance to fall off; in addition, the positive plate grid alloy is also corroded by severe anodization, so the battery is overcharged. Shortexide. 3, the effect of temperature.

Lead-acid battery life is extended with temperature rise. At 10-35 ° C, each liter is 1 ° C, about 5-6 cycles; between 35-45 ° C, each lifting can extend 25 cycles, more than 50 ° C, due to negative electrode Loss of vulcanization capacity. Battery life increases with temperature in a certain temperature range, because the capacity increases with temperature increases.

If the discharge capacity is unchanged, the discharge depth is lowered, and the lack of life is prolonged at the temperature rise. 4, influence of sulfuric acid concentration. Although the acid density is advantageous for the positive electrode plate capacity, the self-discharge of the battery increases, the corrosion of the grid is also accelerated, and the looping of the lead of the lead is also caused, and the cycle life is lowered as the battery has a new product.

5. Effect of discharge current density. As the discharge current density increases, the battery life is lowered because the positive electrode dioxide is loosely falling off under large current density and high acid concentration conditions.

There is still one in failure mode is water. Regarding the opening battery, the water is in normal maintenance, and the sealing battery is not subject to strict control. So, I didn't put the loss of water in the failure mode.

Sealed battery lossless problems, gathered in electric bicycles, because the constant voltage value of charging is too high. Third, the capacity of premature loss (PCL) repair method 1, the characteristics of premature loss of premature loss. When low bismuth or lead calcium is a grid alloy, the capacity of the battery has suddenly declined in the initial (about 20 cycles), so that the battery is invalid.

Almost every circulating battery capacity will fall by 5%, and the speed of capacity is faster and early. In the past few years, the battery of the lead calcium alloy is not named a few battery capacity declines. The decomposition positive plate is not softened, but the positive pole capacity is extremely low.

Today, the reason for this phenomenon has basically found the processing method: 1 Control the content of the positive plate tin, the battery is basically 1.5% -2% tin content; 2 increase the assembly pressure; 3 electrolyte The amount of acid should not be too high. Pay attention in use: 1 Prevent start charging current from continuing too low; 2 Reduce depth discharge; 3 Preventing too much charge; 4 Do not increase battery capacity by excessive active material utilization.

2, the battery that is lost in the early volume, can be restored. The first is that the start charging current is new to 0.3-0.

5ca, and then charge the small current to charge; the secondary electric battery is preferably stored under 40-60 ° C; discharged to 0V with a small current of less than 0.05 cA. The battery voltage reaches a nominal voltage, the discharge will be slow.

This is repeated several times, the capacity of the battery can also be restored. Overtention: Do you have to identify the battery in the top 20 cycles?. If the battery that has decreased capacity in late period, this method can only destroy the positive plate of the battery and cause the positive electrode plate to soften.

The battery of the lead calcium alloy is often inexplicably declining. It is important that the battery imbalance is caused by the battery imbalance. The sufficient voltage of the lead calcium alloy series is high.

Generally 12V battery charging voltage is greater than 16V. When the voltage of the charger is too low, it is easy to cause battery imbalances. The phenomenon occurs: When a set of batter is installed together, each self-discharge of the battery cannot be absolutely equal, self-discharged, and it is not fully charged each time with constant pressure charging.

Decorated gas reactions, the relative area of ​​the electrolyte contact electrolyte is large, and the self-discharge is large. The self-discharge is small, each time can be fully charged, when the electricity is filled with electricity, that is, the gas reaction, generate gas, the polar contact electrolyte surface is relatively reduced, and the self-discharge is reduced. At the same time, the charging voltage is high, and the charger is turned off.

Results The self-discharge is small, and the voltage high is less and smaller, and each time it is sufficient, and the self-discipline is getting more and more, and it is not enough to charge each time, and the smaller the power is used, the smaller the power is Long-term insults will vulcanize. The root of the problem is that the constant voltage charger can not use a constant voltage charger. The constant voltage charger will have the above phenomenon, and the constant voltage value will make the battery thermal out of control.

The best way is to adopt a variety of currents. Multi-voltage multi-stage charger. And when charging the end, there is a high voltage and smaller small current long charge for balancing the battery.

Fourth, overcharge repair over charge often requires high current and high voltage, and large current and high voltage will form a strong side reaction and damage the positive plate of the battery, and form a battery's loss of water. How do you achieve the recharge repair? Today, I have found a very effective way - pulse. The basic principle is to use a high voltage and a large current pulse overcome due to a decrease in the capacity of a variety of primary, because it is in the form of pulse, after the large current pulse is lost, through the battery itself (or additional conditions) Polarization capacity, not to form a serious side reaction.

Due to the birth of this pulse overcharge repair, it is achieved that there is no damage overcharge, in 2000, scholars in many countries in international countries have taken out the excellent verification report. For a time, the overcharge repair mode forms a tide in the international battery industry. The domestic charger has made such a charger at the end of 1999, which has achieved excellent results.

After several years of verification experiments, this approach has greatly extended the cycle life of lead-acid batteries.