What is the reason why the valve controlled sealed lead-acid battery is fire?

2022/04/08

  Author :Iflowpower – Portable Power Station Supplier

Soybean battery work principle lead-acid battery is an energy storage and conversion device, when discharges, the battery is directly converted into electrical energy; when charging is charged directly into chemical energy storage. The charge and discharge process is completed by the chemical reaction. The electrochemical reaction formula of the lead-acid battery is as follows: From the above reaction, it can be seen that if the battery is charged, if it continues charging, the moisture electrolysis is caused.

And the result of the electrolytic water will cause the battery positive electrode portion to have oxygen, the negative electrode is hydrogen, if these gases cannot be recombined, the battery will lose weight. Therefore, it is necessary to regularly hydration and maintenance. The valve-controlled lead-acid battery does not need to add water maintenance, the most important key is that the battery can be compounded in the battery, while inhibiting the precipitation of hydrogen.

Reasons for battery booms The battery connection is loosely depending on the energy calculation formula: Q = I2RT (q represents energy, I represents current, R meter resistance, T represents time), and the power storage will release a certain amount of heat during discharge, discharge current The larger the resistance value, the greater the heat released. Battery connection loose can result in increased contact resistance, and increase over time. When the battery is used, the current can cause heat through the portion, the larger the current flowing, the longer the duration, the more heat generation, the temperature will continue to rise.

When the temperature rises to a certain extent, it will cause charring of the battery terminal to the outer casing material, and the ABS smokes. Connection caused by loose fire scene see Figure 2. Figure 3 is a temperature time curve at a certain discharge of 4 in a high-level battery list.

The battery configuration voltage of the battery is 528V, each group 44, the single battery specification is 12V100AH, and the delivery time is 1 year. As can be seen from the figure, the temperature from the start of the start of the 39th power supply is rapidly rising, and when the discharge is 1 h, the temperature is close to 80 ¡ã C. After the discharge, check, the 39th battery has a loose problem.

Thus, the connection looseness does result in an abnormality of the battery, and there is a fire hazard. The thermal displacement of the battery thermal out-of-control battery refers to the battery overcharge or the ambient temperature leads to excessive charging current, and the heat that occurs will cause the battery to be further warmed. The temperature rise of the battery can cause the internal resistance of the battery, and the decrease in the internal resistance has strengthened the charging current.

Temperature increase and current increase, so that the internal temperature of the battery can be up to 120 ¡ã C, soften the ABS housing (about 90 ¡ã C from the ABS softening point), thereby generating the expansion, leakage, and fire. It should be noted that the normal floating battery may also occur in late period, which is that the charging end battery will generate an electrolytic water reaction, and the efficiency of oxygen recombination does not reach 100%, and the constant electrolyte loss will lead to the isolation The saturation of the plate decreases, which will add a sealed battery's oxygen-composite current, which not only increases the floating current of the battery, but accelerates the heat of the battery and further loss of water, and ultimately causes thermal out of control. Therefore, it is also a kind of charging in nature.

If the battery is overcharged, the rate of internal electrolysis water will be accelerated, these gases are not absorbed, which will constantly accumulate, when the internal pressure exceeds the opening the valve, the hydrogen is discharged, if the hydrogen is mixed, if the site is better It is easy to ignite when there is spark outside. Battery leakage lead-acid battery leakage refers to the battery in use, and the surface of the fire pool caused by the electrolyte surface of the fire pool of the electric circuit. The reason why the battery extract can be divided into three categories: 1 structural sealing damage in the production process, such as polar column and shell welding or adhesive surface existence failure to find out in time.

There is a leakage phenomenon in the use; 2 improper operation during transportation or installation, the caused battery shell is dominated or invisible, and does not take timely exclude; 3 charging settings are unreasonable, so that the battery pack is overchargeable Growth, housing destruction, leakage caused. Root or overcharge. Figure 4 shows the scene of the battery leakage.

In general, the UPS grounding system should comply with IEC60346 standards for low-voltage grounding systems. This means that most of the UPS, the centerline and battery frames of the battery pack are grounded. Therefore, when there is a battery in the battery pack, the leakage electrolyte flows to the battery frame, the battery pack is short-circuited to cause an accident.

Fault detection and prevention of the above fault, such as the battery's obvious leakage liquid and battery connection can be found through the appearance of viewing and regular inspection. But when these means can no longer be faulty, it will immediately discover that many times the time will be the day of the accident. So is there a way to predict from the root caused or delayed? About the connecting strip is always detected by the battery connection resistance and temperature change.

About thermal out-of control, analysis from above, we can draw a conclusion: the most important reason that triggers these faults is to charge. If it is delayed or eliminating the incidence of charging, then it means that it can be effectively delayed and the occurrence of accident prevention accidents. And the battery leakage can be judged by monitoring the insulation performance of the battery output and battery leakage detection.

1 Battery connection Loosen Figure 5 In the battery is internal resistance data for normal operation of a single operator's branch unit 24. As can be seen from the figure, the internal resistance of the battery pack single cell is a normal range, and the consistency is better, and the internal resistance is between 0.2 to 0.

3m. After the battery is shipped for a while, if the connection strip is loose, it will cause the battery's contact resistance to increase, which will also increase the test value of the internal resistance. To verify internal resistance (including connection internal resistance) and connection relaxation relationship, la la la lans the nuts of the # 21 battery and then test the internal resistance again, and the test results are shown in Figure 6.

# 21 There is a large change in the front of the battery internal resistance, which clarifies the direct relationship between internal resistance (including connection internal resistance) and loose connection. It can be seen that by monitoring the connection resistance between the batteries and analyzes the collected data, it is possible to determine whether the battery has a loose risk, preventing the occurrence of fires. 2 The thermal out of control of the battery thermal out-of-control battery is important because the battery is overcharged and high temperature, so as long as it is possible to prevent battery over charge and high temperature can effectively prevent the battery heat loss.

1 Perform appropriate processing, it can effectively prevent battery overcharge; Stop charging to prevent battery packs from charge. Regarding the floating scene, in the case of battery failure, the system should set up the electricity to compensate for the battery due to self-discharge. When the battery is fully charged, the system automatically terminates charging to prevent overcharge caused by continuous floating charge, so that the battery pack always maintains its best state, and effectively extend battery life; 3.

The battery intelligent management system is charged by battery. Conduct intelligent management. When the battery is close to full, if the ambient temperature is detected, the system is submitted and the system will enter the sleep mode (no charging current) through the intelligent control module, and then the battery temperature falls to the normal state.

Continue to charge the battery. This can effectively prevent the temperature and the mutual promotion of the current, thereby eliminating the occurrence of thermal out of contr.

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